New, exciting discoveries at the Sterkfontein cave complex have put South Africa back on the palaeoanthropological map Drew Forrest Once the victim of the cultural boycott and a stunning series of fossil hominid discoveries in East and North-East Africa, South African palaeoanthropology is staging a big comeback. The pendulum began to swing back two years ago with the extraordinary discovery in some of Sterkfontein’s oldest breccia deposits of the virtually intact fossil skeleton of a 3,3-million-year-old ape-man nicknamed”Little Foot”. And this year, in even deeper strata, tantalising hints of older hominids were found. Only a few years ago American anthropologist Donald Johanson part of the team that uncovered the ape-woman”Lucy” in Ethiopia could dismiss South African australopithecines like the Taung child and Mrs Ples as an evolutionary side-show and dead-end. The Sterkfontein cave complex and other South African sites began to look more like the cradle of anthropological studies than the cradle of humankind. Ethiopian and Kenyan fossils were more than a million years older than anything found here. Compounding this, says the doyen of local palaeoanthropology, Phillip Tobias, was a subtle campaign to downgrade South African fossil sites in the 1980s, a side-effect of world protests against apartheid. Personal rivalry and ambition may also have been a factor. Particularly since the arrival of numbers of American scientists on the scene, some feel, the study of human origins has become a fiercely competitive field where researchers are hell-bent on finding new species and talking up their finds. And because it has replaced religious creation myths for many people, it arouses much deeper passions than, for example, specialist research on the evolution of horses or cats. The new Southern African finds do not mean East Africa has dropped out of the picture. It restaked its claim to the earliest find this year when an Ethiopian student, Johannes Haile Selassie, working under Berkeley University’s Tim White, unearthed the 5,5-million-year-old bone fragments of Lucy’s possible ancestor, Ardipithecus ramidus, in the Ethiopian Rift Valley.
Later two researchers working out of Paris found six million-year-old fragments, including a piece of thigh-bone, in the Tugen Hills of central Kenya. They gave it a new generic and species name, Orrorin tugenensis although Tobias says the jury is still out on whether the creature was a true hominid, centrally defined by two-legged locomotion. These discoveries potentially push the point at which our ancestors and the great apes parted evolutionary ways to between seven and 10-million years ago, fuelling long-running skirmishes between what Tobias calls”the molecular men” and”the fossil fellows”. By comparing human and chimpanzee genomes, and assuming a fixed rate of genetic mutation, molecular biologists had traced human origins to between five and seven million years ago.”The new discoveries may require the recalibration of the molecular clock, with additional implications for when modern humans emerged,” Tobias commented. The romance of Little Foot is well known the rediscovery of four tiny foot-bones lying in an archive since 1980, their reclassification as hominid, and the return to the source at Sterkfontein, where the creature was patiently exposed so that its tooth enamel glistened from the rock. Lying uncomfortably on a slope 20m below ground level for hours on end with dental picks, ace British-born anatomist and fossil-hunter Ron Clarke and his assistants, Nkwane Molefe and Stephen Motsumi, have extracted the great prize of a well-preserved skull; the lower jaw; an entire set of permanent teeth; foot, leg and thigh bones; and a magnificent upper limb from shoulder to fingertips. Because the pelvis and spinal column are outstanding they may have been displaced by faulting in the rock Little Foot has been shown only to selected scientists and dignitaries, including South African Cabinet mini-sters and the crown prince of Denmark. Its full impact on the world of palaeoanthropology has yet to be felt. What it has over every other find of similar antiquity is its near-completeness, coupled with the articulation of the bones as in life. In other cases, scattered remains have had to be reassembled, with no way of knowing for certain that the pieces belong to the same jigsaw puzzle. Little Foot’s unique condition has raised new questions for taphonomy, the study of burial sites. Early hominids were not cave-dwellers, and one idea is that predators, including sabre-toothed cats, dragged them into their lairs to feed on them. Clarke has propsed what Tobias calls an”oops clunk” theory about Little Foot that it fell through a hole in the cave roof, to be killed in the fall or die of thirst or blood loss. It was lying face down, and the odd position of its left hand may indicate it was dragging itself forward when it died. For our understanding of human evolution, the two most significant features of this small-brained, roughly 1,4m-tall creature are its foot and its age. The foot, the most perfect yet recovered, has a prehensile big toe, suggesting an arboreal environment. Supporting this, Tobias points out, are fossil lianas found in more recent strata at Sterkfontein where remains of Australopithecus africanus like Mrs Ples were discovered The long-held”savannah hypothesis” of hominid emergence has been exploded by finds in equatorial and southern Africa. But what Little Foot and Sterkfontein point to is the far greater southern reach of the wet forests that were the seedbed of our evolutionary forebears. Of equal significance is the closing of the age gap between south and east African discoveries. In September this year Wits University vice-chancellor Norma Reid announced the discovery of hominid remains at Sterkfontein in an even deeper stratum than”member two” where Little Foot was entombed. This pushes the age of southern ape-men to 3,5-million years, and even towards the four million-year mark. Tobias is confident the age frontier will retreat still further as Sterkfontein’s deepest fossil treasure-troves are explored.”Who knows what will come to light?” He emphasises that it may be misleading to identify the most ancient fossil sites as the source of the human species these deposits may be no more than the oldest available. Palaeoanthropologists working in Kenya and Ethiopia have the advantage of tapping in to six million-year-old strata exposed by the great tectonic wound of the Rift Valley. The implication of Little Foot and the latest Sterkfontein find, and of another important discovery in Chad, is that the”fossil chauvinism” of East African anthropologists is misplaced. The emerging picture is of a continent-wide hominid population inhabiting a great forested belt from northern South Africa to the Red Sea. “Those working in East Africa tended to take the view that the human species originated in a band 10 degrees either side of the equator, where very old remains were being found,” says Tobias.”But fossils have been found at Sterkfontein and other South African sites, such as Makapansgat; in Malawi; and through East Africa northwards. All the evidence points to a pan-African phenomenon.”
Tobias remains convinced that anatomically, Southern australopithecenes consigned by Johanson and some others to a barren side-branch of the human evolutionary tree are our most likely immediate ancestors. Palaeoanthropology is a constantly evolving field where orthodoxies are abruptly overturned by new finds, datings and techniques. This year, for example, the cranium and partial skeleton of an anatomically modern human unearthed in southern China in 1959 were redated to between 100 000 and 140 000 years old a range previously exclusive to Africa. This has raised large questions about the”out of Africa theory” that modern humans emerged from Africa to fan out across the globe. Tobias suggests that there may even have been a reverse drift of Homo sapiens sapiens from Asia to Africa. The newest finds at Sterkfontein lend weight to a continent-wide perspective on our earliest origins. “There is no need for sterile argument about whether humans started out in the East or South of the continent,” Tobias says.”The cradle of humankind was Africa.”