SEXUAL DIMORPHISM IN THE 12TH THORACIC VERTEBRA AND ITS
POTENTIAL FOR SEX ESTIMATION OF HUMAN SKELETAL REMAINS
A Thesis by
Meghan Dawn Voisin
Honours B.A., Wilfrid Laurier University, 2009
Submitted to the Department of Anthropology
and the faculty of the Graduate School of
Wichita State University
in partial fulfillment of
the requirements for the degree of
Master of Arts
May 2011
© Copyright 2011 by Meghan Dawn Voisin
Note: All data used and analyzed in the current manuscript were used with the permission of
Dr. Peer H. Moore-Jansen. None of this data or their derivatives may be published elsewhere
without the written permission of Meghan Voisin and Dr. Moore-Jansen.
All Rights Reserved
SEXUAL DIMORPHISM IN THE 12TH THORACIC VERTEBRA AND ITS
POTENTIAL FOR SEX ESTIMATION OF HUMAN SKELETAL REMAINS
The following faculty members have examined the final copy of this thesis for form and content,
and recommend that it be accepted in partial fulfillment of the requirement for the degree of
Master of Arts with a major in Anthropology.
____________________________________
Peer H. Moore-Jansen, Committee Chair
____________________________________
Robert Lawless, Committee Member
____________________________________
David T. Hughes, Committee Member
____________________________________
Mary Liz Jameson, Committee Member
iii
DEDICATION
To my parents
Michael & Susan Voisin
and my fiancé
Christopher Kiss
Your unconditional love and support
has made me into who I am today.
iv
The whole of a human being is merely a vertebra…
~ Lorenz Oken (1779-1851)
v
ACKNOWLEDGMENTS
I would like to acknowledge and thank numerous individuals for their time, support and
assistance in the preparation and successful completion of this thesis.
Firstly, I would like to thank Dr. Peer Moore-Jansen, who served as my advisor for the
course of my Masters degree as well as the committee chair for my thesis committee. I am and
will be eternally grateful for all of the guidance, support and opportunities that he has so
generously offered me throughout my time here at Wichita State University. Not only have I
gained considerable practical and teaching experiences and skills, but I have also developed and
honed my knowledge and understanding of human skeletal biology as a result of participating in
and being assigned an abundance of projects that forever kept me occupied and challenged.
Thank you, Dr. Moore-Jansen, for your infinite knowledge, support and guidance; the timely
completion and success of this thesis could not have been possible without you.
I would also like to thank the members of my thesis committee: Dr. Robert Lawless, Dr.
David Hughes, and Dr. Mary Liz Jameson. Your efforts, insight and keen editing skills have
greatly contributed to the final draft of this thesis.
I have also been fortunate to receive funding and financial support which has also greatly
offset travel expenditures and influenced the timely completely of this thesis. The Nancy J.
Berner Fund through the Wichita State University Department of Anthropology as well as the
Moore-Jansen scholarship assisted in funding the research expenses during the data collection
portion of my thesis.
As a result of the research that went into this thesis, I have had the tremendous
experience of traveling to Johannesburg, South Africa and Cleveland, Ohio, U.S.A., in order to
use the collections housed at each of these locations. I would like to thank the faculty and
vi
curator of the Raymond A. Dart Collection of Human Skeletons at the University of
Witwatersrand in Johannesburg, South Africa, particularly Brendon Billings and Dr. Jason
Hemingway, for access to the collection as well as your assistance, insight and motivation. I
would also like to thank Lyman Jellema of the Hamann-Todd Human Osteological Collection at
the Cleveland Museum of Natural History for access to the collection as well as your knowledge
and insight.
This experience would not have been the same had it not been for my fellow biological
anthropology graduate students, and I would like to thank them for their motivation, assistance
and friendship. Shannon Arney and Janeal Godrey had assisted me with the testing of the
reliability of my measurement protocol, which I truly appreciate. I would also like to extend a
special thanks to Shannon Arney, Ivy Davis, and James Simmerman…your friendship,
reassurance, motivation, and assistance (not to mention company during far too many late night
study sessions) has made this academic experience a truly memorable one.
I would like to thank my parents, Susan and Michael Voisin, and my sisters, Lauren and
Allison Voisin. Your continued support and belief in me has enabled me to meet my goals in all
of my academic pursuits. I also wish to thank my soon-to-be family for providing me with the
exceptional opportunity to travel to South African and conduct a portion of the research for this
thesis. Your hospitality will never be forgotten.
Finally, I wish to thank my fiancé, Christopher Kiss, who not only allowed me to venture
off to Kansas for two years to pursue a Masters Degree, but provided me with the unconditional
love, support, and motivation that made this thesis possible. Please know that your sacrifices do
not go unrecognized; I owe my dreams to you.
vii
ABSTRACT
The purpose of this study is to determine the presence/degree of sexual dimorphism of
the 12th thoracic vertebra through a quantitative analysis and to further examine its potential and
reliability in the sex estimation of human skeletal remains. This study also explores the agerelated changes of human skeletal remains and how these affect morphological variation
conducive to sex estimation. In order to assess this, the 12th thoracic vertebrae, femur and
sacrum of 168 mature skeletal remains (94 males and 74 females) from the Raymond Dart
Collection in Johannesburg, South Africa and 407 (205 males and 202 females) mature skeletal
remains from the Hamann-Todd Collection in Cleveland, Ohio were analyzed. Only individuals
whose group affiliation was designated as “South African Black” from the Raymond Dart
Collection and “African American” from the Hamann-Todd Collection were measured. This
was done to permit the examination of geographical variance within and between the two
samples.
The morphology of the 12th thoracic vertebra was examined by means of univariate and
multivariate analyses to better assess each effect. These analyses resulted in relatively high
correct classifications of males and females in all samples, with mean measurement values being
larger in males in all measurements. While age-related changes have little effect on the high
reliability of sex estimation in the African American sample, age-related changes decreases the
reliability of sex estimation in the South African sample.
Overall, this study reveals that the 12th thoracic vertebra has potential for use in sex
estimation as a result of the skeletal morphological variation between males and females both
documented in the Raymond A. Dart Collection of Human Skeletons and the Hamann-Todd
Osteological Collection.
viii
TABLE OF CONTENTS
Chapter
I.
Page
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Context in the Field of Anthropology and Biological Anthropology . . . . . . . . . . . . . .1
Statement of Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Research in Skeletal Morphological Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
II.
BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
The Vertebral Column: An Anatomical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
The 12th Thoracic Vertebra: An Anatomical Overview . . . . . . . . . . . . . . . 8
The Sacrum: An Anatomical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Muscles Associated with the Vertebral Column . . . . . . . . . . . . . . . . . . . .13
The Lower Appendage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
The Femur: An Anatomical Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Muscles Associated with the Femur . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Research on the Skeletal Morphology of the Vertebral Column . . . . . . . . . . . . . . . . 22
Research on the Skeletal Morphology of the 12th Thoracic Vertebra . . . .23
Sexual Dimorphism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Sexual Dimorphism in the Human Skeleton . . . . . . . . . . . . . . . . . . . . . . .24
Sexual Dimorphism in the Vertebral Column . . . . . . . . . . . . . . . . . . . . . 25
Sexual Dimorphism in the Sacrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Sexual Dimorphism in the Femur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Age-Related Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Growth and Development in the Human Skeleton . . . . . . . . . . . . . . . . . .29
Degenerative Age-Related Changes in the Human Skeleton . . . . . . . . . .30
Growth and Development in the Vertebral Column . . . . . . . . . . . . . . . . .31
Degenerative Age-Related Changes in the Vertebral Column . . . . . . . . .33
Temporal Variation and Secular Effects in Biocultural Contexts . . . . . . . . . . . . . . . 35
III.
MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Collection History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
The Raymond A. Dart Collection of Human Skeletons . . . . . . . . . . . . . .39
The Hamann-Todd Osteological Collection . . . . . . . . . . . . . . . . . . . . . . .40
Comparison of Raymond Dart and Hamann-Todd Collections . . . . . . . . 42
Study Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
The Raymond A. Dart Collection of Human Skeletons Sample . . . . . . . 44
The Hamann-Todd Osteological Collection Sample . . . . . . . . . . . . . . . . 45
Measurement Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Traditional Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
ix
TABLE OF CONTENTS (continued)
Chapter
Page
Non-Traditional Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Statistical Procedures and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Intra-Observer Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
IV.
RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
Summary Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Estimation of Sex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Sex Estimation in the South African Black Sample . . . . . . . . . . . . . . . . .56
Sex Estimation in the African American Sample . . . . . . . . . . . . . . . . . . .61
Sex Estimation in the Pooled Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Effects of Age-Related Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Effects of Age in the 12th Thoracic Vertebra in South African
Black Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Effects of Age in the 12th Thoracic Vertebra in African
American Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Effects of Age in the Femur in South African Black Samples . . . . . . . . .78
Effects of Age in the Femur in African American Samples . . . . . . . . . . .81
V.
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
Sex Estimation in the 12th Thoracic Vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Sex Estimation in the South African Black Sample . . . . . . . . . . . . . . . . .88
Sex Estimation in the African American Sample . . . . . . . . . . . . . . . . . . .91
Sex Estimation in the Pooled Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Effects of Age in Sex Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Effects of Age in the South African Black Sample . . . . . . . . . . . . . . . . . 98
Effects of Age in the African American Sample . . . . . . . . . . . . . . . . . . 100
Effects of Group Affiliation in Sex Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
Sexual Dimorphism in the 12th Thoracic Vertebra . . . . . . . . . . . . . . . . .103
Potential of the 12th Thoracic Vertebra in Sex Estimation . . . . . . . . . . .104
Effects of Age on the 12th Thoracic Vertebra . . . . . . . . . . . . . . . . . . . . .105
BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
A. Data Collection Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
B. Measurement Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117
C. Univariate Summary Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
x
LIST OF TABLES
Table
Page
1. Vertebral Summary Statistics – male sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
2. Vertebral Summary Statistics – female sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3. Vertebral Summary Statistics – South African Black male sample . . . . . . . . . . . . . . . . . . . .52
4. Vertebral Summary Statistics – African American male sample . . . . . . . . . . . . . . . . . . . . . .52
5. Vertebral Summary Statistics – South African Black female sample . . . . . . . . . . . . . . . . . . 53
6. Vertebral Summary Statistics – African American female sample . . . . . . . . . . . . . . . . . . . . 53
7. Femoral Summary Statistics – male sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
8. Femoral Summary Statistics – female sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9. Femoral Summary Statistics – South African Black male sample . . . . . . . . . . . . . . . . . . . . .54
10. Femoral Summary Statistics – African American male sample . . . . . . . . . . . . . . . . . . . . . . .55
11. Femoral Summary Statistics – South African Black female sample . . . . . . . . . . . . . . . . . . . 55
12. Femoral Summary Statistics – African American female sample . . . . . . . . . . . . . . . . . . . . . 55
13. Stepwise models for South African Black sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
14. Classification rates for step 1 model for the South African Black sample . . . . . . . . . . . . . . .57
15. Classification rates for step 2 model for the South African Black sample . . . . . . . . . . . . . . .58
16. Classification rates for step 3 model for the South African Black sample . . . . . . . . . . . . . . .59
17. Classification rates for step 4 model for the South African Black sample . . . . . . . . . . . . . . .59
18. Classification rates for step 5 model for the South African Black sample . . . . . . . . . . . . . . .60
19. Classification rates for step 6 model for the South African Black sample . . . . . . . . . . . . . . .61
20. Stepwise models for African American sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
21. Classification rates for step 1 model for the African American sample . . . . . . . . . . . . . . . . .62
xi
LIST OF TABLES (continued)
Table
Page
22. Classification rates for step 2 model for the African American sample . . . . . . . . . . . . . . . . .63
23. Classification rates for step 3 model for the African American sample . . . . . . . . . . . . . . . . .63
24. Classification rates for step 4 model for the African American sample . . . . . . . . . . . . . . . . .64
25. Classification rates for step 5 model for the African American sample . . . . . . . . . . . . . . . . .64
26. Stepwise models for Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
27. Classification rates for step 1 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .66
28. Classification rates for step 2 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .67
29. Classification rates for step 3 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .67
30. Classification rates for step 4 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .68
31. Classification rates for step 5 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .68
32. Classification rates for step 6 model for the Pooled sample . . . . . . . . . . . . . . . . . . . . . . . . . .69
33. Stepwise models for vertebral measurements of young South African Black sample . . . . . .70
34. Classification rates for step 1 model for the young South African Black sample . . . . . . . . . 70
35. Classification rates for step 2 model for the young South African Black sample . . . . . . . . . 71
36. Classification rates for step 3 model for the young South African Black sample . . . . . . . . . 71
37. Stepwise models for vertebral measurements of old South African Black sample . . . . . . . . 72
38. Classification rates for step 1 model for the old South African Black sample . . . . . . . . . . . .72
39. Classification rates for step 2 model for the old South African Black sample . . . . . . . . . . . .73
40. Classification rates for step 3 model for the old South African Black sample . . . . . . . . . . . .74
41. Stepwise models for vertebral measurements of young African American sample . . . . . . . .75
42. Classification rates for step 1 model for the young African American sample . . . . . . . . . . . 75
xii
LIST OF TABLES (continued)
Table
Page
43. Classification rates for step 2 model for the young African American sample . . . . . . . . . . . 75
44. Classification rates for step 3 model for the young African American sample . . . . . . . . . . . 76
45. Stepwise models for vertebral measurements of Old African American sample . . . . . . . . . .76
46. Classification rates for step 1 model for the Old African American sample . . . . . . . . . . . . . 77
47. Classification rates for step 2 model for the Old African American sample . . . . . . . . . . . . . 77
48. Classification rates for step 3 model for the Old African American sample . . . . . . . . . . . . . 78
49. Stepwise models for femoral measurements of young South African sample . . . . . . . . . . . .78
50. Classification rates for step 1 model for the young South African Black sample . . . . . . . . . 79
51. Classification rates for step 2 model for the young South African Black sample . . . . . . . . . 79
52. Stepwise models for femoral measurements of old South African Black sample . . . . . . . . . 80
53. Classification rates for step 1 model for the old South African Black sample . . . . . . . . . . . .80
54. Classification rates for step 2 model for the old South African Black sample . . . . . . . . . . . .81
55. Stepwise models for femoral measurements of young African American sample . . . . . . . . .81
56. Classification rates for step 1 model for the young African American sample . . . . . . . . . . . 82
57. Classification rates for step 2 model for the young African American sample . . . . . . . . . . . 82
58. Stepwise models for femoral measurements of old African American sample . . . . . . . . . . . 83
59. Classification rates for step 1 model for the old African American sample . . . . . . . . . . . . . .83
60. Classification rates for step 2 model for the old African American sample . . . . . . . . . . . . . .84
61. Dart Collection Vertebral Measurements – Total Sample . . . . . . . . . . . . . . . . . . . . . . . . . . 123
62. Dart Collection Vertebral Measurements – Male Sample . . . . . . . . . . . . . . . . . . . . . . . . . . 123
63. Dart Collection Vertebral Measurements – Female Sample . . . . . . . . . . . . . . . . . . . . . . . . .123
xiii
LIST OF TABLES (continued)
Table
Page
64. Dart Collection Femoral Measurements – Total Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
65. Dart Collection Femoral Measurements – Male Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
66. Dart Collection Femoral Measurements – Female Sample . . . . . . . . . . . . . . . . . . . . . . . . . 124
67. Dart Collection Vertebral Measurements with Ages – Total Sample . . . . . . . . . . . . . . . . . .124
68. Dart Collection Vertebral Measurements with Ages – Male Sample . . . . . . . . . . . . . . . . . .125
69. Dart Collection Vertebral Measurements with Ages – Female Sample . . . . . . . . . . . . . . . .125
70. Dart Collection Femoral Measurements with Ages – Total Sample . . . . . . . . . . . . . . . . . . 126
71. Dart Collection Femoral Measurements with Ages – Male Sample . . . . . . . . . . . . . . . . . . .126
72. Dart Collection Femoral Measurements with Ages – Female Sample . . . . . . . . . . . . . . . . .126
73. Hamann-Todd Collection Vertebral Measurements – Total Sample . . . . . . . . . . . . . . . . . . 126
74. Hamann-Todd Collection Vertebral Measurements – Male Sample . . . . . . . . . . . . . . . . . . 127
75. Hamann-Todd Collection Vertebral Measurements – Female Sample . . . . . . . . . . . . . . . . 127
76. Hamann-Todd Collection Femoral Measurements – Total Sample . . . . . . . . . . . . . . . . . . .127
77. Hamann-Todd Collection Femoral Measurements – Male Sample . . . . . . . . . . . . . . . . . . . 127
78. Hamann-Todd Collection Femoral Measurements – Female Sample . . . . . . . . . . . . . . . . . 127
79. Hamann-Todd Collection Vertebral Measurements with Ages – Total Sample . . . . . . . . . 128
80. Hamann-Todd Collection Vertebral Measurements with Ages – Male Sample . . . . . . . . . .128
81. Hamann-Todd Collection Vertebral Measurements with Ages – Female Sample . . . . . . . .129
82. Hamann-Todd Collection Femoral Measurements with Ages – Total Sample . . . . . . . . . . 129
83. Hamann-Todd Collection Femoral Measurements with Ages – Male Sample . . . . . . . . . . 129
84. Hamann-Todd Collection Femoral Measurements with Ages – Female Sample . . . . . . . . .129
xiv
LIST OF FIGURES
Figure
Page
1. The Vertebral Column from Anterior, Lateral, and Posterior Views (after Netter 1989) . . . . 7
2. Superior View and Lateral View of a Thoracic Vertebra (after Aiello and Dean 1990) . . . . 10
3. The Posterior and Anterior Views of the Sacrum (after Jacob et al. 1978) . . . . . . . . . . . . . . 11
4. The Superficial Muscles of the Back (after Jacob et al. 1978) . . . . . . . . . . . . . . . . . . . . . . . .14
5. The Intermediate Muscles of the Back (after Jacob et al. 1978) . . . . . . . . . . . . . . . . . . . . . . 16
6. The Anterior and Posterior Views of the Femur (after Aiello and Dean 1990) . . . . . . . . . . .19
7. The Anterior Compartment of the Leg (after Jacob et al.1978) . . . . . . . . . . . . . . . . . . . . . . .20
8. The Medial Compartment of the Leg (after Jacob et al. 1978) . . . . . . . . . . . . . . . . . . . . . . . .20
9. The Posterior Compartment of the Leg (after Jacob et al. 1978) . . . . . . . . . . . . . . . . . . . . . . 20
xv
LIST OF PLATES
Plate
Page
1. Anterior view of a thoracic vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2. Lateral view of a thoracic vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3. Anterior view of the 12th thoracic vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
4. Lateral view of the 12th thoracic vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
5. Anterior view of a lumbar vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
6. Lateral view of a lumbar vertebra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
xvi
CHAPTER 1
INTRODUCTION
Context in the Field of Anthropology and Biological Anthropology
The study of sexual dimorphism in the morphology of skeletal remains is beneficial to
multiple areas of biological anthropology, including but not limited to studies of human variation
and the sex estimation of skeletal remains in past and present human populations.
The
estimation of sex is a crucial variable in both of these instances, and not only allows for
biological reconstructions of past populations to be conducted, but also the identification of
unknown human remains through the generation of biological profiles. A variety of skeletal
elements are currently used in the estimation of sex of skeletal remains. Most commonly these
elements include the pelvic girdle, the skull, as well as the femur. In instances where only few
bones are recovered or where the most commonly used elements for sex estimation are damaged
or fragmentary, it is crucial to understand the potential of other elements as indicators of sex.
Anthropologists working with human skeletal materials must frequently identify the sex of an
individual based on fragmented and few elements. In this case, the degree of sexual dimorphism
of elements not typically used in sex estimation studies would be useful.
The 12th thoracic vertebra is easily identifiable in a disarticulated skeleton as a result of
its unique morphology.
Its place as a transitional vertebra results in the morphological
characteristics of both thoracic and lumbar vertebrae. Thus, the 12 th thoracic vertebra can be
identified consistently which is a difficult task in the majority of vertebral elements. Unlike
other skeletal elements that are frequently and reliably used in the estimation of sex, the vertebral
column is comprised of dense cancelleous bone which assists in the maintenance of its structural
1
integrity throughout taphonomic processes. Thus, there is an increased probability that vertebral
elements will be intact and usable for biological profiling purposes if the skeletal elements that
are more commonly used, such as the fragile composition of the cranium, are absent or damaged.
As the most reliable estimation of factors contributing to the biological profile of an unknown
individual is through the use of a complete, or nearly complete, set of human skeletal remains,
the biological anthropologist is rarely confronted with this situation, and therefore, must be
familiar with a variety of means by which to assess sex from fragmentary and unconventional
skeletal elements.
Statement of Purpose
This study aims to identify and illustrate the presence and degree of sexual dimorphism in
the 12th thoracic vertebra through a quantitative analysis and to further examine its potential in
the sex estimation of human skeletal remains. Specifically, this research addresses how reliably
the sex of human skeletal remains can be estimated using measurements of the 12 th thoracic
vertebra. Also, this study explores age-related changes of human skeletal remains and if and
how they affect morphological variation conducive to sex estimation. Essential to the study is
the hypothesis that measurements of the 12th thoracic vertebra will exhibit size and shape
differences between males and females.
Indeed, it is suggested that of the measurements
obtained of the 12th thoracic vertebra there will be differences exhibited in particular or all
measurements.
In addition to the measurements of the 12th thoracic vertebra, various dimensions of the
sacrum and the femur are also examined. Since the sacrum has a positive correlation with the
sex of an individual (Moore-Jansen and Plochocki 1999) and the femur’s use as a reliable
2
indicator of the stature of an individual (Krogman and İşcan 1986), both of these elements are
measured in order to determine the potential and reliability associated with the estimation of sex
of unidentified human skeletal remains.
This study has pertinent and beneficial applications to the subfields of biological and
archaeological anthropology. Not only would this study assist in the sex estimation of unknown
human skeletal remains, which has forensic, archaeological and paleoanthropological
implications, but also in exploring and increasing the capacity for the understanding of
morphological variation in human populations.
Through the use of the measurements of the 12th thoracic vertebra, sacrum and femur,
this study explores the morphological variability between and within males and females of South
African and American Black samples.
While prior research has been conducted on living
populations with the use of three-dimensional computer tomographic image reconstructions of
the 12th-thoracic vertebra (Sheng-Bo Yu et al. 2008) and radiographs (Taylor and Twomey
1984), the present study relies on the measurements obtained using skeletal material.
By
assessing the presence and degree of variability in Black males and females in two samples,
Raymond A. Dart Collection of Human Skeletons and the Hamann-Todd Osteological
Collection, the present study not only explores the variability present between the sexes, but also
between and within the two geographically distinct samples.
This not only facilitates the
estimation of sex through the use of the 12th thoracic vertebra, but also assesses the degree to
which geographical variation impacts sex estimation.
Along with the potential of the 12th
thoracic vertebra in the estimation of sex in human skeletal remains, this study also explores the
effects of age-related changes, geographical variation, as well as secular effects that play a role
in the reliability of creating a biological profile.
3
Research in Skeletal Morphological Variation
To assess and estimate the sex of unidentified human skeletal remains, a combination of
traditional qualitative and quantitative methods of analysis are usually employed to known
reliable skeletal elements – namely the cranium, pelvic girdle, and long bones, if they are present
and usable. Although previous research has been conducted on the morphological variations
between males and females of the 12th thoracic vertebra (Sheng-Bo Yu et al. 2008; Taylor and
Twomey 1984), these studies were performed through the utilization of various technologies,
such as radiographs and computer tomography as previously mentioned, and were not performed
directly on human skeletal material. Also, previous research had been conducted on single
population and group affiliations (Sheng-Bo Yu et al. 2008), none of which addressed the
morphological variation between populations and how this affects the morphological variation
within and between the sexes.
Since the components of a biological profile of an individual all require an examination
of skeletal morphology and the variation inherent within that morphology, the biological
anthropologist must bear in mind the influences each of these may have on the reliability of each
individual component of biological profiles.
There is has been a considerable amount of
research done on the effects of aging on the human skeleton and how this may influence the
reliability of the creation of biological profiles (Cardoso and Ríos 2011; Scheuer and Black
2000). In order to account for any age-related changes in the measurements of the samples used
in the present study, the sample was divided into two age groups to account for any differences
in morphology that may have been influenced by aging processes. Further, to account for any
discrepancies of the size and shape morphology of the 12 th thoracic vertebra, two measurements
of the femur were taken to act as a control against the stature and size of the individual.
