(Harvard, 422 pages, $29.95)

The evolutionary significance of warfare is overrated, says sociobiologist Sarah Blaffer Hrdy. What made us human—what transformed our ancestors into a uniquely cooperative, hypersocial species of great ape—were not the requirements of inter-tribal combat, as some anthropologists have long contended, but the demands of motherhood. For most of human history, says Hrdy, our population was so small and spread out that there was no reason to fight over survival needs. But human infants’ large, slowly maturing brains and need for large amounts of protein make them uniquely dependent, and mothers found they needed help from other women to raise their babies. That led to the development of group trust and communication not found in our simian relatives. So take a bow, grandmothers, aunts, and other female caregivers, says Hrdy. You enabled humans to conquer the world.

“Our species is lucky” to have Sarah Hrdy, said Claudia Casper in the Toronto Globe and Mail. In two earlier books—about the evolutionary role of female sexuality and the dark side of maternal instincts—she “exponentially expanded” our understanding of humanity’s origins. Her latest proves to be another “mind-expanding, paradigm-shifting, rigorously scientific yet eminently readable treatise.” Though dense with research citations and field-specific vocabulary, this book will reorient your perspective on everyday life. Begin by tossing out your daydreams about “the primeval nuclear family, with dad off hunting big game and mom tending the cave and the kids,” said Julia Wallace in Salon.com. Fathers are important to child rearing in Hrdy’s primeval tableau. But the defining social unit is a flexible, mother-centered network of caregivers.

Let’s not undervalue “the extraordinary social skills” of the babies themselves, said Natalie Angier in The New York Times. Hrdy’s networks and our resulting cooperative skills would never have come to be if newborns didn’t arrive “knowing how to work the crowd.” Long before television, a burbling infant was “the best show in town.” Mothers and Others raises the frightening prospect that our modern habit of limiting most child-rearing duties to mothers and fathers could actually endanger the best part of ourselves, said Camilla Power in the London Times Higher Education supplement. Just maybe, we have thrown “into reverse” the “evolution of empathy.”