Human Evolution Chapter 19 1 Human evolution Closest

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 cm 3, 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 cm 3, some would assign both to Australopithecus • Homo ergaster (1. 8 – 1. 5 mya) – East Africa, brain 850 cm 3, 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 mt. DNA 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) 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

mt. DNA phylogeny of 3 Neanderthals and several hundred modern humans (Fig. 19. 21) 24

An evolutionary tree of complete mt. DNAs 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