Mothers and Others: The Evolutionary Origins of Mutual Understanding by Sarah Blaffer Hrdy Belknap Press/ Harvard University Press, 422 pp., $29.95; $19.95 (paper)

Sarah Blaffer Hrdy is one of the most original and influential minds in evolutionary anthropology. She first became known for her field study of Hanuman langurs, the sacred monkeys that range widely in the Indian peninsula. They are large and sometimes dangerous, and Hrdy was among that second generation of bold primatologists, just behind Jane Goodall and Diane Fossey, who did original work with primates.

Hrdy discovered, among other things, that dominant males in a group are challenged from time to time by roving adventurers who can mate only by defeating them. If defeated, the former leaders slink away, often wounded, while their successors attack and kill all infants under six months old. This brings their mothers back into heat, and the slain infants are supplanted by the new males’ offspring. Females resist this bravely, but to little avail.

If such behavior had been limited to langurs, it might have been an anomaly. But thanks in no small part to Hrdy’s leadership, it was also documented in chimpanzees, patas monkeys, lions, and many other species. Competitive infanticide was seen as a dark side of Darwinism, and a confirmation that no part of nature is free from the amoral logic of natural selection.

Hrdy went on to write a well-received book on the evolution of females, The Woman That Never Evolved.1 The mythic figure of that title was the soft, generous, seductive, maternal idol of the prehistoric world that served in the minds of many as a foil to their own muscular ancestors; these heroes needed something to fight for, fight over, and defend, and ideally she should be the defenseless, feminine figure of their dreams. In fact, this idol was not what she seemed, and by carefully demonstrating the power and aggressiveness of primate females both human and prehuman, Hrdy discredited this founding figure.

Many years later, Hrdy took on another heroine of anthropology and psychology, the good mother. This persona, a natural extension of the woman that never evolved, was the mother that never evolved—the one who renounced every other earthly ambition or delight, gave birth to new life in a spasm of ecstatic pain, and took her infant into her arms, prepared to sacrifice her own life for the welfare of her young.

But this goddess too was a mere apparition. As Hrdy suggested in Mother Nature,2 the primate mother who evolved into the human species was calculating the odds of her infant’s survival when weighed against her own, because if she neglected the latter, she would lose not only this infant but all future ones.

As for the descendants of those primates, we know that a human mother can calculate not just with regard to another’s offspring, but also her own. On this view, neglect and abuse of children and even infanticide are…