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"Y" is the answer - not the question
on September 21, 2003
A few years ago a furor arose over the announcement that a calculation of mitochondrial DNA mutation rate formulated an "African Eve". Since then other genetic ancestral studies have been undertaken. Most notable of these was the determination that Neanderthal was not a direct ancestor of modern humans. Spencer Wells provides an enthralling overview of the research tracking changes in the Y [male] chromosome. The studies verify again that our origins are African. Somewhere, around 60 000 years ago, lived one man, a flesh and blood individual, from whom we've all descended. His progeny, in an amazingly short span, scattered around the globe. The scattering isn't news, but the verification of the paths and chronology is lucid and vividly outlined in this book.
The key to the tracking, as Wells makes abundantly clear, are various polymorphisms [changes] in the Y chromosome. These mutations are reflected in today's populations and the rate of their diversity indicates the approximate age of the various regional groups. These changes, nearly all prefixed "M" [male?] are used as ingredients in recipes Wells offers as illustrative metaphor. It's a clever ploy, so long as you remember ingredients may only be added, never removed nor replaced. That's how genetics works, he reminds us. He portrays the build-up of recipe ingredients with maps and diagrams. The diagrams are almost redundant as the clarity of his prose enables you to envision them.
Following the paths of migration, Wells shows how some archaeological finds offer support for the patterns he sees. Fossils are rare, elusive and sometimes misunderstood. Genetics, buried deep in our cells, are unequivocal in providing their evidence. Dating methods are briefly described and their shortcomings mercilessly paraded. Wells doesn't give the paleoanthropologists much voice. His story needs telling and the reader may go elsewhere for countering information. Yet he acknowledges the importance of confirming information from various digs around the world.
Wells firmly addresses a great anomaly - if modern humans arose from the evolutionary bouillabaisse about 60 millennia ago, how did the Aborigines arrive in Australia at nearly the same time? His answer is that the track followed shore routes, not inland ones. Hunter-gatherer groups, subject to the whims of climate, food resources and population pressure took the softest trail. Africa to Australia during ice ages was a gentle, if lengthy, stroll.
Nit-picking department: Wells' opening gun is turned on the racial "expert" Carleton Coon, who asserted the human races each followed a separate evolutionary path. Coon has been refuted in so many ways by so many researchers, Wells' effort seems superfluous. There are more competent scientists adhering to the "Multiregional" thesis. Some of these researchers might have been given a small voice in an annotated bibliography. While Wells offers a reading list for each chapter, a full bibliography would be an enhancement. Many of his references are remote. That doesn't tarnish the value of this book. [stephen a. haines - Ottawa, Canada]