Inferior: How Science Got Women Wrong—and the New Research That's Rewriting the Story

by Angela Saini

The rare infanticides turned out instead to be carefully calculated. And they were committed by males from outside the breeding group. “When I first did see infants missing, and then later I actually saw a male attack infants, it was very goal-directed stalking, as if by a shark. Day after day, hour after hour.” What was making a male commit this gruesome killing was the expectation that, without her baby, a mother would have to mate again. If he didn’t kill the infant, he would have to wait a year before she finished nursing and started ovulating. She couldn’t mate any sooner.

Older siblings had a more positive effect than anyone besides the mother. After this came grandmothers, then fathers, followed far behind them all by grandfathers.