Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [33]
Other experts whom Leakey contacted provided further support for his claims. John Napier, a hand specialist at the Royal Free Hospital in London, concluded that the ‘pre-Zinj’ hand bones displayed modern features, including a long opposable thumb. Its hands, he said, were capable of two types of grip, a power grip and a precision grip, both essential requisites for a toolmaker. Such a hand, he noted, would have had the ‘physical capacity’ to make the small pebbletools found at Olduvai. The foot bones added to the evidence. Examined by Michael Day of the Royal Free Hospital, they indicated that ‘pre-Zinj’ was bipedal, walking upright, not just occasionally but habitually.
In sum, the corpus of evidence that Leakey assembled depicted a small, slenderly built creature, with a relatively large brain, larger than any australopithecine, humanlike teeth and hands capable of making tools. It lived nearly 2 million years ago; and, according to Leakey, was a direct precursor of modern man.
Announcing their findings in a joint paper published in Nature on 4 April 1964, Leakey, Tobias and Napier set off a storm of controversy. For in order to incorporate ‘pre-Zinj’ within the genus Homo, they needed to rework the definition of Homo.
‘We have come to the conclusion that, apart from Australopithecus (Zinjanthropus), the specimens we are dealing with from Bed I and the lower part of Bed II at Olduvai represent a single species of the genus Homo and not an australopithecine’, they wrote. ‘But if we are to include the new material in the genus Homo (rather than set up a distinct genus for it, which we believe to be unwise), it became necessary to revise the diagnosis of this genus’.
They set the new cerebral Rubicon at 600 cubic centimetres. ‘The cranial capacity is very variable but is, on average, larger than the range of capacities of members of the genus Australopithecus, although the lower part of the range of capacities in the genus Homo overlaps with the upper part of the range of Australopithecus; the capacity is (on average) larger relative to body-size and ranges from about 600 c.c. in earlier forms to more than 1,600 c.c.’
This new species of human was given the name Homo habilis. The name had been devised by Raymond Dart to describe what was said to be the world’s first toolmaker, someone who was ‘able, handy, mentally skilful, vigorous’—a ‘handy man’.
Although Leakey had previously held firm to his belief that Zinjanthropus had been the ‘earliest known stone-tool making man’, he now agreed that Zinjanthropus was no more than an australopithecine probably incapable of making tools. But by switching his allegiance with such nonchalance from Zinjanthropus to Homo habilis as the toolmaker, he endured severe criticism.
There was even harsher condemnation of his arbitrary attempt to make radical alterations to the accepted definition of Homo in order to shoehorn ‘pre-Zinj’ into it. Le Gros Clark continued to insist that ‘pre-Zinj’ was an australopithecine. ‘One is led to hope that [Homo habilis] will disappear as rapidly as he came’, wrote Le Gros Clark. Critics also accused Leakey of confusing cultural notions about ‘man the toolmaker’ with morphological evidence. They pointed out that even though stone tools had been found with both Zinjanthropus and Homo habilis, Leakey had seen fit to claim that it was ‘probable’ that Homo habilis had been the ‘more advanced toolmaker’—without producing any evidence. He had merely assumed that because Homo habilis appeared to have a larger brain, it was the more likely candidate to have