Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [38]
The team also came across evidence of ancient stone tools. While collecting samples of volcanic ash for dating purposes, a young American geologist, Kay Behrensmeyer, discovered a number of lava flakes lying on the surface of the ‘tuff’—a layer of consolidated ash. An excavation at the site, which became known as the Kay Behrensmeyer Site, or KBS, revealed more stone tools. The tools came from a layer that Leakey estimated was at least as old as the oldest layer at Olduvai—about 1.9 million years old. Samples of the tuff sent to England for analysis, however, suggested a date of 2.6 million years. This meant that the tools at KBS were the oldest that had ever been discovered. Leakey was naturally delighted by the finding. But it marked the start of a controversy that plagued the scientific community for a decade.
By the end of the second expedition, the volcanic badlands of East Turkana were considered to be one of the most promising fossil sites ever discovered. Impressed by Clark Howell’s multidisciplinary approach at Omo—where American and French scientists were still at work—Leakey set out to establish a similar research project based at Koobi Fora, recruiting a wide range of specialist scientists. His principal role became acting as their coordinator. With each new season, the tally of fossil finds soared—skulls, jaws and limb bones. In 1970, it included sixteen hominid specimens; in 1971, twenty-six.
The 1972 season produced an even more spectacular result. Stopping to examine a small pile of fragmented fossils on the surface of a steep gully, a novice member of the Hominid Gang, Bernard Ngeneo, who had been taken on at Koobi Fora as a cook’s assistant, thought he saw a piece of hominid bone. Other members of the search team had previously noticed the same pile but had assumed the fragments were antelope remains and had not bothered to investigate. After weeks of sieving, some 150 broken pieces of a hominid skull were recovered from the site. The task of piecing them together was undertaken by Leakey’s wife, Meave, and a British-born anatomist, Alan Walker. Both possessed a particular aptitude for such painstaking work. As children, growing bored with ordinary jigsaw puzzles, they had both taken to making them more difficult by turning the pieces upside down, hiding the picture. Duly reassembled, the skull appeared to have a cranium capacity of about 800 cubic centimetres, far larger than the brain size of any known australopithecine and also Louis Leakey’s Homo habilis. Moreover, it seemed to be far older. From its stratigraphic position below the KBS tuff, its age was estimated as at least 2.6 million years, possibly as old as 2.9 million years. It was given no name but was known by its catalogue number: 1470.
A difference of opinion soon emerged at Koobi Fora about the status of 1470. Alan Walker observed that apart from its large brain, it differed little from Australopithecus africanus. Leakey disagreed. He was convinced that it was a species of Homo—and therefore represented the world’s ‘earliest known man’. To avoid the kind of controversy that had erupted over Homo habilis, in an article in Nature, Leakey attributed it to an indeterminate species of Homo and called it Homo sp. indet.
In jubilant mood, Leakey took the skull to Nairobi to show his father, knowing how pleased he would be to see such evidence supporting his long-cherished belief in human antiquity. Their relationship had been strained for many years, but this was a cause for celebration. Louis’s whole face lit up. A Homo skull with a large brain dating back more than 2 million years vindicated his decision to establish a new human species for ‘pre-Zinj’—Homo habilis. Furthermore, it helped validate his contention that early humans and australopithecines had lived a contemporary existence, making it unlikely that australopithecines were a human ancestor.