By studying early hominids (large, bipedal primates) that date back to millions of years, anthropologists can track the development of the human race. When exploring anthropology, keep these important points in mind:
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The evolutionary process shapes species by replication, variation, and selection, leading to adaptation.
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Humans are one of roughly 200 species of the Primate order, a biological group that's been evolving for about 60 million years.
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Hominids appear (only in Africa) by at least 4 million years ago with the following adaptive characteristics: bipedalism (habitually walking on two legs), encephalization (larger brains than expected for their body size), small teeth (smaller teeth than expected for their body size — the canines in particular).
| Hominid Group, Diet, and Tool Use | Some Genera and Species Included | Fossil Finds | Dates | Evolutionary Fate |
|---|---|---|---|---|
| Gracile australopithecines: omnivorous diet with little tool use | Australopithecus afarensis, Australopithecus africanus | A. afarensis in Ethiopia, and A. africanus at many sites in South and East Africa | Over 4 million years ago (A. afarensis) to about 2 million years ago (later A. africanus) | A. afarensis probably ancestral to A. africanus; A. africanus probably ancestral to early Homo |
| Robust australopithecines: more herbivorous diet with little or no tool use. | Australopithecus aethiopicus, Australopithecus robustus | A. aethiopicus and A. boisei in East Africa, A. robustus in South Africa | Over 2 million years ago (A. aethipoicus) to about 1 million years ago (late A. robustus) | Extinction around 1 million years ago |
| Early Homo: omnivorous diet with more animal tissue consumption and survival relying on tool use. | Homo habilis, Homo rudolfensis, earliest Homo erectus | Olduvai Gorge, Tanzania and Koobi Fora, Kenya | Earliest Homo around 2.5 million years ago; clearly H. erectus by 1.8 million years ago | Evolved into H. erectus by 1.8 million years ago |
