Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [46]
In December 1975, at the end of the Hadar season, Johanson took his First Family to Nairobi to show the Leakeys and to gain their opinions. ‘When I spread out the haul of new bones, they were an instant sensation’, Johanson wrote. ‘Nothing that combined their extreme antiquity, their remarkable quality and their profusion had ever been encountered before’. Examining the fossils, both Mary and Richard Leakey concurred with Johanson that they appeared to be early examples of the genus Homo.
Among the scientists who had gathered around a specimen table at the Nairobi Museum was Tim White, a twenty-five-year-old graduate student from the University of Michigan who had spent two seasons with Richard Leakey’s team at Koobi Fora. Although known for his prickly and abrasive temperament, White had impressed Leakey with his sharp intellect and passion for scientific accuracy. When Mary Leakey was seeking specialist help with the anatomical description of her Laetoli hominids, Richard had recommended White. Mary Leakey, too, had been impressed by the quality of White’s work. But on this occasion White was unusually reticent.
Johanson noticed him ‘lurking’ in the background—‘an owl-eyed young man with thick glasses, lank blond hair and a white lab coat’—and assumed him to be shy. But White was simply wary of Johanson’s brash presentation. ‘I was just being sensibly cautious’, White subsequently recounted in conversation with Johanson. ‘There you were, the smooth young hotshot, shooting off your mouth about all your great fossils. I’d never met you before. I didn’t know if you could tell a hippo rib from a rhino tail. I was just waiting for you to fall on your face, say something really dumb’.
In due course, White stepped forward to examine the Hadar specimens. ‘I think your fossils from Hadar and Mary’s fossils from Laetoli may be the same’, he said.
It was an idea that would eventually explode into yet another controversy.
The 1976 season at Laetoli brought further stunning success. By sheer chance, a group of scientists on a short visit from Kenya stumbled across an entirely new phenomenon: ancient footprints. Walking back to Mary’s camp one morning in July, they began to amuse themselves by tossing lumps of dried elephant dung at each other. Searching for more dung supplies, Andrew Hill, a palaeontologist who worked for the Nairobi Museum, jumped down into a flat gully and spotted what appeared to be elephant tracks. Falling to his knees to examine them, he realised they were not fresh tracks but fossilised elephant footprints preserved in a layer of volcanic ash. Scattered around them lay the prints of other animals—antelope, buffalo and giraffe. Tiny indentations in the tuff later turned out to be caused by ancient raindrops.
The focus of attention at Laetoli switched to this new locality—Site A, as it was called. The profusion of prints uncovered was extraordinary. Site A alone contained 18,400 prints, ranging from elephant to insect tracks. But Mary’s team soon discovered that the same layer of volcanic ash—the Footprint Tuff—occurred elsewhere at Laetoli. By the end of the 1976 season, they had found three more sites with animal prints, and the eventual total reached eighteen.
Piecing together what had happened at Laetoli, an American geologist, Richard Hay, concluded that about 3.6 million years ago, the volcano Sadiman began a spate of eruptions, showering the plains below with light ashfalls. The ashfalls continued for a period of several weeks, leaving a series of fine laminations on the ground, just as the dry season was giving way to the onset of rains. The ash contained a