Sun, Oct 27, 2002 page18

• Following DNA's footprints makes for a fascinating journey

  Racial purity gets little encouragement in a book that sees humanity for all its diversity, as deriving from a primordial Eve

  • By Bradley Winterton / CONTRIBUTING REPORTER
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  Written history relates exactly how people of European ancestry came to be living in Australia or North America. But how did the Chinese come to be in China, the Indians in India, and the Australian Aborigines in Australia? This fascinating book, by deducing ancient human migration patterns from a study of the DNA of present populations, offers new answers to these old questions.

  For over century, ethnographers seeking to understand the histories of different human groups relied on the evidence of old bones and pottery, together with what was shown by language. But for the last 20 years a molecular study of living people has provided a different kind of evidence. Central to such research are what are called "markers" in the Y-chromosomes carried by all males. These are mutations that have occurred at a particular point in time in a single male individual, and are subsequently passed down from father to son. They have been numbered, and a discussion of the significance of the M45, the M175 and so on, all nowadays very extensive, is at the heart of this intriguing book.

  It was demonstrated a decade ago by the same means that, astonishing as it may seem, all human beings descend from a single woman, a primordial "Eve," who lived in Africa around 150,000 years ago. Now it is possible to trace the histories of the various human subgroups, and so piece together an understanding of when they migrated from Africa to where their core populations are still found today.

  This line of research demonstrates, for instance, that Australia's Aborigines arrived in Australia along a route following the coast of southern Asia 60,000 years ago, long before the present inhabitants of most of Asia got to where they are.

  The population of modern Europe, too, can be shown to have arrived, not by a seemingly direct route from Africa via the Middle East, but from Central Asia, and at a comparatively recent date.

  The Chinese are shown to have almost certainly arrived in China in two streams, one north of the Himalayas, the other south. Chromosome marker differences can still be detected that separate many inhabitants of northern China from their southern counterparts.

  As for the Native American populations, north and south of the equator, it's likely these arrived, crossing from Siberia to Alaska, in two waves. The first penetrated to the south, while the second was content to remain in the north. But neither population is likely to have been in the Americas longer than 15,000 years. And it is quite possible they all descend from a few dozen, or at most one or two hundred, founding individuals.

  Many other things are demonstrated by this research. The successful extraction in 1997 of DNA sequences from Neanderthal remains, for instance, proves beyond doubt that this was a separate species from modern man. The claim that Europeans evolved separately, from part-Neanderthal ancestors, is here finally put to rest.

  With regard to Europeans, the key marker here is the M137, dated as originating around 30,000 years ago. It is found with exceptional frequency in modern Irish and Basque populations, suggesting the earliest migrants moved, or were later pushed, furthest west.

  Nineteenth century studies in language confirm this. Basque, for example, is unrelated to any other European language.

  Ideas of "racial purity" get no encouragement from this book. Our common origin is in fact one of its central themes. But such ideas have a long history, and the Nazis were not the only people to embrace them. There was a strong push in 20th century China, for example, both Republican and Communist, to claim a specific Chinese racial identity and history. Rather than descending from African forebears, the Chinese, it was argued, may have evolved on their own direct from Homo Erectus, an earlier hominid whose remains have been found not far from Beijing.

  This claim is entirely dismissed by DNA research. The Chinese are no more descended from a regional forebearer than Europeans are descended from a Neanderthal one. We all derive from ancestors who left Africa 10, 20, 40 or 50 thousand years ago.

  These minute DNA variations are of outstanding value in the search for mankind's origins, but they have a dark side too. They mean, at least in theory, that DNA-specific biological weapons could be developed, fine-tuned to affect only people of a specific ethnicity. There is some evidence that this terrifying prospect may be only just round the corner.

  In one current conflict zone such a weapon would be difficult to perfect, however. The DNA patterns of Arabs and the majority of Israelis are so close that researchers, however fiendish, would be hard pressed to target the other grouping exclusively.

  As usual, there are some things to be said on one side and some things on the other. The way many nations see ethnic diversity as an impediment to unity, for example, can be deplored. Villagers are relocated, the language of the majority becomes compulsory in schools, and before long the young from these minorities actually feel embarrassed to admit to their heritage. This is a route on which minority cultures die, and with them all identifiable traces of humanity's diverse origins.

  On the other hand, the ethnic mix that is already a feature of urban centers, and that the modern ease of mobility is certain to make more common, rather than being seen as lamentable (as exponents of racial purity would have it) can be viewed as highly desirable. Biological weapons targeted at a specific racial group could only be feasible when the ethnic groupings are separate and distinct. Inter-breeding of ethnicities makes biological weapons aimed at specific groups outdated before they are even a reality.

  Such areas of thought, however, are not this book's main preoccupation. Human brotherhood is what it primarily demonstrates. Racial hatred, let alone inter-racial war, is something a contemplation of its contents ought to consign to the garbage collector's wagon.

  The book is magnificently illustrated with photographs by Mark Read. What makes his pictures so special is that, rather than being of "tribal" peoples in the way we have become accustomed to in works of ethnography, they are of modern men -- in baseball caps worn back-to-front, broad-brimmed outback hats, or knitted rasta scull-caps. This makes the book's central statements as to who we are and where we came from even more relevant than, to anyone who thinks about it, they are already.

  Publication Notes

  Publication Notes:

  The Journey of ManBy Spencer Wells

  224 pages

  Allen Lane
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