that all human behavior, including altruism, economics, politics, sex, love, war, obesity, rape, and religion, is best understood in the light of the qualities that enabled our remote ancestors to survive. But who knows exactly why a given remote human ancestor survived? The farther back we go, the more significant these individual fates become. A widely accepted theory in genetics holds that a single woman, “mitochondrial Eve,” who lived between 190,000 and 130,000 years ago, is the ancestor of every living human being. Was she especially fit? Especially lucky? Specially chosen? We just don’t know.

 that all human behavior, including altruism, economics, politics, sex, love, war, obesity, rape, and religion, is best understood in the light of the qualities that enabled our remote ancestors to survive. But who knows exactly why a given remote human ancestor survived? The farther back we go, the more significant these individual fates become. A widely accepted theory in genetics holds that a single woman, “mitochondrial Eve,” who lived between 190,000 and 130,000 years ago, is the ancestor of every living human being. Was she especially fit? Especially lucky? Specially chosen? We just don’t know.