The Journey of Man: A Genetic Odyssey [Paperback]

In part, the book is a summary of refutations against the ideas of anthropologists who maintained that different races were subspecies that arose in different regions at different times. No such hypotheses could be tested in the time they were issued, and now they can. DNA in the cells from mitochondria, and the DNA in the male Y chromosome do not shuffle the way ordinary chromosomes do, and thus are very stable from one generation to the next. Mutations happen, and accumulate, and may be used to see how closely related humans from different regions of the world are. The genetic results of both mitochondrial and Y chromosome research confirm each other, and are unambiguous. We are all out of Africa. We stayed in Africa as humans for generations, and almost all the genetic variation we were going to get was within us at that time. Then around 40,000 years ago, propelled perhaps because of weather changes, we started our travels. _Journey_ has good diagrams, but a map showing the flow of different Y chromosome linkages around the world can be regarded with awe, for the history it shows and for the scientific advances that have made such a diagram possible.

Our current way of living has wrought changes in plenty of the subjects in this book. The trail of languages in many ways parallels the trail of genes around the world, but as we develop a global culture, languages are dying out at a faster rate than ever before. Also, there is greater mixing of genes from different cultures now that easy travel makes possible the meeting of members of tribes that would never have met before. It could be that we have passed the heyday for the sort of research reported here, as populations swap genes in unprecedented ways. Nonetheless, Wells's book is full of enthusiasm for basic research, and the results described here are fascinating. We can look back at our origins with new respect for how long and how strange a journey it has been, and with the increasing realization that that our one species has one shared history.

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]