The Origin and Dispersal of Modern Humans

Transcription

1 OK -- Enough! Stop following me! The Origin and Dispersal of Modern Humans The questions regarding when, where, and how our species emerged and spread to dominate the planet, along with what happened to the Neanderthals and other late archaic groups in that process, are the oldest and most debated questions in the study of human evolution

2 For a long time, two contrasting models for Modern Human Origins predominated Multiregional Evolution Replacement (Out of Africa) Wolpoff Rightmire Stringer Klein

3 Assimilation Model (Smith) posits limited interbreeding and gene flow between archaic and modern human populations in some overlapping geographical zones and is supported by fossil genomic data. Evolutionary relationships among modern humans, Neanderthals and Denisovans as inferred from genomic data. Red arrows mark genetic evidence of interbreeding. Black arrows mark possible additional gene flow. From: Lalueza-Fox, C and Gilbert, MTP (2011) Current Biology 21:

4 Anatomical H. erectus Modernity Archaic H. sapiens Anatomically Modern H. sapiens

5 Vertical forehead Reduced or absent brow ridges Globular cranium Rounded rear vault Reduced face Canine fossa Pronounced chin Cranial Modernity Pentagonal vault

6 Homo sapiens Omo-Kibish I Ethiopia kya

7 Homo sapiens? (Some archaic features) kya Omo Kibish II, Ethiopia

8 D. Brill Herto 1, Ethiopia (160 kya)

9 Herto kya Modern features: high rounded neurocranium, parietal expansion, prominent forehead, and non-projecting face. Archaic features: prominent, medially thick supraorbital torus with supratoral sulcus, wide interorbital breadth, large heavily built zygomatic bones, very large vertical face, and long foramen magnum. On the verge of anatomical modernity, but not yet fully modern. Adult male found in Ethiopia (Afar) in 1997 (published in 2003). (AP Photo/Tim White, Nature)

10 Klasies River Mouth South Africa H. sapiens kya

11 Homo sapiens? Vertical forehead Klasies River Mouth (South Africa) kya Reduced brow ridge Chin

12 Skhul Qafzeh

13 Homo sapiens Near East Qafzeh 9 Israel 100 kya

14 Homo sapiens Middle East Skhul 5 Israel 100 kya

15 While genetic and archeological data suggest a rapid migration of modern humans out of Africa and into SE Asia by at least 60 kya, mainland SE Asia has lacked fossil evidence for early modern human occupation. Reconstruction of the modern human skull discovered in Tam Pa Ling (PNAS 2012): 50 ka cal BP In 2012, a modern human cranium from Tam Pa Ling, Laos, was reported with a C14 and luminescence dating of ca. 50,000 yrs Thus, this find appears to establish a modern humans in SE Asia at this time.

16 among the oldest directly dated EMHs in NE Asia An early modern human from Tianyuan Cave, Zhoukoudian, China. Dated to 42,000 39,000 kya using direct accelerator mass spectrometry radiocarbon. Note the modern chin morphology.

17 Fossil and archaeological evidence indicates that modern H. sapiens reached Australia by as early as 50 kya

18 What happened to Homo neanderthalensis when modern Homo sapiens spread across Europe?

19 Low brachial (arm) and crural (leg) indices. Forearm and lower leg are relatively short. Lagar Velho, Lapedo Valley, Portugal kya Neandertal, modern human Admixture? or Convergent Climatic adaptation?

20 cm Lagar Velho midfacial morphology (Franciscus, 2002)

21 +YOU SEARCH YOUTUBE MAPS PLAY NEWS GMAIL DRIVE BOOKS WALLET OXFORD University Press 2006 There is considerable minor variation in aspects of the neurocranium and the upper facial skeleton, and some variation in craniofacial robusticity, but the pattern is a consistent one that separates them from the Neandertals

22 Neandertals and modern humans could definitely interbreed, and, in fact, some of them unequivocally did. 7 May 2010

23 Denisovans

24 2014: Ust-Ishim 45,000 year old modern human femur

25 Peştera cu Oase 1 (2002) Romania Acc C kya BP Previous oldest directly dated modern human in Europe

26 The first study to incorporate Y-chromosome information from a Neanderthal

27 40,000 Europe 100,000 NE 25,000 Siberia 50,000 Eurasia 15,000 New World But why did modern humans spread globally and become the lone survivors? 200,000 Africa 56,000 Africa Origins and Dispersal of Modern Humans 40,000 Australia 30,000 S. Pacific Full Behavioral Modernity: persistent symbolism, extended social networks, cumulative cultural ratcheting, cumulative technology, global spread (LSA and UP) Sporadic Behavioral Modernity (Late MSA in Africa, and Mousterian in Europe) Anatomical and Genetic Modernity (African MSA)

28 Did superior technology and hunting skills of modern H. sapiens allow them to out-compete H. neanderthalensis and other pre-modern humans?

