Born in Africa

A GOLDEN AGE of exploration followed the discovery of Zinj. The scientific community was by now generally agreed that Africa rather than Asia was the most likely birthplace of humankind. Inspired by Louis Leakey’s publicity campaign and by television programmes about Zinj, popular interest in human origins soared. A new generation of students took up the cause of palaeoanthropology. Funds for more fieldwork were readily available.

At Olduvai, the Leakeys were able to construct a permanent camp for the first time, to recruit full-time African staff and to invite specialist scientists to assist them. Mary spent most of her time there directing excavations, making only short visits to Nairobi. Louis was preoccupied with his work as curator of the National Museum in Nairobi and with numerous other projects and joined her for weekends and vacations. Each year he conducted long lecture tours in the United States, thrilling American audiences with impassioned accounts of his work on human origins and raising more funds. ‘As the years passed’, wrote Mary in her memoirs, ‘his reception in at least some parts of the States turned to outright hero-worship’.

The 1960 season at Olduvai proved highly productive. In May, the Leakeys’ nineteen-year-old son, Jonathan, wandering off on a fossil hunt of his own, discovered a fragment of the mandible of a sabre-toothed cat lying on the surface about 100 yards from the Zinj site. Hoping to find further remains, Jonathan sieved through surface deposits. Nothing more of the cat turned up, but he found instead a hominid tooth and toe bone. With growing excitement, a new excavation was started at what became known as ‘Jonny’s site’. In August, Mary uncovered fourteen foot bones there—the first discovery of the foot of an early human. In the following weeks, ‘Jonny’s site’ yielded remains from several different specimens—hand bones, parts of a skull and a lower jaw complete with thirteen opalescent teeth. The skull bones appeared distinctly different from those of its neighbour Zinj: They were thinner; the braincase was larger; there was no sagittal crest.

Assessing the evidence, Louis Leakey became increasingly convinced that the fossils from ‘Jonny’s site’ represented a new species, a primitive Homo, possibly the toolmaker he had long sought. He was also struck by the similar age of the two sites. The fossils at ‘Jonny’s site’ had come from deposits one foot lower than the Zinj deposits, making them slightly older but contemporary. What this meant, Leakey believed, was that ‘two entirely distinct hominids’ had lived together at Olduvai, ‘side by side’.

Determined to avoid controversy, Louis compiled a straightforward report of the new discoveries for publication in Nature in February 1961, refraining from speculation. He gave a similarly cautious account at a press conference at the headquarters of the National Geographic Society in Washington in February. The skull, he said, belonged to a juvenile about eleven years old. Because it had lived many thousands of years before Zinjanthropus, it was known simply as ‘pre-Zinjanthropus’. He went no further than to say that it seemed to be ‘a quite distinct type of hominid’.

But when a reporter asked him what had caused a hole in the skull and the fracture radiating from it, Leakey could not resist a bit of speculation and opened up a new chapter of controversy. The child had died, he suggested, as the result of an injury. ‘I think we can take it for granted that the child was hit on the head by a blunt instrument. It was murder most foul’.

Newspapers around the world seized on the idea, running headlines proclaiming ‘World’s First Murder’. In England, the scientific establishment, noting that Leakey’s account in Nature had made no mention of a blow to the head, reacted with disdain. A correspondent for the London Times reported: ‘British anthropologists were left wondering during the weekend what new consideration of evidence had led Dr L.S.B. Leakey ... to bring in a verdict of murder, hundreds of thousands of years after the event’. The New Scientist rebuked Leakey for indulging in ‘wild speculations’ and accused him of making an important field of science look ‘more than a little ridiculous’. The magazine Punch ran a satirical article entitled ‘More Secrets from the Past: Oboyoboi Gorge’, featuring the exploits of a well-known anthropologist Dr C.J.M. Crikey.

