Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [63]
Nevertheless, the clear possibility remained that there were at least two different bipedal human ancestors living at the same time more than 3 million years ago. Palaeoanthropologists saw this as evidence of ‘adaptive radiation’, the rapid diversification of species—splitting again and again—that occurs after an initial evolutionary innovation. Although adaptive radiation had long been accepted as a fundamental principle of animal evolution, as shown, for example, by the proliferation of the cat family, when it came to human evolution, many experts had preferred to stick to the notion of linear development. ‘We used to look for simplicity because we wanted a neat picture’, observed Daniel Lieberman, a George Washington University palaeontologist. Since the 1970s, there had been a growing body of evidence to suggest that more than one species or lineage of hominid had existed simultaneously—but only from 2 million years ago. Lucy had been portrayed as the single common ancestor. But the discovery of Kenyanthropus platyops pushed back the boundaries of multiple species to at least 3.5 million years. ‘It shows that our past is like that of any other mammal’, said Leakey. ‘[We have] a very complicated diverse past with lots of different species; many of which became extinct’.
No sooner had Kenyanthropus platyops appeared on the stage than another remarkable discovery was made by researchers exploring the Tugen Hills, a sixty-mile stretch of rugged terrain west of Lake Baringo in central Kenya. The fossils discovered there dated back 6 million years—the oldest bones yet known. But the occasion was remembered as much for an outbreak of vicious rivalry among palaeoanthropologists as for the discovery itself.
The Tugen Hills, a huge fault block standing in the middle of the Rift Valley, had long excited the interest of geologists and palaeontologists. Its layers of sediments provided a window on the past stretching back 16 million years. Since expeditions had first been launched there in the 1960s, thousands of animal fossils had been discovered.
In 1974, a thirty-one-year-old geologist, Martin Pickford, spotted a hominid molar in the 6-million-year-old Lukeino Formation, but its significance was overshadowed by the discovery of Lucy that same year. Pickford had an aptitude for rough terrain. Although born in Britain, he had spent much of his childhood on a Kenyan farm. While at school in Nairobi, he had befriended Richard Leakey. As a geology student, he worked in the Tugen Hills over a period of eight years during the 1970s, earning a doctorate from the University of London. Many colleagues, however, found his blunt manner and aloofness difficult to take. For his part, Pickford appeared to relish his role as an outsider.
In 1980, a British-born Harvard professor, David Pilbeam, was awarded a grant to establish a new research enterprise covering the Tugen Hills and the adjacent valley around Lake Baringo—the Baringo Paleontological Research Project. Pilbeam chose as field director Andrew Hill, an affable British-born geologist who had first worked in the Tugen Hills as a student in 1968. The appointment was approved by Richard Leakey, then the director of Kenya’s National Museums, who had ultimate control over the granting of research permits. Despite Pickford’s years of research in the Tugen Hills, he was not invited to join the project. Pickford was given a post as a geologist at the National Museums, but he felt aggrieved at being excluded from the Tugen Hills project and from palaeontological work. In 1984, his contract was not renewed.
The following year, Pickford embarked on a project to explore fossil sites in Uganda previously surveyed in the 1950s by a renowned British geologist, William Bishop. He was accompanied by a French palaeontologist, Brigitte Senut, from the National Museum of Natural History in Paris. On their way to Uganda, they decided to stop off in Nairobi to study Bishop’s notebooks, which were held by Kenya’s National Museums.
It was a fateful visit. Leakey accused Pickford of attempting to