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Our Earliest Hominid Ancestors  Australopithecus Afarensis About 4.2 million years ago the first Australopithecus species evolved: Australopithecus anamensis. Australopithecus anamensis was about the size of a modern chimpanzee but males were much larger than females, (ref.)it had a large habitat range from Kenya to Ethiopia. By around 3 million years ago the Australopithecus species were dominating large areas of Africa and had branched out into distinct species: Australopithecus afarensis had a brain about 1/3rd the size of modern humans(ref.)and lived in a large area stretching from Tanzania to Ethiopia, meanwhile in South Africa, Australopithecus africanus had a slightly larger brain, smaller teeth, and a pelvis that was better adapted to upright walking.(ref.)(See map 2: 3 million years ago) Large Jaws versus Large Brains By 2 million years ago, some Australopithecines were adapting to a diet of nuts and seeds by evolving huge teeth and powerful jaw muscles, these became a separate species known as Paranthropus,(ref.)colloquially known as “Nutcracker Man”. Whilst other Australopithecines were evolving in a very different direction, becoming taller (i.e. Australopithecus sediba), and then developing smaller teeth but a larger brain so that they were capable of making tools out of stone. These became known as the genus Homo. The first Homo species was Homo habilis (“Handy Man”). For almost a million years the hominid species with large brains (Homo) and the hominid species with large jaws (Paranthropus) lived alongside each other in East Africa. But the brain size of the Homo species kept growing through the process of natural selection: the smarter hominids with the best tool making skills were better able to survive and pass their genes on. Eventually the big brained Homo species simply out competed the large jawed Paranthropus species, which went extinct by about 1 million years ago. (ref.) The most successful species of the genus Homo in this period was Homo erectus. This species, by 1.4 million years ago had developed a brain size of 1,000 cubic centimetres (ref.)(about 70% of the size of modern man). Not only did Homo erectus come to dominate Africa after all the other hominid species went extinct, but it was also the first hominid species to migrate out of Africa and settle in Asia and Europe. (See map 4: 1.6 million years ago) |
