New Models or Hypotheses to learn for Part III 1 Out of Africa vs Multiregional Where how Homo sapiens arose given that humans were already spread across a large geographic area 2 Gradualism vs Punctuated equilibrium The rate by which speciation occurs Question about evolution to or origin of modern H sapiens Did all regional populations evolve or just one Multiregional model All the far flung H erectus populations became Archaic H sapiens who became modern H sapiens So all H sapiens worldwide would be about the same age as seen in modern genetic variation all show up modern about the same time and we d see some regional traits that trace back to the local H erectus populations Assumes widespread gene flow which we have today but back then there were fewer people and only foot transportation Out of Africa model Even though first H erectus and then Archaic H sapiens were geographically widespread Only some populations in Africa first evolved into modern H sapiens They then spread out and replaced the other Archaic H sapiens populations You d expect the oldest population in Africa to have accumulated more genetic diversity among modern people You d expect to find the oldest modern H sapiens first in one area in Africa while all other populations were still Archaic H sapiens You would not expect to find the same regional traits that were in local H erectus populations Mostly Out of Africa Model 1 Homo erectus spread out of Africa 2 Modern Homo sapiens originated in Africa and spread out 3 Gene flow was not restricted or one way so that present genetic variability reflects both local older developments and more recent African developments LIKELY TEST QUESTION What evidence would support either hypothesis Fossil evidence Cultural evidence Modern genetic evidence 30 000 ya 36 000 ya 18 000 ya 195 000 ya FOSSIL EVIDENCE 120 000 ya Feder and Park 2007 310 Major early Homo sapiens sites Theories or models on the rate of speciation a Gradualism change is slow and gradual enough change accumulates we call something a new species Fossil evidence transitional forms showing gradual change b Punctuated equilibrium A species has a long period of equilibrium little to no change punctuated by a burst of change into a new species Perhaps through the mechanism of macromutation a mutation with far reaching results What examples have we seen in the fossil record for human evolution Punctuated equilibrium Bipedalism First H erectus Within H erectus equilibrium Gradualism Archaic Homo sapiens transitional between H erectus and H sapiens Mini review of hominid lineage during the Pleistocene 1 8 mya 10 000 ya Homo habilis 2 4 1 5 mya only in Africa body not modern cranium not modern Does have first larger brain than Australopithecine First to make stone tools Possibly had language More meat scavenged Homo habilis 2 4 to 1 5 mya in eastern and southern Africa 500 to 800 x of 680 ml John Gurche Smithsonian Institution Homo erectus 1 8 mya 250 000 ya earliest H ergaster First to radiate out of Africa First modern body but stocky muscular Cranium not modern but average size falls within modern size New tools Acheulian hand axe Has language shelter fire clothing By end is hunting rather than scavenging Tied to Expensive Tissue Hypothesis Brain got substantially larger when the gut shrank as evidenced by the change in rib cage shape Homo erectus 1 8 mya to 250 000 ya 800 to1250 x of 1000 ml Radiate out of Africa Jolly White 1995 268 John Gurche Homo erectus 1 8 mya to 250 000 ya 800 to1250 x of 1000 ml Africa Europe Asia Archaic Homo sapiens 800 000 30 000 ya Transitional between H erectus and H sapiens Modern body muscular Cranium not modern Widespread geographically Africa Europe Asia Lot of regional variation Several regional populations recognized Two regional populations we recognize H heidelbergensis in Europe 800 000 100 000 ya Levallois prepared core stone tool technology H neanderthalensis around the Mediterranean 300 000 30 000 ya Mousterian tools made from flakes First to bury dead ice Feder Park 2001 264 All archaic are not Neandertals Neandertals are simply one regional population the Mediterranean one Homo neanderthalensis 300 000 to 30 000 ya John Gurche Homo neanderthalensis 300 000 to 30 000 ya John Gurche Homo neanderthalensis 300 000 to 30 000 ya John Gurche Were Neandertals OUR ancestors DNA indicates they were to a small extent they were otherwise a regional population of archaic H sapiens who went extinct Any gene flow with anatomically modern H sapiens was minor Anatomically modern Homo sapiens Earliest finds date to 195 000 150 000 ya in eastern and southern Africa These are transitional between Archaic and modern By 100 000 ya unquestionably modern Homo sapiens no longer transitional in eastern Africa By 30 00 ya ALL humans are anatomically modern H sapiens except hobbits H floresiensis It is H sapiens who colonize the remaining areas of the world e g America Australia Siberia
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