New Evidence of a Second Kind of Hominin

By 1963, teeth representing five individuals from three Olduvai localities were available. All of them showed the absence of the "australopithecine bulge." They were smaller teeth. In these respects they differed from those of A. africanus. Their traits pointed to a distinctive population, whatever its systematic position, that showed features approaching those of Homo.

Independently of my studies on the teeth, Napier, Davis and Day had been analyzing the hand- and foot-bones from FLK NN I. They concluded that they were close in their morphology to those of Homo sapiens. They could not, however, show that their structure was different from those of A. africanus or other australopithecines, because of the lack of adequate remains of the latter. It could be said that Bed I, Olduvai Gorge, included teeth that showed Homo departures and hand- and foot-bones that were remarkably like those of later forms of Homo. If the teeth and the limb-bones had belonged to members of the same hominin population, it was one characterised by Homo-like features not in a single, but in three major structural-functional complexes. It was now beginning to look as though we were dealing with a population with three character-complexes all pointing consistently in the same direction.

As a fourth and critical line of evidence, in 1963 I turned my attention to the parietal bones and the endocranial capacity. Working in Johannesburg, Alun Hughes and I made a new reconstruction of the biparietal arch of OH 7 and a partial endocast that fitted snugly within this arch. As analogues we made a series of part-endocasts of other specimens for which there were fairly reliable estimates of the total endocra-nial capacity and for which there were clear impressions of the outlines of the parietal bones. From these I devised a method by which to compute the estimated total endocranial capacity of OH 7. By the end of 1963 the first result was obtained. I was amazed at its high value, 675-680 cm3. At that time, the mean capacity for A. africanus was 504 cm3, though later studies by Holloway cropped this average to 441-442 cm3. The mean for Homo erectus at that stage was 974 cm3. Thus, the estimated value for OH 7 lay between the means for A. africanus and H. erectus. The OH 7 value also lay between the highest value in the A. africanus observed range and the smallest value in the H. erectus observed range. The value for OH 7 was 40-50% greater than the A. africanus mean. We needed more specimens with similarly large capacities. Without them, we could not, however, be sure if this large value, considered alone, was the trait of an isolated and perhaps freakish specimen - with, as some suggested, hydrocephalus! - or the hallmark of a population.

Therefore no fewer than four character-complexes - brain, teeth, hands and feet - were displayed by OH 7 and, at least in respect of the teeth, by the remains of four other individuals stemming from MK, FLK NN, and FLK. If all of those remains represented members of the same species, we were surely dealing not with an isolated extreme variant of the australopithecines, but with a population four of whose major character-complexes approached those of later members of the genus Homo. It was clearly a population that had moved away from the A. africanus pattern towards the Homo pattern of structure in all of the anatomical regions available for study and comparison.

At this crucial juncture late in December, 1963, Napier and I felt that we were able to recognize a new species at Olduvai. We were preparing to publish with Louis Leakey the evidence for this conclusion, when dramatic tidings reached us from East Africa.

Most important to the proving of the point came a shower of new hominin fossils from Olduvai Bed II in October and November 1963. These comprised OH 13, a delicately constructed, probably female hominin specimen from MNK II; OH 14 and OH 15; and OH 16, consisting of the teeth and hundreds of fragments of a probable male skull. This fresh haul of hominin specimens, showing some features in common with the Bed I specimens, was the main factor in clinching my realisation that we now had to deal with a population, not a few isolated sports. It was a population that seemed to be represented from the lowest part of Bed I into the middle of Bed II, some two metres below Tuff IIB: this time range was about a quarter of a million years.

The first news of the exciting 1963 finds was brought to Johannesburg by Louis and Mary Leakey late in December 1963. In January 1964, I left for Nairobi to finalize my volume on A. boisei and to study the newly discovered Olduvai specimens. Tentative reconstructions of the calvariae of both OH 13 and OH 16 enabled Ronald J. Clarke, then working at the Kenya National Museum, to make partial endocasts of both specimens. Using the part-endocast method with analogues that I had introduced, we obtained estimates of the total capacity of OH 13 and OH 16 and each was over 600 cm3. It became plain that this Olduvai group of early Pleistocene fossil homi-nins had a mean capacity that was nearly 50% greater than the mean value for A. africanus. OH 7 was no hydrocephalic pathotype - but the type specimen of a population.

When Louis Leakey showed me the maxilla and mandible of OH 13, with their small, slender but long teeth, Ron Clarke who was standing by, recalls vividly how my eyes widened and shone: I turned to Leakey and said, "Louis, this is Homo". Clarke remembers how at that moment Louis gave vent to his characteristic, heaving, panting chuckle of sheer delight!

If there was a quintessential instant of conversion, that was it: no force of argument, coercion or power of personality, but the irresistible weight of evidence - and five or six lines of evidence at that! These were the factors that led me to have a change of mind, and to be converted to the view that we had a new and different species at Olduvai.

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