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Unformatted text preview: DEC 14 th 1230-1530 2 nd Floor Student Union Building LECTURE 27 The Four Forces of Evolution->Mutation Only source of new variation->Selection Acts to diverge populations directionally->Drift Acts to diverge populations randomly->Migration Genetic glue KEY EVENTS Bipedal 6.0.mya Loss of honing complex 6.0mya Reduced canine dimorphism 3.5mya Regular use of modified stone tools 2.6mya Regular use of animal carcasses 2.5mya First relative brain enlargement 2.0mya First major dispersal event (diaspora) 2.0mya Earliest Homo sapiens 160,000 Ardipithecus->Not a knuckle walker (knuckle walking is a derived trait, has evolved twice in history convergent/parallel evolution) The Neanderthals Earliest = Krapina, Croatia (~130kya) Latest = Zafarraya in southeastern Spain (~160kya) He rto 160kya anatomically modern but not like any modern human Humans have little mtDNA variation, equivalent to a chimp subspecies Sources of Variation-Geographic differentiation-Growth (ontogeny)-Idiosyncrasies...
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- Spring '08