BOOK REVIEW / Skeletons in the family cupboard: Origins reconsidered: In Search of What Makes Us Human by Richard Leakey and Roger Lewin, Little Brown pounds 18.99

'IF I'D KNOWN then what bitter academic and personal battles lay ahead', says Richard Leakey in his latest collaboration with Roger Lewin, 'I would have gone off to do something more peaceful, like being an army general. But fossil-hunting was in my blood.' The search for Darwin's missing link has always attracted large personalities with strong views. Richard Leakey's parents were among the most illustrious names in the business, and for two decades the son has continued where they left off. It is a measure of the man that he thinks that when one joins the army it is as a general.

Richard Leakey's most famous controversy was in the 1970s, when he argued with Donald Johanson about 'Lucy', a three-million-year-old skeleton named after the Beatles song. Nearly all the interesting fossils from this period, when our ancestors were just starting to use crude tools, have been found either by the Leakey family or by Johanson. Their points of debate hinge on delicate matters of dating and tooth size, and concern the number and sequence of ape-man species in the period.

For an outsider, it is sometimes difficult to understand why these questions should generate so much heat. Richard Leakey's accounts of fossil-hunting in Origins Reconsidered will help remedy this. Fossil sites are characteristically in hostile and inaccessible parts of the world, with no certainty that they will yield anything worthwhile. Leakey describes the logistic obstacles, the slow grind of the search, and the huge rush of excitement when an important fossil is found. Nobody who goes through all that is going to take kindly to the suggestion that their unique skull is just a deformed individual from some well-known species.

These days Leakey can take a more distant view of anthropological controversy. In 1989 President Daniel arap Moi appointed him director of the Kenya Wildlife Service, and he now spends his time not fossil-hunting in the bush but protected from poaching magnates by armed guards. Even so, he devotes an appreciable part of this book to a reprise of the dispute with Johanson, and is generous enough to concede that the intervening years have won most anthropologists over to Johanson's side. Leakey himself is holding out, though, and bets that future evidence will vindicate him.

He may be right. The castles of paleoanthropological theory are built on such flimsy foundations of tooth and bone that it is not uncommon for new evidence to rewrite the textbooks. A case in point is the way modern genetic techniques have transformed assumptions about our relationship to living apes, such as chimpanzees and gorillas. As Leakey explains, until recently it was widely agreed that our ancestral line split off from that of all living apes about 20 million years ago. But DNA analysis has now convinced everyone that we and the chimpanzees had a common ancestor as recently as 5 million years ago. We and the chimps are therefore sibling species, who share the gorilla as a cousin.

Rather more controversial is the use of DNA analysis to decide the provenance of modern humans. Everybody agrees that a million years ago the last ape-man, homo erectus, left Africa and dispersed over the world. But did the final evolutionary step, to homo sapiens, then occur independently in different regions? Or did it occur only once, in Africa again, and then spread out to displace the regional erectus populations? This is clearly a highly charged question, but Leakey and many other authorities now opt for the latter alternative, and hold that all living humans share descent from an 'African Eve' who lived as few as 150,000 years ago.

As an introduction to paleoanthropology, Origins Reconsidered is not entirely successful. It contains too little background for the beginner, and not enough detail for the enthusiast. But inside this book there is another struggling to get out. Leakey offers his readers tantalising snippets of his own life. In his teens he reacted against his academic parents, and left school to set up a successful safari company. Yet by his mid-twenties he was a world-famous fossil-hunter and director of the National Museums of Kenya. In 1979 he suffered kidney failure and was saved by a transplant from his younger brother. He used to count Donald Johanson a friend, but no longer. Right now he is probably the elephant's best bet against extinction.

Richard Leakey is not yet 50, and perhaps has no wish to write his autobiography yet. But when he does it will be a story worth reading.