There used to be several species of Homo - eventually gave rise to Homo erectus - about 1.8 millions yr ago ( may be older) - originated in East Africa - migrated extensively - Indonesia (Java man), China ( Peking Man) - compared to other Homo species - larger brain - flatter face, prominent brow ridges - height and walking similar to modern humans - tooth wear patterns - indicate meat eating - active users of tools - tool use evidence is present in the Australopithecus lines - first evidence of extensive tool use Homo habilis - contemporary of H. erectus
With large brains, migration and tool use Homo erectus was quite successful - lived as families in cave communities as recently as 35,000 yr ago - hunter gatherer society - males /female pairing - most primates have harems - co-existed for some time with Homo sapiens Homo sapiens Two main theories on their origin 1. Out of Africa hypothesis 2. Multi regional hypothesis
Out of Africa hypothesis • - H. erectus moved out of Africa • - population that remained behind evolved and gave rise to Homo sapiens • - from this single source, Homo sapiens migrated outward and displaced the H. erectus population • - this hypothesis predicts • - only one speciation event occurred in a restricted African population • - all humans should show a high degree of relatedness
Multi regional hypothesis • Homo sapiens evolved out of an interbreeding network of H. erectus that had migrated through out much of the world • - fossil record shows a gradual transition from archaic to modern human taking place at multiple sites outside of Africa. • Proposal - H erectus becomes gradually transformed into H. sapiens rather than being replaced by it.
Modern Homo Sapiens • Regional-Continuity Model (Milford Wolpoff, UMich) • Humans evolved more or less simultaneously across the entire Old World from several ancestral populations. • Rapid-Replacement Model (Chris Stringer, NHM London) • Humans evolved only once--in Africa from H. heidelbergensis ancestors--and then migrated throughout the Old World, • replacing their archaic predecessors. Also called the “Out of Africa” and “Killer Ape” hypothesis.
Support for Out of Africa - African populations have more diversity in DNA than non-African population - mitochondrial DNA analysis indicates a common African ancestor - calculation indicates origin about 200,000 yr ago