Friday, September 28, 2007

Before the Dawn

Before the Dawn Recovering the Lost History of Our Ancestors by Nicholas Wade

One of the many pleasures of reading is when you come across a book that is not only well crafted but also informs you and causes you to think about some subject in a way you have not done before. It is even nicer when it sometimes confirms things you had suspected but could not prove.

I have just recently finished Nicholas Wade's Before the Dawn which was published in 2006 and basically brings you up to date on what the cascading DNA research tells us about the development of human beings.

I have always been fascinated by human history and pre-history. I can recall even in early grades being intrigued by, but not quite understanding, the well illustrated Time-Life type books laying out the evolution of man through his various shapes and capabilities. I found the plethora of forms (australopithecines, homo erectus, cro-magnon man, Neanderthals, etc.) fascinating and confusing. Who was first, who followed whom, how were they related, how did they interact, etc.

It wasn't till much later that I began to understand that part of my confusion was not from my short-comings of comprehension as I had imagined, but simply the sparsity and contradictoriness of the archaeological record. Archaeologists, historians and paleontologists were telling the best story they could but spinning that story from a thin factual basis.

For all that DNA was discovered fifty or so years ago and despite the impression that what we are beginning to understand now seems like light years of progress, it only seems so because we knew so little. We are still at the beginning of understanding the information wrapped up in DNA and its biological, evolutionary and historical implications. Twenty years from now we will see our current knowledge as only the first stair-step up a very long stairway.

That said, it is easy to lose track, in the midst of all the new reports of discoveries, the set-backs of assumptions, and the bold extrapolations of knowledge, just where we are in our knowing. What has been settled, what has been indicated but is yet to be proven, what old assumptions have been rendered inoperative, and what are the likely scenarios for the future given the research underway now.

Wade does a great job of winnowing out some of the chaff from the wheat. He is suitably cautious about what is known, what is speculated, and what is still unknowable. In the first few chapters he basically brings you up to speed on current knowledge and thinking and then begins to take you further and further afield where knowledge is less and less certain. He is clear that we journeying in un-chartered seas and that the final chapters are substantially speculation based on a few meager indicators. It is fascinating speculation none-the-less.

One of the other things Wade does well is integrate what we have discovered from DNA with that which is known from the archaeological record, from the study of languages, and socio-biology. In some instances the records are mutually supportive, in others there are contradictions that are not yet resolved.

A few of the nuggets which Before the Dawn either confirmed for me or revealed for the first time.

• Modern man's departure from Africa can be dated now with reasonable certainty to 50,000 - 100,000 years ago across the southern straights of the Red Sea. Wade goes for the nearer date of departure of 50,000 years.

• The initial departure from Africa consisted of an amazingly small group of people, probably less than a thousand people and possibly only 150. The most ancient lineages and most diverse DNA remains in Africa.

• In what seems like a generational forced march, people then proceeded along the shorelines of South Asia, splitting in southeast-asia, one group heading north and back into the interior of Asia but also then outwards into the Pacific and ultimately and belatedly into North America across the Bering Straights twelve to fifteen thousand years ago, while the second group headed southwards into Australia 40,000 years ago.

• Europe was most likely populated by people moving up from South and Central Asia into continental Europe 45,000 years ago.

• Modern man coexisted with Neanderthals in Europe for some fifteen thousand years before the Neanderthals disappeared. Whether there was any population mixing in those fifteen thousand years remains to be determined though the evidence suggests not.

• The development of the differences in racial features among the diaspora of modern humans pretty much occurred as recently as only 10,000 years ago.

• The evolution of the human genome continues apace with some capabilities, such as lactose tolerance in northwestern Europe, arising only 7,000 years ago.

• The interface between physical/biological evolution and cultural/behavorial/intellectual development remains murky, confused, confusing, and subject to preposterous abuse by polemicists, but does indicate some possible linkages.

• And on and on.

Wade does a good job of presenting complex ideas well, hedging his arguments with caution, and yet laying out the surprising amount of knowledge that has been accumulated in five brief years. While archaeologists and biologists will always have to work hand in hand, we are no longer hostage to random and occasional discoveries of bones and settlements. We now have a much more detailed record to which to turn, albeit in a language we scarcely yet understand.

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