GENESIS appears to have taken place in Africa. That was where Australopithecus afarensis first picked up its knuckles and walked. And Australopithecus begat Homo habilis, and Homo habilis begat Homo erectus. Then, a million years or so ago, Homo erectus left the African Eden and headed east, not, like Cain, into the land of Nod, but into Asia. It was there that, in the guise of ``Java Man'', fossils of Homo erectus first led 19th-century European scientists to face the fact that man's origins might not lie in the white man's continent. That Homo erectus eventually begat Homo sapiens is not in doubt--but the manner of the begetting is. Some believe that the transformation into Homo sapiens happened across the whole of the geographic range where Homo erectus had settled. Others think Homo erectus split into many local forms, one of which became modern Homo sapiens while the others died out. This accords with a famous computer analysis of the distribution of genes in today' s world which implies that modern Homo sapiens burst out of Africa in a second exodus about 100,000 years ago. The ``second exodus'' theory has taken a bashing recently. People have re-run the computer analysis and found it less compelling than it seemed. The other theory, ``transformationism'', is coming back into fashion as more fossils are found to support it. Fossils combining features from erectus and sapiens and coming from Asia, not Africa, would offer especially strong support. A new discovery and a recent reinterpretation seem to have provided just that. The discovery was made by Li Tianyuan of the Hubei Institute of Archaeology in Wuhan, China. In the current edition of Nature, he and Dennis Etler of the University of California at Berkeley describe two skulls found near the Han river in Yunxian, an area of central China. The Yunxian skulls are between 350,000 and 500,000 years old, and though battered and bereft of jaw-bones they are better specimens than any other human fossils of the same age found in China. They have flattened sapiens-like faces of a sort which later became widespread and erectus-like brain cases which subsequently disappeared. Comparing their finds with other, more fragmentary, fossils from eastern Asia, Dr Li and Dr Etler think that this combination might be a general characteristic of people from this area and period. Their conclusion complements the reinterpretation of a fossil from another part of Asia. Some years ago the Narmada river in India yielded up the oldest human fossil so far found in the sub- continent. Consisting of little more than the right half of the cranium, and dating from between 100,000 and 180,000 years ago, it was initially classified as erectus--convenient, if tenuous, evidence suggesting that the species could have been spread continuously from Africa to East Asia.
Nod only, but also
Dibyendu Kanti Bhattacharya, an anthropologist at the University of Delhi, disagrees. He believes that Narmada Man (who was probably, in fact, a woman in her 30s) is better thought of as an archaic form of Homo sapiens. Whatever the label, the skull is a mixture of erectus-like and sapiens- like features. ``The fossil'', says Dr Bhattacharya, ``belongs to an individual who had too much brain matter for an erectus, having a remarkable vault with a capacity anywhere between 1,200 and 1,400 cubic centi-metres''. This compares with an average cranial capacity for modern humans of 1,400 cubic centi-metres. Other Homo erectus fossils have been much less brainy than this (though tentative reconstruction of the Yunxian skulls suggests that they, too, might have large vaults). The height and width of the skull are also large for an erectus specimen; in thickness, however, it is closer to erectus than sapiens. The Yunxian and Narmada skulls seem to support those who believe that Homo erectus, a widespread species, was united by movements of population and gene-flow. This would have enabled characteristics that evolved in different places--faces in East Asia, the modern brain case probably in Africa- -to come together. Homo sapiens would thus have arisen in an almost seamless transition, rather than being an uppity local form that, cut off from its neighbours, evolved into something new and then overran them. However plausible that seems, caution would be wise. The study of human evolution is littered with theories that once seemed convincing but are now as dead as the fossils they were based on.
Copyright 1992 by Economist Newspaper, NA, Inc. Text may not be copied without the express written permission of Economist Newspaper, NA, Inc. Fried, E., East of Eden.., Vol. 323, Economist, 06-06-1992, pp 92.