Jared Diamond in the New York Times:
For over a decade, National Geographic’s Genographic Project has been collecting saliva samples from willing participants, analyzing small pieces of their mother’s and father’s DNA (so-called mitochondrial DNA and Y chromosome DNA, respectively). In return, there is fascinating personal information to be had — about individual ancestries, and about close relatives whose existence had been previously unknown.
But geneticists can now achieve far more than those limited analyses could, and can approach their dream of using genetic evidence to reconstruct past human migrations. One reason is that methods for extracting DNA from bones of ancient humans who lived tens of thousands of years ago have improved. It’s possible now to separate their DNA from all the bacterial and modern human DNA that contaminates those bones. Another reason is that, due especially to the Harvard geneticist David Reich and his colleagues, we now have efficient methods for analyzing whole ancient human genomes, not just the few percent contributed by mitochondrial DNA and the Y chromosome.
In “Who We Are and How We Got Here,” Reich summarizes this rapidly advancing field. He begins with a crash course on genetics and DNA sequencing, then discusses the Neanderthals and “ghost populations” whose existences are inferred from genetic evidence although they no longer exist. Most of the book then consists of chapters reconstructing the histories of modern Europeans, Indians, Native Americans, East Asians and Africans. Concluding chapters probe the controversial subject of race and identity, and prospects for new discoveries. I’ll illustrate Reich’s chapters with three examples: Neanderthals, Europeans and Polynesians.