To help him establish a proper identity for ‘pre-Zinjanthropus’, Leakey sought the opinion of a number of other experts. Among them was Wilfred Le Gros Clark, Britain’s leading palaeoanthropologist. From the outset, Le Gros Clark was doubtful about Leakey’s claim about a new hominid; from all the evidence he had seen, he told Leakey in June 1961, he considered the fossils to be inseparable from Australopithecus. The South African anatomist Phillip Tobias took a similar view. ‘My present feeling about the child is that it is an australopithecine’, he wrote in May 1962 after studying the skull.

Leakey insisted, however, that ‘pre-Zinjanthropus’ was not an australopithecine. ‘Mary and I are sure (more and more so every time we go over the data) that it is NOT Australopithecus’, he wrote to Tobias in December 1962. Instead, he argued, it was ‘a very primitive Homo’.

But Tobias continued to hold out. A major obstacle he faced was the size of the brain. The scientific consensus at the time was that a hominid needed to exceed a certain brain size to qualify for the genus Homo. According to Le Gros Clark, a large brain was a ‘distinctive human trait’. Although there was no agreement among anatomists about a specific threshold, the general size they settled on ranged from 700 to 800 cubic centimetres.

The first estimate that Tobias gave for the ‘pre-Zinj’ brain size was between 600 and 700 cubic centimetres. He told Leakey that this made it ‘difficult to reconcile with Homo’. But Leakey would not relent. ‘Phillip took a lot of persuading’, Mary Leakey recalled. ‘Louis had to bludgeon Phillip to convince him. No one lightly names a new hominid species. But Louis loved it’.

The turning point came in 1963 when Mary found further specimens that appeared to be related to ‘pre-Zinj’. In all, Olduvai yielded the remains of eight ‘pre-Zinj’ hominids, providing sufficient evidence for Tobias to change his mind. ‘They all had bigger brains and narrower teeth and a number of other features ... which showed a nearer approach to the genus Homo than to Australopithecus’, he explained later. Nevertheless, the final estimate for the brain size that Tobias produced—about 680 cubic centimetres—meant that ‘pre-Zinj’ still fell short of the accepted threshold for human membership.

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 made the tools.

Leakey was unrepentant. Addressing a gathering in Washington, DC, he declared:

To me the most significant step that ever was taken in human history, the thing that turns animal into man was this step of making tools to a set and regular pattern. This is why we chose that definition of Homo ... Once he had made the simplest of tools, he immediately opened himself a completely new food supply—and enhanced his chances of competing with other creatures.

And in a later press release, he urged colleagues ‘to review all their previous ideas about human origins and to substitute for those theories new ones which were more in keeping with the facts that are now known’.

Although reaching his sixties and suffering from arthritic pains in his hip joints and other ailments, Louis Leakey kept up a frenetic pace of activity. As well as establishing a Centre for Prehistory and Palaeontology in Nairobi, he took an increasing interest in primate research. He fostered the careers of three young primatologists—or ‘ape ladies’, as they were sometimes called—who went on to achieve worldwide fame: Jane Goodall, whom he despatched to study chimpanzees in the forests bordering Lake Tanganyika; Dian Fossey, whom he sent to the Virunga Mountains to study highland gorillas; and Birute Galdikas, whom he helped to study orang-utans in Indonesia. He was also instrumental in opening a new chapter in African exploration.

At a luncheon given by Kenya’s leader, Jomo Kenyatta, at State House in Nairobi in 1965, Leakey met Ethiopia’s Emperor Haile Selassie, who asked him why fossils had been found in Tanganyika (Tanzania) and Kenya but not in Ethiopia. ‘Well, Your Royal Highness’, replied Leakey, ‘if you would allow us to go and search in your country, I know where we might find something’. Haile Selassie wanted to know why he had not already been there to look. ‘Well’, replied Leakey, ‘it’s always been difficult. Your government has not given us the facilities’. ‘All right’, said Haile Selassie, ‘I’ll arrange it’.