4
Morphological variation in the human skeleton is also largely attributed to group affiliation, or
the geographical location and ethnic background of an individual or group (Giles 1966). This
study assesses the morphological variation within a sample and between two geographically
different samples in order to assess how group-affiliated skeletal variation affects the reliability
of sex estimation.
The impact of group affiliation is reduced in this study by only using
specimens documented socially as of a Black group affiliation. By collecting data from a South
African Black sample and an American Black sample, the effects of geographical variation can
be analyzed. Finally, the samples included in this study only contain individuals that were born
in select years (with a preference of a ten year birth range when possible) to account for potential
morphological variation that may be the result of non-biological change.
The following chapters consist of the background, materials and methods, results, and
discussion. The second chapter is that of the background and will provide an overview of the
anatomy and associated muscles of the skeletal elements that are used in this study, address the
concept of sexual dimorphism, and explore relevant past research conducted on the skeletal
elements used in this study. A general overview of age-related changes in the human skeleton
and the vertebral column will also be provided, and the concepts of temporal variation and the
effects of secular change will be addressed and explored. The third chapter consists of the
materials and methods portion. It is comprised of a brief history of both collections used in this
study, the composition of study samples, the development of the measurement protocol, an
overview of the measurements employed, and the means of analysis and intra-observer errors
will also be contained in this chapter. The fourth chapter is comprised of a report of the results
of all statistical analyses conducted for this study, while the fifth and final chapter explores and
discusses these results in association with the purpose of this study.
5
CHAPTER 2
BACKGROUND
Introduction
In order to successfully account for any distortions in the results of this study, the biases
and influences involved in the estimation of sex of human skeletal remains are discussed. This
chapter consists of an overview of the skeletal anatomy, musculature associated with and
affecting the skeletal elements in question, as well as the effects of skeletal morphological
variation associated with sexual dimorphism of the human skeleton and the specific elements of
the 12th thoracic vertebrae, sacrum and femur. The patterns of growth and development as well
as the degenerative effects of aging and other age-related changes are examined in terms of the
morphological effects on the skeletal elements of this study. Finally, a conspectus of other
relevant research conducted on the vertebral column and femur, and the morphological variation
associated with temporal variation and secular change are discussed.
The Vertebral Column: An Anatomical Overview
The vertebral column is comprised of four segments: cervical vertebrae, thoracic
vertebrae, lumbar vertebrae, and sacral vertebrae (Figure 1).
The cervical vertebrae are
positioned most superiorly, with the first cervical vertebra (also commonly referred to as atlas)
articulating with the occipital bone at the base of the skull. This portion of the vertebral column
entails seven vertebrae which are located in the neck region and terminate with the seventh
cervical vertebra at the base of the neck. The vertebral column then transitions into the thoracic
vertebrae which are composed of twelve vertebrae. These vertebrae were named after their
anatomical region, the thorax, and each of these vertebrae contain the morphological features of
6
costal facets, or areas where a rib articulates with a vertebra. As a result of this, the twelve
vertebrae in this portion of the vertebral column are congruent with the number of ribs in the
human skeleton. The portion of the vertebral column that is located in the lower back region are
the lumbar vertebrae, which consist of five vertebrae. Lastly, the sacral vertebrae range from
four to six in number and fuse (complete fusion normally occurs by around 25 years of age, but
can deviate slightly from this due to human variation) together to form the sacrum (White et al.
2011). The vertebral column as a whole serves several purposes. Firstly, it is the “back bone” of
the skeleton and as such, it not only functions to hold the skeleton erect, but serves as an anchor
for several crucial muscle groups, which allow for the majority of human movement, from
locomotion to sitting upright to carrying items (Aiello and Dean 1990). Also, the vertebral
column houses and acts as a protective barrier to the spinal cord, as well as numerous cranial
nerves and the vertebral arteries.
Figure 1. The Vertebral Column from Anterior, Lateral, and Posterior Views. After Netter 1989:150.
7
The 12th Thoracic Vertebra: An Anatomical Overview
The 12th thoracic vertebra is unique in comparison to other thoracic vertebrae as it
contains morphological characteristics not seen in the other eleven vertebrae in this portion of the
vertebral column. These unique morphological characteristics are the result of this vertebra
being a “transitional vertebra”, meaning that it is the last vertebra in the thoracic vertebral
segment and positioned between the 11th thoracic vertebra above and the 1st lumbar vertebra
below (Schwartz 2007). As a result of this, the 12th thoracic vertebra contains a combination of
morphological characteristics, of which specific characteristics can typically only be found
within their respective vertebral segment (Plates 1-6).
Plate 1. Anterior view of
a thoracic vertebra
Plate 2. Lateral view of a
thoracic vertebra
Plate 3. Anterior view of
the 12th thoracic vertebra
Plate 5. Anterior view of a
lumbar vertebra
Plate 4. Lateral view of the
12th thoracic vertebra
Plate 6. Lateral view of a
lumbar vertebra
8
There are several morphological characteristics that are specific only to thoracic
vertebrae (Figure 2) as a result of the region that these vertebrae are located in and its associated
functions. Since these vertebrae are located in the thorax region, it is only these vertebrae that
are associated with the ribs. Each rib articulates in two places on each of the thoracic vertebrae:
the lateral faces of the centum or vertebral body, and the transverse processes. The location
where the rib articulates with the thoracic vertebra can be visually observed and identified as a
result of the feature formed to accommodate this articulation. These features are referred to as
costal facets, where costal refers to the features origins, the ribs, and facet being the
classification type of the feature (Matshes et al. 2005). Other morphological characteristics
specific to the thoracic vertebral segment are the shape and orientation of the superior and
inferior articular facets. In this case, both the superior and inferior articular surfaces are flat and
parallel to each other. The superior articular surfaces face dorsally, while the inferior articular
surfaces face anteriorly. With the shape and orientation of the articular facets being the same on
all of the thoracic vertebrae, this allows for the flat and parallel superior articular facets of one
thoracic vertebra to fit against, or articulate with the flat and parallel inferior articular facets of
the thoracic vertebra above and vice versa (Cox and Mays 2000). This differs from the lumbar
vertebral portion of the vertebral column which follows the thoracic vertebrae. In the lumbar
vertebrae, the superior articular facets are curved, facing both dorsally and medially, whereas the
inferior articular facets are also curved and can be observed when viewing the vertebrae laterally.
In this case, the dorsal facing and medially oriented superior articular facets of one lumbar
vertebra allow for the articulation of the laterally oriented inferior articular facets of the lumbar
vertebra immediately superior to it (White et al. 2011). The 12th thoracic vertebra is unique in
terms of its articular facet orientation. The superior half of the 12th thoracic vertebra exhibits
9
typical thoracic vertebral characteristics, with the superior articular facets being flat, parallel and
oriented dorsally. The inferior half of the vertebra, however, exhibits lumbar characteristics,
with the inferior articular facets being curved laterally (Matshes et al. 2005). This allows for the
12th thoracic vertebra to articulate with the 11th thoracic vertebra superiorly and the 1st lumber
vertebra inferiorly. The 12th thoracic vertebra also exhibits the thoracic characteristic of a costal
facet for the articulation with the 12th and final rib (Aiello and Dean 1990).
Finally, the
morphology of the spinous process is intermediate to those typically portrayed by the thoracic
and lumbar vertebral columns, with it being more horizontal than the inferiorly oriented thoracic
spinous processes, but is not yet at the same horizontal plane as the typical lumbar vertebrae
(White et al. 2011). It is the result of this combination of thoracic and lumbar traits that
classifies the 12th thoracic vertebra as a transitional and “lumbarized” vertebra, making it unique
and easily discernable while amongst other vertebrae (Matshes et al. 2005; Cox and Mays 2000).
Figure 2. Superior View (left) and Lateral View (right) of a Thoracic Vertebra.
After Aiello and Dean 1990:276.
10
The Sacrum
The sacrum comprises the final segment of the vertebral column (Figure 3). It is located
in the pelvic region, and the sacrum together with the right and left os coxae compose the pelvis
girdle. Even though the sacrum is no longer located in the back region like the other vertebrae, it
is still classified as a portion of the vertebral column as it carries out the same functions; it
houses and provides a protective barrier for the spinal cord, and allows for various blood vessels
and nerves to transport through this area (Cox and Mays 2000; White et al. 2011). It is in the
sacrum that the spinal cord terminates, with the cauda equina and filum terminale, or the most
distal portion of the spinal cord, anchoring to the distal portion of the sacrum (Netter 1989;
Carter 2000a&b). In this case, the sacrum also functions to secure the spinal cord.
Figure 3. The Posterior (left) and Anterior (right) Views of the Sacrum. After Jacob et al. 1978:114.
In a mature adult, the sacrum is visibly different from the preceding vertebral elements.
Even though the sacrum is comprised of several vertebrae, these individual vertebrae fuse
throughout one’s childhood, with complete or nearly complete fusion occurring in early
11
adulthood – approximately 25 years of age, with females typically being slightly earlier than that
of males (Belcastro et al. 2008). As a result of this, there are 4-6 (5 is most typical) sacral
vertebrae, however, they are fused together to form a single bone in a skeletally mature
individual (Schwartz 2007).
While having similar morphological features to those of the other vertebral segments, the
sacrum also has features that are unique to this skeletal element. Each vertebral element in the
sacrum has a centrum, or vertebral body, and a neural arch composed of a right and left pedicle
and a spinous process. These vertebrae also have the features of the superior and inferior
articular surfaces, which not only allow the vertebrae to articulate with the element above and
below it, but it is also a point of fusion (Cox and Mays 2000). All of the morphological
characteristics mentioned above are the same as those exhibited in regular vertebrae. Apart from
these, the most superior portion of the sacrum is referred to as the promontory which is the
portion of the sacrum that articulates with the fifth lumbar vertebra above. Also, whereas in the
upper three segments of the vertebral column the vertebrae ascend in size, with the first few
cervical vertebrae being the smallest overall and the following vertebrae progressively increasing
in size, with the largest vertebrae being the last few vertebrae in the lumber vertebral segment,
this typical pattern of vertebral size increase is reversed in the sacrum (Matshes et al. 2005). In
this case, the first sacral vertebra is the largest and the following vertebrae decrease in size until
the smallest vertebrae, which is the one most distal. Since the largest sacral vertebrae are located
at the proximal portion of the sacrum, the lateral portions of the bone (known as the transverse
processes in other vertebrae) are also significantly larger in this area. It is the result of this that
the alae, or wings of the sacrum, are formed which is the area that articulates with the right and
left os coxae; an articulation referred to as the sacroiliac (SI) joint which enables the formation of
12
the pelvic girdle (Aiello and Dean 1990; White et al. 2011). The fusion of the sacral vertebrae
also allows for the formation of foramen, or natural forming holes that allows arteries, veins and
nerves to run through and provide nutrients to the bone, on either side of the vertebral bodies. In
an anatomically typical sacrum that has 5 vertebrae there will be four foramena on either side of
the sacrum which allows for the passage of the four sacral nerves, which together compose the
nerve network of the sacral plexus (Carter 2000a&b; Matshes et al. 2005). The sacrum ends at
the inferior surface of the fifth, or most inferior sacral vertebra where it articulates with the first
coccygeal vertebra, which is the most superior portion of the coccyx and is more commonly
referred to as the “tailbone”.
Muscles Associated with the Vertebral Column
There are a number of muscles that originate and insert on aspects of the vertebral
column in order to support, contract, flex and rotate the back region, as well as to allow for the
movements associated with everyday life, such as turning the head and walking. The muscles of
the back region that are associated with the vertebral column are classified by layers: the
superficial layer (Figure 4), or the muscles closest to the surface of the back, the deep layer, or
the muscles in closest proximity to the vertebral column, and the intermediate layer which are
those muscles sandwiched between the deep and superficial muscle layers (Carter 2000a&b).
13
Figure 4. The Superficial Muscles of the Back. After Jacob et al. 1978:19.
The superficial layer of muscles associated with the vertebral column (Figure 4) consists
of two large muscles: the trapezius and the latissimus dorsi. The trapezius is a large trapezoidalshaped muscle located in the neck to mid-back which functions to stabilize and retract the
scapula, as well as enabling the upward rotation and abduction of the arms (McMinn and
Hutchings 1977). While the trapezius inserts on portions of the clavicle and scapula, this muscle
originates from various features of the occipital bone of the cranium, as well as the spinous
processes from the last, or seventh, cervical vertebra down to the twelfth thoracic vertebra. The
14
latissimus dorsi, a large broad muscle in the mid to lower back, has several functions, including:
stabilization of the shoulder, adduction, medial rotation, flexion, and extension of the arms. Not
unlike the trapezius, the latissimus dorsi inserts on a bone not associated with the vertebral
column, the humerus, but originates from the os coxae, ribs and the spinous processes of the
seventh thoracic vertebra, all of the lumbar vertebrae, as well as the first sacral vertebra (Carter
2000a&b; Hiatt and Gartner 1987).
There are seven muscles which comprise the intermediate layer of muscles (Figure 5): the
rhomboideus major, rhomboideus minor, levator scapulae, serratus posterior superior, serratus
posterior inferior, and the two splenius muscles. Both, the rhomboideus major and rhomboideus
minor function together to retract the scapula by elevating the medial border of the scapula
(Carter 2000a&b; Tortora 1983). The rhomboideus minor is smaller and lies just superior to the
rhomboideus major, but both muscles lie directly underneath of the trapezius. Both rhomboids
insert on the scapula, but the rhomboideus major originates from the spinous processes of the
second to fifth thoracic vertebrae, whereas the rhomboideus minor originates from the spinous
processes of the seventh cervical vertebra and first thoracic vertebra, as well as a feature on the
occipital bone of the cranium (Steele and Bramblett 1988; Netter 1989). The levator scapulae
muscle also lies underneath of the trapezius and functions to elevate the scapula from its medial
angle. Like the rhomboids, the levator scapulae inserts on the scapula, but originates from the
transverse processes of the first through to the fourth cervical vertebrae. Together, the serratus
posterior superior and serratus posterior inferior muscles function to expand and increase the
capacity of the thorax, which allows for deep breathing (Carter 2000a&b; McMinn and
Hutchings 1977). This occurs as the serratus posterior superior elevates the upper ribs while the
serratus posterior inferior depresses the lower ribs, thus increasing the volume of the thorax
15
region and providing for an increased quantity of air during periods of deep inhalation. The
serratus posterior superior originates from the spinous processes of the seventh cervical to the
third thoracic vertebrae and the occipital bone, inserts on the second to fifth ribs and lies
underneath the rhomboids in the upper back area (Netter 1989). The serratus posterior inferior
muscle originates from the eleventh thoracic to the second lumbar vertebrae, inserts on the ninth
through to the twelfth rib and lies underneath the latissimus dorsi in the lower back.
Figure 5. The Intermediate Muscles of the Back. After Jacob et al. 1978:20.
Finally, there are two splenius muscles which lie underneath the trapezius in the neck region, the
splenius capitis and splenius cervicis. Together these muscles function to extend the head as
well as the lateral rotation and flexion of the neck which enables the head to turn to the side
16
(Tortora 1983). Both splenius muscles originate from the occipital bone as well as the spinous
processes of the seventh cervical through to the sixth thoracic vertebrae. The splenius capitis,
however, inserts onto the occipital bone and the mastoid process of the temporal bone, while the
splenius cervicis inserts onto the transverse processes of the first to the third cervical vertebrae
(Carter 2000a&b; Hiatt and Gartner 1987).
Lastly, the deep layer of muscles associated with the vertebral column are referred to as
intrinsic muscles of the back and are comprised of two major groups of muscles: the three
muscles classified as the erector spinae muscles, and the three muscles classified as the
transversospinalis muscles. As the name implies, the erector spinae muscles function to hold the
vertebral column upright or extended, and consist of (from most medially located to most
laterally located): the spinalis, longissimus and iliocostalis muscles (Carter 2000a&b). All three
of the erector spinae muscles have the similar points of origination of the lumbar vertebrae,
ilium, and the sacrum. Their points of insertion, however, are slightly different with the spinalis
inserting onto the spinous processes of the vertebra, the longissimus inserting onto the ribs,
mastoid process and transverse processes of the cervical vertebrae, and the iliocostalis inserting
onto the ribs and the fourth through sixth cervical vertebrae (Hiatt and Gartner 1987). The
transversospinalis muscles consist of three muscles located in layers one atop of the other. The
most superficial of the transversospinalis muscles is the semispinalis muscles which allow the
back to bend laterally and control the degree of flexion in the back. The intermediate layer is the
multifidus muscles which function in the lumbar region to maintain lumbar lordosis by extending
the spine (Tortora 1983). The last and deepest layer contains the rotatores muscles which allow
for the rotating of the back in the thoracic region. All three of these layers of muscles originate
on the spinous processes and insert on the transverse processes of the vertebrae, but in a slightly
17
different arrangement which enables each to perform their particular function. The semispinalis
muscles insert on the transverse processes of every fifth vertebrae, the multifidus muscles on the
transverse processes of every third vertebrae, and the rotatores on the transverse processes of
every vertebrae (Carter 2000a&b; Hiatt and Gartner 1987).
The Lower Appendage
The Femur: An Anatomical Overview
The femur (Figure 6) is the bone in your upper leg, often referred to as the “thigh bone”
and is the largest bone in the human body. The femur is part of the appendicular skeleton and is
classified as a long bone. Long bones occur in the appendicular skeleton and contain two
epiphyses or areas where a growth plate occurs in younger individuals until they are skeletally
mature. These epiphyses are located at a proximal end of a bone (usually where the “head” of
the bone occurs) and at the distal portion of the bone. In between the two epiphyses lies the
diaphysis, or shaft of the bone (Cox and Mays 2000). In the case of the femur, the proximal
epiphyseal end of the bone contains the femoral head, which fits into the acetabulum of the os
coxa to form the ball-and-socket joint commonly referred to as the hip. This portion of the bone
also contains two features – the greater and lesser trochanters, which are attachment sites for
several quadriceps and hamstring muscles (Netter 1989). The distal epiphyseal end of the femur
forms the top portion of “the knee”. It is here that the femur articulates with the proximal end of
the tibia, which together forms the hinge joint known as the knee. There is a concave circular
feature present at the distal end of the femur which identifies the articulation location of the
18
patella, or the “knee cap”, which is a heart-shaped sesamoid bone (White et al. 2011). The femur
is an integral bone of the human skeleton, as its morphology enables a striding, habitual bipedal
gait, it supports the body when upright and bears and distributes the majority of weight through
the legs when upright (Aiello and Dean 1990).
Figure 6. The Anterior (left) and Posterior (Right) Views of the Femur. After Aiello and Dean 1990:401.
Muscles Associated with the Femur
There is an amplitude of muscles associated with the femur that all contribute to the
actions of flexion, extension, abduction, adduction, and medial and lateral rotation of the thigh
and leg. The muscles of the thigh are categorized based on location, with them being divided
into the muscles of the anterior (Figure 7) and medial thigh (Figure 8) as well as those of the
posterior thigh (Figure 9).
The anterior and medial thigh are further subdivided into two
compartments: the anterior compartment and the medial compartment, both of which are
19
anatomically divided by fascia, or a segment of connective tissue; while the posterior thigh is
regarded as only one compartment (Carter 2000a&b).
Figures 7 – 9. The Anterior Compartment (Fig. 7, left), the Medial Compartment (Fig. 8, center),
and the Posterior Compartment (Fig. 9, right). After Jacob et al. 1978:188-190.
The anterior compartment of the anterior and medial thigh consists of the quadriceps
femoris muscle group and the sartorius muscle. The quadriceps femoris muscle group consists
of four muscles: the rectus femoris, vastus lateralis, vastus medialis, and the vastus intermedialis
(McMinn and Hutchings 1977). All four muscles insert via the patellar tendon to the patella and
all muscles, with the exception of the rectus femoris which originates from the ilium, originate
along the diaphysis of the femur. The quadriceps femoris muscles work together to allow for the
flexion and extension of the leg.
The sartorius muscle, also contained within the anterior
20
compartment, crosses over the quadriceps femoris muscles from its lateral origin on the ilium to
its medial insertion on the tibia. As a result of its origin and insertion locations, the sartorius
crosses over both the hip and knee joints which allow this muscle to carry out the actions of the
flexion of the thigh and the leg (McMinn and Hutchings 1977; Carter 2000a&b).
The second compartment of the anterior and medial thigh is the medial compartment,
which consists of six muscles: the gracilis, pectineus, adductor longus, adductor brevis, adductor
magnus, and the obturator externus. All of these muscles function to medially rotate the hip and
adduct the thigh and leg, originating from the os coxae and inserting either on the femur or the
tibia. There are, however, two muscles in this compartment which also enable other functions.
In addition to being an adductor, the gracilis muscle, being the only muscle in the medial
compartment to cross both the hip and knee joints, also allows for the flexion of the leg.
Additionally, the obturator externus muscle also acts as a stabilizer for the hip joint and enables
the lateral rotation of the thigh (Carter 2000a&b).
The posterior thigh is a single compartment that consists of the hamstring muscles,
gastrocnemius, popliteus, and plantaris muscles. There are three muscles that comprise the
hamstrings: the semitendinosus, semimembranosus, and the biceps femoris. All of these muscles
have a common origin, being the ischium and all enable the actions of the extension of the thigh
and flexion of the leg. Both, the semitendinosus and semimembranosus insert onto the tibia,
while the biceps femoris inserts onto the fibula. The gastrocnemius, plantaris and popliteus
muscles all originate from the distal portion of the femur, but have different insertion locations
and functions (Netter 1989). The gastrocnemius (commonly referred to as the “calf” muscle)
inserts on the calcaneus, which is the bone that makes up the heel of the foot, and assists in the
flexion of the leg and plantar flexion of the foot. The plantaris muscle inserts on the calcaneus
21
via the calcaneus tendon and is an unnecessary muscle as it has no real function, and as a result is
often harvested for tendon repairs or transplants if needed. Finally, the popliteus muscle inserts
on the posterior surface of the tibia and performs the actions of the flexion of the leg and the
medial rotation of the tibia (Carter 2000a&b).
Research on the Skeletal Morphology of the Vertebral Column
Previous research has demonstrated that elements of the vertebral column yield
morphological variation, particularly variation due to sex and age differences.
Taylor and
Twomey (1984) examined 166 lateral radiographs taken of juvenile and adolescent individuals of
both sexes, which were then measured for height and transverse diameter for the 12 th thoracic
vertebra through to the 3rd lumbar vertebra. Their study revealed that female vertebrae were
overall smaller than males, with this difference being marginal at a young age and increasing
throughout adolescence. It has also been shown that the vertebral bone densities, dimensions and
cross-sectional areas of the first through third lumbar vertebrae exhibit differences between
males and females. These differences begin in childhood, increase throughout growth and
development processes, and reach the greatest disparity upon sexual and skeletal maturity
(Gilsanz et al. 1994b; 1997).
When studying the effects of age as is reflected in the changes of the vertebral body of
the lumbar vertebrae, Allbrook (1956) found that the height of the vertebral bodies shows an
increase in the measurements with age. This increase is also greater in males than in females.
Age-related changes are also observed in the increased transverse breadths of the vertebral
bodies. It has been suggested that this increase in the transverse breadth of the vertebrae is not
simply degeneration due to aging, but also bears a functional significance as this broadening
22
would provide stability in the face of cancelleous bone loss (Ericksen 1974; 1976). It has also
been suggested that the osteophytic growths, which increase the breadth of the vertebral bodies,
grow in response to the increase in stress placed on the vertebrae as aging renders the
intervertebral discs less adequate to absorb this stress. As a result, this broadening of the
vertebral bodies are a compensation mechanism to alleviate some stress via a larger and broader
support base (Hadley 1964). The aforementioned research all demonstrates the value of aspects
of the vertebral column for use in the estimation of sex as a result of the inherent morphological
variation.
Research on the Skeletal Morphology of the 12th Thoracic Vertebra
There has been considerable progress made with quantitative studies involving the degree
of sexual dimorphism as well as the potential of non-standard elements and their use for sex
estimation. One such study was carried out by Sheng-Bo Yu et al. (2008) and involved 33
measurements which were applied to three-dimensional models of 12th thoracic vertebra of 102
Korean individuals. Using discriminant function analysis, they determined that 3 measurements
of the 12th thoracic vertebra provided a 90% accuracy of sex within the Korean sample. This
study is useful in acknowledging the potential for sex estimation using this element, however,
Sheng-Bo Yu et al. stipulates that the accuracy in this study may only be reflective of a Korean
population, since no other populations were used.
