Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past

"Population mixture is central to human nature," writes Reich (genetics, Harvard Med. Sch.), but politics, historical injustices, Western advantage, technical issues, and local sensitivities affect the conduct, interpretation, and dissemination of ancestral genomic research. The field changes rapidly, perhaps even rendering portions of this book inaccurate before its release. We do know our ancestors repeatedly interbred with other hominids, at widely separated times. What ancient DNA analysis also reveals is human history punctuated by multiple migratory waves, sometimes of people returning to areas they departed millennia before. Vanished prehistoric "ghost populations" manifest themselves today as segments of our chromosomes. Socially powerful men of the past—whether the Bronze Age or the era of colonialism—are overrepresented in our present-day genomes. Reich acknowledges the concerns of those who fear talk of biological differences between populations will lead to an upwelling of racism based upon genetic determinism. Unfortunately, his argument that scientists can steer discussion toward informed inclusion is unconvincing.