29 Upper Paleolithic blades bone, antler, ivory composite tools regional differences exotic materials

30 Was symbolic behavior and intensified social behavior the key to modern human success and dominance?

31 Blombos Cave, South Africa Ochre piece engraved with abstract designs (75 kya) Beads made from marine shells

32 Chauvet Cave Southern France Dated to ca. 32 kya

33 Vogelherd, Austria Upper Paleolithic mobilary art Sungir, Russia

34 Bone flute from Hohle Fels archaeological horizon Vb. bone and ivory flutes from the early Aurignacian period of southwestern Germany demonstrate the presence of a wellestablished musical tradition at the time when modern humans colonized Europe, more than 35,000 calendar years ago. Conard et al. (2009) Nature advance online publication doi: /nature08169

35 Venus figurines, such as the Venus of Willendorf from Austria, are found at numerous Upper Paleolithic sites in Europe. These figurines have long been interpreted as reflecting an emphasis on fertility.

36 Modern H. sapiens in the Upper Paleolithic buried their dead in elaborate burials. Arene Candide, Italy (20 kya) Red ochre was used to cover the body, which was adorned with ivory pendants and shell hats. Note the flint blade placed in the hand. This contrasts with the relatively simple burials of the Neandertals, who co-existed with modern H. sapiens in Europe.

37 The Skhul 5 burial and symbolism

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39 Irhoud ka Skhul Qafzeh ka Singa >133ka Herto ka Omo ka Eliye Springs >200ka Ngaloba ka Border Cave ka

40 40,000 Europe 100,000 NE 25,000 Siberia 50,000 Eurasia 15,000 New World 200,000 Africa 56,000 Africa Origins and Dispersal of Modern Humans 40,000 Australia 30,000 S. Pacific Full Behavioral Modernity: persistent symbolism, extended social networks, cumulative cultural ratcheting, cumulative technology, global spread (LSA and UP) Sporadic Behavioral Modernity (Late MSA in Africa, and Mousterian in Europe) Anatomical and Genetic Modernity (African MSA)

41 Craniofacial feminization in Homo sapiens 100,000 year old male from Skhul Cave (Israel) Recent male (scaled to same frontal chord length)

42 Additional work: Cieri RL, Churchill SE, Franciscus RG, Tan J, Hare B. (2014) Craniofacial feminization, social tolerance, and the origins of behavioral modernity. Curr Anthropol

43 Cieri RL, Churchill SE, Franciscus RG, Tan J, Hare B. (2014) Craniofacial feminization, social tolerance,and the origins of behavioral modernity. Curr Anthropol

44 The Self-domestication Model: Later anatomically modern humans are a selfdomesticated species where selection for behavioral modifications in the social environment allowed enhanced social tolerance, extended social networks and larger population densities with male and female movement between groups

45 Grandchild Child Behavioral Modernity Modern humans and wider social networks Kin and ingroup members Parent Grandparent Outgroup members Archaic humans and small social networks In or Child outgroup member Parent

46 The Self-domestication Model: Male movements between groups occurred through fear and aggression dampening via neuroendocrine shifts, and reduced levels of adult circulating testosterone. These changes, in turn, led to developmental timing alterations, which then produced a secondary cascade of diagnostic morphological shifts that define our species: gracilization ( feminization ), neotenizing of crania

47 "Major Transitions of Life on Earth" Modern humans have become a spectacular outlier species on the planet dominating and singularly affecting the Earth s major ecosystems How and why? The 6 th Extinction Permian-Triassic Extinction 3 th 1 st Ordovician-Silurian Extinction 2 nd Late Devonian Extinction 4 th Triassic-Jurassic Extinction 5 th Cretaceous K-T Extinction 500 million years ago Present day