Therefore, other geographically variant
samples must be incorporated into studies to also assess the effects of group affiliation and
geographical variation on 12th thoracic vertebral morphology. As mentioned above, Taylor and
Twomey (1984) demonstrated that the maximum length and height of the 12 th thoracic vertebral
23
body in children revealed a disparity between males and females with males being overall larger
and this trend only being increased throughout adolescence.
While both of these studies
exemplify sexual dimorphism and the potential for the estimation of sex in the 12th thoracic
vertebra, they utilized radiographs and computed tomography scans rather than utilizing and
testing on a human skeletal collection sample as is the case in the present study.
Sexual Dimorphism
Sexual Dimorphism in the Human Skeleton
While the human skeleton as a whole has a relatively small degree of sexual dimorphism
in terms of size differences between the sexes in comparison to other non-human primates, there
are various skeletal elements with comparatively significant differences between males and
females as a result of the differences in function, muscular development and general size and
shape morphological variations. Essentially, sexual dimorphism is the size and shape differences
between males and females. While all mammals exhibit varying degrees and patterns of sexual
dimorphism, the pattern associated with modern humans is that males tend to be larger than
females. These differences stem primarily from functional differences between the sexes and
overall robusticity. Females tend to be more gracile, with less prominent muscle attachment sites
and a broader pelvic girdle to accommodate for the function of rearing children. Males tend to
be larger overall, with larger and more prominent muscle attachment sites, larger and more
robust skeletal elements and a larger mean stature. This is speculated to be the result of the
male’s innate function to protect and ensure the survivability and reproductive success of a
24
population (France 1988). Sexual dimorphism, if present, is usually minor in children with the
disparity between males and females increasing throughout adolescence, and the greatest
difference between the sexes being once sexual and skeletal maturity is reached (Gilsanz et al.
1994b; 1997). Sexual dimorphism in the human skeleton can be found in varying degrees in the
majority of bones with the most common morphological variation due to the disparity of size in
males and females. Males tend to be more muscular overall than females, and if certain muscles
are consistently in use in males, for example, but not in females, this would increase the distance
between the differences in morphology between the sexes (France 1988; McCarter 2006). The
more pronounced muscularity in males is reflected on skeletal elements via the muscle
attachment sites; increased muscularity and robustness in males of a population presents larger
and more prominent muscle attachment sites than females of the same population (France 1988).
Sexual Dimorphism in the Vertebral Column
Gilsanz et al. (1994b) conducted research concerning the sexual dimorphism present in
various aspects of the first through third lumbar vertebrae. Vertebral bone densities, dimensions
and cross-sectional areas were obtained via computed tomography scans to assess the differences
between the sexes in individuals between the ages of four and twenty that were categorized in
groups based on chronological age, bone age, weight, and height. The results of Gilsanz’s
research showed that all variables were greater in males with minor differences appearing in
childhood and increasing throughout adolescence, with the greatest disparity between males and
females being once sexual maturity was reached (Gilsanz 1994b).
This study revealed no
differences in the heights of the vertebral bodies at any age between the sexes (Gilsanz et al.
25
1994b; 1997). Taylor and Twomey (1984) also discovered that sexual dimorphism was apparent
in a child’s thoracic and vertebral column.
Through the utilization of radiographs, it was
demonstrated that the vertebral bodies of females in the sagittal plane were more slender than
males of the same age, weight and height from eight years of age. This difference between the
sexes only increased with age (Taylor and Twomey 1984). Through the utilization of computed
tomography scans of a living Korean population, the sexual dimorphism of the 12th thoracic
vertebra has also been shown to have statistically significant results (Sheng-Bo Yu et al. 2008).
Studies (Marino 1995; Wescott 1999) have also demonstrated the reliability in estimating
the sex of an individual through sexually dimorphic quantitative measurements of atlas, or the
first cervical vertebra. Since the first cervical vertebra articulates with the occipital condyles of
the cranium, a load-bearing region, it was hypothesized that the function of the first cervical
vertebra would result in morphological differences in the sexes of a population. These findings
were applied by Marino (1995) to a test sample of the Terry Collection with the sex estimation
accuracy falling between 75-85%. Wescott (1999) also demonstrated that the second cervical
vertebra, as well as the first, could estimate the sex of an individual to a similar reliability as
using any single traditionally used skeletal element.
A study of the sexual dimorphism of the vertebral neural canal concluded that there are
differences in the dimensions of the vertebral neural canal between males and females and that
these differences could largely be attributed to functional reasons (Clark 1988). Since the
vertebral neural canal tends to be significantly larger in males in the transverse dimension,
females have a larger vertebral neural canal in the anterioposterior dimension, which is beneficial
in the case of pregnancy. During the period of pregnancy, females experience extra compressive
forces on the vertebral column, especially that of the lumbar vertebrae which accounts for the
26
lumbar lordosis during this time (Porter et al. 1980). An increased anterioposterior dimension of
the vertebral neural canal can potentially counter this force by providing protection for the spinal
cord throughout this time of excessive compression (Clark 1988; Porter et al. 1980)
Sexual Dimorphism in the Sacrum
There have been numerous studies linked to the reliability of sex estimation through the
quantitative assessments of sexual dimorphic traits of the sacrum (Moore-Jansen and Plochocki
1999; Plochocki 2010; Flander 1978). With the sacrum being designated as a portion of the
pelvic girdle, which is a known reliable and frequently used means of estimating sex, the
sacrum’s location and function does imply that it may also have potential in sex estimation. In
order for the pelvic inlet of females to be enlarged for the accommodation of child rearing, it has
been proposed that female sacra exhibit a lesser degree of sacral curvature which would be
useful in sex estimation (Plochocki 2010). Recent research into the sexual dimorphism of the
sacrum has focused on the subtense or degree of curvature at various points along the anterior
surface, as well as the traditional anterior lengths and breadths measurements of the sacrum.
Flander (1978) carried out research on the statistical significance of sexually dimorphic
traits in the sacrum in a Black sample. It was deduced that the means of the measurements were
significantly separated between males and females, with the most significant measurements
being that of the sacral curvature with males having a significantly greater curvature mean than
females. In the study, the measurements of the anterior length and breadth of the sacrum did not
prove to be statistically significant. This study also noted that while the degree of curvature was
found to be statistically significant in the Black sample, previous research has suggested that
27
Black populations have a tendency for a greater degree of curvature and that this may not be
applicable or as statistically significant in other group affiliations (Flander 1978). Additional
studies have supported this, with the depth of the sacral curvature being larger in males than in
females and the maximum curvature depth consistently being at the articulation between the
second and third sacral vertebrae in both sexes (Moore-Jansen and Plochocki 1999; Plochocki
2010; Trotter 1926).
Also, Flander (1978) found that one of the most significantly sexual dimorphic traits to
be the anterior straight breadth of the sacrum at the first sacral vertebra. The reliability of the
maximum sacral breadth as sexually dimorphic is somewhat controversial, with some researchers
finding it an accurate representation of sex, while others claim that the measurement is unusable
in sex estimation (Benazzi et al. 2009).
Research suggests that the sacrum not only exhibits sexually dimorphic patterns, but that
the accuracy of sex estimation differs in each sex, with this accuracy also being influenced by
morphological variation associated with group affiliation. It has been demonstrated that Black
females are the most positively correlated with sexually dimorphic measurements of the sacrum,
with the accuracy in a study conducted by Moore-Jansen and Plochocki (1999) being in the 96th
percentile. While still highly reliable, the accuracy of sex estimation in the White female sample
of this study was 88%. The male samples of both group affiliations, however, were not proven
to be reliable, with 58% of Black males and 53% of White males being correctly classified
(Moore-Jansen and Plochocki 1999).
28
Sexual Dimorphism in the Femur
There has been significant research conducted on the correlations of the femur and the
sex of the individual. With the femur being the largest and strongest bone in the human body, it
can withstand most taphonomic processes and is consistently shown to be a reliability indicator
of sex even when in a fragmentary form. The maximum and bicondylar lengths, circumference
of the diaphysis, maximum vertical and anterioposterior diameters of the head all have proven to
be highly reliable in the estimation of sex as males tend to be significantly larger than females in
all of the aforementioned measurements (Krogman and İşcan 1986). Since the femur is the site
of the origins and insertions of several major muscle groupings as previously discussed, the
morphology of muscle attachment sites have also been used as a successful indicator of sex.
As it is the longest bone in the human body, the femur distinguishes itself by a positive
correlation with the stature of an individual.
Males tend to be larger than females and
correspondingly, males also tend to be taller in stature (Krogman and İşcan 1986). For the
purposes of this study, measurements of the femur are included in order to account for the size
variation due to the stature of the individual, and also as a control and a means to assess the
reliability of sexual dimorphism in the 12th thoracic vertebra.
Age-Related Changes
Growth and Development in the Human Skeleton
As can be observed with the naked eye, humans grow from birth, incrementally gaining
size and stature until they are skeletally mature adults. This growth is accompanied by the
29
growth of the skeleton as well as morphological variation in the individual bones as they mature
to their adult form. Being familiar with the growth and development patterns of human skeletal
remains is crucial as it is reflective of the age of the individual.
Degenerative Age-Related Changes in the Human Skeleton
Shortly after humans reach skeletal maturity, at approximately thirty years of age, the
human body begins to gradually degenerate. This degeneration manifests itself in several forms
throughout the human body, affecting the morphological variation of the skeleton and the
composition of lean muscle mass in particular (McCarter 2006).
While aging is a natural
biological process, it occurs as a result of the decrease in the maintenance and reproduction of
body cells after peak reproductive potential has been achieved (Crews 1993). Overall, females
tend to encounter the degenerative effects of aging, in terms of skeletal as well as muscular
decline, at a less gradual rate than males as a result of the hormonal fluctuations that occur with
the onset of menopause (Twomey et al. 1983; Wise 2006).
One of the most common conditions associated with the aging of the human skeleton is
that of degenerative arthritis. This form of arthritis is the result of progressive degeneration of
the hyaline cartilage, which is located on the articular surfaces of joints (Ortner and Putschar
1981). The joint most commonly affected by degenerative arthritis in the human skeleton is that
of the knee, followed by the other major joints of the hip, shoulder and elbow, all of which are
those that withstand the majority of weight, tension and strain from everyday activities
throughout one’s life (Heine 1926; Ortner and Putschar 1981). Degenerative changes of skeletal
material can occur in several forms, not always being a loss of bone as the term “degeneration”
30
implies. Inflammation as a result of the reduction or friction of cartilage on the surfaces of bone
can result in osteoblastic (bony growths or deposits) processes, such as eburnation or osteophytic
lipping. Age-related degenerative changes can also present itself in the form of osteoclastic
processes (bone loss), such as pitting on the articular surfaces of bones.
While this study focuses on the manifestation of age-related changes in the human
skeleton, as a biological anthropologist the effects of sarcopenia must also be considered when
assessing morphological variation in the human skeleton. Sarcopenia is the decline in muscle
mass and muscle function associated with the aging of an individual (McCarter 2006). Since the
skeletal and muscle systems of the body work together to allow for movement, stability and the
protection and nutrient supply of internal organs, the natural muscle degeneration of an elderly
individual must be considered when assessing age-related changes through skeletal
morphological variation. Increases in age are also reflective in increases of human variation in
the form of skeletal morphological variation, as not all age-related changes and degenerative
processes act upon all individuals in similar patterns, as some patterns are specific to
geographical, sociocultural and environmental factors (Crews 1993).
Growth and Development in the Vertebral Column
The vertebral column grows in response to the functional demands of the human body
and undergoes a large transformation in the first year of one’s life. In this case, an infants’
vertebral column has a primary curvature, or a gentle single curve while in utero, as there are no
external factors or needs that act on the vertebral column at this time. A few months after birth,
the infant develops normal curvature of the vertebral column in the cervical region, which
31
corresponds with the need for an infant to be able to support their weight while sitting or holding
themselves upright and to support the weight of their heads on their own. Finally, nearing the
first year of life, a second curve forms in the lumbar region of the vertebrae in order for balance
and proper weight distribution during walking (Carter 2000a; Taylor 1975). There are three
primary ossification centers of the vertebrae: one on either side of the vertebral body, separating
it from the neural arch, and one along the sagittal plane at the spinous process. The neural arches
begin to fuse within the last few months of the first year of life, and this fusion first occurs in the
upper lumbar and low thoracic vertebrae, with the cervical vertebrae fusing later, in the first few
months of the second year, and the last to fuse being the most inferior lumbar vertebrae at up to
six years of age.
The ossification centers between the vertebral bodies and neural arches
commence fusion a little later, typically between two and five years of age (Scheuer and Black
2000). For the growth patterns of the thoracic vertebral column specifically, the transverse
processes are the first epiphyses to commence fusion, followed by the annular epiphysis and then
the spinous process at approximately eleven, fourteen and fifteen years, respectively (Cardoso
and Ríos 2011). Through a study of the epiphyseal fusion growth patterns in the presacral
vertebrae of children, Cardoso and Ríos (2011) concluded that there are no statistically
significant sex differences in vertebral fusion, however, in several epiphyses there is a trend
towards slightly earlier fusion in females.
The sacrum fuses from twenty-one primary ossification centers with fusion commencing
at the neural arches between two and five years of age, with the vertebral bodies fusing up to six
years of age. The primary ossification centers around the laminae begin fusing between seven
and fifteen years of age (Scheuer and Black 2000). The secondary ossification centers of the
vertebral body epiphyseal plates, spinous processes and transverse processes commence fusion
32
between ten and twenty years of age (Belcastro et al. 1957). As mentioned earlier, the sacral
vertebrae fuse together, however all sacral vertebrae remain open until puberty and fuse from the
most inferior sacral vertebrae upwards to the most superior, which usually remains open until
around twenty-five years of age. In a study conducted by McKern and Stewart (1957), age
estimations were performed on a sample from interpreting the growth and development patterns
of the sacrum. In this case, it was concluded that an individual is estimated to be less than
twenty years of age if any vertebral bodies have failed to fuse. An individual is estimated to be
less than twenty-three years of age if all but the space between the first and second sacral
vertebrae has fused, with the age of complete fusion of all sacral vertebrae estimated between
twenty-three up to thirty-two years of age (McKern and Stewart 1957).
As a result of the
growth patterns mentioned above, the vertebral column as a whole is usually considered
completely fused by around twenty-five years of age in females and up to thirty years of age in
males (McKern and Stewart 1957; Scheuer and Black 2000).
Degenerative Age-Related Changes in the Vertebral Column
While the vertebral column is composed of dense cancelleous bone to meet the external
requirements and consistent weight distributed throughout it, these skeletal elements, not unlike
any other bone in the human skeleton, begin to degenerate shortly after complete skeletal
maturity has been obtained. In fact, the most stress projected onto the vertebral column occurs
during our habitual form of locomotion – bipedalism. While in the upright position, the weight
of the human body is absorbed and distributed down the spinal column to the lower limbs to
walk efficiently through the use of a striding gait.
33
In between each vertebra there is a
cartilaginous disk which functions to cushion the weight and reduce friction in between each
vertebra. However, over time these cartilaginous discs begin to degenerate, contributing to the
degenerative conditions associated with old age, such as osteoarthritis (Novak and Šlaus 2011).
As the cartilaginous discs degenerate with age in the thoracic and lumbar vertebrae
specifically, the load that is absorbed and distributed down the vertebral column when in the
upright position undergoes a shift. Rather than the anterior portion of the vertebral bodies
bearing the compressive load, as it does throughout childhood and into adolescence, the load is
shifted more posteriorly to the neural arch (Brown et al. 2008). This transition affects both males
and females equally, and places a tremendous amount of stress on the apophyseal joints that are
located inferiorly and superiorly to the base of the spinous process at the most posterior portion
of the neural arch. This leads to a considerable amount of spinal compression, with the tenth to
eleventh thoracic and second to fifth lumbar vertebrae being the most affected by this apophyseal
joint degeneration (Derevenski 2000). Apophyseal joint degeneration commences at thirty years
of age, regardless of whether observable characteristics of this are present or not. Throughout
aging and as the degeneration becomes more pronounced, apophyseal joint degeneration can
result in subchondral bone reactions sparked by cartilage loss and compression in the vertebral
column and can also result in mild to extreme cases of synovitis, which is the inflammation of
the synovial membranes between the joints (Derevenski 2000).
While the present study is
assessing the effects of age on the skeletal morphological variation in the 12 th thoracic vertebra,
any specimens with severe pathological conditions such as those listed above, were excluded
from the sample as the integrity and measurements of the bone would be compromised.
34
Temporal Variation and Secular Effects in Biocultural Contexts
Not all skeletal variation is the result of senescence and other biological-based
morphological variations, but that of secular variation. Secular variation is a form of nongenetic, biological change that can act on the skeletal morphology of a population over time, but
is not rooted in the purely biological expressions of morphological variations, such as the
standard patterns of growth and development previously discussed. Rather, secular variation can
alter the morphology of skeletal elements as a result of plastic and microevolution responses to
sociocultural and environmental factors that largely affects successive generations (MooreJansen 1989).
Secular variation affects the phenotypic expression rather than the genetic
composition of individual, and morphological variation attributed to secular variation is most
commonly the result of the physical environment, malnutrition, disease, status, sociocultural
practices and forms of lifestyle (Johnston and Zimmer 1989).
Previous studies have demonstrated that the greatest impact of environmental influences
resulting in the secular variation of the human skeletal framework occurs in infancy and early
childhood between the ages of six months and three years of age. Also, the human body is also
susceptible to plastic change during puberty until skeletal maturity is reached (McCullough and
McCullough 1984). An indicator of secular change in a population, and one that has been
frequently addressed is that of stature and the change in mean statures in a population. Jantz and
Jantz’s (1999) research on the variation in long bone length, which contributes to the overall
stature of an individual, as evidence of secular change between the 19th to late 20th century in the
United States reveals discrepancies in the driving forces behind secular influences on skeletal
material. While the rates of disease and nutrition in a population’s environment typically causes
disruption in typical growth and development patterns, this study demonstrates that perhaps the
35
leading cause of secular change in the United States is that of status. In this study, the most
positive correlations between causality variables and secular effects in adult stature were found
to be the effects of low income distribution resulting in lower standards of nutrition, lower birth
weights and maternal pregnancy weights (Jantz and Jantz 1999). Another study that focused on
the secular change exhibited in the stature of children in a Japanese population found differences
in the mean statures prior to and following World War Two. In this case, children six years of
age and twelve years of age formed the two study groups with the mean statures recorded
between 1934-1937, prior to the Second World War.
Mean statures were also compiled
following the War, between 1951-1958 for children of the same age groups, which revealed a
slight increase in stature (between 1 and 4 centimeters) in these age groups. It is speculated that
this secular trend is the result of the influx of Western goods and food sources and increased
levels of nutrition following the War (Kimura 1984).
It has been argued that while secular change can play a large role in the skeletal
morphology of a population, not all individuals in that population will be affected to the same
degree. In a study conducted by Wolanski and Kasprzak (1976), males and females of the same
population responded differently to the same environmental stresses. It was concluded that
males are the most effected by environmental changes, with females being more resistant. This,
however, may be selected for, as a higher resistance in the females of a population will help
maintain the reproductive fitness of a population (Jantz and Jantz 1999; Stinson 1985; Wolanski
and Kasprzak 1976).
In the case of the present study, the samples from each collection consisted of specimens
born within a ten year range in order to account for and minimize the effects of secular variation.
Through employing this selection criterion, the morphological variation present in the elements
36
studied can be attributed to sexual dimorphism and not be confused with differences between the
sexes that may have been plastic responses to environmental and sociocultural factors.
37
CHAPTER 3
MATERIALS AND METHODS
Introduction
Two human osteological collections, the Raymond A. Dart Collection of Human
Skeletons and the Hamann-Todd Human Osteological Collection, were utilized for the present
study. Both of these collections are comprised of a significant quantity of human skeletal
remains, with the Raymond A. Dart Collection being the largest and most used and referenced
human skeletal collection in Africa, and the Hamann-Todd Collection being one of the largest
and most referenced collections in the United States. These collections have both been used
extensively by anthropologists, anatomists, other researchers, and students alike and specimens
of both collections have been used as a means to assess and create standards of measurements for
the estimation of aging, sexing, stature, and group affiliation of individuals.
Both of these collections were selected specifically for this sample as a result of their
sample composition. With the present study assessing the morphological variability in the 12 th
thoracic vertebra between two geographical varieties of a group affiliation, as well as between
two age groups, the collections utilized must have a large enough sample to accommodate the
particular selection criteria. The first collection used was that of the Raymond A. Dart collection
as a result of the collection composition being primarily that of South African Blacks between
the ages of 20-70 years. In order to minimize the effects of temporal variation and secular
change, the ten year birth year period of 1910-1919 was selected for this collection, as it had an
abundance of skeletally mature South African Black specimens born within this time frame. The
Hamann-Todd Osteological Collection was then selected as this collection provided a large
sample of skeletally mature African American specimens. The approximate birth years of the
38
specimens in this sample were also close to that of the South African Black sample, which
allows for a good comparative study.
Collection History
The Raymond A. Dart Collection of Human Skeletons
The Raymond A. Dart Collection of Human Skeletons is located in the Department of
Anatomical Sciences at the University of the Witwatersrand in Johannesburg, South Africa. This
collection was created in 1921 after Raymond Dart had travelled to the United States and Canada
and was greatly influenced by the value of the Terry and Hamann-Todd human skeletal
collections that had recently emerged there (Hunt and Albanese 2005; Tobias 1985).
The
collection was begun shortly after beginning his appointment as the Chair of the anatomy
department at this institution, and currently houses over 2,600 complete human skeletons. The
human skeletal remains accessioned into the collection were derived from cadaver origins under
the provision of the South African Human Tissues Act and were provided to aid in the
advancement of medical and biological research, as teaching specimens, and for other beneficial
educational purposes.
Initially, the majority of cadavers received by Dart were those of
unclaimed remains that had demised in hospitals in the Gauteng provincial region, and this was
the prevalent form of donation until 1958 which marked the dawn of a bequeathment program
for individual and family donation to the collection upon death (Dayal et al. 2009; Tobias 1985).
The collection was entitled “The Raymond A. Dart Collection of Human Skeletons” by
Dart’s successor and previous student, Doctor Tobias V. Phillips in 1959 (Dayal et al. 2009;
39
Hunt and Albanese 2005). Tobias added to this collection through the accession of human
skeletal material that would allow for this collection to have a more equal representation of both
sexes as well as the various populations residing in South Africa (Dayal et al. 2009).
While this collection contained an extraordinary amount of human skeletal remains,
databases were in disarray and no electronic form was in existence for some period of time. It
wasn’t until the 1980s that an electronic database of all human skeletal remains and associated
information, such as sex, age at death, date of birth, etcetera was compiled.
This greatly
supplemented the advantageous use of this collection (Dayal et al. 2009).
Of the 2,600 human skeletal remains in this collection, the majority consists of South
African males. The collection is divided primarily into the group affiliations of South African
Africans (72%), South African Whites (18%), with the remaining 10% constituting a variety of
minority populations within South Africa. Also, of the 2,600 skeletons, approximately 71% of
this are males with the remaining 29% being females. The population demographics of this
collection is said to be representative, in terms of population affinity, of the current population in
South Africa (Dayal et al. 2009).
The Hamann-Todd Osteological Collection
The Hamann-Todd Osteological Collection is located in the Cleveland Museum of
Natural History in Cleveland, Ohio. While created at the Western Reserve Medical School (now
Case Western Reserve University) by Doctor Carl August Hamann in 1893, Hamann was
succeeded in 1912 by Doctor T. Wingate Todd after being appointed Dean of the medical school.
To date, there are approximately 3,100 complete human skeletal remains, born between 1825 and
40
the mid-20th century, of cadaver-derived origins in this collection, all with age, sex, group
affiliation, height, weight, occupation, pathological conditions, cause of death, anthropometric
measurements, and even source of donation when possible (de la Cova 2011; Hunt and Albanese
2005; Kelley and El-Najjar 1980). The majority of cadavers were inspected before and after
their autopsies by Todd, in order to compile and report any pathological and somatological
conditions that were observed and that could affect skeletal measurements and deductions.
