A split in the hominin lineage
The result in terms of teeth:
LHS “gracile”
RHS “robust”
Lower jaws of a robust (left) and gracile (right) Australopithecine.1
Stone tools
• From about 2.5 Mya stone
tools being to appear in the
archaeological record in the
same areas of Africa where
hominin fossils,
fossils including
new species, are found.
• Who made the tools?
2
Homo habilis
Olduvai Gorge
• > 1.75 mya
• Differences in teeth
and brain
• Leakey, Napier, &
Tobias (1964)
• OH7
3
1
‘The Handy Man’
• Redefinition of
genus
• Morphological
space between
Australopithecines
and H. erectus
4
Brains & Bodies
5
Tool Making
• Lumping vs. Splitting
6
2
KNM-ER 1470
• East Turkana
• 2.2-1.8 MYA
• Homo rudolfensis?
7
KNM-ER 1813
• East Turkana, Kenya
• 2.4-1.6 MYA
8
OH62
Olduvai Gorge, Tanzania
1.85- 1.75 mya
OH62 compared to a modern
human
9
3
Fossils of Early Homo
OH 24
KNM ER 1470
KNM-ER-1470
OH 7
KNM-ER-1813
10
Kenyanthropus platyops
•
•
•
•
West Turkana, Kenya
KNM-WT 40000
3.5 to 3.2 MYA
Meave Leakey
Kenyanthropus platyops
Homo rudolfensis
11
Other Recent Finds
• Shungura, OmoValley
• Stekfontein, S.A. Sts 19
• Chemeron, Lake Baringo,
Kenya
y 2.4 mya
y
• Uraha, Malawi 2.5-2.3
mya
Mandible of Homo rudolfensis from Malawi
12
4
Anatomy
13
Homo habilis & Homo rudolfensis
H. rudolfensis: flatter,
broader face, broader
postcanine teeth with
more complex crowns
and roots and thicker
enamel, larger cranium
Olduvai: Homo habilis
Lake Turkana: H. habilis & H.
rudolfensis.
3735 & 1813: H. habilis
1470: H. rudolfensis
Malawi: H. rudolfensis.
Chemeron: ?
14
Phylogeny
•
•
•
•
•
How many species?
Problems of lumping vs. splitting
Single species hypothesis
Single-species
Definition of species
Processes (e.g., punctuated equilibrium,,
Red Queen etc.)
15
5
Skelton &McHenry (1992)
5 Functional complexes:
heavy chewing (34 traits)
anterior dentition (11 traits)
basicranium flexion (11 traits)
prognathism/ orthognathism (8 traits)
encephalization (3 traits)
16
Key Questions
Relationship of A afarensis to early and later hominins
Relationships among the robust australopithecines
Origin of the genus Homo
17
Skelton &McHenry (1992)
18
6
Interpretations
?
?
?
These four possible interpretations of the early hominin record agree in placing the early undisputed
australopithecines (A. anamensis and A. afarensis) at the base, although Hypothesis ONE returns to the
idea that there may be more than one species in A. afarensis. Otherwise, most disagreement comes from
how the robust Australopithecines are placed, and how much homoplasy this involves. Only one of the trees
(Hypothesis THREE) supports putting these species in a separate genus. NB not all known species are
included here, simply because we do not have sufficient information on them!
19
Chronological ranges of lineages of early
African Hominins
20
7