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Overview of Human Evolution Hominids Through Time Lake Turkana, Kenya Kenyanthropus platyops Found in 2001 west of Lake Turkana in northern Kenya. Found in deposits dating between 3.2 and 3.5 mya
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Kenyanthropus platyops • Found in 2001 west of Lake Turkana in northern Kenya. • Found in deposits dating between 3.2 and 3.5 mya • Shows mixture of features, including very small, chimpanzee like braincase and flat, vertically straight face also seen in much later, more human-like specimens from the same area • Distinct from A. afarensis which lived in the same region and at the same time • However,some suggest the cranium is too damaged to properly diagnose
The Transition to More Modern-Like Hominids Homo habilis Homo rudolfensis Homo erectus ergaster • These hominids lived at approximately the same time (1.8 – 1.6 mya) around Lake Turkana in western Kenya • Cranium & brow of H. habilis more similar to H. erectus • Face & skeletonof H. habilis , however, more similar to that of australopithecines • Face & skeleton of H. rudolfensis more similar to H. erectus • Cranium of H. rudolfensis shaped quite differently from H. erectus, appears surprisingly modern, while face is very similar to the much earlier Kenyanthropus • How these specimens relate to each other and other hominids is still much debated!
Homo habilis at Olduvai Gorge, Tanzania • While brain case and face of H. habilis more human-like • Skeletal remains discovered at Olduvai Gorge in 1986 by Don Johanson revealed limb sizes and proportions nearly identical to those seen in australopithecines • H. habilis had mosaic of ancestral and derived features! • 2 distinct forms of human— H. habilis & H. erectus--lived in East Africa slightly after 1.8 mya • Found in 1968 @Olduvai Hominid 24 above and at far right, was most complete specimen of H. habilis known until the discovery of similar material at Lake Turkana in the mid 1970s • Brain size & face showed definite advances towards more human-like form than seen in australopithecines
The Turkana Boy Skeleton • 90% of the skeleton of an adolescent male H. erectus found west of Lake Turkana in the mid 1980s • Approx. 1.6 mya, a very modern skeleton, virtually indistinguishable from that of fully modern human • Represents early form of H. erectuscalled H. ergaster: retains features seen in other hominids from East Africa (smaller facial bones, smaller cranial capacity—850 v. 950 ml) • Recent finds in the former Soviet rebulic of Georgi dated to 1.8 mya have been interpreted as a result of dispersal of early H. erectus “out of Africa” • However, some suggest that H. erectus may have evolved “out of Africa” and dispersed into the AF continent when other native hominids were present
Four Contemporaneous Hominid Species from Lake Turkana Australopithecus boisie Homo erectus ergaster Homo habilis Homo rudolfensis
First Dispersal “Out of Africa” at 1.8 mya or Earlier? Three Crania from Dmanisi, Georgia