During this process, all abnormalities and preexisting conditions, including any evidence of
dietary deficiencies, disease, lesions, osteoclastic or osteoblastic bone abnormalities, etcetera,
were carefully interpreted and recorded (Kelley and El-Najjar 1980).
Being as the majority of specimens housed in the Hamann-Todd Osteological Collection
were born before the “Prebiotic Era”, or prior to the creation and distribution of antibiotics, the
cause of death in the majority of specimens in this collection was due to systemic or other
infections. Of these diseases and illnesses, the disease which affected a large percentage of the
population at this time, and is also reflected in the specimens, is tuberculosis. Tuberculosis is the
reported cause of death in approximately 20% of the specimens in the Hamann-Todd Collection.
This chronic infectious disease can present itself if varying forms and degrees, from latent to
hyperacute, and can affect the composition and integrity of skeletal elements in the same manner.
When lesions are present in the human skeleton, they have a tendency to affect the lower
thoracic and lumbar vertebrae in the form of pitting, decalcification, and vertebral collapse.
Although there is a large variance in the physical manifestation of tuberculosis on the human
skeleton due to the variables of host resistance, sex, genetic predisposition and virulence of the
disease, studies have shown that Blacks have an increased susceptibility over those of those
group affiliations (Kelley and El-Najjar 1980). While tuberculosis is not only known to have
41
osteoclastic effects on the skeletal structures of an individual, but also can result in the collapse
of the vertebral bodies (Kelley and El-Najjar 1980); no specimens that exhibited pathological
conditions that could skew or disable a measurement on any of the three elements used in this
study were used.
The proportion of Black specimens within this collection is said to be representative of
The Great Migration of Southern African Americans following the American Civil War. During
this time, large populations of African ancestry migrated from the enslavement of the southern
regions of the United States to more densely populated cities in the north in order to seek new
beginnings, employment and freedom. Two cities that saw an influx in African American
populations during this time is that of St. Louis, Missouri and Cleveland, Ohio which are evident
in the osteological collection of both, the Terry Collection and the Hamann-Todd Collection.
Also, census data in both of these locations during this time reveals that African Americans had a
higher prevalence of biological stress, disease, higher death rates and the highest frequency of
tuberculosis, as is evident in the demographics of both of the aforementioned collections (de la
Cova 2011).
Comparison of Raymond Dart and Hamann-Todd Collections
The Raymond A. Dart Collection of Human Skeletons and the Hamann-Todd
Osteological Collections were assembled as approximately the same time and are largely
composed of individuals of low socioeconomic standing. The obvious difference between the
two is the differences in geographic populations in which both collections consist of. Both of
these collections were employed for this very reason. By assessing the sexual dimorphism and
42
potential for the estimation of sex in each collection, the data sets can then be compared to assess
for the variation present in the pooled sample that can be attributed to geographical or population
variation. In this case, the measurements of the 12th thoracic vertebra will not only be assessed
for skeletal variation due to sexual dimorphism, but for the skeletal variation that exists between
South African Blacks and American Blacks. By studying the effects of population variation and
its effects on the reliability of the estimation of sex, one is able to infer the how applicable this
study will be in other group affiliations that have not yet been researched.
Study Samples
In order to account for apparent biases inherent in a skeletal population, such as
representativeness of the samples (Ubelaker 1978), a protocol of measurements (refer to
Appendix B) was developed and if any known conditions that would affect the integrity and
reliability of a measurement were observable on a specimen, they were expelled from the sample
used. Both, the protocol and selection criteria for this study will be further discussed in the
following sections. Data was collected from two samples, both of which consisted of a relatively
large sample and an equal distribution of males, females and of both age groups (skeletally
mature to 40 years of age, and above 40 years of age). With each of these variables equally
represented in both samples, the skeletal morphological variation resulting from sexual
dimorphism, age-related changes, stature, group affiliation, and temporal or secular variation can
be accounted for and the reliability of the results of the analysis of the measurements can be
assessed.
43
The Raymond A. Dart Collection of Human Skeletons Sample
Measurements were collected from a sample of 168 specimens of known age, sex and
group affiliation in the Raymond A. Dart Collection of Human Skeletons. The specimens in this
sample consisted of 94 males, 56 of which were 40 years of age and under, and 38 being over 40
years of age. The remaining 74 specimens were female, with the younger adult and older adult
subgroups consisting of 38 and 36 specimens, respectively. All of these specimens were born
within a ten year range, between the years of 1910 and 1919 in order to account for and
minimize the effects of secular variation as this study relies on assessing sexual dimorphism
resulting from a combination of senescence and biological differences. This specific ten year
period was selected for multiple reasons. Firstly, since the samples of this study focuses on the
group affiliation of Blacks, specifically South African Black, in this case, limiting the external
variation of the specimens is integral to the success of this study. This ten year range limits
external influence as it precedes the period of European colonialism and the influx of Western
goods and dietary sources. This period also precedes Apartheid in South Africa and the major
political transformations and migration movements out of South Africa that occurred during this
time (Tobias 1985). Finally, the range of 1910-1919 contains a large proportion of specimens in
the Raymond Dart Collection, which allows for a more regimented selection criterion to be
enforced as there is the option of replacing more less desirable specimens (being those that
exhibit a form of pathological condition or damage) for a more desirable ones.
44
The Hamann-Todd Osteological Collection Sample
Measurements were collected from a sample of 407 specimens of known age, sex and
group affiliation in the Hamann-Todd Osteological Collection. The specimens in this sample
consisted of 205 males, 105 of which were 40 years of age and under, and 100 being over 40
years of age. The remaining 202 specimens were female, with the younger adult and older adult
subgroups consisting of 100 and 102 specimens, respectively. With American Blacks being less
frequent in this collection, only the male specimens in the younger adult subgroup able to remain
within a ten year birth date to account for secular change. The older adult male subgroup was
increased to those born within a twelve year period and the younger adult female subgroup was
increased to a fifteen year period. Having a constricted range for years of birth was not possible
in the older adult female subgroup; however, as all skeletally mature American Black females in
the Hamann-Todd Collection had to be used in order to meet the quota of 100 specimens.
Measurement Protocol
The protocol for this study was developed in the Biological Anthropology Laboratory in
Wichita State University, Wichita, Kansas through using specimens from a combination of
collections. To test the potential for quantifying sexual dimorphism in the 12th thoracic vertebra
and its preliminary use in the sex estimation of skeletal remains, a case study using a sample of
the WSU Biological Anthropology Laboratory skeletal collections was performed. For this
study, 9 of the measurements listed in the protocol (refer to Appendix B) for the 12th thoracic
vertebra were taken from 11 skeletal remains of known age, sex and group affiliation. These
measurements were then analyzed using univariate analysis, which revealed a positive
45
correlation between the measurement values and the sex of the individual of particular
measurements. The protocol was developed as a result of this case study, with three additional
measurements of the 12th thoracic vertebrae included, as well as measurements of the femur. As
a result, the protocol is comprised of 17 traditional and non-traditional measurements which were
specifically selected for or designed to assess the degree of sexual dimorphism in the
measurements, if it is present in all measurements, and to analyze the degree of reliability of each
measurement in estimating the sex of an individual.
Although this study focuses on the measurements of the 12th thoracic vertebra, additional
measurements from the sacrum and the femur of each individual were also performed. Since the
sacrum is a known sexually dimorphic element, 3 measurements were taken with the purpose of
correlating them with the measurements of the vertebrae to ensure the degree of sexual
dimorphism in the 12th thoracic vertebrae. However, due to the high variance associated with the
sacral measurements in all samples, the femur was used as a control for sex instead. The femur
is an element with a correlation to the living stature and sex of an individual and is also used in
this study to discern possible discrepancies between the measurements, the degree of sexual
dimorphism and the overall size of the individual. Discrepancies in the values of the 12 th
thoracic vertebrae may be due to the stature of the individual, and a femoral standard may be
able to account for these differences as a result of its known correlation to living stature size of
an individual.
All measurements were performed with standard osteometric instruments, including: an
osteometric board, Mitutoyo sliding calipers, and a GPM coordinate caliper. All measurements
performed with calipers were recorded in millimetres to the nearest tenth, with the osteometric
board measurement recorded in centimetres (to correspond with stature estimation protocols) to
46
the nearest tenth. All measurements were initially entered on Data Collection Forms (Appendix
A) and were then later entered electronically into Excel while screening for potential errors.
Traditional Measurements
A total of 9 traditional measurements were employed during this study. There were four
12th thoracic traditional vertebral measurements taken using sliding calipers.
These
measurements include the maximum sagittal length of the vertebra and maximum length of the
vertebral foramen at the sagittal plane, which were adopted from Wescott’s (1999) study and
previously Marino (1995).
The remaining 2 traditional measurements of the 12th thoracic
vertebra were adopted after Sheng-Bo Yu et al.’s (2008) study and consist of the maximum
width of the transverse processes, as well as the maximum breadth of the inferior articular
surfaces.
Three traditional measurements of the sacrum were also performed. Two measurements
were performed with sliding calipers and consisted of the maximum height of the sacrum and the
maximum breadth of the sacrum, both from the anterior surface (Flander 1978; Moore-Jansen
and Plochocki 1999; Plochocki 2010; Trotter 1926). The remaining measurement, the degree of
curvature (subtense), was conducted with coordinate calipers (Moore-Jansen and Plochocki
1999; Plochocki 2010; Trotter 1926). While these measurements have been recorded for all
samples, they were omitted in the current study as the analysis of univariate statistics revealed a
high variance, making it apparent that these measurements would be an unreliable means of sex
estimation.
47
Finally, two traditional measurements of the femur were used. The bicondylar length of
the femur was taken using an osteometric board, and the maximum vertical diameter of the
femoral head was performed using sliding calipers (Krogman and İşcan 1986; Moore-Jansen et
al. 1994).
Non-Traditional Measurements
There were 8 non-traditional measurements of the 12th thoracic vertebra that were
designed and implemented specifically for the present study. All non-traditional measurements
were performed using sliding calipers and consisted of the following measurements: maximum
height of vertebral body, length of vertebral body at sagittal plane, maximum width of vertebral
body, maximum width of vertebral foramen, maximum breadth of superior articular surfaces,
length of vertebral body and vertebral foramen, maximum width of pedicles, and the length of
the spinous process. These measurements were created as a result of their correlation to muscle
attachment sites, compression force areas, or indication of a potential variation by other
researchers.
Statistical Procedures and Analysis
In order to assess the effects of age and the potential for the estimation of sex after all of
the data had been collected, statistical procedures were used to analyze all measurements
individually, as well as in multivariate contexts. For the univariate statistical analysis, each
measurement of the 12th thoracic vertebra has been analyzed separately, with the means, standard
deviations, variance and ranges being calculated and analyzed for each. In this case, each
48
measurement was assessed for its degree of sexual dimorphism and its potential in sex
estimation. Multivariate analyses of variance were then performed using the measurements of
the 12th thoracic vertebra as well as the femur, in order to discern the effects of sex, age and
possible limits of the skeletal collection. Multivariate analyses were performed through the
utilization of Statistical Analysis Software (SAS). A PROC STEPWISE with a MAXR option
(SAS Statistical Institute Inc. 1985; 1999) was used in order to identify optimal discrimination
models to apply to the calibration and test samples to discern the reliability of a combination of
measurements through correct classifications. A PROC DISRIM was performed to calculate
correct classification of males and females for each of these samples (SAS Statistical Institute
Inc. 1985; 1999). The calibration sample was used initially to derive models and determine the
efficiency of the correct classification of each sex. These models were then applied to the test
samples to calculate the correct classifications of each sex on independent samples.
Intra-Observer Error
Another aspect that could affect the reliability of the use of the 12 th thoracic vertebra as
an indicator of sex, is the replicability potential of the measurements, or the degree to which the
measurements could be performed reliability and consistently.
In order to assess this, the
replicative ability of the measurements, or the intra-observer error was measured. All twelve
measurements of the 12th thoracic vertebra were performed twice on a case study sample, using
the WSU BAL skeletal collections. This revealed insignificant differences between the two
instances of measurements.
Additionally, several individuals performed all twelve
measurements of a 12th thoracic vertebra by following the protocol (Appendix B). These sets of
measurements had an insignificant difference between the measurers (<3.00%), which is well
within the acceptable error rate range (Droessler 1981).
49
CHAPTER 4
RESULTS
Summary Statistics
Through the analysis of the summary statistics, several observations regarding the
morphological variation of the 12th thoracic vertebra within and between sexes, age groups and
geographical samples can be discerned. The measurements of the 12 th thoracic vertebra and the
femur reveal differences and similarities in size and shape morphology among the samples.
All results in the summary statistics are recorded in millimeters and are rounded to the
nearest tenth of a millimeter. Univariate summary statistics for all samples are located in the
appendix (Appendix C). The summary statistics of the means for the 12th thoracic vertebrae
measurements from the male samples in both collections (Table 1) reveal an increase in size in
the African American sample as opposed to the South African Black sample. The maximum
sagittal length (MSVL), maximum width of the vertebral body (MWVB), maximum width of the
superior articular facets (MWSA), length of the vertebral body and foramen (LVBF), width of
the pedicles (MWIP) and length of the spinous process (MLSP) reveal the greatest differences in
the size of these features between the two samples.
The mean measurements of the 12th thoracic vertebrae in the South African Black and
African American female samples (Table 2) reveal a similar trend. The mean measurements in
the African American female sample are all slightly larger than that of the South African Black
female sample, with only the maximum sagittal length (MSVL) of the 12th thoracic vertebra
exhibiting a rather large difference between both samples.
50
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 1. Vertebral Summary Statistics – male sample
South African Black
n = 94
Measurement
Mean
St. Dev.
Maximum Sagittal Length of Vertebra
72.1
4.2
Maximum Height of Vertebral Body
23.0
1.8
Vertebral Body Length at Sagittal Plane
27.8
3.8
Maximum Width of Vertebral Body
39.5
2.9
Maximum Length of Vertebral Foramen
16.6
1.7
Maximum Width of Vertebral Foramen
18.2
1.9
Maximum Width of Transverse Processes
49.9
7.0
Maximum Width Superior Articular Surfaces
35.8
3.4
Length Vertebral Body and Foramen
43.8
3.6
Maximum Width of Pedicles
32.7
2.6
Maximum Length of Spinous Process
31.4
3.4
Maximum Width Inferior Articular Surfaces
28.1
3.4
African American
n = 205
Mean.
St. Dev.
77.4
4.6
23.2
1.9
29.5
2.4
42.4
2.9
17.4
1.6
19.6
2.1
51.7
6.4
38.1
4.0
46.2
2.9
34.8
3.1
33.6
3.8
29.9
3.8
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 2. Vertebral Summary Statistics – female sample
South African Black
n = 74
Measurement
Mean
St. Dev.
Maximum Sagittal Length of Vertebra
68.0
5.4
Maximum Height of Vertebral Body
21.9
1.6
Vertebral Body Length at Sagittal Plane
24.9
2.1
Maximum Width of Vertebral Body
36.7
2.8
Maximum Length of Vertebral Foramen
17.1
1.6
Maximum Width of Vertebral Foramen
18.0
2.0
Maximum Width of Transverse Processes
45.4
7.4
Maximum Width Superior Articular Surfaces
33.9
4.3
Length Vertebral Body and Foramen
40.8
2.9
Maximum Width of Pedicles
30.2
2.6
Maximum Length of Spinous Process
29.8
3.6
Maximum Width Inferior Articular Surfaces
27.4
3.2
African American
n = 202
Mean.
St. Dev.
70.3
3.9
22.5
1.5
25.5
2.2
37.4
2.8
17.4
1.6
19.0
1.6
46.2
4.1
34.8
3.2
42.4
2.5
31.7
2.8
30.7
3.3
27.7
3.2
The summary statistics for the differences in the measurements of the 12 th thoracic
vertebrae in the South African Black (Table 3) and African American male samples (Table 4)
reveals slight differences between the two age groups. The majority of the mean measurements
show a trend for the slight enlargement of this element as age increases, with the most significant
being the maximum sagittal length of the vertebra in both cases. The length (MLVF) and width
of the vertebral foramen (MWVF) and width of the pedicles (MWIP) in South African Black
51
males, and the length of the vertebral foramen (MLVF) and width of the superior articular
surfaces (MWSA) in African American males exhibit the opposite, by slightly reducing in size
from the younger adult to the older adult age group.
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 3. Vertebral Summary Statistics – South African Black male sample
≤ 40 years of age
> 40 years of age
n = 56
n = 38
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Maximum Sagittal Length of Vertebra
71.6
4.1
72.8
4.4
Maximum Height of Vertebral Body
23.0
1.9
23.1
1.6
Vertebral Body Length at Sagittal Plane
27.8
4.6
27.9
2.1
Maximum Width of Vertebral Body
39.0
2.8
40.3
2.9
Maximum Length of Vertebral Foramen
16.9
1.5
16.1
1.9
Maximum Width of Vertebral Foramen
18.3
1.8
18.2
2.1
Maximum Width of Transverse Processes
49.5
6.9
50.4
7.3
Maximum Width Superior Articular Surfaces
35.5
3.3
36.1
3.5
Length Vertebral Body and Foramen
43.6
2.4
44.1
4.8
Maximum Width of Pedicles
32.8
2.5
32.6
2.7
Maximum Length of Spinous Process
31.0
3.2
32.0
3.6
Maximum Width Inferior Articular Surfaces
27.8
3.2
28.6
3.6
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 4. Vertebral summary statistics – African American male sample
≤ 40 years of age
> 40 years of age
n = 105
n = 100
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Maximum Sagittal Length of Vertebra
76.5
4.3
78.3
4.6
Maximum Height of Vertebral Body
23.2
2.0
23.3
1.9
Vertebral Body Length at Sagittal Plane
29.2
2.3
29.9
2.5
Maximum Width of Vertebral Body
41.7
2.6
43.2
3.1
Maximum Length of Vertebral Foramen
17.4
1.5
17.3
1.7
Maximum Width of Vertebral Foramen
19.5
2.2
19.7
2.1
Maximum Width of Transverse Processes
51.5
6.4
52.0
6.4
Maximum Width Superior Articular Surfaces
38.1
4.2
38.0
3.9
Length Vertebral Body and Foramen
45.8
2.6
46.7
3.1
Maximum Width of Pedicles
34.2
3.0
35.3
3.1
Maximum Length of Spinous Process
33.1
3.6
34.2
3.8
Maximum Width Inferior Articular Surfaces
29.6
3.5
30.2
4.0
A comparison of the mean measurements between the two age groups in the South
African Black (Table 5) and African American female samples (Table 6) reveals a similar trend.
The majority of the measurement means exhibit an increase from the younger to older adult age
52
groups in both samples. Like the South African Black male sample, the length (MLVF) and
width of the vertebral foramen (MWVF) and width of the pedicles (MWIP) in the South African
Black female sample reduces in size in the older age group. This is the case in the height of the
body (MHVB), length of the vertebral foramen (MLVF) and width of the inferior articular
surfaces (MWIA) in the African American female sample. The maximum sagittal length of the
vertebra (MSVL) increases the largest of the measurements in both cases.
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 5. Vertebral summary statistics – South African Black female sample
≤ 40 years of age
> 40 years of age
n = 38
n = 36
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Maximum Sagittal Length of Vertebra
66.7
4.0
69.4
6.4
Maximum Height of Vertebral Body
21.9
1.7
22.0
1.4
Vertebral Body Length at Sagittal Plane
24.0
1.8
25.8
2.0
Maximum Width of Vertebral Body
35.8
2.8
37.6
2.4
Maximum Length of Vertebral Foramen
17.3
1.5
16.8
1.8
Maximum Width of Vertebral Foramen
17.9
1.9
18.1
2.1
Maximum Width of Transverse Processes
44.3
6.3
46.5
8.3
Maximum Width Superior Articular Surfaces
33.5
5.0
34.4
3.4
Length Vertebral Body and Foramen
39.6
2.6
42.0
2.8
Maximum Width of Pedicles
29.7
2.7
30.8
2.4
Maximum Length of Spinous Process
29.2
3.7
30.4
3.5
Maximum Width Inferior Articular Surfaces
27.0
3.5
27.9
2.8
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
Table 6. Vertebral summary statistics – African American female sample
≤ 40 years of age
> 40 years of age
n = 100
n = 102
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Maximum Sagittal Length of Vertebra
69.3
3.7
71.4
3.9
Maximum Height of Vertebral Body
22.7
1.5
22.4
1.6
Vertebral Body Length at Sagittal Plane
24.9
1.8
26.2
2.3
Maximum Width of Vertebral Body
36.5
2.7
38.3
2.7
Maximum Length of Vertebral Foramen
17.6
1.5
17.2
1.5
Maximum Width of Vertebral Foramen
18.9
1.7
19.2
1.5
Maximum Width of Transverse Processes
45.7
4.4
46.8
3.9
Maximum Width Superior Articular Surfaces
34.5
3.3
35.1
3.1
Length Vertebral Body and Foramen
42.0
2.3
42.8
2.6
Maximum Width of Pedicles
31.2
2.8
32.2
2.8
Maximum Length of Spinous Process
30.3
3.4
31.1
3.2
Maximum Width Inferior Articular Surfaces
27.9
3.2
27.5
3.2
53
Measurements of the femur in the South African Black and African American male
samples (Table 7) and female samples (Table 8) reveals differences between the sexes and the
collections. In both sexes, the African American samples exhibit larger means in both of the
measurements of the femur. The South African Black and African American male samples also
exhibit larger mean measurements than the female samples in both measurements of the femur.
Code
FBL
FHVD
Table 7. Femoral summary statistics – male sample
South African Black
n = 94
Measurement
Mean
St. Dev.
Bicondylar Length of Femur
45.0
2.4
Vertical Diameter of Femoral Head
45.2
2.5
African American
n = 205
Mean.
St. Dev.
47.2
2.5
48.0
2.5
Code
FBL
FHVD
Table 8. Femoral summary statistics – female sample
South African Black
n = 74
Measurement
Mean
St. Dev.
Bicondylar Length of Femur
41.6
2.0
Vertical Diameter of Femoral Head
40.1
2.1
African American
n = 202
Mean.
St. Dev.
43.6
2.3
42.1
2.4
Not unlike the summary statistics of the 12 th thoracic vertebra, the mean measurements of
the femur also reveal a trend towards a slight enlargement of the measurements from the younger
adult age group to the older adult age group. Mean values of both measurements of the femur in
the South African Black male samples (Table 9) show a slight increase in the older adult age
group as opposed to the younger adult age group.
Code
FBL
FHVD
Table 9. Femoral summary statistics – South African Black male sample
≤ 40 years of age
> 40 years of age
n = 56
n = 38
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Bicondylar Length of Femur
45.0
2.5
45.2
2.2
Vertical Diameter of Femoral Head
44.9
2.3
45.6
2.7
54
The mean values of the femoral measurements of the African American male samples
(Table 10) only expresses this trend in one of the measurements. There is a slight increase in the
mean value of the vertical diameter of the femoral head (FHVD) from the younger to the older
adult age group. The mean value of the bicondylar length of the femur (FBL) reduces slightly in
the older age group of this sample.
Code
FBL
FHVD
Table 10. Femoral summary statistics – African American male sample
≤ 40 years of age
> 40 years of age
n = 105
n = 100
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Bicondylar Length of Femur
47.3
2.5
47.2
2.6
Vertical Diameter of Femoral Head
47.9
2.7
48.1
2.3
The summary statistics of the femoral measurements of the South African Black female
sample (Table 11) and the African American female sample (Table 12) reveal a trend similar to
that exhibited in all previously examined elements.
The mean values of both of the
measurements of the femur increase slightly from the younger adult age group to the older adult
age group in both, the South African Black and the African American female samples.
Code
FBL
FHVD
Table 11. Femoral summary statistics – South African Black female sample
≤ 40 years of age
> 40 years of age
n = 38
n = 36
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Bicondylar Length of Femur
41.4
1.8
41.9
2.2
Vertical Diameter of Femoral Head
39.5
1.8
40.7
2.3
Code
FBL
FHVD
Table 12. Femoral summary statistics – African American female sample
≤ 40 years of age
> 40 years of age
n = 100
n = 102
Measurement
Mean
St. Dev.
Mean.
St. Dev.
