Few ideas have been more toxic or harmful, or have been used for worse ends, than the idea of the biological reality of race, and with it the idea that humans of different races are biologically different from each other. But Nicholas Wade, inconvenient as it may be, believes that there is truth in this view. Race is inherently not a bright-line distinction; by definition it means that the more human populations are kept apart from each other and for longer periods of time, the more they will evolve their own distinct, separate traits under the selective pressure known as Darwinian evolution. Wade’s most controversial claims involve the genetic basis of human social habits, such as the genetic basis for the tendency to be more or less violent. Inevitably such assertions get caught up in questions of “better” and “worse,” which are pernicious; Wade argues the more subtle point that some traits are more adaptive for some specific environments than others and that science needs to set its course for the truth, come what may, taboos or no. With brave, scrupulous care and lucidity, Wade forays into this scientific minefield and endeavors to arrive at a coherent summary of what the new genetic science does and does not tell us about race and human history. This will not be the final word on the subject, but it will begin a mighty and in some respects overdue conversation.