Mapping Human History by Steve Olson, Bloomsbury, £17.99, ISBN 07475606
EXCAVATING the human genome for clues to human evolution and migrations is a something of a battlefield. The ground rules of this new science – known as historical genetics or archaeogenetics – are still being worked out, and there is vigorous disagreement about which approaches are best. So where can you find a balanced overview of what has been achieved?
In the brilliant if idiosyncratic Where Do We Come From? (Springer-Verlag, 2001), Jan Klein and Naoyuki Takahata make their sympathies plain: get it from the horse’s mouth. Science writing, they argue, is best done by practising scientists, because journalists bring with them “sensationalism, superficiality and ephemerality”.
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I am not so sure. Scientists in an emerging discipline inevitably favour their own perspective, and at worst can end up the sole hero of their own epic narrative of discovery. A good science journalist, on the other hand, will talk to dozens of scientists and can arbitrate between different points of view.
Steve Olson’s Mapping Human History is a perfect example of this. The acknowledgements page is a Who’s Who of historical genetics, and the rest of the book fulfils that promise: it’s the most balanced, accessible and up-to-date survey of the field currently available. Moreover, Olson includes personal and anthropological observations that add to, rather than distract from, his story. For example, his discussion of the problems faced by a woman growing up in South Africa with a Sotho mother and a European father not only enlivens the text but also vividly brings out the history of human dispersal.
Olson’s tour of human variation starts (as did modern humans) in sub-Saharan Africa about 65,000 years ago and winds up in Hawaii. Olson does not dwell on outworn debates such as “out of Africa” versus “multiregional” origins for modern humans but concentrates on the likely routes the early moderns took as they moved out to fill up the world. Archaeology and palaeoclimatology provide the primary evidence, and the details are filled out – as far as is possible – by the evidence of gene distributions, mainly from the maternally-inherited mitochondrial DNA and the paternally- inherited Y chromosome. Along the way, he spotlights cases such as the history of the Jews or patterns of immigration in modern France.
This is also a book about race, emphasising the way in which genetic and genealogical approaches to human history have debased the concept. Olson’s “American dream” style of optimism may not appeal to everyone, and some of the subtler misconceptions of race – discussed, for example, in Marek Kohn’s The Race Gallery (Jonathan Cape, 1995) – don’t get much of a look-in here.
But the main point is that modern human biological diversity has arisen largely from a series of migrations across the planet in the relatively recent past, and that point is well made. More importantly, perhaps, Olson thoroughly deconstructs the mystique of ancestry.
Olson’s style is as readable as they come and avoids technicalities. Specialists might frown over this, but for anyone else it will be a great relief. This doesn’t mean he over-simplifies the subject, though. He cites many of his sources clearly and in a manner that encourages us to follow up lines of thought, although he is not always as well-read in history and archaeology as he is in genetics.
In spite of its scientific credibility, this is not really a book about methods. The differences in approach of the many researchers whose interpretations are woven seamlessly into Olson’s grand narrative are not really subjected to detailed scrutiny. In fact, as anyone working in this field knows, the quality of different analyses varies enormously, and evaluating the contributions of different researchers is a major headache. Another more critical book, pointing more to the discontinuities in research traditions, would be very welcome. But even so, Olson is going to be a hard act to follow.