Bicondylar Length of Femur
43.5
2.2
43.6
2.4
Vertical Diameter of Femoral Head
41.6
2.2
42.6
2.4
The analysis of the summary statistics of the 12th thoracic vertebra and femur
demonstrates the similarities and differences within and between sex groups, age groups, as well
55
as both collections, or geographical samples, employed in this study. The mean values of the
females of both collections are more similar to each other than either is to their respective male
sample, and vice-versa. Also, the South African Black samples are more similar to each other
than they are to the African American samples. The mean values of the measurements of both
the 12th thoracic vertebra and the femur are larger in the male samples and the African American
samples than in the female and South African Black samples. The male samples also exhibit a
greater degree of difference in comparing collections and age groups than do the female samples.
Estimation of Sex
Sex Estimation in the South African Black Sample
A combination of PROC STEPWISE and PROC DISCRIM procedures were performed
to illustrate the potential and reliability of sex estimation through the use of specific
measurements of the 12th thoracic vertebra. A PROC STEPWISE procedure with the MAXR
option was applied to the measurements of the 12th thoracic vertebra in the South African Black
sample (Table 13).
This produced six models with an R-squared value that increases
significantly with every additional model. All six models have an overall model probability of
<.0001, with each measurement having a partial probability of <.05. The four-variable model of
step six was the last one generated to be used, as the R-squared value did not increase
significantly beyond 0.3973 and several of the individual measurements in each model exceeded
a <.05 probability, reducing the reliability of the measurement. The best single-variable model
in the South African Black sample is that of the maximum width of the pedicles (MWIP) (Table
56
14). This model has an R-squared value of 0.1883 and an F-value of 22.74. In terms of the
estimation of sex, this model correctly classifies 69.49% of males and 68.33% of females with an
overall correct classification of 68.91% in the calibration sample. In the test sample, this model
correctly classified 67.65% of males and 64.29% of females, for an overall correct classification
of 66.67% in the test sample.
Table 13. Stepwise models for South African Black sample
Variables
R2
Model F
Maximum Width of Pedicles (V10)
0.1883
22.74
Partial F
22.74
P
<.0001
2
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Pedicles (V10)
0.2743
18.33
11.49
13.03
0.0010
0.0005
3
Maximum Height of Vertebral Body (V2)
Vertebral Body Length at Sagittal Plane (V3)
0.2872
19.54
15.02
17.14
0.0002
<.0001
4
Maximum Height of Vertebral Body (V2)
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width Superior Articular Surfaces (V8)
0.3618
18.14
15.51
11.57
11.22
0.0002
0.0010
0.0012
5
Maximum Height of Vertebral Body (V2)
Vertebral Body Length at Sagittal Plane (V3)
Maximum Length of Vertebral Foramen (V5)
Maximum Width Superior Articular Surfaces (V8)
0.3888
15.11
17.79
9.72
4.20
12.00
<.0001
0.0024
0.0432
0.0008
6
Maximum Height of Vertebral Body (V2)
Maximum Length of Vertebral Foramen (V5)
Maximum Width Superior Articular Surfaces (V8)
Length Vertebral Body and Foramen (V9)
0.3973
15.65
13.77
12.35
9.75
11.19
0.0003
0.0007
0.0024
0.0012
Step
1
All measurements are significant at α=.05
(P=<.0001)
Table 14. Classification rates for step 1 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
41/59
18/59
Male
23/34
11/34
69.49%
30.51%
67.65%
32.35%
Female
Total
Correct
19/60
31.67%
41/60
68.33%
Female
82/119
68.91%
Total
Correct
57
5/14
35.71%
9/14
64.29%
32/48
66.67%
The two-variable model (Table 15) estimates sex through the combined measurements of
the vertebral body length at the sagittal plane (SLVB) and the maximum with of the pedicles
(MWIP). This model is associated with an increased R-squared value of 0.2743 and an F-value
of 18.33. This model correctly classifies 75.00% of males and 83.33% of females, with an
overall correct classification of 79.31% in the South African Black calibration sample. When
applied to the test sample, this model correctly classifies 76.47% of males and 78.57% of
females, for an overall correct classification of 77.08%.
Table 15. Classification rates for step 2 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
42/56
14/56
Male
26/34
8/34
75.00%
25.00%
76.47%
23.53%
Female
Total
Correct
10/60
16.67%
50/60
83.33%
Female
92/116
79.31%
Total
Correct
3/14
21.43%
11/14
78.57%
37/48
77.08%
The best two-variable model (Table 16) still uses the vertebral body length at the sagittal
plane measurement (SLVB), as in the previous model, in addition to the maximum height of the
vertebral body (MHVB) instead of the maximum width of the pedicles (MWIP). This model has
an associated R-squared value of 0.2872 and an F-value of 19.54. When applied to the South
African Black calibration sample, this model correctly classifies 77.19% of males and 76.67% of
females for an overall correct sample classification of 76.92%. When applied to the test sample,
this model correctly classifies 67.65% of males and 85.71% of females for an overall correct test
sample classification of 72.92%.
58
Table 16. Classification rates for step 3 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
44/57
13/57
Male
23/34
11/34
77.19%
22.81%
67.65%
32.35%
Female
Total
Correct
14/60
23.33%
46/60
76.67%
Female
90/117
76.92%
Total
Correct
2/14
14.29%
12/14
85.71%
35/48
72.92%
The best three-variable model (Table 17) uses the combination of the maximum height of
the vertebral body (MHVB), vertebral body length at the sagittal plane (SLVB), and the
maximum width of the superior articular surfaces (MWSA) measurements for the estimation of
sex. This model has an R-squared value of 0.3618 and an F-value of 18.14. This model
correctly classifies 77.19% of males and 75.00% of females, for an overall correct classification
of 76.07% in the South African Black calibration sample. In terms of the test sample, this model
correctly classifies 61.76% of males and 92.86% of females for an overall correct classification
of 70.83% in this sample.
Table 17. Classification rates for step 4 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
44/57
13/57
Male
21/34
13/34
77.19%
22.81%
61.76%
38.24%
Female
Total
Correct
15/60
25.00%
45/60
75.00%
Female
89/117
76.07%
Total
Correct
1/14
7.14%
13/14
92.86%
34/48
70.83%
The next model (Table 18) is a four-variable model that is comprised of the
measurements of the maximum height of the vertebral body (MHVB), the vertebral body at the
sagittal plane (SLVB), the maximum length of the vertebral foramen (MLVF) and the maximum
59
width of the superior articular surfaces (MWSA). This model has an R-squared value of 0.3888
and an F-value of 15.11. This model correctly classifies 80.70% of males and 73.33% of
females, with an overall correct classification of 76.92% in the calibration sample.
When
applied to the test sample, this model correctly classifies 61.76% of males and 92.86% of
females, with an overall correct classification of 70.83%.
Table 18. Classification rates for step 5 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
46/57
11/57
Male
21/34
13/34
80.70%
19.30%
61.76%
38.24%
Female
Total
Correct
16/60
26.67%
44/60
73.33%
Female
90/117
76.92%
Total
Correct
1/14
7.14%
13/14
92.86%
34/48
70.83%
Lastly, the best four-variable model (Table 19) consists of the measurements of the
maximum height of the vertebral body (MHVB), the maximum length of the vertebral foramen
(MLVF) and the maximum width of the superior articular surfaces (MWSA). Rather than also
using the measurement of the vertebral body length at the sagittal plane (SLVB), this model
utilizes the length of the vertebral body and foramen (LVBF). This model is associated with an
R-squared value of 0.3973 and an F-value of 15.65. When applied to the South African Black
calibration sample, this model correctly classifies 82.46% of males and 73.33% of females, with
an overall correct calibration classification of 77.78%. This model also correctly classifies
76.47% of males and 85.71% of males, for a total correct classification of 79.17% in the test
sample.
60
Table 19. Classification rates for step 6 model for the South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
47/57
10/57
Male
26/34
8/34
82.46%
17.54%
76.47%
23.53%
Female
Total
Correct
16/60
26.67%
44/60
73.33%
Female
91/117
77.78%
Total
Correct
2/14
14.29%
12/14
85.71%
38/48
79.17%
Sex Estimation in the African American Sample
A separate PROC STEPWISE with the MAXR option and PROC DISCRIM procedures
were then applied to the measurements of the 12th thoracic vertebra in the African American
sample (Table 20). This produced five models, each of which has an R-squared value that
increases incrementally over the preceding model. All overall models have a probability of
<.0001, with each individual measurement in each model having a partial probability of <.05.
This stepwise model was stopped after the fifth step model, as numerous measurements had a
probability over <.05 in following models with the R-squared model not increasing significantly
beyond 0.5352. The best single-variable model (Table 21) consists of the measurement of the
maximum width of the vertebral body (MWVB) and has an associated R-squared value of
0.4442 and an F-value of 215.77. This model correctly classifies 80.71% of males and 82.86%
of females, for an overall correct classification of 81.79% in the African American calibration
sample. When applied to the test sample, this model correctly classifies 81.67% of males and
73.33% of females for a total correct classification of 77.50%. The best two-variable model
(Table 22) utilizes the maximum width of the vertebral body (MWVB) in addition to the
measurement of the vertebral body length at the sagittal plane (SLVB). The R-squared value of
this model is 0.5068, while the F-value is 138.20. This model correctly classifies 82.86% of
61
males and 85.00% of females, for a total correct classification of 83.93% for the African
American calibration sample. In terms of the test sample, this model correctly classifies 88.33%
of males and 85.00% of females, for an overall correct classification of 86.67%.
Table 20. Stepwise models for African American sample
Variables
R2
Model F
Maximum Width of Vertebral Body (V4)
0.4442
215.77
Partial F
215.77
P
<.0001
2
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
0.5068
138.20
34.14
56.57
<.0001
<.0001
3
Maximum Sagittal Length of Vertebra (V1)
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
0.5207
97.06
7.80
13.07
25.09
0.0056
0.0004
<.0001
4
Maximum Sagittal Length of Vertebra (V1)
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Width Superior Articular Surfaces (V8)
0.5279
74.64
5.49
12.47
22.88
4.06
0.0198
0.0005
<.0001
0.0449
5
Maximum Sagittal Length of Vertebra (V1)
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Width of Vertebral Foramen (V6)
Maximum Width Superior Articular Surfaces (V8)
0.5352
61.25
6.05
10.78
26.22
4.14
5.68
0.0146
0.0012
<.0001
0.0428
0.0178
Step
1
Male
Female
Total
Correct
Table 21. Classification rates for step 1 model for the African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
113/140
27/140
Male
49/60
11/60
80.71%
19.29%
81.67%
18.33%
24/140
116/140
17.14%
82.86%
229/280
81.79%
Female
Total
Correct
62
16/60
26.67%
44/60
73.33%
93/120
77.50%
Male
Female
Total
Correct
Table 22. Classification rates for step 2 model for the African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
116/140
24/140
Male
53/60
7/60
82.86%
17.14%
88.33%
11.67%
21/140
119/140
15.00%
85.00%
235/280
83.93%
Female
Total
Correct
9/60
51/60
15.00%
85.00%
104/120
86.67%
The best three-variable model is step 3 (Table 23), which consists of the maximum
sagittal length of the vertebra (MSVL), along with the measurements of the vertebral body length
at the sagittal plane (SLVB) and the maximum width of the vertebral body (MWVB). The Rsquared value of this model is 0.5207, while the F-value is 97.06. This model correctly classifies
85.00% of males and 85.71% of females, for an overall correct classification of 85.36% in the
calibration sample. In the African American test sample, this model correctly classifies 88.14%
of males and 83.33% of females, for a total correct classification of 85.71%.
Male
Female
Total
Correct
Table 23. Classification rates for step 3 model for the African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
119/140
21/140
Male
52/59
7/59
85.00%
15.00%
88.14%
11.86%
20/140
120/140
14.29%
85.71%
239/280
85.36%
Female
Total
Correct
10/60
50/60
16.67%
83.33%
102/119
85.71%
The best four-variable model (Table 24) consists of the following measurements: the
maximum sagittal length of the vertebra (MSVL), the vertebral body length at the sagittal plane
(SLVB), the maximum width of the vertebral body (MWVB), and the maximum width of the
superior articular surfaces (MWSA). This model has an associated R-squared value of 0.5279,
63
with an F-value of 74.64. When applied to the African American calibration sample, this model
correctly classifies 84.29% of males and 86.43% of females, for an overall correct classification
of 85.36% for this sample. In terms of the test sample, this model correctly classifies 89.83% of
males and 85.00% of females, with an overall correct classification of 87.40%.
Male
Female
Total
Correct
Table 24. Classification rates for step 4 model for the African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
118/140
22/140
Male
53/59
6/59
84.29%
15.71%
89.83%
10.17%
19/140
121/140
13.57%
86.43%
239/280
85.36%
Female
Total
Correct
9/60
51/60
15.00%
85.00%
104/119
87.40%
For the last model of the African American sample, the five-variable model (Table 25) is
comprised of the maximum sagittal length of the vertebra (MSVL), the vertebral body length at
the sagittal plane (SLVB), the maximum width of the vertebral body (MWVB), the maximum
width of the superior articular surfaces (MWSA), along with the maximum width of the vertebral
foramen (MWVF). This model has an R-squared value of 0.5352, with an F-value of 61.25.
This model correctly classifies 86.43% of males and 85.71% of females, with an overall correct
calibration classification of 86.07%. When applied to the test sample, this model correctly
classifies 89.83% of males and 83.33% of females, with an overall classification of 86.55%.
Male
Female
Total
Correct
Table 25. Classification rates for step 5 model for the African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
121/140
19/140
Male
53/59
6/59
86.43%
13.57%
89.83%
10.17%
20/140
120/140
14.29%
85.71%
241/280
86.07%
Female
Total
Correct
64
10/60
50/60
16.67%
83.33%
103/119
86.55%
Sex Estimation in the Pooled Sample
To discern the potential classification of the 12th thoracic vertebra on the entire sample, a
PROC STEPWISE with the MAXR option and a PROC DISCRIM (Table 26) was performed on
the pooled sample (the South African Black sample together with the African American sample).
This produced six models with an overall probability of <.0001, with the sixth model (the best
five-variable model) being the last used as a result of the decreased reliability of the following
models due to numerous measurements in the models being over <.05 or the model probability
value being over <.0001. Also, the models following the sixth one did not have R-squared
values that increased significantly beyond 0.4454.
Step
1
Table 26. Stepwise models for Pooled (South African Black + African American) sample
Variables
R2
Model F Partial F P
Maximum Width of Vertebral Body (V4)
0.3432
193.35
193.35
<.0001
2
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
0.4094
127.88
41.33
60.97
<.0001
<.0001
3
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Width Superior Articular Surfaces (V8)
0.4239
90.27
35.68
42.18
9.30
<.0001
<.0001
0.0025
4
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Width of Vertebral Foramen (V6)
Maximum Width Superior Articular Surfaces (V8)
0.4354
70.75
32.96
49.92
7.45
12.46
<.0001
<.0001
0.0067
0.0005
5
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Width of Vertebral Foramen (V6)
Maximum Width Superior Articular Surfaces (V8)
Length Vertebral Body and Foramen (V9)
0.4397
57.45
16.13
38.39
10.01
10.84
2.84
<.0001
<.0001
0.0017
0.0011
0.0926
6
Vertebral Body Length at Sagittal Plane (V3)
Maximum Width of Vertebral Body (V4)
Maximum Length of Vertebral Foramen (V5)
Maximum Width Superior Articular Surfaces (V8)
Length Vertebral Body and Foramen (V9)
0.4454
58.79
7.68
27.33
13.85
10.33
7.09
0.0059
<.0001
0.0002
0.0014
0.0081
65
The best single-variable sex estimation model (Table 27) consists of the maximum width
of the vertebral body measurement (MWVB). This model has an R-squared value of 0.3432, and
an F-value of 193.35. When applied to the pooled calibration samples, this model correctly
classifies 76.88% of males and 78.50% of females, with an overall correct classification of
77.69%. Then applied to the pooled test samples, this model correctly classifies 74.47% of
males and 75.68% of females, for an overall correct classification of 75.00%.
Male
Female
Total
Correct
Table 27. Classification rates for step 1 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
153/199
46/199
Male
70/94
24/94
76.88%
23.12%
74.47%
25.53%
43/200
157/200
21.50%
78.50%
310/399
77.69%
Female
Total
Correct
18/74
56/74
24.32%
75.68%
126/168
75.00%
The best two-variable model (Table 28) consists of the measurement of the vertebral
body length at the sagittal plane (SLVB), along with the maximum width of the vertebral body
(MWVB). This mode has an R-squared value of 0.4094 and an F-value of 127.88. This model
correctly classifies 80.61% of males and 82.00% of females, for an overall correct classification
of 81.31% of the pooled calibration sample. For the test sample, this model correctly classifies
76.60% of males and 82.43% of females, for an overall correct classification of 79.17%.
The best three-variable model (Table 29) uses the maximum width of the superior
articular surfaces (MWSA) measurement along with the vertebral body length at the sagittal
plane (SLVB) and maximum width of the vertebral body measurements (MWVB). The Rsquared value of this model is 0.4239 and the F-value is 90.27. When applied to the Pooled
calibration sample, this model correctly classifies 78.57% of males and 83.00% of females, for
66
an overall correct classification of 80.81%. For the test sample, this model correctly classifies
76.60% of males and 83.78% of females, for a total correct classification of 80.72%.
Male
Female
Total
Correct
Male
Female
Total
Correct
Table 28. Classification rates for step 2 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
158/196
38/196
Male
72/94
22/94
80.61%
19.39%
76.60%
23.40%
36/200
164/200
18.00%
82.00%
322/396
81.31%
Female
Total
Correct
13/74
61/74
17.57%
82.43%
133/168
79.17%
Table 29. Classification rates for step 3 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
154/196
42/196
Male
72/94
22/94
78.57%
21.43%
76.60%
23.40%
34/200
166/200
17.00%
83.00%
320/396
80.81%
Female
Total
Correct
12/74
62/72
16.22%
83.78%
134/166
80.72%
For the best four-variable model (Table 30), the maximum width of the vertebral foramen
(MWVF) was added to the measurements of the vertebral body length at the sagittal plane
(SLVB), maximum width of the vertebral body (MWVB), and the maximum width of the
superior articular surfaces (MWSA). This model is associated with a 0.4354 R-squared value
and a 70.75 F-value. For the calibration sample, this model correctly classifies 78.06% of males
and 83.50% of females, for an overall correct classification of 80.81%. For the test sample, this
model correctly classifies 76.60% of males and 83.78% of females, for an overall correct
classification of 79.76% for the pooled test sample.
67
Male
Female
Total
Correct
Table 30. Classification rates for step 4 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
153/196
43/196
Male
72/94
22/94
78.06%
21.94%
76.60%
23.40%
33/200
167/200
16.50%
83.50%
320/396
80.81%
Female
Total
Correct
12/74
62/74
16.22%
83.78%
134/168
79.76%
For the first five-variable model (Table 31), the length of the vertebral body and foramen
measurement (LVBF) was added to the vertebral body length at the sagittal plane (SLVB),
maximum width of the vertebral body (MWVB), maximum width of the vertebral foramen
(MWVF), and the maximum width of the superior articular surfaces (MWSA). The R-squared
value associated with this model is 0.4397, while the F-value is 57.45. When applied to the
Pooled calibration sample, this model classifies 78.06% of males correctly and 84.00% of
females correctly, for an overall correct classification of 81.06%. In terms of the test sample,
this model correctly classifies 76.60% of males and 83.78% of females, for a total correct
classification of 79.76%.
Male
Female
Total
Correct
Table 31. Classification rates for step 5 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
153/196
43/196
Male
72/94
22/94
78.06%
21.94%
76.60%
23.40%
32/200
168/200
16.00%
84.00%
321/396
81.06%
Female
Total
Correct
12/74
62/74
16.22%
83.78%
134/168
79.76%
Finally, the last model (Table 32) is the best five-variable model for the sex estimation of
the 12th thoracic vertebra in the pooled samples.
This model consists of the following
measurements: the vertebral body length at sagittal plane (SLVB), maximum width of vertebral
68
body (MSVB), maximum length of vertebral foramen (MLVF), maximum width of the superior
articular surfaces (MWSA), and length of the vertebral body and foramen (LVBF). This model
has an R-squared value of 0.4454 and an F-value of 58.79. This model correctly classifies
78.06% of males and 83.00% of females, for an overall correct classification of 80.56% for the
calibration sample. For the test sample, this model correctly classifies 77.66% of males and
81.08% of females, for an overall correct classification of 79.17% for the pooled test sample.
Male
Female
Total
Correct
Table 32. Classification rates for step 6 model for the Pooled sample
Calibration Sample
Test Sample
Male
Female
Male
Female
153/196
43/196
Male
73/94
21/94
78.06%
21.94%
77.66%
22.34%
34/200
166/200
17.00%
83.00%
319/396
80.56%
Female
Total
Correct
14/74
60/74
18.92%
81.08%
133/168
79.17%
Effects of Age-Related Changes
Effects of Age in the 12th Thoracic Vertebra in South African Black Samples
To assess the effects of age in the estimation of sex through the measurements of the 12 th
thoracic vertebra, another PROC STEPWISE with the MAXR option and associated PROC
DISCRIM procedures were performed for both age groups of both samples. The stepwise model
for the young age group in the South African Black sample (Table 33) consists of three models.
Each model has a probability value of <.0001, with each measurement in each model having a
partial probability of <.05. Only the three models generated were used, as a result of the
following models having increased model and partial probabilities, as well as the R-squared
value not significantly increasing beyond 0.4933. The best single variable model (Table 34)
69
consists of the measurement of the maximum width of the vertebral body (MWVB). This model
has an R-squared value of 0.4158 and an F-value of 94.68. This model correctly classifies
70.00% of males and 63.33% of females, with an overall correct classification of 66.67% in the
young South African Black calibration sample. For the young test sample, this model correctly
classifies 69.23% of males and 87.50% of females for an overall correct classification of 73.53%.
Step
1
Table 33. Stepwise models for vertebral measurements of young South African Black sample
Variables
R2
Model F Partial F P
Maximum Width of Vertebral Body (V4)
0.4158
94.68
94.68
<.0001
2
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
0.4654
57.46
12.24
16.45
0.0006
<.0001
3
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
Maximum Width Inferior Articular Surfaces (V12)
0.4933
42.51
8.04
17.04
7.21
0.0053
<.0001
0.0082
Table 34. Classification rates for step 1 model for the young South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
21/30
9/30
Male
18/26
8/26
70.00%
30.00%
69.23%
30.77%
Female
Total
Correct
11/30
36.67%
19/30
63.33%
Female
40/60
66.67%
Total
Correct
1/8
12.50%
7/8
87.50%
25/34
73.53%
The best two-variable model (Table 35) uses the combination of the maximum width of
the vertebral body (MWVB) measurement along with the maximum sagittal length of the
vertebra (MSVL). The R-squared value associated with this mode is 0.4654, with an F-value of
57.46. This model correctly classifies 65.38% of males and 65.53% of females, for an overall
correct classification of 65.45% for the young South African Black calibration sample. For the
70
young test sample, this model correctly classifies 68.00% of males and 75.00% of females, for an
overall correct classification of 69.70%.
Table 35. Classification rates for step 2 model for the young South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
17/26
9/26
Male
17/25
8/25
65.38%
34.62%
68.00%
32.00%
Female
Total
Correct
10/29
34.48%
19/29
65.52%
Female
36/55
65.45%
Total
Correct
2/8
25.00%
6/8
75.00%
23/33
69.70%
In addition to the maximum sagittal length of the vertebra (MSVL) and the maximum
width of the vertebra body (MWVB), the best three-variable model (Table 36) also uses the
maximum width of the inferior articular surfaces measurement (MWIA). This model has an Rsquared value of 0.4933, with an F-value of 42.51. While applying this model to the young
South African Black calibration sample, this model correctly classifies 69.23% of males and
65.52% of females, for an overall correct classification of 67.27%. For the test sample, this
model correctly classifies 76.00% of males and 75.00% of females, for an overall correct
classification of 75.76%.
Table 36. Classification rates for step 3 model for the young South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
18/26
8/26
Male
19/25
6/25
69.23%
30.77%
76.00%
24.00%
Female
Total
Correct
10/29
34.48%
19/29
65.52%
Female
37/55
67.27%
Total
Correct
71
2/8
25.00%
6/8
75.00%
25/33
75.76%
A PROC STEPWISE with the MAXR option and a PROC DISCRIM was also performed
on the older adult age group for the South African Black sample (Table 37). This resulted in the
same three models as was tested on the younger adult age group of this sample. The best singlevariable model (Table 38) consists of the maximum width of the vertebral body measurement
(MWVB), has an R-squared value of 0.4158 and an F-value of 94.68. When applied to the older
age group of the South African Black calibration sample, the correct classification is 62.07% for
males and 70.00% for females, with an overall correct calibration of 66.10%. For the older test
sample, the correct classification is 50.00% for males and 66.67% for females, with an overall
correct classification of 57.14%.
