Forbidden Archeology: The Hidden History of the Human Race

In August of 1972, Bernard Ngeneo, a member of Leakey’s team, found at Lake Turkana a shattered skull that appeared to give an answer. Richard’s wife Meave, a zoologist, reconstructed the skull, designated ER 1470. Alan Walker of the University of Nairobi estimated that its cranial capacity was over 810 cc (R. Leakey 1973a, p. 449), bigger than the robust australopithecines. For example, the robust OH 5 Australopithecus boisei specimen from Olduvai, formerly called Zinjanthropus, had a cranial capacity of just 530 cc (R. Leakey 1973a, p. 450). The ER 1470 skull was in fact as large as some smaller Homo erectus skulls, which range between 750 and 1100 cc. The average human skull is about 1400 cc. Among adult humans, the very lowest cranial capacities are in the low 800s (Brodrick 1971, p. 84).

Viewed from the rear, the sides of the reconstructed ER 1470 skull were nearly vertical, as in Homo sapiens. In Australopithecus and Homo erectus, the sides of the skull, seen from the rear, slope noticeably towards each other at the top (Figure 9.1, p. 556). Furthermore, the domed forehead of ER 1470 was not as receding as that of Australopithecus or Homo erectus, and the brow ridges were smaller. The skull walls of ER 1470 were thinner than those of Australopithecus or Homo erectus. Also, the foramen magnum, the opening in the base of the skull for the spinal cord, was located farther forward than in Australopithecus. In other words, several features of the somewhat primitive ER 1470 skull were characteristic of advanced species of the genus Homo ( Fix 1984, pp. 50–51; R. Leakey 1973a, p. 448 ).

Richard Leakey initially hesitated to designate a species for the ER 1470 skull, but eventually decided to call it Homo habilis. This strengthened the evidence for Homo habilis from Olduvai Gorge, announced by Louis Leakey in the 1960s.

What made the ER 1470 skull so unusual was its age. The stratum yielding the skull lay below the KBS Tuff, a volcanic deposit with a potassium-argon age of 2.6 million years. The skull itself was given an age of 2.9 million years, as old as the oldest australopithecines. The KBS Tuff’s age was later challenged, with critics favoring an age of less than 2 million years (Section 11.6.5 ).

 11.6.2 Evolutionary Significance of the ER 1470 Skull

Louis Leakey was pleased with his son’s discovery. ER 1470 vindicated his long-held view that a line of human ancestors, separate from Australopithecus and Homo erectus, extended far into the past.

Richard Leakey also believed his find had revolutionary implications for human evolution. “Either we toss out this skull or we toss out our theories of early man,” he wrote in National Geographic ( R. Leakey 1973b, p. 819). “It simply fits no previous models of human beginnings.” The model most widely accepted involved three steps. Australopithecus africanus, with some specimens as much as 3 million years old (Groves 1989, p. 198 ), gave rise to early Homo (H. habilis and then H. erectus), which in turn gave rise to Homo sapiens. But Leakey (1973b, p. 819) believed that the ER 1470 skull, larger and more humanlike than that of Australopithecus africanus, “leaves in ruins the notion that all early fossils can be arranged in an orderly sequence of evolutionary change.”

J. B. Birdsell (1975) of UCLA agreed this was true, even if the ER 1470 skull proved to be 2 million rather than 2.9 million years old. “From the very nature of its characteristics cranium 1470 does not seem to fit the standard scheme of the three grades of human evolution,” he wrote in the second edition of his textbook Human Evolution ( Fix 1984, p. 60).

In a National Geographic article, Richard Leakey included a chart showing two separate lines of hominid development. On one line, at about 3 million years ago, Leakey placed the ER 1470 hominid. Next on this line came Homo habilis at roughly 2 million years ago. At 1 million years ago, Homo habilis gave way to Homo erectus, which was followed at the very top of the chart by Homo sapiens.

The second (completely separate) line in Richard Leakey’s chart showed Australopithecus starting at 3 million years ago and finishing at 1 million years ago. Leakey (1973b, p. 819) commented: “Probably a relative rather than a forebear of mankind, apelike Australopithecus existed for at least 2 million years before it reached an evolutionary dead end.” Leakey believed, however, that further research would turn up a common ancestor for Australopithecus and the Homo line at around 4 million years ago.