A lower jaw and other skull and skeletal remains found in 1960 and 1963 in the Olduvai Gorge, Kenya, by Louis Leakey and others, could be the oldest species of our own genus, Homo. This hominid had a large brain, in the range of 630-700 cm3, and its hands had the manipulative ability to make tools, hence its name Homo habilis (literally 'handy man'). A more complete skull
(Figure 11.11) found ten years later near Lake Turkana (formerly Lake Rudolf) in Kenya, by Richard Leakey, was also assigned to H. habilis. This specimen showed a brain size of about 700 cm3.With a height of only 1.3 m, this falls within the modern human range.
The identity of these early Homo specimens from Olduvai and Lake Turkana has been much debated, but most palaeoanthropologists now recognize two species, H. habilis for the Olduvai and some Lake Turkana specimens, and H. rudolfensis for other Lake Turkana specimens, including the fine skull (Figure 11.11). These species are distinguished (Wood and Collard, 1999) on the basis of a number of characters. Homo rudolfensis has a larger mean brain size, but appears to be primitive in other skull features (smaller 'eyebrow ridge', palate large). These two species differ so much from later species of Homo that they might even be better assigned to an australopith genus (Wood and Collard, 1999).
The remains of H. habilis and H. rudolfensis are dated as 2.4-1.5 Myr old and they have been found in association with the remains of various species of australopith. This conjures up the striking notion of four or five different human species living side by side and presumably interacting in various ways.
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