Step
1
Table 37. Stepwise models for vertebral measurements of old South African Black sample
Variables
R2
Model F Partial F P
Maximum Width of Vertebral Body (V4)
0.4158
94.68
94.68
<.0001
2
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
0.4654
57.46
12.24
16.45
0.0006
<.0001
3
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
Maximum Width Inferior Articular Surfaces (V12)
0.4933
42.51
8.04
17.04
7.21
0.0053
<.0001
0.0082
Table 38. Classification rates for step 1 model for the old South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
18/29
11/29
Male
4/8
4/8
62.07%
37.93%
50.00%
50.00%
Female
Total
Correct
9/30
30.00%
21/30
70.00%
Female
39/59
66.10%
Total
Correct
2/6
33.33%
4/6
66.67%
8/14
57.14%
The best two-variable model (Table 39) consists of the maximum width of the vertebral
body (MWVB) as well as the maximum sagittal length of the vertebra (MSVL). This model has
72
an R-squared value of 0.4654 and an F-value of 57.46. For the older age group of the South
African Black calibration sample, this model correctly classifies 59.26% of males and 67.86% of
females, with an overall correct classification of 63.64%. For the older test sample, this model
correctly classifies 75.00% of males and 66.67% of females, for an overall correct classification
of 71.43%.
Table 39. Classification rates for step 2 model for the old South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
16/27
11/27
Male
6/8
2/8
59.26%
40.74%
75.00%
25.00%
Female
Total
Correct
9/28
32.14%
19/28
67.86%
Female
35/55
63.64%
Total
Correct
2/6
33.33%
4/6
66.67%
10/14
71.43%
The final model for the older age group of the South African Black sample (Table 40) is
the best three-variable model and consists of the maximum sagittal length of the vertebra
(MSVL), the maximum width of the vertebral body (MWVB), and the maximum width of the
inferior articular surfaces (MWIA) of the 12th thoracic vertebra. This model has an R-squared
value of 0.4933 and an F-value of 42.51.
When applied to the old South African Black
calibration sample, this model correctly classifies 59.26% of males and 67.86% of females, for a
total correct classification of 63.64% in this sample. When applied to the test sample, this model
correctly classifies 75.00% of males, 83.33% of females, and 78.57% overall in the sample.
73
Table 40. Classification rates for step 3 model for the old South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
16/27
11/27
Male
6/8
2/8
59.26%
40.74%
75.00%
25.00%
Female
Total
Correct
9/28
32.14%
19/28
67.86%
Female
35/55
63.64%
Total
Correct
1/6
16.67%
5/6
83.33%
11/14
78.57%
Effects of Age in the 12th Thoracic Vertebra in African American Samples
The same procedures (a PROC STEPWISE with MAXR option and PROC DISCRIM)
were performed for the assessment of the effects of age in the African American samples. In
order to deduce the effects of age between both, the South African Black and the African
American samples, the stepwise model for the young African American sample (Table 41) is the
same as those used in the South African Black samples above. For the best single-variable
model (Table 42), the maximum width of the vertebral body (MWVB) is once again used. This
model’s R-squared value is 0.4158, with an F-value of 94.68. When applied to the young age
group in the African American calibration sample, this model correctly classifies 85.71% of
males, 82.86% of females, with an overall correct classification of 84.29%. For the test sample,
this model correctly classifies 80.00% of males and 80.00% of females, for 80.00% overall.
For the best two-variable model (Table 43), the R-squared value is 0.4654 and the Fvalue is 57.46 for the maximum sagittal length of the vertebra (MSVL) and the maximum width
of the vertebral body (MWVB). For this model, 87.14% of males and 84.29% of females are
classified correctly, for an overall correct classification of 85.71% in the young African
American calibration sample. For the test sample, 83.33% of males and 86.67% of females were
classified correctly, for an overall correct classification of 85.00%.
74
Step
1
Table 41. Stepwise models for vertebral measurements of young African American sample
Variables
R2
Model F Partial F P
Maximum Width of Vertebral Body (V4)
0.4158
94.68
94.68
<.0001
2
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
0.4654
57.46
12.24
16.45
0.0006
<.0001
3
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
Maximum Width Inferior Articular Surfaces (V12)
0.4933
42.51
8.04
17.04
7.21
0.0053
<.0001
0.0082
Table 42. Classification rates for step 1 model for the young African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
60/70
10/70
Male
24/30
6/30
85.71%
14.29%
80.00%
20.00%
Female
Total
Correct
12/70
58/70
17.14%
82.86%
118/140
84.29%
Female
Total
Correct
6/60
20.00%
24/30
80.00%
48/60
80.00%
Table 43. Classification rates for step 2 model for the young African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
61/70
9/70
Male
25/30
5/30
87.14%
12.86%
83.33%
16.67%
Female
Total
Correct
11/70
59/70
15.71%
84.29%
120/140
85.71%
Female
Total
Correct
4/30
13.33%
26/30
86.67%
51/60
85.00%
For the last model of the younger age group of the African American sample, the best
three-variable model (Table 44), the maximum sagittal length of the vertebra (MSVL), maximum
width of the vertebral body (MWVB), and the maximum width of the inferior articular surfaces
(MWIA) are used. This model has an R-squared value of 0.4933 and an F-value of 42.51. This
model correctly classifies 87.14% of males and 84.29% of females, for an overall correct
75
classification of 85.71% in the calibration sample. For the test sample, this model correctly
classifies 83.33% of males, 86.67% of females, and 85.00% overall.
Table 44. Classification rates for step 3 model for the young African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
61/70
9/70
Male
25/30
5/30
87.14%
12.86%
83.33%
16.67%
Female
Total
Correct
11/70
59/70
15.71%
84.29%
120/140
85.71%
Female
Total
Correct
4/30
13.33%
26/30
86.67%
51/60
85.00%
Lastly, the PROC STEPWISE with the MAXR option and the PROC DISCRIM
procedures were applied to the older adult age group in the African American sample. Once
again, the stepwise model (Table 45) for this sample contains the same measurements and step
models as the preceding stepwise models.
Step
1
Table 45. Stepwise models for vertebral measurements of old African American sample
Variables
R2
Model F Partial F P
Maximum Width of Vertebral Body (V4)
0.4158
94.68
94.68
<.0001
2
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
0.4654
57.46
12.24
16.45
0.0006
<.0001
3
Maximum Sagittal Length of Vertebra (V1)
Maximum Width of Vertebral Body (V4)
Maximum Width Inferior Articular Surfaces (V12)
0.4933
42.51
8.04
17.04
7.21
0.0053
<.0001
0.0082
The best single-variable model (Table 46) uses the maximum width of the vertebral body
(MWVB), has an R-squared value of 0.4158 and an F-value of 94.68. When applied to the older
age group of the African American calibration sample, this model correctly classifies 77.14% of
males and 84.29% of females, for an overall correct classification of 80.71%. For the test
76
sample, this model correctly classifies 86.67% of males and 83.87% of females, for an overall
correct classification of 85.25%.
Table 46. Classification rates for step 1 model for the old African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
54/70
16/70
Male
26/30
4/30
77.14%
22.86%
86.67%
13.33%
Female
Total
Correct
11/70
59/70
15.71%
84.29%
113/140
80.71%
Female
Total
Correct
5/31
16.13%
26/31
83.87%
52/61
85.25%
For the best two-variable model (Table 47), the maximum sagittal length of the vertebra
(MSVL) is used in addition to the maximum width of the vertebral body (MWVB). This model
has an R-squared value of 0.4654 and an F-value of 57.46. This model correctly classifies
78.57% of males and 82.86% of females, with an overall correct classification of 80.71% for the
older African American calibration sample. For the older test sample, this model correctly
classifies 75.86% of males and 90.32% of females, for an overall correct classification of
83.33%.
Table 47. Classification rates for step 2 model for the old African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
55/70
15/70
Male
22/29
7/29
78.57%
21.43%
75.86%
24.14%
Female
Total
Correct
12/70
58/70
17.14%
82.86%
113/140
80.71%
Female
Total
Correct
3/31
9.68%
28/31
90.32%
50/60
83.33%
For the three-variable model (Table 48), the maximum width of the inferior articular
surfaces (MWIA) is added to the measurements of the maximum sagittal length of the vertebra
(MSVL) and the maximum width of the vertebral body (MWVB). This model has an R-squared
77
value of 0.4933 and an F-value of 42.51. For the older calibration sample, this model correctly
classifies 80.00% of males, 84.29% of females, and 82.14% overall. For the test sample, this
model correctly classifies 86.21% of males and 87.10% of females, for an overall correct
classification of 86.67%.
Table 48. Classification rates for step 3 model for the old African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
56/70
14/70
Male
25/29
4/29
80.00%
20.00%
86.21%
13.79%
Female
Total
Correct
11/70
59/70
15.71%
84.29%
115/140
82.14%
Female
Total
Correct
4/31
12.90%
27/31
87.10%
52/60
86.67%
Effects of Age in the Femur in South African Black Samples
The effects of age in the estimation of sex are also assessed in the femoral measurements
in order to test the results against the reliability of the 12 th thoracic vertebra.
A PROC
STEPWISE with the MAXR option and the PROC DISCRIM procedures were employed. The
stepwise model for the younger adult age group of the South African Black sample (Table 49)
revealed two models. Both models have a probability value of <.0001.
Table 49. Stepwise models for femoral measurements of young South African Black sample
Step Variables
R2
Model F Partial F Model P
P
1
Vertical Diameter of Femoral Head (F2) 0.5483 167.53
167.53
<.0001
<.0001
2
Bicondylar Length of Femur (F1)
Vertical Diameter of Femoral Head (F2)
0.5538
85.03
1.69
59.34
<.0001
0.1960
<.0001
The best single-variable model (Table 50) uses the vertical diameter of the femoral head
(FHVD). This model has an R-squared value of 0.5483 and an F-value of 167.53. For the young
78
adult age group in the South African Black calibration sample, this model correctly classifies
90.00% of males and 93.33% of females, for an overall correct classification of 91.67%. For the
young test sample, this model correctly classifies 88.46% of males and 100.00% of females, for
an overall correct classification of 91.18%.
Table 50. Classification rates for step 1 model for the young South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
27/30
3/30
Male
23/26
3/26
90.00%
10.00%
88.46%
11.54%
Female
Total
Correct
2/30
6.67%
28/30
93.33%
Female
55/60
91.67%
Total
Correct
0/8
0.00%
8/8
100.00%
31/34
91.18%
The two-variable model for the younger adult age group of the South African Black
sample (Table 51) also uses the bicondylar length of the femur (FBL) in addition to the vertical
diameter of the femoral head (FHVD). The R-squared value associated with this model is
0.5538, with an F-value of 85.03. When applied to the young calibration sample, this model
correctly classifies 90.00% of males and 93.33% of females, with an overall correct classification
of 91.67%. For the test sample, this model correctly classifies 88.46% of males and 100.00% of
females, for an overall correct classification of 91.18%.
Table 51. Classification rates for step 2 model for the young South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
27/30
3/30
Male
23/26
3/26
90.00%
10.00%
88.46%
11.54%
Female
Total
Correct
2/30
6.67%
28/30
93.33%
Female
55/60
91.67%
Total
Correct
79
0/8
0.00%
8/8
100.00%
31/34
91.18%
A PROC STEPWISE with the MAXR option and a PROC DISCRIM was employed for
the older adult age group for the South African Black sample, and resulted in the same stepwise
model (Table 52) as is used above, in order to assess the age related changes exhibited in the two
measurements of the femur.
Step
1
2
Table 52. Stepwise models for femoral measurements of old South African Black sample
Variables
R2
Model F Partial F Model P
P
Vertical Diameter of Femoral Head (F2) 0.5483 167.53
167.53
<.0001
<.0001
Bicondylar Length of Femur (F1)
Vertical Diameter of Femoral Head (F2)
0.5538
85.03
1.69
59.34
<.0001
0.1960
<.0001
For the best single-variable model (Table 53), the vertical diameter of the femoral head
(FHVD) is used. This model has an R-squared value of 0.5483 and an F-value of 167.53. For
the calibration sample of the older age group of the South African Black sample, this model
correctly classifies 86.67% of males and 90.00% of females, for an overall correct classification
of 88.33%. For the test sample of the older adult age group, this model correctly classifies
75.00% of males and 83.33% of females, for an overall correct classification of 78.57%.
Table 53. Classification rates for step 1 model for the old South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
26/30
4/30
Male
6/8
2/8
86.67%
13.33%
75.00%
25.00%
Female
Total
Correct
3/30
10.00%
27/30
90.00%
Female
53/60
88.33%
Total
Correct
1/6
16.67%
5/6
83.33%
11/14
78.57%
The bicondylar length of the femur (FBL) is used in addition to the vertical diameter of
the femoral head (FHVD) in the two-variable model of the old South African Black sample
(Table 54). The R-squared value of this model is 0.5538, with an F-value of 85.03. For the
80
calibration sample, this model correctly classifies 86.67% of males and 93.33% of females, with
an overall correct classification of 90.00% in the older adult age group. For the test sample, this
model correctly classifies 87.50% of males and 100.00% of females, for an overall correct
classification of 92.86% in this sample.
Table 54. Classification rates for step 2 model for the old South African Black sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
26/30
4/30
Male
7/8
1/8
86.67%
13.33%
87.50%
12.50%
Female
Total
Correct
2/30
6.67%
28/30
93.33%
Female
54/60
90.00%
Total
Correct
0/6
0.00%
6/6
100.00%
13/14
92.86%
Effects of Age in the Femur in African American Samples
A PROC STEPWISE with the MAXR option and a PROC DISCRIM was applied last to
both age groups of the African American samples. Not unlike the stepwise models for the South
African Black samples, the stepwise model for the younger age group in the African American
sample (Table 55) contains the same measurements in order to test the age effects across the
samples.
Step
1
2
Table 55. Stepwise models for femoral measurements of young African American sample
Variables
R2
Model F Partial F Model P P
Vertical Diameter of Femoral Head (F2) 0.5483
167.53
167.53
<.0001
<.0001
Bicondylar Length of Femur (F1)
Vertical Diameter of Femoral Head (F2)
0.5538
85.03
1.69
59.34
<.0001
0.1960
<.0001
The best single-variable model for the younger adult age group in the African American
sample (Table 56), consists of the single measurement of the vertical diameter of the femoral
head (FHVD). This model has an R-squared value of 0.5483, with an F-value of 167.53. While
81
being applied to the young African American calibration sample, this model correctly classifies
87.14% of males and 91.43% of females, with an overall correct classification of 89.29%. For
the test sample, this model correctly classifies 90.00% of males and 90.00% of females, for an
overall correct classification of 90.00%.
Table 56. Classification rates for step 1 model for the young African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
61/70
9/70
Male
27/30
3/30
87.14%
12.86%
90.00%
10.00%
Female
Total
Correct
6/70
8.57%
64/70
91.43%
125/140
89.29%
Female
Total
Correct
3/30
10.00%
27/30
90.00%
54/60
90.00%
For the two-variable model (Table 57), the vertical diameter of the femoral head
(FHVD), as well as the bicondylar length of the femur (FBL) are used. This model is associated
with a 0.5538 R-squared value and an 85.03 F-value. This model correctly classifies 87.14% of
males and 92.86% of females, with an overall correct classification of 90.00% in the young
African American calibration sample. In the test sample, this model correctly classifies 90.00%
of males and 90.00% of females, for an overall correct classification of 90.00%.
Table 57. Classification rates for step 2 model for the young African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
61/70
9/70
Male
27/30
3/30
87.14%
12.86%
90.00%
10.00%
Female
Total
Correct
5/70
7.14%
65/70
92.86%
126/140
90.00%
Female
Total
Correct
82
3/30
10.00%
27/30
90.00%
54/60
90.00%
For the older adult age group of the African American sample, the stepwise model (Table
58) is again, the same as the other femoral stepwise models and was performed through the use
of the PROC STEPWISE with the MAXR option and PROC DISCRIMs.
Step
1
2
Table 58. Stepwise models for femoral measurements of old African American sample
Variables
R2
Model F Partial F Model P P
Vertical Diameter of Femoral Head (F2) 0.5483
167.53
167.53
<.0001
<.0001
Bicondylar Length of Femur (F1)
Vertical Diameter of Femoral Head (F2)
0.5538
85.03
1.69
59.34
<.0001
0.1960
<.0001
The best single-variable model (Table 59) consists of the measurement of the vertical
diameter of the femoral head (FHVD) and has an R-squared value of 0.5483, with an F-value of
167.53. For the old African American calibration sample, this model correctly classifies 87.14%
of males and 85.71% of females, with an overall correct classification of 86.43%. For the test
sample, this model correctly classifies 90.00% of males and 86.89% of females, for an overall
correct classification of 86.89%.
Table 59. Classification rates for step 1 model for the old African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
61/70
9/70
Male
27/30
3/30
87.14%
12.86%
90.00%
10.00%
Female
Total
Correct
10/70
60/70
14.29%
85.71%
121/140
86.43%
Female
Total
Correct
5/31
16.13%
26/31
83.87%
53/61
86.89%
Lastly, the two-variable model of the older adult age group of the African American
sample (Table 60), the bicondylar length of the femur (FBL) is used along with the vertical
diameter of the femoral head (FHVD). This model is associated with an R-squared value of
0.5538 and an F-value of 85.03. For the calibration sample of the older age group of the African
83
American sample, this model correctly classifies 84.29% of males and 84.29% of females, for an
overall correct classification of 84.29%. In the test sample, this model correctly classifies
83.33% of males and 83.87% of females, for an overall correct classification of 83.61%.
Table 60. Classification rates for step 2 model for the old African American sample
Calibration Sample
Test Sample
Male
Female
Male
Female
Male
59/70
11/70
Male
25/30
5/30
84.29%
15.71%
83.33%
16.67%
Female
Total
Correct
11/70
59/70
15.71%
84.29%
118/140
84.29%
Female
Total
Correct
5/31
16.13%
26/31
83.87%
51/61
83.61%
Overall, males exhibit higher values than females for all vertebral measurements in both,
the South African Black sample and the African American sample (Tables 1-6). Also, in all
vertebral measurements the African American sample is larger than the South African Black
sample in both of the sexes (Tables 1-2). In terms of the effects of age-related changes, there is a
slight increase in the majority of the vertebral measurements in the older adult age group (those
over 40 years of age) as opposed to the younger adult age group (skeletally mature to 40 years of
age) in males and females of both samples (Tables 3-6). These vertebral differences are also
reflected in the summary statistics of the femoral measurements (Tables 7-12). In this case, the
femoral measurements of males are larger than that of females in both samples (Tables 7-8), the
African American samples exhibit larger measurements than the South African Black samples of
the same sex, and finally, measurements tend to increase slightly in age in both sexes and
samples (Tables 9-12).
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CHAPTER 5
DISCUSSION
Introduction
In order to understand and interpret the results of this study, there are essential
foundations and background information that are pertinent to the success and insight obtained in
the present study. The preceding chapters, most specifically the first and second chapters,
outlined an essential and general overview of crucial topics and information. Firstly, the context
of the present study within the realm of anthropology, particularly biological anthropology was
introduced. In order for a study to be successful, it must have relevant applications in the field of
study. In this case, the study of sexual dimorphism in the 12 th thoracic vertebra and its potential
for the estimation of sex in human skeletal remains can be beneficial in multiple avenues of
anthropology. Not only does it provide insight into the morphological variations inherent within
this element, as well as within and between sexes, age groups and across cultures, but it provides
an opportunity for application within the subfields of forensic anthropology, osteology, mortuary
archaeology, paleodemography, among others.
It is rather difficult to grasp an understanding of a single component of the human
skeleton without first understanding how it functions within the framework of the human body.
This is the case with the anatomy and skeletal morphology of the 12 th thoracic vertebra.
Therefore, an overview of the anatomy and biology of the human skeleton, the vertebral column
as a whole, as well as the single components of the 12 th thoracic vertebra and the sacrum was
explored.
As the muscular structure and development plays a large role in the skeletal
morphological variation of elements (France 1988; Carter 2000a&b), an overview of the muscles
that directly attach in some way to the vertebral column, thus having the potential to affect the
85
size and shape morphology of vertebrae, was examined. Also, the skeletal composition and
muscular associations with the femur were also discussed as a result of this element being used
as a control within this study. Past research that was conducted on the vertebral column, the 12 th
thoracic vertebra, sacrum and femur was also discussed in order to provide relevant background
and explore the potential of these elements in the present study.
The concept and impact of sexual dimorphism on the morphology of the human skeleton
and its individual elements was also explored.
Sexual dimorphism, being the differences
between males and females with the trend being that males are larger than females (Gilsanz et al.
1994b; Gilsanz et al. 1997; France 1988) is in large part, the reason behind which skeletal
elements are reliable indicators of sex.
Several studies have been conducted on sexual
dimorphism as it is manifested in the vertebral column (Gilsanz et al. 1994b; Wescott 1999;
Marino 1995), the 12th thoracic vertebra (Taylor and Twomey 1984; Sheng-Bo Yu et al. 2008),
the sacrum (Moore-Jansen and Plochocki 1999; Plochocki 2010; Flander 1978), and the femur
(Krogman and İşcan 1986), all of which were examined for its relatedness and potential in the
present study.
An important aspect of the present study is the effect of age-related changes on the 12 th
thoracic vertebra and how these changes may affect the reliability of its use as an estimator of
sex. An overview of various age-related changes in the human skeleton, both in terms of growth
and development (Gilsanz et al. 1994b; Gilsanz et al. 1997), as well as forms of degenerative
changes (Ortner and Putschar 1981; Heine 1926; McCarter 2006) was addressed. The growth
and development of aspects of the vertebral column (Taylor 1975; Scheuer and Black 2000) as
well as the degenerative changes that are prone to occur in the vertebral column (Brown et al.
86
2008; Derevenski 2000) were examined in more detail due to its pertinence in the morphological
variation and reliability of measurements of the 12 th thoracic vertebra.
The concepts of temporal variation and secular effects were also explored in order to
address the non-genetic alterations and influences on the human body. Various studies have
previously been conducted (Moore-Jansen 1989; Johnston and Zimmer 1989; Jantz and Jantz
1999; Kimura 1984) in attempt to understand how to account for and minimize, as well as study
the effects of both of these concepts on human populations.
Finally, a brief history on both, the Raymond A. Dart Collection of Human Skeletons and
the Hamann-Todd Osteological Collection was provided. These histories illustrate why these
collections were selected for this study as well as how the study samples were composed from
each collection. This current chapter will go on to address, analyze and discuss the results
reported in the previous chapter.
Sex Estimation in the 12th Thoracic Vertebra
Through the analysis of the measurements of the 12 th thoracic vertebra with statistical
procedures, it is evident that the 12th thoracic vertebra is a sexually dimorphic element with the
potential for use as an estimator of sex. The mean values of all measurements illustrate the
differences, with males being larger than females in the means of all measurements.
The
classification of the correct sex is relatively high in all samples, with the highest correlation of
correct classification of sex being achieved through the use and combination of different
measurements. The combination of the measurements of the vertebral body length at the sagittal
plane and the maximum width of the pedicles has the highest classification of sex in the South
African Black sample. In the African American sample, the model that has the highest correct
87
classification of males and females consists of the measurements of the vertebral body length at
the sagittal plane, which is included in the South African Black classification previously
mentioned, along with the maximum sagittal length of the vertebra, maximum width of the
vertebral body and the vertebral foramen, and the maximum width of the superior articular
surfaces.
Overall, the African American sample has a higher correlation with correct
classification of males and females than the South African Black sample, although this may be
due to the differences and representativeness of the samples.
Sex Estimation in the South African Black Sample
When applying the multivariate analyses to the sample of South African Black males and
females, the results demonstrate varying correct classification results depending on the
combination of measurements used. Of the models generated during the stepwise procedure, six
were selected in terms of their reliability and quantity of measurements used (Table 13).
Typically, each model selected to be used increases by one variable over the preceding model.
In this case, two two-variable models, and two four-variable models were selected here.
