PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22New Models or Hypotheses to learnfor Part III1. Out-of-Africa vs. Multiregional Where/how Homo sapiens arose given that humans were already spread across a large geographic area2. Gradualism vs Punctuated equilibrium The rate by which speciation occursQuestion 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 becameArchaic H. sapiens, who became modern H. sapiens- So all H. sapiens worldwide would be about the sameage (as seen in modern genetic variation), - all show up modern about the same time, and- we’d see some regional traits that trace backto the local H. erectus populationsAssumes widespread gene flow (which we have today,but back then there were fewer people and only foottransportation)Out-of-Africa model:Even though first H. erectus and then Archaic H. sapienswere geographically widespread,Only some populations in Africa first evolved intomodern H. sapiens. They then spread out and replacedthe other Archaic H. sapiens populations- You’d expect the oldest population in Africa to haveaccumulated more genetic diversity among modernpeople;- You’d expect to find the oldest modern H. sapiens firstin one area in Africa while all other populations werestill Archaic H. sapiens- You would not expect to find the same regional traitsthat were in local H. erectus populationsMostly Out of Africa Model1. Homo erectus spread out of Africa2. Modern Homo sapiens originated inAfrica and spread out3. Gene flow was not restricted or one-way,so that present genetic variability reflectsboth local older developments and more recent African developmentsLIKELY TEST QUESTION:What evidence would support either hypothesis?Fossil evidenceCultural evidenceModern genetic evidence(Feder and Park 2007:310)Major early Homo sapiens sites195,000 ya120,000 ya36,000 ya30,000 ya18,000 yaFOSSIL EVIDENCETheories or models on the rate of speciationa. Gradualism change is slow and gradual enough change accumulates, we call something a new speciesFossil evidence: transitional forms showing gradual changeb. Punctuated equilibriumA species has a long period of equilibrium(little to no change), punctuated by a burst of changeinto a new speciesPerhaps through the mechanism of macromutation(a mutation with far-reaching results)What examples have we seenin the fossil record for human evolution?Punctuated equilibrium GradualismBipedalism!First H. erectus?Within H. erectus(equilibrium)Archaic Homo sapiens(transitional betweenH. erectus and H. sapiensMini-review of hominid lineageduring 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 habilis2.4 to 1.5 mya in eastern and southern Africa500 to 800 (x of 680) mlJohn 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 scavengingTied to Expensive Tissue Hypothesis:Brain got substantially larger when the gut shrank,as evidenced by the change in rib cage shapeHomo erectus1.8 mya to 250,000 ya800 to1250 (x of 1000) mlRadiate out of Africa(Jolly & White 1995:268)Homo erectus1.8 mya to 250,000 ya800 to1250 (x of 1000) mlAfrica, Europe, AsiaJohn GurcheArchaic Homo sapiens800,000 - 30,000 yaTransitional between H. erectus and H. sapiens Modern body (muscular) Cranium not modernWidespread geographically (Africa, Europe, Asia)Lot of regional variationSeveral regional populations recognizedTwo regional populations we recognize:H. heidelbergensis in Europe (800,000-100,000 ya) Levallois prepared core stone tool technologyH. neanderthalensis around the Mediterranean (300,000 - 30,000 ya) Mousterian tools made from flakes. First to bury dead.Feder & Park 2001:264)ice All archaic are not NeandertalsNeandertals are simply one regional population - the Mediterranean oneHomo neanderthalensis300,000 to 30,000 yaJohn GurcheHomo neanderthalensis300,000 to 30,000 yaJohn GurcheHomo neanderthalensis300,000 to 30,000 yaJohn GurcheWere Neandertals OUR ancestors?DNA indicates they were to a small extent -- theywere otherwise a regional population ofarchaic H. sapiens who went extinctAny gene flow withanatomically modern H. sapiens,was minorAnatomically modern Homo sapiensEarliest finds date to 195,000-150,000 yain eastern and southern AfricaThese are transitional betweenArchaic and modernBy 100,000 ya, unquestionably modern Homo sapiens (no longer transitional)in eastern AfricaBy 30,00 ya,ALL humans are anatomically modern H. sapiens(except “hobbits,” H. floresiensisIt is H. sapiens who colonize the remaining areasof the world: e.g., America, Australia,
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