Monkey business and the hunt for early man

Few people can be unaware that there has been something of a revolution in our understanding of human evolution. New finds from Africa, from the fringes of Europe and from Asia have upset established notions of the pattern and timing of humanity's origin and spread. New evidence of evolutionary relationships (notably from DNA) and novel approaches to diet and environmental reconstruction have all impacted on how we view earlier hominids, their affinities and behaviour. There is, as publishers and booksellers readily recognise, a regular need for updated accounts to bring these discoveries to a wider audience.

Not so well known is the corresponding expansion of knowledge about ape evolution - the context, of course, from which hominids emerged.

Our improved understanding of ape and hominid radiations points to the same conclusion - both were much more complex than anyone realised even a few years ago, and both raise many more questions than can be convincingly answered. But we do at least have growing numbers of ape fossils from Asia, the Middle East and Europe, as well as from East Africa. So it makes good sense to contextualise any up-to-date survey of hominid evolution within our current understanding of that broader ape radiation. Here is just such an account, written with great clarity and authority by two researchers from the Natural History Museum. Chris Stringer is well known as a Neanderthal expert who has long brought his subject to a wider audience, for example through his co-authored books, In Search of the Neanderthals and African Exodus . Peter Andrews is a recognised authority on ape evolution, with excavation experience in Africa, Europe and Asia, and with a particular interest in fossil ape ecology and habitat reconstruction.

Both authors are past collaborators in fieldwork and publication, notably on a seminal paper that kick-started the "out of Africa" debate on modern human origins.

The text falls into three main sections. "In search of our ancestors" provides an overview of extant ape ecology, modern human diversity and a summary of relevant functional studies. It also reviews factors influencing fossilisation (taphonomy), excavation methods, hi-tech approaches to studying fossils, dating and climatic frameworks. Six of the authors' field sites then serve as case studies to exemplify these principles. Three sites (Rusinga, Pasalar and Rudabanya) have yielded fossil apes, and three (Olduvai, Boxgrove and Gibraltar) hominids. Here, as elsewhere, the text is complemented and reinforced by photographs, diagrams and colour reconstructions.

The "Fossil evidence" constitutes the book's main section. An excellent introductory survey leads us through the normally bewildering complexities of the fossil ape record - bewildering, among other reasons, because workers appear unable to agree on just what constitutes an ape. Here, Andrews is a caring guide: the reader is gently introduced to the notion of shared derived features (in this case, flexible elbows and lack of a tail) unencumbered by the usual cladistic jargon (that comes later), followed by a summary of ape evolution that is a clear and authoritative account.

Two major points stand out: the radiation was extensive and evolutionarily complex, and that we know next to nothing about the ancestry of the surviving ape remnant. What we can see by mid-late Miocene times is a widely distributed array of apes that had expanded beyond their African homeland, confusingly mosaic in their affinities but showing clear adaptive responses to the environmental changes of the period. The large, thick-enamelled molars and massively constructed jaws of some fossils outclass even gorillas, indicating highly resistant diets of hard fruits, nuts and seeds in mixed seasonal habitats. This array provides the context for human origins, and there is a succinct, well-illustrated treatment of the current trio of contenders for earliest hominid: Sahelanthropus (Chad), Ardipithecus (Ethiopia) and Orrorin from Kenya. They lead on to the more extensive and better-known Australopithecus from the Rift Valley and Transvaal. The section on early Homo covers fairly familiar ground: Homo habilis (one species or two?), Homo erectus (ditto) and expansion beyond Africa. Again the account is clear and up to date, with the important Dmanisi discoveries featured. The relatively expanded treatment of later human evolution is built, perhaps inevitably, around the out of Africa and multiregional models. Neanderthals mean that the European record is given expanded coverage, but there is also a clear account of the colonisation of Australia and - again reflecting the book's currency - a section on the Flores hobbit Homo floresiensis . A clear and balanced treatment of the role of DNA studies in human evolution, refreshing for eschewing the spectacular claims sometimes made for molecular evidence, completes this section.

The final part attempts an adaptive synthesis of the preceding material. Two crucial functional complexes - locomotion and feeding - are surveyed across the fossil record, with the environmental interplay of ground dwelling, arboreality, food resources and social behaviour as themes for scenarios of ape and human evolution. Overviews of the spread of apes and Homo beyond Africa are complemented by a case study of human occupation of the Americas.

A survey of tools and tool-making in human evolution picks up from section two, and the earliest art and its implications for social complexity, cognition, symbolism and language are reviewed. There is even a cautious evaluation of evolutionary psychology. The final overview stresses the chancy, unpredictable nature of evolutionary change and its outcomes, concluding on the decidedly downbeat note that if we do not mend our ways, climatic disruption resulting from global warming could force us to continue our evolution off the planet rather than on it.

It is difficult to fault this book. As a survey of human evolution it provides everything that a fresh, imaginative introductory course on the subject should, and it will doubtless rapidly gain use as a university text. But its style and format make it accessible - and attractive - to a far larger audience and it deserves the widest readership. It is clearly and authoritatively written, attractively illustrated with plenty of reconstructions to catch the imagination, well bound and inexpensive.

With a volume of this calibre, authors and publishers have a sure-fire winner.

Alan Bilsborough is professor of anthropology and pro vice-chancellor, Durham University.