Although there is only a slight increase in the R-squared values between both of the same
number variable models, different measurements were contained in each model. For example, in
the two-variable model (Table 15), the two measurements of the vertebral body length at the
sagittal plane (SLVB) and the maximum width of the pedicles are used (MWIP). The step 3
model (Table 16) was determined to be the best two-variable model as a result of the
replacement of the maximum width of the pedicles (MWIP) measurement from the preceding
model with the maximum height of the vertebral body (MHVB), in addition to still having the
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vertebral body length at the sagittal plane measurement (SLVB). By keeping both of these
models, the applications are increased, as there is an option to use one model over the other
based on the condition of the 12th thoracic vertebra. If the neural arch was damaged, for
instance, the other (best) two-variable model could be utilized as both measurements are
contained in the vertebral body, whereas the first two-variable model would be unusable. The
stepwise model uses a combination of the following six of the total twelve measurements of the
12th thoracic vertebra: the maximum height of the vertebral body, the vertebral body length at the
sagittal plane, the maximum length of the vertebral foramen the maximum width of the superior
articular surfaces, the length of the vertebral body and foramen, and the maximum width of the
pedicles.
When applying the stepwise models to the male calibration samples, the correct
classification results improve with each additional model step. In the best single-variable model
(Table 14), a mere 69.49% of males were classified correctly through the use of the maximum
width of the pedicles. This classification rate greatly improved with the addition of the vertebral
body length at the sagittal plane measurement, with a correct male classification of 75.00%. The
correct classification of males becomes more reliable in the two four-variable models (Tables 1819), with correct classifications of 80.70% and 82.46% respectively. As a result of both of these
correct classification rates being quite high, it is concluded that these two models consistently
classifies South African males. In the male test sample, the first two-variable and best fourvariable models (Tables 15 and 19) provide the greatest degree of classification with a correct
male classification of 76.47%. The correct classification rates of the test sample for the male
samples in each model are significantly lower than the associated calibration sample
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classification rate. This may be due to the small test sample sizes in the South African Black
samples.
For the female calibration sample, the classification results are the highest in the first
two-variable model (83.33%), which incorporates the measurements of the vertebral body length
at the sagittal plane (SLVB) as well as the maximum width of the pedicles (MWIP) (Table 15).
The classification rates of the female test sample are significantly higher, with females being
more correctly classified than males in five of the six step models (Tables 14-19). The lowest
rate of classification is the single variable model with correct classification of females at 64.29%
(Table 14). With each variable addition, this classification rate is improved, from 64.29% to
78.57%, to 85.71%, up to a correct female classification rate of 92.86%. It is concluded that the
high correct classification rates in the first two-variable through to the best four-variable models
(Tables 15-19) are all consistent classifiers of South African females.
The individual measurements selected as the best single-variable model, being the
maximum width of the pedicles (MWIP), is somewhat surprising as it is a non-traditional
measurement that has not been previously researched. This measurement was incorporated into
the protocol in support of the hypothesis of an observable size increase in males, in this case in
the width of the 12th thoracic vertebra. The two measurements that occur the most frequently in
the step models are the maximum height of the vertebral body (MHVB) and the vertebral body
length at the sagittal plane.
The reliability of both of these measurements was somewhat
expected, due to the success of these measurements in previous studies and in other vertebral
elements (Taylor and Twomey 1984; Gilsanz et al. 1994b; Sheng-Bo Yu et al. 2008). However,
there were several other measurements that were expected to play a role in the correct
classification of males and females as a result of their usefulness in other populations and in
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other vertebral elements. One such measurement is that of the maximum sagittal length of the
vertebra (MSVL). This measurement was found to be highly reliable in a study conducted on a
living Korean population (Sheng-Bo Yu et al. 2008), on the first and second cervical vertebrae
(Wescott 1999; Marino 1995) as well as on the radiographic study of American children
(Twomey and Taylor 1984).
The measurements of the maximum width of the transverse
processes (MWTP) and the maximum length of the spinous process (MLSP) were also expected
to assist in the correct classification of males and females as a result of their association with a
large amount of muscles. Both of these features serve as anchoring points for the origins and
insertions of muscles (Carter 2000a&b; Netter 1989; France 1988). These measurements were
also successfully applied in previous studies of sexual dimorphism in other vertebral
measurements (Taylor and Twomey 1984; Gilsanz et al. 1994b).
Sex Estimation in the African American Sample
The utilization of the stepwise models for the African American sample reveals a high
correct sex classification in all step models. This procedure generated five step models (Table
20), which incrementally increase from a single-variable model to a five-variable model, with
each increase also increasing the R-squared value of the model along with the rate of correct
classification.
These five step models consist of a combination of five of the twelve
measurements of the 12th thoracic vertebra: the maximum sagittal length of the vertebra
(MSVL), the vertebral body length at the sagittal plane (SLVB), the maximum width of the
vertebral body (MWVB), the maximum width of the vertebral foramen (MWVF), and the
maximum width of the superior articular surfaces (MWSA).
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In the male calibration sample, the best single-variable model (Table 21) correctly
classifies 80.71% of males by using the single measurement of the maximum width of the
vertebral body (MWVB). The addition of another measurement in each following step model
increases the correct classification rate in the calibration sample of males from 80.71% to
82.86%, 85.00% up to 86.43% of correctly classified males in the best five-variable model of the
male calibration sample (Table 25). The male test sample displays similar results in regards to
the classification rates of males. The test sample incrementally increases its correct classification
rate with each measurement added. The best single-variable model correctly classifies 81.67%
of males, up to a correct classification rate of 89.83% in the four and five-variable models. As a
result of the high correct classification rates, it is concluded that the three, four, and five-variable
models (Tables 23-25) are consistent in correctly classifying African American males.
The African American females have similar classification rates to that of their male
counterparts. In the calibration sample, 82.86% of females are classified correctly in the singlevariable model (Table 21).
This classification rate increases with the addition of new
measurements, with the highest correct classification rate occurring at the four-variable model
which classifies 86.43% of females correctly. When applied to the female test sample, the same
trend occurs, with the best single-variable model having the lowest rate of classification, with
73.33% of females being classified correctly. The classification rate increases in each additional
step model, with the highest rate of correct classification of females being 85.00%. Based on the
trends listed above, it has been concluded that the most reliable and consistent step models for
the correct classification of females are the same step models for that of African American
males, being the three, four, and five-variable models (Tables 23-25).
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The stepwise models and associated classification rates are quite different when
comparing the African American samples to the South African Black samples. Only two of the
same measurements appear in both samples, the vertebral body length at the sagittal plane
(SLVB) and the maximum width of the superior articular surfaces (MWSA). The remaining
measurements in each sample are unique to that sample. Two measurements that were expected
to be sexually dimorphic, the maximum width of the transverse process (MWTP) and length of
the spinous process (MLSP), once again did not appear in this sample. However, the maximum
sagittal length of the vertebra (MSVL) and the maximum width of the vertebral body (MWVB)
occur in numerous step models in this sample associated with a high rate of classification. This
suggests that these measurements may in fact be reliable in the estimation of sex, as was
previously demonstrated in studies of various vertebral elements (Taylor and Twomey 1984;
Gilsanz et al. 1994b; Wescott 1999; Marino 1995). Both, males and females have significantly
higher rates of correct classification in the African American sample than in the South African
Black sample. While this may be due to the large size difference in the samples of each, it has
also been suggested that Black African populations exhibit a tremendous amount of variation in
their vertebral morphology, more so than any other group affiliation (Allbrook 1955).
Sex Estimation in the Pooled Sample
The stepwise models of the pooled (both, the South African Black and African American
samples) result in six step models (Table 26), each of which has a higher R-squared value and a
higher rate of classification when applied to the male and female pooled samples. Not unlike the
South African stepwise models, this model also consists of two step models with the same
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number of variables. The two five-variable models (Tables 31-32) have a single measurement
difference; the maximum width of the vertebral foramen (MWVF) is in the first five-variable
model, while the maximum length of the vertebral foramen (MLVF) is in second and best fivevariable model. Although the sixth step model is the best five-variable model, both were used in
the case of damage to the posterior portion of the neural arch or to the spinous processes. In
cases where the length of the vertebral foramen cannot be taken, the first five-variable model can
be employed instead. The pooled sample incorporates six of the twelve 12th thoracic vertebra
measurements within its stepwise models: the vertebral body length at the sagittal plane (SLVB),
the maximum width of the vertebral foramen (MWVF), the maximum length of the vertebral
foramen (MLVF), the maximum width of the vertebral body (MWVB), maximum width of the
superior articular surfaces (MWSA), and the length of the vertebral body and foramen (LVBF).
Two of these measurements, the vertebral body length at the sagittal plane (SLVB) and the
maximum width of the superior articular surfaces (MWSA) are used in this sample, as well as
both of the other samples.
There is only one measurement that appeared in the African
American stepwise models that does not appear in the pooled, with two measurements used in
the South African Black stepwise models not appearing in the pooled sample. Interestingly, the
first two step models consist of the same variables as the first two step models of the African
American sample, with the remaining step models being more closely aligned with the African
American stepwise models than the South African Black stepwise models. This may be the
result of a combination of the African American sample consisting of a larger sample size with
slightly higher rates of correct classification than that of the South African Black sample.
For the male calibration sample, the classification results improve with the addition of
another measurement in the two-variable model. The best single-variable model (Table 27) uses
94
the measurement of the maximum width of the vertebral body (MWVB) and correctly classifies
76.88% of males. With the incorporation of the measurement of the vertebral body length at the
sagittal plane (SLVB), the classification rate increases to 80.61%, the highest rate of
classification for the male calibration sample (Table 28). In the male test sample, the best singlevariable model has a classification rate of 74.47%. This increases to 76.60% with the addition of
the second variable. This classification rate does not increase until the best five-variable model,
where 77.66% of males are classified correctly (Table 32). As a result of the trends of the
classification rates, it is concluded that the two and five-variable models (Tables 28 and 31) are
reliable classifications of sex for the pooled male sample.
The female calibration sample reveals a higher rate of classification than that of the
pooled males, with the first step model correctly classifying 78.50% of females (Table 27). This
rate increases to 82.00% with the addition of the second variation (Table 28), with this
classification rate peaking at 84.00% in the first five-variable model (Table 31). For the test
sample, the one-variable model correctly classifies 75.68% of females, with this rate increasing
to 82.43% in the two-variable model. The highest rate of classification for the female test
sample is 83.78%, which occurs in the three through five-variable models (Tables 29-31). As a
result of this, the most consistent classification models for the pooled female sample are the three
and best five-variable models (Tables 29-32).
As was the case in the South African Black sample and African American sample,
females tend to have a higher rate of correct classification than males for the majority of the step
models. The reasons for this are currently unknown at this time, but it may be the result of a
lower variability in the skeletal morphology of the female samples. The most frequently used
variables in the pooled samples are the measurements of the vertebral body length at the sagittal
95
plane (SLVB) as well as the maximum width of the vertebral body (MWVB). Both of these
measurements have been shown to exhibit sexual dimorphism in the 12 th thoracic vertebra in a
computer tomography-based study conducted on a living Korean population (Sheng-Bo Yu et al.
2008).
The most frequently used elements in the stepwise models of all samples did not correlate
with those deemed most reliable by previous studies.
In Taylor and Twomey’s (1984)
radiographic study of the lower thoracic and lumbar vertebrae, the maximum sagittal length of
the vertebra and the maximum height of the vertebral body were discerned as having the greatest
disparity between males and females. The maximum sagittal length of the vertebra (MSVL) has
also been displayed as being a reliable indicator of sex in CT scans of the 12 th thoracic vertebra
(Sheng-Bo Yu et al. 2008) as well as in other elements in the vertebral column (Wescott 1999;
Marino 1995; Gilsanz et al. 1994b). The maximum sagittal length of the vertebra (MSVL) only
appears in three stepwise models in the African American samples, while the maximum height of
the vertebral body (MHVB) measurement only appears in four of the stepwise models in the
South African Black samples. While each may be reliable in their respective samples, it was
anticipated that they would appear frequently in the same samples. Finally, the absence of the
measurements the maximum width of the transverse processes (MWTP) and the maximum
length of the spinous process (MLSP) from the stepwise models of all samples was surprising as
they function as muscle attachment sites for a large portion of the muscles in the back (Carter
2000a&b; Netter 1989). It was assumed by the researcher that these measurements would
display a large degree of sexual dimorphism as muscle attachment sites of other skeletal
elements, such as the femur and cranium, are considered consistently reliable indicators of sex
(France 1988).
96
Effects of Age in Sex Estimation
In order to discern the effects of age and age-related changes that occur and may
influence the reliability of the measurements and classification of specimens, the data sets were
separated by age group and were assessed via multivariate analyses. The same was done for the
measurements of the femur in order to test the reliability of the 12th thoracic vertebra. With the
use of statistical procedures, it is apparent that the degree of correct classification of age is still
reliable in the African American samples. The mean values of all measurements illustrate the
differences between the sexes and the age groups, with the trend being that both sexes slightly
increase in the mean value of the measurement from the younger adult age group to the older
adult age group in the majority of measurements. A single stepwise model (Table 33) was
performed and applied to all samples to see the differing results due to the effects of age. Three
step models were generated, with the one-variable model using the measurement of the
maximum width of the vertebral body (MWVB). While proving to be reliable in the African
American and Pooled samples when age was not a factor, this measurement did not appear in the
stepwise models of the South African Black samples. The best two-variable model incorporated
the measurement of the maximum sagittal length of the vertebra (SLVB) in addition to the first
measurement. The best three-variable model consists of the maximum width of the inferior
articular surfaces (MWIA) in addition to the other two previously mentioned measurements. A
single stepwise procedure (Table 49) was also performed for the measurements of the femur.
Since only two measurements of the femur were taken, there were only two step models
generated. The one-variable model uses the measurement of the vertical diameter of the femoral
head (FHVD), with the two-variable model also incorporating the bicondylar length of the femur
(FBL). For femoral measurements, the classification of the correct sex is relatively high in all
97
samples and all age groups, with the correct classifications of the 12 th thoracic vertebral
measurements being high in all age groups and sexes in the African American sample. The
correlation of high classification rates with the African American sample is similar to the trend in
classification of sex without taking the effects of aging into consideration. The South African
Black samples, in both instances have a lower classification rate of the correct sex.
Effects of Age in the South African Black Sample
Multivariate analyses were applied to both age groups, the young adult South African
Black sample and the old adult South African Black sample, in order to assess how age-related
changes may affect the correct classification rates of sex. When applying the stepwise models to
the young male calibration sample, the highest rate of classification occurs in the best onevariable model (Table 34), with a correct male classification of 70.00%. The same stepwise
model was applied to the old male calibration sample, which revealed that the best one-variable
step model (Table 38) in this case also had the highest rate of correct classification but is
significantly lower than that of the younger age group with only 62.07% of males being correctly
classified. In the test sample, the highest rate of classification in the young male sample occurs
in the three-variable model, with 76.00% of males being classified correctly. In the older male
test sample, this rate decreased slightly to a 75.00% correct classification rate. The application
of the stepwise model to the measurements of the femur reveals the inadequacy of the
classification rates of sex in relation to the measurements of the 12 th thoracic vertebra for this
sample. In contrast to a classification rate of 70.00% in the young and 62.07% in the old age
98
groups of the South African Black sample, the femur correctly classifies 90.00% in the young
(Table 50) and 86.67% in the older age groups (Table 53).
In the case of the calibration sample of young South African Black females, the best onevariable model (Table 34) is correctly classified at 63.33% with this value only slightly
increasing in the following models to 65.52%.
These rates of classification for females,
however, increase in all step models in the older female sample to 67.86% and 70.00%,
respectively (Tables 38-40). In contrast to the male South African Black male sample, the rate of
classification for females increases from the younger to the older age group. Similar to the use
of the femoral classification rates for both age groups, the 12 th thoracic vertebral classification
rates have a decreased consistency as a result of the influence of age-related changes. Opposed
to the correct classification of 65.52% of young females for the vertebrae, the femur can
correctly classify 93.33% of young females. This trend remains the same for the older age
groups with a 93.33% classification rate for the femoral measurements and only a 70.00%
classification rate for the vertebral measurements.
Overall, the rate of correct classification of males’ decreases from the young to the old
age group, with the classification rate slightly increasing for that of females. As a result of the
low correct classification rates of the young and old age groups in the South African Black
sample, it can be concluded that the reliability of the estimation of sex is adversely influenced by
the effects of aging and in this case, cannot be consistently classified.
99
Effects of Age in the African American Sample
The same stepwise model was applied the younger adult and older adult age groups in the
African American sample. For the calibration sample of young African American males (Table
42), the best one-variable model correctly classified 85.71% of males, with this classification rate
slightly increasing to 87.14% in the two and three-variable models (Tables 43-44).
In
comparison to the calibration sample of old African American males, the best one-variable
model (Table 46) correctly classifies 77.14% of males, with this also slightly increasing to
78.57% and 80.00% in the two and three-variable models (Tables 47-48). While the rates of
classification increase in each step model of each age group, the classification rate is still lower
in each model of the older calibration sample. Even though the classification rates of males
decrease from the younger to the older age groups, the rates of correct classification are still high
enough to provide a reliable classification of sex. In this case, it can be concluded that the two
and three-variable models of both age groups provide a consistent correct classification of sex.
When the classification rates of the femoral measurements are contrasted with those of the
vertebrae, it becomes apparent that the vertebral classification rates are comparable to those the
femur. For instance, the peak classification rate of males in the younger age group is 87.15%
(Table 43) in the vertebral measurements, opposed to 87.14% for the femoral measurements
(Table 56). For the older age groups, the femur correctly classifies 87.14% of the older males
(Table 59), with the vertebral measurements correctly classifying 80.00% (Table 48).
For the young female calibration sample, the best one-variable model (Table 42)
correctly classifies 82.86% of females, with this classification rate increasing to 84.29% in the
two and three-variable models (Tables 43-44). In the older female calibration sample, the best
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one-variable model (Table 46) correctly classifies 84.29% of females, an increase in
classification over the younger age group. The two and three-variable models for the older
female calibration sample correctly classify at 82.86% and 84.29% (Tables 47-48). As a result,
no significant age related changes can be discerned in the African American sample, and as a
result of the relatively high classification rates, it can be concluded that the two and threevariable models for each age group can be regarded as consistent in terms of rates of
classification. The classification rates for the femoral measurements yield a 92.86% correct
classification of younger females (Table 57) opposed to 84.29% for vertebral measurements.
However, in terms of the older age groups, the femoral classification is more comparable to that
of the vertebra, with a correct classification of 85.71% for the femur (Table 59), compared to
84.29% for the vertebra.
As a result, it can be inferred that the correct classification rate is higher and more
reliable in the younger age groups across samples, than it is in the older age groups. Even
without the comparison of the femoral classification rates, it is evident that the reliability of the
measurements of the 12th thoracic vertebra in the South African Black samples is reduced
considerably as a result of age-related changes. The African American samples, however, not
only prove to have consistent classification rates for both sexes and age groups, but these rates
are even comparable to those of the femur.
It was expected that the measurements of the maximum width of both, the superior
(MWSA) and inferior articular facets (MWIA) would increase in age as it has been documented
that a natural shift in the placement of tension and stress to the posterior neural arch at the
apophyseal joints from the vertebral body occurs (Brown et al. 2008; Derevenski 2000).
However, only the inferior articular surfaces measurement (MWIA) was included in the stepwise
101
model, and as a result, the whole the apophyseal joint in relation to the effects of age cannot
properly be assessed.
Effects of Group Affiliation in Sex Estimation
In order to test the reliability of sex estimation of the 12 th thoracic vertebra, a protocol
should be tested on a variety of populations to ensure a certain degree of accuracy (Giles 1966).
While the effects of group affiliation was not initially a part of this study, the combined data set
of the African American sample along with the South African Black sample, provides an
interesting, albeit preliminary, glimpse into the effects of geographical variation on the skeletal
morphology of the 12th thoracic vertebra.
As a result of numerous comparative studies on the effects of group affiliation on
morphological variation, it has been suggested that those of African descent have more
morphological variation than populations of other group affiliations. One such variability is the
number of presacral vertebrae present.
Numerous studies (Allbrook 1955; Bornstein and
Peterson 1966; Lanier 1939; Shore 1930; Willis 1923) have found that Blacks have a higher
frequency of the presence of a twenty-fifth presacral vertebra than any other group affiliation,
and that males have a higher frequency of this than females (Kaufman 1974; Lanier 1939). This
was evident in the Raymond Dart Collection (South African Black) sample used, as the majority
of male specimens used presented with twenty-five presacral vertebrae in the form of a sixth
lumbar vertebra. Also, those of Black descent have a rather high frequency (24.3% of a research
study sample) of superior articular facet asymmetry in the 12 th thoracic vertebra. In this case, the
asymmetry of these features presents itself as a left “lumbar type” facet (or a concave, mediallyoriented facet typical of those in the lumbar vertebrae), with a typical thoracic right articular
102
facet (Allbrook 1955). This asymmetry was also expressed frequently in the specimens of the
Raymond Dart Collection sample. While nothing beyond univariate statistics were applied to
both samples in order to discern differences attributed to geographical variation, this would be an
interesting study to pursue at a later time.
Summary
The objective of this study was three-fold: to determine the presence and degree of sexual
dimorphism in the 12th thoracic vertebra, to assess reliability of measurements of the 12 th
thoracic vertebra to discern its potential for use in the estimation of sex of unknown individuals,
and finally, to assess whether age-related changes influence the skeletal morphology or
reliability of the measurements of the 12th thoracic vertebra. Through the use of a combination
of univariate and multivariate procedures, each of these objectives has been explored.
Sexual Dimorphism in the 12th Thoracic Vertebra
The results of this study highlight the differences in the morphology of the 12 th thoracic
vertebra, thus validating the presence of sexual dimorphism in this element. Overall, all mean
measurements of the 12th thoracic vertebra are larger in males, than they are in females. This
disparity between the male and female specimens is also exhibited when considering both age
groups as well as the differences between the sexes in both of the collections employed for this
study. The degree of sexual dimorphism inherent in the 12th thoracic vertebra was also tested
through the rates of correct classifications of each sex using a variety of combinations of
measurements.
While the female and male correct classification rates were not always
103
comparable in every step model, the relatively high classification rates demonstrate that not only
is the 12th thoracic vertebra sexually dimorphic, but that the degree of sexual dimorphism is high.
Potential of the 12th Thoracic Vertebra in Sex Estimation
Upon the observation that the 12th thoracic vertebra is sexually dimorphic, the potential
and reliability of this element as an estimator of sex comes into question. Through the use of
stepwise and discriminate analyses, it became apparent that the 12th thoracic vertebra can be used
as a consistent and relatively reliable indicator of sex, assuming that the correct variables are
consistently applied to the correct group. The comparison of the two collections in this study
allowed for the differences in skeletal morphology between the two geographically variant
samples to be observed. As a result of this, it is concluded that this study will not be as reliable
if applied universally. In order to increase the reliability and potential of measurements of the
12th thoracic vertebra being used in sex estimation, the protocol and selection criteria outlined in
this study should be applied to samples from other populations to account for skeletal
morphological variations that may skew or inaccurately represent the results. As expressed in
this study, with the differences in the measurements and classification rates of African American
and South African Black samples, correct classifications rely largely on the correct analysis.
Future studies concerning the morphological variation in the 12 th thoracic vertebra due to the
effects of group affiliation should be conducted in order to account for error caused by this form
of variation.
104
Effects of Age on the 12th Thoracic Vertebra
Through the comparison of two age groups, those deemed skeletally mature to 40 years
of age and those over 40 years of age, the effects of age-related changes have become apparent.
For instance, the classification rates of the South African Black samples were relatively high
until the age groups were considered, then neither males nor females could be classified to a rate
considered to be consistent or reliable. However, the African American samples were correctly
classified regardless of the age restrictions applied. Since external influences, geographical
location for instance, play a role in the how age-related changes are manifested, future studies
should incorporate a variety of populations in order to account for the differences in age-related
processes that can be attributed to group affiliation and sociocultural factors.
The results of this study offer an alternative means for the sex estimation of human
skeletal remains. Since the stepwise models presented relatively high classification rates for
males and females in both samples, the success of this study as a means of reliable identification
cross-culturally relies on the results of this study being applied to a variety of populations.
