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Journey of Man

Do all humans share a common ancestor, and if we do, why do we look so dissimilar? A look at these questions.

india Updated: Apr 11, 2003 15:27 IST

Journey of Man
A Genetic Odyssey

Spencer Wells
Pages: 224
Price: Rs 495

At some point in our lives, most of us have wondered about our ancestors, especially ones that lived before our collective living memory. Even when we have bought the scientists' monkey-to-man stories, it has been with some inner scepticism, some 'hope' that these uppity scientists would some day be proved wrong and irrefutable proof that god created man in his image would surface.

Well, for those who ascribe to this view, this is not the book to read. Or perhaps it is. For it is a remarkable foray into the search for who our ancestors were. Do we share a common ancestor, and if we do, why do humans look so dissimilar from each other? Are we the same species at all? Was there a first human, and where did he or she live? There are many queries that have troubled human thought and philosophy for long, some of which this book seeks to answer.

The book looks for concrete answers, and comes up with an amazing array of answers. And from within the human body instead of taking the archaeological route. The writer, a British geneticist has put together a fascinating tale of how man began in Africa (for all those who remain unconvinced, read the book) and spread through the world. And in a twinkling of an eye, when one looks at the evolutionary time scale.

Wells traces the mutations, which serve as markers to trace the geographical paths that humans took over the last few thousand years. As all humans today belong to the same species, they share common ancestry. "...this means that all modern humans were in Africa until at least 60,000 years ago." Yes, that's the time when 'Adam,' from whom all humans are descended today, lived!

For such a technical subject, the book is surprisingly accessible and just about anyone interested in the subject will be able to follow the detecting that takes you all across the globe. The massive extent of experimentation and research is traced, right from Darwin and the earliest geneticists to the path breaking work being done by groups in numerous laboratories. Samples have been collected from remote corners, literally as quite often the search has meant looking for isolated groups that have preserved the genetic code. Human remains dating back to prehistoric times have been made to reveal their secrets. Though a significant part of the proof comes from hypotheses drawn at earlier stages, the tale is convincing. That the writer has been part of the research process has helped in making the issue more comprehensible to the lay reader.

The basic tool in the search has been the Y chromosome, which is perhaps why the book is the journey of man and not humans (no chauvinist angle here). The DNA is perfectly replicated from father to son, except in rare cases. The search has been for common ancestors as well as for markers that indicate divergence. By looking at DNA from many sources, the scientists can tell which groups are ancestral and how and when the divergences have taken place. By plotting these on a map, paths of divergence have also been traced.

Thedating for the arrival of Homo sapiens in each continent or area has been separately traced, and it makes for fascinating reading. Considering that apes first appeared about 23 million years ago, it has taken the modern man very long to come out of Africa. The spread, once the Sahara was crossed, was fairly rapid, notwithstanding the dry, inhospitable or water parts that perhaps pushed back the journey by a generation or two. The 'coastal superhighway' is cited as a possible route for the journey from Africa to Australia via South Asia.

Visual support, especially the photographs, however do not make much sense without sense without explanatory notes. The maps are helpful though, as are the tables and other graphics. Perhaps what those not inclined to wade through the book can do is to catch the equally fascinating documentary prepared on the same research.

The book is a fascinating story of reconstruction of human history. Those who believe in differences caused by birth among humans, and practice the same, will be disappointed to know that all the world is kin after all.

First Published: Apr 11, 2003 15:27 IST