Ch 11 Modern Homo sapiens

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SummaryFinal redtape

Modern human morphology

Origins and dispersal

Important fossil finds

Modern human/Upper paleolithic culture

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Modern humans - morphology and overview

Anatomically modern human = AMH

*Continued evolutionary trends: bipedalism, tool manufacturing, dental reduction, brain size

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Origins and dispersal - Regional Continuity Model

Question: Why is there uniform morphology across populations?

Regional Continuity ModelMilford Wolpoff

-Local populations in Europe, Asia, and Africa evolved from Middle Pleistocene hominins to AMH

Confirms the hypothesis-Frequent migrations between the different geographically-dispersed premodern populations during Pleistocene

SO: gene flow prevented local populations from evolving separately

Disconfirms the hypothesisRecent genetic data ultimately fails to confirm the multiregional models

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Complete Replacement

-African origin ~200 kya then dispersed and replaced Old World populations-no interbreeding with premodern H. sapiens

Disconfirms the hypothesisNewer molecular evidence of interbreeding between humans and Neandertals

Partial Replacement Model(s)

SO: revise to partial replacement - AMH emerged in Africa and then interbred with premodern humans in the various regions

Confirms the hypothesis-African origins but 1-4% interbreeding between AMH and premodern populationsModern Africans lack Neandertal genes - so interbreeding likely occurred AFTER AMH left Africa ~80-50 kya

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Origins and dispersal - Replacement Models

Important fossil findsAfrica

* Omo Kibish, Ethiopia - earliest fossils for Homo sapiens radiometrically dated ~195 kya

* Herto, Ethiopia ~160-154 kya based on cranial morphology (nearly identical to modern cranial morphology)Fossil finds used to argue for AMH originating in Africa

Near East

* Skhul and Qafzeh Caves; Israel-both sites ~130-100 kya and 120-90 kya, respectfully with the remains of 30 individuals retaining some premodern human traits

Note: Tabun site has Neandertal dated ~120 kya which adds some support to the area being a place where AMH and Neandertal interbred 6

Important fossil finds

Asia

* Zhoukoudian Caves again-AMH dated ~27 kya

Oceania

-All Australians descending from participants of a single migratory event ~50 kya-AMH inhabited areas around New Guinea and Aus ~50 kya

* Lake Mungo - 30-25 kya according to archaeological finds

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Modern human/Upper paleolithic culture

Upper Paleolithic ~40 kya in Europe -emergence of new tool types made of materials like bone, antler, etcCultural finds in Eurasia feature elaborate burials with grave goods

Warming trend ~30 kya resulted in tundra and steppe across Eurasia where large game was huntedIntense period of glaciation ~20 kya

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Modern human/Upper paleolithic culture

Magdalenian-spear thrower - atlatl appearsPunch blade technique - standardized blades for various usages - burins and borers

Hypothesis: more effective tools and usage of fire aided in meat processing might have played a role in AMH dental reduction

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Modern human/Upper paleolithic culture

-emergence of cave paintings in W Europe and portable artVenus figurines

-function/purpose of cave art not fully understood

Rock art also found in Africa dating ~28 kyaAlso find finely crafted bone tools dated ~80 kya

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-human evolution makes sense only in a cultural context

Sickle-cell trait - adopting slash-and-burn agriculture resulted in humans living closer to/in mosquito breeding areas-so HbS became more frequent in the population-interacted with DDT

Lactose intolerance - produce less of the enzyme lactaseLactase persistence - European groups sharing descent from Middle Eastern populations who were pastoralists^-Cultural dependence on milke increased the frequency of lactose tolerance in populations via natural selection

Examples that we're still evolving?

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Some Ch 12 - Biocultural Evolution