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Human Evolution
Chapter 19
1
Human evolution
• Closest living relatives
• Fossil hominids (“missing links”)
• Origin and spread of Homo sapiens
2
Which species is the sister taxon to
H. sapiens?
3
The
phylogeny
of apes as
first
proposed by
Huxley
(1863) and
universally
accepted
today (Fig.
19.1)
4
The phylogeny of apes based on immunological distance as
proposed by Sarich and Wilson (1967) (Fig. 19.2)
5
Possible phylogenies of humans and the
African great apes (Fig. 19.3)
6
The phylogeny of mitochondrial cytochrome oxidase II in
humans and great apes (Ruvolo et al. 1994) (Fig. 19.4)
7
Gene trees vs. species trees (Fig. 19.5)
8
Divergence times for the apes based upon a variety of proteincoding genes (Stauffer et al. 2001) (Fig. 19.6)
(heavy bars ± 1 SE; light bars 95% CI)
9
Fossil hominids – the recent ancestry of
humans
• “hominid” is traditionally taken to mean any
species more closely related to humans than to
chimpanzees; a bipedal member of the ape clade
• The fossil evidence indicates that bipedality
evolved before increased brain size
• Trends in hominid evolution:
–
–
–
–
Increase in brain size
Increase in body size
Vertical or “flat” face
Tool use
10
Prominent hominid fossil species – 1
• Autralopithecus afarensis (3.9 – 3.0 mya)
– East Africa, “Lucy”, Donald Johanson 1974, brain size
400 - 500 cm3, females 3’ 7”, males 4’ 7” – 4’ 11”,
evidence for bipedality comes from skeletons and
fossilized footprints (Laetoli, Tanzania, 3.6 mya)
• Australopithecus africanus (2.8 – 2.4 mya)
– South Africa, “Taung child”, Raymond Dart 1924,
similar in size to A. afarensis. A. africanus and A.
afarensis are grouped together as gracile
australopithecines
11
Prominent hominid fossil species – 2
• Autralopithecus (Paranthropus) boisei (2.3 – 1.4
mya)
• Australopithecus (Paranthropus) robustus (2.0 –
1.0 mya)
– East Africa, A. boisei and A. robustus are grouped
together as robust australopithecines, brain slightly
larger than gracile australopithecines, large teeth, robust
jaws, massive jaw muscles, possibly tool users
12
Prominent hominid fossil species – 3
• Homo habilis (1.9 – 1.6 mya)
• Homo rudolfensis (2.4 – 1.8 mya)
– East Africa, probable tool users, brain 510 – 775 cm3,
some would assign both to Australopithecus
• Homo ergaster (1.8 – 1.5 mya)
– East Africa, brain 850 cm3, some refer to this species as
African Homo erectus to distinguish from H. erectus in
Asia and Europe
13
Oldowan stone tools from Hadar, Ethiopia (Kimbel
et al. 1996) (Fig. 19.27)
2.3 million years old
14
Prominent hominid fossil species – 4
• Homo erectus (1.8 – 0.4 mya)
– Africa, Asia, Europe, first hominid outside of Africa, Java Man,
Peking Man
• Homo heidelbergensis (0.6 – 0.2 mya)
– Africa, descendant of H. ergaster? Separate species or transitional
form between H. ergaster/erectus and H. sapiens?
• Homo neanderthalensis (0.3 – 0.03 mya)
– Middle East, Europe, Separate species or transitional form between
H. ergaster/erectus and H. sapiens? Some classify Neanderthals as
archaic H. sapiens
15
Homo sapiens
• First fossils of anatomically modern humans about
100,000 years old in Africa and Israel, and
somewhat later in Europe and Asia
• Originated from some population or populations
of the H. ergaster/erectus lineage,
contemporaneous with Neanderthals in Middle
East and Europe
16
Summary of the fossil evidence of the recent ancestry of
humans (Wood 2002) (Fig. 19.15)
17
Brain size vs. body size in a variety of hominids and
great apes (Fig. 19.31)
18
Cladogram and phylogeny of Homo sapiens and its
recent ancestors and extinct relatives (Fig. 19.16)
19
Hypotheses
concerning
the
transition
from Homo
ergaster/
erectus to
Homo
sapiens
(Fig. 19.17)
20
Genetic diversity of
humans vs. African
great apes based on
mtDNA sequence
differences between
all possible pairs of
individuals
(Gagneux 1999)
(Fig. 19.18)
21
Evidence of geographic structure in living human
populations (Rosenberg et al. 2002) (Fig. 19.19)
Based on 377
microsatellite loci
in 1,056
individuals from
52 populations
22
Phylogenetic predictions of the African replacement model vs. the
multiregional evolution model (Leiberman 1995) (Fig. 19.20)
23
mtDNA phylogeny of 3 Neanderthals and several hundred
modern humans (Fig. 19.21)
24
An
evolutionary
tree of
complete
mtDNAs of
53 humans
(Ingman et al. 2000)
(Fig. 19.22)
25
Divergence times of species trees, population trees, and
gene trees (Fig. 19.23)
26
Phylogenetic tree for 14 human populations based on allele
frequencies at 30 microsatellite loci (Bowcock et al. 1994)
(Fig. 19.21)
27
Genetic
diversity at
a single
locus
among the
people of
seven
geographic
regions
(Tishkoff
et al. 1996)
(Fig.
19.25)
28