The Young Scientist Program
http://ysp.wustl.edu
Washington University Medical School
Funding provided by The Leon Lowenstein Foundation
Homology of Forelimbs
For YSP Volunteers: How to Run this Activity
Module Overview
Students will learn what homologous structures are by studying the forelimb of various
animals. They will determine if the chicken wing is homologous to human forelimbs by dissecting
the chicken wing and sketching the underlying bone structure.
Curriculum Links
Missouri Science Standards
EC.4.3.A.9-12.b. Evidence for the nature and rates of evolution can be found in anatomical
and molecular characteristics of organisms and in the fossil record: Evaluate the evidence that
supports the theory of biological evolution (e.g., fossil records, similarities between DNA and
protein structures, similarities between developmental stages of organisms, homologous and
vestigial structures)
Next Generation Science Standards
MS-LS4-2. Apply scientific ideas to construct an explanation for the anatomical similarities
and differences among modern organisms and between modern and fossil organisms to infer
evolutionary relationships. [Clarification Statement: Emphasis is on explanations of the
evolutionary relationships among organisms in terms of similarity or differences of the gross
appearance of anatomical structures.]
HS-LS4-1. Communicate scientific information that common ancestry and biological
evolution are supported by multiple lines of empirical evidence. [Clarification Statement: Emphasis
is on a conceptual understanding of the role each line of evidence has relating to common
ancestry and biological evolution. Examples of evidence could include similarities in DNA
sequences, anatomical structures, and order of appearance of structures in embryological
development.]
Goals:
1. To describe what a homologous structure is.
2. To give examples of homologous structures using forelimbs.
3. To discuss how homologous structures support the theory of evolution.
Materials:
 bleached chicken wing
 dissection tools
 paper towels
 disposable gloves
 hand sanitizer
The Young Scientist Program
http://ysp.wustl.edu
Washington University Medical School
Funding provided by The Leon Lowenstein Foundation
Homology of Forelimbs
INTRODUCTION: In this activity you will observe the forelimbs of different animals and determine if they
are homologous structures. A homologous structure is a similarity between organisms due to
common ancestry. Homologous structures are evidence for evolution because they show how
organisms are related to a common ancestor they evolved from.
MATERIALS: bleached chicken wing, dissection tools, paper towels, disposable gloves, hand sanitizer
PROCEDURE:
1. Observe the six limbs in the picture that was given to you.
2. Record your observations in the chart below.
3. To fill in the information about the chicken wing, dissect the wing.
4. Peel the skin off the chicken wing. Trim the muscles off the bones.
Chicken
(sketch it below)
Whale flipper
Frog front arm
Horse front leg
Lion front leg
Human arm
Bat wing
Chicken wing
Bones in the upper limb
(humerus, radius, ulna)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
Humerus (yes/no)
Radius (yes/no)
Ulna (yes/no)
# of fingers
Function of the Limb
(Flying, swimming, grasping, etc)
The Young Scientist Program
http://ysp.wustl.edu
Washington University Medical School
Funding provided by The Leon Lowenstein Foundation
CONCLUSIONS:
1. How are the forelimbs of the whale, frog, horse, lion, human, bat, and chicken the same?
2. How are the forelimbs of the human and chicken different?
3. How are the forelimbs of the human and chicken similar?
4. Are the humerus, radius, and ulna homologous structures?
5. What does that tell us about our relationship to chickens, lions, horses, etc?
6. How is this evidence for evolution?
OPTIONAL:
Homologies: Create a color key, then color in the bones for the human, lion, and pig forearms.
color
r= Radius
u= Ulna
e= Trapezoid
g= Hamatum
h= phalanges
(fingers)
Human
Lion
Pig