Somewhere in Africa, more than a million years ago, a line of apes began to rear their young differently than their Great Ape ancestors. From this new form of care came new ways of engaging and understanding each other. How such singular human capacities evolved, and how they have kept us alive for thousands of generations, is the mystery revealed in this bold and wide-ranging new vision of human emotional evolution.

Mothers and Others finds the key in the primatologically unique length of human childhood. If the young were to survive in a world of scarce food, they needed to...