"At the end of the 19th century, everyone knew that people were defined by their race and sex and were fated by birth and biology to be more or less intelligent, able, nurturing, or warlike. But one rogue researcher looked at the data and decided everyone was wrong. Franz Boas was the very image of a mad scientist: a wild-haired immigrant with a thick German accent. By the 1920s he was also the foundational thinker and public face of a new school...