In
conclusion, this study reveals that the 12th thoracic vertebra has potential for use in sex
estimation as a result of the skeletal morphological variation between males and females both
documented in the Raymond A. Dart Collection of Human Skeletons and the Hamann-Todd
Osteological Collection.
105
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106
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APPENDICES
114
APPENDIX A
DATA COLLECTION FORMS
DART DATA COLLECTION FORM (Voisin 2010)
Observer: Meghan Voisin
ID#: ___________
Date: 01 /
Dart#: ___________
/2011
Age: ___________
Vertebral Measurements (mm)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
ID#: ___________
Sacral Measurements (mm)
1. MAH
2. MAB
3. DCS
____________
____________
____________
Femoral Measurements
1. FBL
____________cm
2. FHVD ____________mm
Dart#: ___________
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
Sacral Measurements (mm)
1. MAH
2. MAB
3. DCS
____________
____________
____________
Femoral Measurements
1. FBL
____________cm
2. FHVD ____________mm
115
Sex: ___________
Notes: _____________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
Age: ___________
Vertebral Measurements (mm)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Page: ______ of ______
Sex: ___________
Notes: _____________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
HAMANN-TODD DATA COLLECTION FORM (Voisin 2011)
Observer: Meghan Voisin
ID#: ___________
Date:____ /
H-T#: ___________
Age: ___________
Vertebral Measurements (mm)
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
ID#: ___________
Sacral Measurements (mm)
4. MAH
5. MAB
6. DCS
____________
____________
____________
Femoral Measurements
3. FBL
____________cm
4. FHVD ____________mm
H-T#: ___________
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MLSP
MWIA
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
____________
Sacral Measurements (mm)
4. MAH
5. MAB
6. DCS
____________
____________
____________
Femoral Measurements
3. FBL
____________cm
4. FHVD ____________mm
116
Sex: ___________
Notes: _____________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
Age: ___________
Vertebral Measurements (mm)
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
Page: ______ of ______
__ /2011
Sex: ___________
Notes: _____________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
APPENDIX B
MEASUREMENT PROTOCOL
DEMONSTRATION OF VERTEBRAL MEASUREMENTS
1. Maximum sagittal length of vertebra
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is defined as “the sagittal length
of the vertebra from the most anterior point on
the body to the posterior edge of the spinous
process” (Wescott 2000)
2. Maximum height of vertebral body
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is the maximum height from the
inferior vertebral body surface to the superior
vertebral body surface at the most anterior face
of the vertebral body.
3. Length of vertebral body at sagittal plane
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is the sagittal length of the
vertebral body from the most anterior face of
the body to the most posterior face of the
vertebral body.
117
4. Maximum width of vertebral body
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is the maximum width of the
vertebral body, measured from the most lateral
left point to the most lateral right point of the
vertebral body.
5. Maximum length of vertebral foramen at
sagittal plane
This measurement is taken using vernier
calipers and is recorded in mm. This
measurement is defined as “the internal length
of the vertebral foramen measured at the
inferior edge of the foramen in the median
plane” (Wescott 2000)
6. Maximum width of vertebral foramen
This measurement is taken using vernier
calipers and is recorded in mm. This
measurement is the maximum internal width of
the vertebral foramen, measured from the most
lateral left point to the most lateral right point
of the vertebral foramen.
118
7. Maximum width of transverse processes
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is defined as being “measured
from the tip of the left transverse process to
that of the right” (Yu et al. 2008)
8. Maximum breadth of superior articular
surfaces
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is performed from the most
lateral surface of the left superior articular
facet to the most lateral surface of the right
superior articular facet.
9. Length of vertebral body and vertebral
foramen
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is performed from the most
anterior point of the vertebral body to the most
posterior point of the vertebral foramen.
119
10. Maximum width of pedicles
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is from the most lateral surface
of the left pedicle to the most lateral surface of
the right pedicle.
11. Maximum Length of spinous process
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is performed by placing the tip of
the top arm of the caliper at the most superior
edge with the tip of the bottom arm at the most
inferior edge of the spinous process.
12. Maximum breadth of inferior articular
surfaces
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is defined as being “measured
horizontally from the anterior border of the
lamina to its tip” (Yu et al. 2008)
120
DEMONSTRATION OF SACRAL MEASUREMENTS
1. Maximum anterior height
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is defined as “the distance from a
point on the promontory in the midsagittal
plane to a point on the anterior border of the tip
of the sacrum measured in the midsagittal
plane” (Moore-Jansen et al. 1994)
2. Maximum anterior breadth
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is defined as “the maximum
transverse breadth of the sacrum at the level of
the anterior projection of the auricular surface”
(Moore-Jansen et al. 1994)
3. Degree of curvature (subtense) of anterior
face
This measurement is taken using a coordinate
caliper and is recorded in mm. This
measurement is the deepest point of concavity
on the anterior surface of the sacrum and is
measured from the plane of the anterior height
measurement down to the anterior face of the
sacrum for the greatest degree of concavity.
121
DEMONSTRATION OF FEMORAL MEASUREMENT
1. Bicondylar length of femur
This measurement is taken using an
osteometric board and is recorded in cm. This
measurement is defined as “the distance from
the most superior point on the head of the
femur to a plane drawn along the inferior
surfaces of the distal condyles” (Moore-Jansen
et al. 1994)
2. Vertical diameter of femoral head
This measurement is taken using a sliding
caliper and is recorded in mm. This
measurement is the “maximum diameter of the
femur head measured on the border of the
articular surface” by rotating “the arms of the
calipers around the femur head to find the
maximum diameter” (Moore-Jansen et al.
1994).
122
APPENDIX C
UNIVARIATE SUMMARY STATISTICS
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Table 61. Dart Collection Vertebral Measurements – Total Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
n
158
167
165
167
168
168
148
168
165
167
160
168
Mean
70.3
22.5
26.5
38.3
16.8
18.1
47.9
35.0
42.5
31.6
30.7
27.8
Var.
27.0
3.1
12.0
10.1
2.8
3.7
56.0
15.1
13.0
8.2
12.8
10.8
St. Dev.
5.2
1.8
3.5
3.2
1.7
1.9
7.5
3.9
3.6
2.9
3.6
3.3
Table 62. Dart Collection Vertebral Measurements – Male Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
n
87
93
91
93
94
94
83
94
91
93
89
94
Mean
72.1
23.0
27.8
39.5
16.6
18.2
49.9
35.8
43.8
32.7
31.4
28.1
Var.
17.8
3.2
14.4
8.4
2.9
3.6
49.3
11.3
12.6
6.7
11.5
11.4
St. Dev.
4.2
1.8
3.8
2.9
1.7
1.9
7.0
3.4
3.6
2.6
3.4
3.4
Table 63. Dart Collection Vertebral Measurements – Female Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
123
n
71
74
74
74
74
74
65
74
74
74
71
74
Mean
68.0
21.9
24.9
36.7
17.1
18.0
45.4
33.9
40.8
30.2
29.8
27.4
Var.
29.3
2.5
4.4
7.8
2.7
3.8
54.2
18.2
8.7
6.9
13.2
10.0
St. Dev.
5.4
1.6
2.1
2.8
1.6
2.0
7.4
4.3
2.9
2.6
3.6
3.2
Range
38.6 – 82.4
18.2 – 28.2
18.6 – 57.3
30.3 – 48.4
12.0 – 20.2
14.0 – 23.4
31.4 – 73.1
25.0 – 54.1
30.8 – 68.2
24.4 – 40.8
18.5 – 39.2
19.2 – 42.2
Range
63.8 – 82.4
18.2 – 28.2
21.7 – 57.3
34.2 – 48.4
12.0 – 20.1
14.0 – 22.5
40.3 – 71.7
28.7 – 47.5
38.3 – 68.2
27.5 – 40.8
21.0 – 38.3
20.6 – 42.2
Range
38.6 – 76.9
18.4 – 25.5
18.6 – 29.8
30.3 – 42.3
13.1 – 20.2
14.2 – 23.4
31.4 – 73.1
25.0 – 54.1
30.8 – 49.1
24.4 – 36.0
18.5 – 39.2
19.2 – 35.0
Code
FBL
FHVD
Code
FBL
FHVD
Code
FBL
FHVD
Code
MSVL
Table 64. Dart Collection Femoral Measurements – Total Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
168
168
Mean
43.5
42.9
Var.
7.8
11.8
St. Dev.
2.8
3.4
Table 65. Dart Collection Femoral Measurements – Male Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
94
94
Mean
45.0
45.2
Var.
5.7
6.0
St. Dev.
2.4
2.5
Table 66. Dart Collection Femoral Measurements – Female Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
74
74
Mean
41.6
40.1
Var.
4.0
4.5
St. Dev.
2.0
2.1
Range
37.0 – 53.0
36.0 – 51.0
Range
40.1 – 53.0
39.2 – 51.0
Range
37.0 – 45.8
36.0 – 46.5
Table 67. Dart Collection Vertebral Measurements with Ages – Total Sample
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
124
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
69.5
71.2
22.5
22.5
26.2
26.9
37.7
39.0
17.1
16.4
18.1
18.2
47.4
48.5
34.7
35.3
42.0
43.1
31.6
31.7
30.2
31.2
27.5
28.2
Var.
21.9
32.3
3.6
2.6
17.2
5.3
10.4
9.0
2.2
3.5
3.3
4.3
50.2
63.3
17.1
12.6
10.2
16.2
9.0
7.3
12.2
13.2
11.0
10.5
St. Dev.
4.7
5.7
1.9
1.6
4.1
2.3
3.2
3.0
1.5
1.9
1.8
2.1
7.1
8.0
4.1
3.5
3.2
4.0
3.0
2.7
3.5
3.6
3.3
3.2
Range
58.0 – 78.8
38.6 – 82.4
18.2 – 26.9
20.0 – 28.2
18.6 – 57.3
21.7 – 32.0
30.3 – 45.1
32.8 – 48.4
13.6 – 20.1
12.0 – 20.2
14.7 – 22.4
14.0 – 23.4
31.4 – 69.7
38.7 – 73.1
25.0 – 54.1
27.2 – 47.5
30.8 – 48.0
35.4 – 68.2
24.4 – 40.8
25.1 – 39.0
18.5 – 38.3
21.0 – 39.2
19.2 – 35.3
20.6 – 42.2
Code
MSVL
Table 68. Dart Collection Vertebral Measurements with Ages – Male Sample
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
Code
MSVL
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
71.6
72.8
23.0
23.1
27.8
27.9
39.0
40.3
16.9
16.1
18.3
18.2
49.5
50.4
35.5
36.1
43.6
44.1
32.8
32.6
31.0
32.0
27.8
28.6
Var.
16.5
19.3
3.6
2.6
21.0
4.5
7.8
8.6
2.2
3.6
3.2
4.4
47.6
52.7
10.6
12.5
6.0
23.1
6.3
7.3
10.0
13.2
10.3
13.0
St. Dev.
4.1
4.4
1.9
1.6
4.6
2.1
2.8
2.9
1.5
1.9
1.8
2.1
6.9
7.3
3.3
3.5
2.4
4.8
2.5
2.7
3.2
3.6
3.2
3.6
Range
63.8 – 78.8
63.8 – 82.4
18.2 – 26.9
20.0 – 28.2
21.7 – 57.3
24.2 – 32.0
34.2 – 45.1
35.3 – 48.4
13.6 – 20.0
12.0 – 20.1
15.2 – 22.4
14.0 – 22.5
40.3 – 69.7
40.3 – 71.7
28.7 – 42.6
30.8 – 47.5
38.6 – 48.0
38.3 – 68.2
28.6 – 40.8
27.5 – 39.0
23.8 – 38.3
21.0 – 38.3
23.0 – 35.3
20.6 – 42.2
Table 69. Dart Collection Vertebral Measurements with Ages – Female Sample
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
125
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
66.7
69.4
21.9
22.0
24.0
25.8
35.8
37.6
17.3
16.8
17.9
18.1
44.3
46.5
33.5
34.4
39.6
42.0
29.7
30.8
29.2
30.4
27.0
27.9
Var.
15.8
41.0
3.1
1.9
3.3
3.9
8.1
5.9
2.1
3.2
3.5
4.3
39.2
69.0
24.7
11.4
7.0
7.7
7.5
5.8
13.8
12.2
12.0
7.8
St. Dev.
4.0
6.4
1.7
1.4
1.8
2.0
2.8
2.4
1.5
1.8
1.9
2.1
6.3
8.3
5.0
3.4
2.6
2.8
2.7
2.4
3.7
3.5
3.5
2.8
Range
58.0 – 73.5
38.6 – 76.9
18.4 – 25.5
20.0 – 24.6
18.6 – 28.1
21.7 – 29.8
30.3 – 40.5
32.8 – 42.3
14.2 – 20.1
13.1 – 20.2
14.7 – 20.7
14.2 – 23.4
31.4 – 58.7
38.7 – 73.1
25.0 – 54.1
27.2 – 41.0
30.8 – 44.6
35.4 – 49.1
24.4 – 35.0
25.1 – 36.0
18.5 – 36.6
23.1 – 39.2
19.2 – 33.8
24.0 – 35.0
Code
MSVL
MHVB
Code
MSVL
MHVB
Code
MSVL
MHVB
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Table 70. Dart Collection Femoral Measurements with Ages – Total Sample
Measurement
Maximum Sagittal Length of Vertebra
Age
<40
>40
<40
>40
Maximum Height of Vertebral Body
Mean
43.5
43.6
42.7
43.2
Var.
8.1
7.6
11.5
12.2
St. Dev.
2.9
2.7
3.4
3.5
Range
37.3 – 53.0
37.0 – 48.7
36.0 – 50.1
36.0 – 51.0
Table 71. Dart Collection Femoral Measurements with Ages – Male Sample
Measurement
Maximum Sagittal Length of Vertebra
Age
<40
>40
<40
>40
Maximum Height of Vertebral Body
Mean
45.0
45.2
44.9
45.6
Var.
6.3
5.0
5.1
7.2
St. Dev.
2.5
2.2
2.3
2.7
Range
40.4 – 53.0
40.1 – 48.7
40.2 – 50.1
39.2 – 51.0
Table 72. Dart Collection Femoral Measurements with Ages – Female Sample
Measurement
Maximum Sagittal Length of Vertebra
Age
<40
>40
<40
>40
Maximum Height of Vertebral Body
Mean
41.4
41.9
39.5
40.7
Var.
3.3
4.8
3.4
5.1
St. Dev.
1.8
2.2
1.8
2.3
Range
37.3 – 44.5
37.0 – 45.8
36.0 – 43.7
36.0 – 46.5
Table 73. Hamann-Todd Collection Vertebral Measurements – Total Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
126
n
406
407
407
407
407
407
394
407
407
407
406
407
Mean
73.9
22.9
27.6
39.9
17.4
19.3
49.1
36.5
44.3
33.2
32.2
28.8
Var.
30.5
3.2
9.2
14.6
2.5
3.7
36.9
15.9
10.9
11.1
14.6
13.3
St. Dev.
5.5
1.8
3.0
3.8
1.6
1.9
6.1
4.0
3.3
3.3
3.8
3.6
Range
60.8 – 94.4
17.6 – 28.3
21.4 – 37.0
29.1 – 51.8
12.8 – 24.5
14.5 – 25.7
36.6 – 83.3
26.2 – 52.1
37.0 – 55.7
25.3 – 47.4
23.6 – 51.8
20.0 – 43.3
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Code
MSVL
MHVB
SLVB
MWVB
MLVF
MWVF
MWTP
MWSA
LVBF
MWIP
MWSP
MWIA
Code
FBL
FHVD
Code
FBL
FHVD
Code
FBL
FHVD
Table 74. Hamann-Todd Collection Vertebral Measurements – Male Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
n
204
205
205
205
205
205
203
205
205
205
204
205
Mean
77.4
23.2
29.5
42.4
17.4
19.6
51.7
38.1
46.2
34.8
33.6
29.9
Var.
20.7
3.7
5.8
8.7
2.7
4.5
40.9
16.4
8.3
9.6
14.1
14.1
St. Dev.
4.6
1.9
2.4
2.9
1.6
2.1
6.4
4.0
2.9
3.1
3.8
3.8
Range
66.6 – 94.4
17.6 – 28.3
23.8 – 37.0
35.6 – 51.8
12.8 – 22.4
14.6 – 25.7
37.6 – 83.3
29.4 – 52.1
37.7 – 55.7
27.6 – 47.4
23.9 – 45.6
22.7 – 43.3
Table 75. Hamann-Todd Collection Vertebral Measurements – Female Sample
Measurement
Maximum Sagittal Length of Vertebra
Maximum Height of Vertebral Body
Vertebral Body Length at Sagittal Plane
Maximum Width of Vertebral Body
Maximum Length of Vertebral Foramen
Maximum Width of Vertebral Foramen
Maximum Width of Transverse Processes
Maximum Width Superior Articular Surfaces
Length Vertebral Body and Foramen
Maximum Width of Pedicles
Maximum Length of Spinous Process
Maximum Width Inferior Articular Surfaces
n
202
202
202
202
202
202
191
202
202
202
202
202
Mean
70.3
22.5
25.5
37.4
17.4
19.0
46.2
34.8
42.4
31.7
30.7
27.7
Var.
15.5
2.4
4.6
7.9
2.4
2.7
17.1
10.3
6.1
7.9
11.0
10.2
St. Dev.
3.9
1.5
2.2
2.8
1.6
1.6
4.1
3.2
2.5
2.8
3.3
3.2
Range
60.8 – 81.9
18.5 – 27.0
21.4 – 33.3
29.1 – 45.1
13.0 – 24.5
14.5 – 24.2
36.6 – 59.4
26.2 – 45.0
37.0 – 50.5
25.3 – 40.3
23.6 – 51.8
20.0 – 37.7
Table 76. Hamann-Todd Collection Femoral Measurements – Total Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
407
407
Mean
45.4
45.1
Var.
9.2
14.5
St. Dev.
3.0
3.8
Table 77. Hamann-Todd Collection Femoral Measurements – Male Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
205
205
Mean
47.2
48.0
Var.
6.5
6.4
St. Dev.
2.5
2.5
Range
38.0 – 53.3
36.7 – 55.6
Range
40.5 – 53.3
42.0 – 55.6
Table 78. Hamann-Todd Collection Femoral Measurements – Female Sample
Measurement
Bicondylar Length of Femur
Vertical Diameter of Femoral Head
n
202
202
127
Mean
43.6
42.1
Var.
5.2
5.6
St. Dev.
2.3
2.4
Range
38.0 – 49.9
36.7 – 49.4
Table 79. Hamann-Todd Collection Vertebral Measurements with Ages – Total Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
73.0
74.8
22.9
22.9
27.1
28.0
39.2
40.7
17.5
17.3
19.2
19.4
48.7
49.4
36.3
36.6
43.9
44.7
32.8
33.7
31.7
32.6
28.8
28.9
Var.
29.4
30.1
3.1
3.3
8.9
9.2
13.7
14.2
2.4
2.7
3.9
3.4
38.8
34.9
17.2
14.7
9.6
12.0
10.6
11.2
14.2
14.7
11.7
15.0
St. Dev.
5.4
5.4
1.8
1.8
3.0
3.0
3.7
3.8
1.5
1.6
2.0
1.8
6.2
5.9
4.1
3.8
3.1
3.5
3.2
3.3
3.8
3.8
3.4
3.9
Range
60.8 – 90.8
63.6 – 94.4
18.5 – 28.3
17.6 – 27.3
21.4 – 34.7
22.0 – 37.0
29.1 – 48.0
31.9 – 51.8
13.3 – 24.5
12.8 – 21.7
14.6 – 25.7
14.5 – 24.6
36.6 – 73.7
37.6 – 83.3
26.2 – 52.1
28.4 – 47.7
37.0 – 52.1
37.0 – 55.7
25.3 – 43.7
26.3 – 47.4
23.6 – 51.8
24.5 – 45.6
22.2 – 41.5
20.0 – 43.3
Table 80. Hamann-Todd Collection Vertebral Measurements with Ages – Male Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
128
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
76.5
78.3
23.2
23.3
29.2
29.9
41.7
43.2
17.4
17.3
19.5
19.7
51.5
52.0
38.1
38.0
45.8
46.7
34.2
35.3
33.1
34.2
29.6
30.2
Var.
18.9
21.2
3.8
3.6
5.1
6.2
7.0
9.4
2.4
3.0
4.7
4.4
40.8
41.3
17.4
15.5
6.6
9.8
8.8
9.9
13.3
14.4
12.0
16.3
St. Dev.
4.3
4.6
2.0
1.9
2.3
2.5
2.6
3.1
1.5
1.7
2.2
2.1
6.4
6.4
4.2
3.9
2.6
3.1
3.0
3.1
3.6
3.8
3.5
4.0
Range
66.6 – 90.8
69.3 – 94.4
19.2 – 28.3
17.6 – 27.3
23.8 – 34.7
24.0 – 37.0
35.6 – 48.0
37.0 – 51.8
13.3 – 22.4
12.8 – 21.7
14.6 – 25.7
15.0 – 24.6
38.0 – 73.7
37.6 – 83.3
30.3 – 52.1
29.4 – 47.7
39.8 – 52.1
37.7 – 55.7
27.6 – 43.7
29.4 – 47.4
23.9 – 43.7
24.5 – 45.6
22.7 – 41.5
23.1 – 43.3
Table 81. Hamann-Todd Collection Vertebral Measurements with Ages – Female Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
SLVB
Vertebral Body Length at Sagittal Plane
MWVB
Maximum Width of Vertebral Body
MLVF
Maximum Length of Vertebral Foramen
MWVF
Maximum Width of Vertebral Foramen
MWTP
Maximum Width of Transverse Processes
MWSA
Maximum Width Superior Articular Surfaces
LVBF
Length Vertebral Body and Foramen
MWIP
Maximum Width of Pedicles
MWSP
Maximum Length of Spinous Process
MWIA
Maximum Width Inferior Articular Surfaces
Age
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
<40
>40
Mean
69.3
71.4
22.7
22.4
24.9
26.2
36.5
38.3
17.6
17.2
18.9
19.2
45.7
46.8
34.5
35.1
42.0
42.8
31.2
32.2
30.3
31.1
27.9
27.5
Var.
13.7
15.2
2.2
2.5
3.4
5.1
7.1
7.1
2.4
2.4
3.0
2.3
18.9
14.9
10.7
9.9
5.4
6.6
7.9
7.6
11.5
10.4
10.0
10.4
St. Dev.
3.7
3.9
1.5
1.6
1.8
2.3
2.7
2.7
1.5
1.5
1.7
1.5
4.4
3.9
3.3
3.1
2.3
2.6
2.8
2.8
3.4
3.2
3.2
3.2
Range
60.8 – 77.7
63.6 – 81.9
18.5 – 26.4
18.7 – 27.0
21.4 – 31.7
22.0 – 33.3
29.1 – 42.8
31.9 – 45.1
13.5 – 24.5
13.0 – 21.3
15.3 – 24.1
14.5 – 24.2
36.6 – 59.4
38.3 – 56.6
26.2 – 45.0
28.4 – 44.0
37.0 – 48.1
37.0 – 50.5
25.3 – 40.3
26.3 – 38.3
23.6 – 51.8
24.8 – 40.3
22.2 – 37.7
20.0 – 36.1
Table 82. Hamann-Todd Collection Femoral Measurements with Ages – Total Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
Age
<40
>40
<40
>40
Mean
45.5
45.4
44.8
45.3
Var.
9.2
9.3
15.9
13.0
St. Dev.
3.0
3.0
4.0
3.6
Range
38.6 – 53.2
38.0 – 53.3
36.7 – 55.6
37.0 – 54.4
Table 83. Hamann-Todd Collection Femoral Measurements with Ages – Male Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
Age
<40
>40
<40
>40
Mean
47.3
47.2
47.9
48.1
Var.
6.5
6.6
7.3
5.5
St. Dev.
2.5
2.6
2.7
2.3
Range
40.5 – 53.2
40.9 – 53.3
42.8 – 55.6
42.0 – 54.4
Table 84. Hamann-Todd Collection Femoral Measurements with Ages – Female Sample
Code
MSVL
Measurement
Maximum Sagittal Length of Vertebra
MHVB
Maximum Height of Vertebral Body
Age
<40
>40
<40
>40
129
Mean
43.5
43.6
41.6
42.6
Var.
4.8
5.6
5.0
5.8
St. Dev.
2.2
2.4
2.2
2.4
Range
38.6 – 49.9
38.0 – 49.3
36.7 – 47.3
37.0 – 49.4