Forbidden Archeology: The Hidden History of the Human Race

In order to put an end to the controversy, Richard Leakey decided to call in additional researchers. “It was only in 1980,” wrote Leakey, “that a broad consensus was finally achieved. . . . Glynn [Isaac] and I decided we should invite other geophysicists to work on the KBS date. Eventually we managed to arrange for several different laboratories to evaluate the same material from split samples, using two methods: fission-track dating, as well as conventional potassiumargon. This was done quietly and with little fanfare. As a result, it became quite clear that the KBS tuff is no more than 1.9 million years old . . . it would be prudent to think of the skull KNM-ER 1470 as being about two million years old” (R. Leakey 1984, p. 170).

The case of the KBS Tuff is intriguing. Initially, Leakey had potassiumargon dates, faunal evidence, paleomagnetic dates, and fission track dates supporting an age of 2.6 million years. Then, a few years later, he said new potassiumargon dates, faunal evidence, and fission track dates favored an age of 1.9 million years.

Richard Leakey’s allusion to consensus is instructive. Researchers party to such an agreement may announce that their consensus must be correct because it is supported by dating methods A, B, and C. But as we have seen, various dating methods tend to give age ranges broad enough to support a number of age determinations.

Many place excessive, even unquestioning, faith in published age determinations, unaware of the many sources of error inherent in current dating methods. They do not adequately appreciate the crucial role that the judgements of individual researchers play in arriving at a published date from among the spread of dates often obtained from a series of tests. These complex judgements can easily be influenced by the researcher’s expectations and preconceptions.

11.7 Oh 62: Will The Real Homo Habilis Please Stand Up?

Artists, working from fossils and reports supplied by paleoanthropologists, have typically depicted Homo habilis as having an essentially humanlike body except for its apelike head (Figure 11.9).

Figure 11.9. Left: This drawing (after Johnson and Edey 1981, p. 286) shows Homo habilis, as generally depicted before 1987. Below the head, the anatomy is essentially human. Right: After OH 62 was found at Olduvai Gorge in 1987, a new picture of Homo habilis (after Budiansky 1987, p. 10) emerged, far smaller and more apelike than before.

Occasionally, scientists have raised questions about such depictions. “Were the australopithecines hairy? Was Homo habilis slightly less hairy, just to give it a hint of human respectability?” asked Richard Leakey. “Certainly, all the portraits ever painted of our ancestors show this kind of pattern. But as no artist has ever seen a living hominid, and as we have no way of knowing whether they were naked or not, it will remain a favorite topic of after-dinner speculation and fantasy forevermore” ( Leakey and Lewin 1978, p. 66).

In any case, a very humanlike portrait of Homo habilis persisted until 1987. In that year, Tim White and Don Johanson reported they had found in lower Bed I at Olduvai the first Homo habilis individual (OH 62) with postcranial bones clearly associated with a cranium.

Johanson and his coworkers (1987, p. 205) stated: “This specimen’s

craniodental anatomy indicates attribution to Homo habilis, but its postcranial anatomy, including small body size [ less than 3.5 feet] and relatively long arms, is striking similar to that of some early Australopithecus individuals.” Drawings of the new Homo habilis (Figure 11.9) were decidedly more apelike than those of the past.

Wood (1987, p. 188) noted: “The shape and size of the proximal femur, and the anatomy and relative lengths of the limb bones, both run counter to the view which sees H. habilis as a biped with a postcranial skeleton that is essentially modern human in its morphology, proportions and, by inference, function.”

Johanson and his coworkers (1987, p. 209) concluded it was likely that scientists had incorrectly attributed to Homo habilis many postcranial bones discovered prior to 1987.

11.7.1 Implications for the eR 1481 and eR 1472 Femurs