Our ancestors were Australopithecines 2 – 3 MYA, a good fraction of Chapter 6. Of the known late Australopithecine species, those considered to be closest to the root of the human family tree are africanus (S. Africa, 2 – 3.5 MYA; see Chapter 7 gallery), sediba (S. Africa, 2 MYA) and garhi (Ethiopia, 2.5 MYA). It is impossible to pinpoint the Australopithecus / Homo juncture down to the species level, but our ancestors of 2 – 3 MYA probably bore a strong resemblance to one of these known specimens.The oldest fossil assigned to Homo so far has been H. habilis (eastern and southern Africa, 1.5 – 2.5 MYA). Habilis still had an Australopithecine body: chimp-sized, with long arms and short legs. Its human-like qualities were a flatter face, larger brain, and tool-making skills. Some habilis specimens show early signs of the forward-projecting nose. 1Homo ergaster (eastern and southern Africa, 1.4 – 1.9 MYA) was an early African version (or ancestor) of Homo erectus. Two views are shown below.
Homo ergaster / erectus had a body virtually identical to ours, just slightly more robust. (This model is an adolescent boy). The main differences between ergaster / erectus and sapiens were in the face and skull. Erectus had prominent brow ridges and a long, flat skull. The teeth and jaws were large, with no chin. Otherwise, he was clearly recognizable as human.
Human appearances didn’t change much for the rest of Chapter 6. Paleontologists give different names to specimens based on their time / place and slightly different proportions. For instance, Homo heidelbergensis (at least 600 – 400 TYA) had a slightly larger brain and more rounded skull than erectus. It was found in Europe and Africa after 500 TYA, at a time when the erectus habitat was restricted to southeast Asia. 2
Continue to Chapter 5 (target completion date 12/31/18)
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