Don Johanson
Hadar, Ethiopia
Hadar
Turkana
Olduvai
& Laetoli
Hadar Knee Joint
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„
Don Johanson, 1973
Hadar, Ethiopia
Age: 3-4 million years
Significance: The distal
femur and proximal tibia
fragments articulate at an
angle characteristic of
bipedal hominids, rather
than quadrupedal apes.
This confirmed that the
Hadar fossils were
hominids.
Australopithecus afarensis
Lucy
(A.L. 288)
Australopithecus afarensis
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Don Johanson, 1974
Hadar, Ethiopia
Age: 3.2 million years
Significance: The most famous fossil of our
century, and the most complete specimen
of any hominid this old. Three and a half
feet tall and fully bipedal with a chimpsized brain, Lucy represents
Australopithecus afarenis, the earliest welldescribed hominid species.
A.L. 333 “First Family”
Australopithecus afarensis
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„
Don Johanson, 1975
Hadar, Ethiopia
Age: 3.2 m
Significance: Hadar location 333 yielded the remains of nine adults and four juveniles
(including the child shown above and many of the Hadar jaws at the right). If its
discoverers are correct in their assumption that these individuals died together in a
catastrophic event, the site offers a cross-section of an afarensis population.
Meanwhile: Laetoli fossils & prints
Dating Hadar
Lucy
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„
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„
Potassium-Argon
Fission Track
Paleomagnetism
Biostratigraphy
First Family
At first, Johanson shared Mary &
Richard Leakey’s Interpretation:
„
Two types
‹ Lucy = “primitive”
‹ First family & Laetoli = Homo
)
Evidence:
• Small molars
• Age of 1470
Homo is very old
„ Lucy not our ancestor
(See Leakey’s phylogeny in Origins)
„
Richard Leakey’s Phylogeny in Origins (1977)
H. sapiens
1 million years
A. robustus
H. erectus
2 million years
A. africanus
3 million years
Lucy?
1470
Homo sp.
4 million years
5 million years
?
“First Family”
Laetoli Footprints
Why did Johanson Change?
„
Biostratigraphy?
„
Date of KBS tuff?
„
Allometry?
If Lucy, First Family, & Laetoli are one, what are they?
Not Homo!
How are hominid teeth different?
„
„
„
„
„
„
Canine size & shape
Canine dimporphism
Diastema
Canine and molar wear
Dental arcade shape
Premolar cusps
Hadar Teeth: Transitional
„
„
„
„
„
„
Canine size & shape
Canine dimporphism
Diastema
Canine and molar wear
Dental arcade shape
Premolar cusps
Don Johanson’s Phylogeny in Lucy (1981)
H. sapiens
1 million years
A. robustus
H. erectus
2 million years
1470
H. habilis
A. africanus
3 million years
Lucy & “First Family”
A. afarensis
4 million years
5 million years
?
Laetoli Footprints
Richard Leakey’s Phylogeny in Origins (1977)
H. sapiens
1 million years
A. robustus
H. erectus
2 million years
A. africanus
3 million years
Lucy?
1470
Homo sp.
4 million years
5 million years
?
“First Family”
Laetoli Footprints
Don Johanson’s Phylogeny in Lucy (1981)
H. sapiens
1 million years
A. robustus
H. erectus
2 million years
1470
H. habilis
A. africanus
3 million years
Lucy & “First Family”
A. afarensis
4 million years
5 million years
?
Laetoli Footprints
Species: Australopithecus afarensis
„
„
„
„
„
„
„
Hadar + Laetoli fossils
Fully bipedal
Oldest hominid, 3-4 mya
Smallest brain
Extreme dimorphism
Transitional dental
morphology
Common ancestor of other
hominids
Don Johanson’s Phylogeny in Lucy (1981)
H. sapiens
1 million years
A. robustus
H. erectus
2 million years
1470
H. habilis
A. africanus
3 million years
Lucy & “First Family”
A. afarensis
4 million years
5 million years
?
Laetoli Footprints
Johanson’s reinterpretation of
Australopithecines
„
Robusts are younger
„
Small molars ancestral (retained in Homo)
„
Large molars a derived Australopithecus trait
‹ Relativity of “ancestral” & “derived”
„
Graciles evolved into robusts
A Scientific Objection to Johanson Phylogeny
„
One species or two @ Hadar?
‹ Yves Coppens is among dissenters
„
„
“First family” interpretation circular?
Doubts linger
A. L. 444 - 2
Australopithecus
afarensis
„
„
„
„
Yoel Rak, 1992
Hadar, Ethiopia
Age: 3 million years
Cranial capacity: 500 cc
Significance: This large male is the
most complete adult afarensis skull
yet. It has fueled both sides of the
debate about the number of species
at Hadar.
Next...
Explaining Hominids