Who We Are and How We Got Here; Ancient DNA and the New Science of the Past by David Reich – A Book Review

This review is a companion piece to my earlier review of Gregory Cochran’s “The 10,000 Year Explosion: How Civilization Accelerated Human Evolution.”  These two books lay out step by step how the new tool of ancient DNA isolation has allowed geneticists to turn museum fossils into an amazingly detailed history of the inter-relations between and movements of, the various branches of the human species as it emerged out of Africa 50,000 to 150,000 years ago and went on to settle the planet.

It is truly remarkable how comparing DNA sequences between modern and ancient humans has allowed these researchers to answer historical mysteries such as who were the first Indo-European speakers (the Yamnaya) and where did they live (the Russian Steppe).  We can determine if the Native Americans are essentially the direct descendants of the ancestors of the East Asians or was there some other component involved.  We can find out where the blond hair and blue eyes of the Northern Europeans came from.  We can even find out how many concubines Genghis Kahn must have had.

So, this book is full of facts to satisfy our curiosity about where we all came from.  But there is another dimension to this book that is also interesting.  David Reich is an academic scientist.  He interacts constantly with the very politically correct denizens of the social sciences.  He describes his run-ins with anthropologists and bio-ethicists who accuse him of racism for identifying various biological traits with specific human races.  Even though these traits such as sickle-cell anemia are widely known to reside almost exclusively in one racial group or another, these academics were so conditioned to reject the concept of physical race differences that even mentioning them in the context of biomedical research was the equivalent of heresy.

To his credit, Reich recognizes the intellectual weakness inherent in this response but it is obvious by the compromises he will commit to assuage the discomfort of his colleagues that he feels more comfortable himself being on the “side of the angels.”  For instance, after his research clearly showed that the present population of India is the result of the Yamnaya invading from the north and mixing in with the earlier inhabitants he allowed the feelings of his Indian colleagues to force him to rename these groups Ancestral North Indians and Ancestral South Indians.

And Reich is much harsher toward those on the right who speculate about natural selection at work in the differences measured between present day groups.  He is obviously unwilling to assume a neutral position along the spectrum of opinion on human biodiversity and feels more comfortable aligning himself at least in spirit with those whose opinions about human racial differences fly in the face of his own research.

So, Reich’s book is both fascinating and aggravating at one and the same time.  I imagine virtue signaling is the price he thinks he has to pay to get this book accepted by the academic community and then New York Times Book Review.

My recommendation is to read this book.  But be sure to read Cochran’s book along with it to see an opinion that isn’t captured in an orbit around the black hole that is Modern Academia.

The 10,000 Year Explosion – A Book Review

I just finished reading Gregory Cochran’s and Henry Harpending’s 2010 book “The 10,000 Year Explosion: How Civilization Accelerated Human Evolution.”  In some senses this book seems to be a rebuttal of Jared Diamond’s book “Guns, Germs and Steel, The Fates of Human Societies.”  Diamond’s thesis was that geography was the basis for all the differences between the levels of human technological progress across the world.  The underlying message of Diamond’s book is that all humans are exactly the same biologically.  An Australian Aborigone and Albert Einstein are equally likely to discover general relativity as long as they were both living in Eurasia at the right time in the right place.  In my review of Diamond’s book I stated that the results of geographic isolation clearly had great impact on the ability of neighboring peoples to benefit from the latest technological technology discoveries.  But I also doubted that this provided any proof that there were no meaningful differences between different human population groups.

“The Ten Thousand Year Explosion” is the answer to Diamond’s assertion on equivalence of human populations.  Cochran and Harpending provide a thesis on why human populations would differ and then a litany of examples of where they do.  The book is a fascinating story of how modern humans expanded out of Africa at the end of the last Ice Age and interacted and replaced the archaic humans who preceded them in colonizing Eurasia.  It is truly amazing that in a few short years Neanderthals and other archaic humans have gone from a few bones sitting in a museum display to creatures whose DNA can be compared gene by gene with our own.  Cochran and Harpending examine the genetic evidence and put forth the case that hybridization of modern humans with Neanderthals in Europe is the most likely explanation for the explosion of genetic and cultural changes that occurred when these two human populations interacted.  Their thesis is that the introduction of new alleles (genetic options) gave these humans added flexibility to adapt to their new environment and this led to selection for physical and mental characteristics that in turn gave rise to advances in agriculture, technology, culture and language.

Another message that Cochran and Harpending stress is that human evolution has not slowed even now.  A final example to reinforce this idea is the case of the Ashkenazi Jews.  Cochran and Harpending analyze the history of the Ashkenazi people and the genetic linkage between their higher average intelligence as a group and a number of genetic diseases that are linked to brain function.  He points out that these changes occurred in a period of less than a thousand years and are the result of natural selection reinforced by reproductive isolation and selective advantage based on occupation.

The 10,000 Year Explosion is a fascinating book.  You’ll learn that there literally was a tribe that gave rise to all the Indo-European speaking tribes (Celts and Greeks and Romans and Slavs and Germans and Aryans) and that this pastoral tribe went on to conquer and mix with people over half of Eurasia because they could digest lactose in milk.  And they were epic poets in Ireland, Greece and India.  The book is full of interesting facts and thought provoking ideas.  And I think it will convince most people that Jared Diamond is only looking at half the story by neglecting the genetic and other physical evidence about human history that is now available to scientists.  It turns out nature and nurture are inextricably linked and progress breeds change and vice versa.  We continue to change and to deny this is silly and counterproductive.