The Globe and Mail, May 9, 2009

Mothers and OthersBy: Sarah Blaffer HrdyPublisher: Belknap/Harvard University Press, 422 pages, $38.95

The time I had set aside to rewrite this review was spent at the clinic with my son, getting him antibiotics and a tetanus shot after a skateboard accident left sizable deposits of his skin on the neighbourhood pavement. Even now, when my children are older and in many ways can take care of themselves, I want an allomother. My children aren’t self-provisioning yet, nor would they have been back in the “old” Pleistocene days, when allomothers often made the difference between life and death.

In 2009, what we don’t know about human evolution dwarfs what we do know the way a watermelon dwarfs a pea. Sarah Blaffer Hrdy, professor emerita of anthropology at the University of California-Davis, and one of the most brilliant pioneers in her field, has exponentially expanded our knowledge, breaking open the whole area of mothering and female sexuality in evolutionary studies.

Her first book. The Woman That Never Evolved, published in 1981, was a scientifically pure, clear-eyed look at the role of female sexuality in shaping human evolution. Her second, Mother Nature: A History of Mothers, Infants and Natural Selection, was ground-breaking in its examination of mothering and evolution. In Mother Nature, Hrdy radically reframed the way we look at sex selection, infanticide, post-partum depression, sibling rivalry, maternal resource allocation and breastfeeding, just to name a few topics. Which children survived to reproduce and pass on their genes and which didn’t had everything to do with the behaviour of their mothers.

Both of these earlier books were academic works with crossover appeal to lay readers. They were named variously: New York Times Notable Book, one of the best books of the year by Publisher’s Weekly and Library Journal, outstanding Academic Book of the Year and finalist for a Pen (West) Literary Award.

Mothers and Others: The Evolutionary Origins of Mutual Understanding, Hrdy’s much-awaited new book, is another mind-expanding, paradigm-shifting, rigorously scientific yet eminently readable treatise. Somehow less depressing than Mother Nature, which explored much of the dark side of mothering—yes, there is a very dark side—Mothers and Others lays the foundation for a new hypothesis about human evolution.

Traits that anthropologists used to believe separated humans from other great apes—tool-making, walking, hunting co-operatively, fighting wars—have all been found to exist in other species. The new thinking is that what distinguishes human beings is “the ability to participate with others in collaborative activities with shared goals and intentions.” Included in this conceptual basket are what Hrdy calls prosocial or emotionally modern behaviours, such as identification, altruism, compassion, co-operation, gift-giving, mind-reading, mutual understanding, goodwill and caring.

Hrdy believes that the origin of prosocial behaviour in humans is to be found in the way our ancestors raised their offspring. With modern primates, infants are raised exclusively by their mothers until they are weaned, but early human infants were too high-cost for a female to provision alone. Hrdy re-examines data regarding hunter-gatherer societies and compares it with new research in comparative primatology, sociobiology, neuroendocrinology, human behavioural ecology and cognitive psychology and concludes that early hominin mothers had to rely on help from allomothers to raise surviving offspring. Allomothers include grandmothers, sisters, cousins, older siblings, non-reproductive adults and pre-reproductive children in a flexible child-rearing system called co-operative breeding.

Co-operative breeding, Hrdy claims, provided the evolutionary foundation for bigger brains, longer lifespans and language by making the extended childhood and the high caloric resources possible in conditions very unlike those of modern humans.

Hrdy’s theory explodes a number of orthodoxies. She debunks the notion that humans evolved bigger brains to hunt or wage war on each other, asking, with her trademark understated irony, “Do we really want to rely on out-group hostility and reflexively genocidal urges as the explanation of choice for the emergence of peculiarly prosocial natures?” She drives a final nail into the coffin of the notion that human infants were raised in nuclear family models. The truth is the family model has always been much more flexible and open; mothers have always and necessarily sought help where they could find it. A child raised exclusively by mom and pop would be an exception, not the rule. 

Mothers and Others may be marginally less accessible than its author’s previous work; despite Hrdy’s delightful personal flourishes, she has included more exhaustive references to experiments and research in support of her theories. Also, this undertaking is so ambitious in its cross-disciplinary scope that keeping track of the vocabulary for the lay reader can begin to seem like trying to remember who’s who in a long Russian novel.

That said, Mothers and Others is overflowing with fascinating information and thinking. It’s a book you read, pausing regularly to consider the full import of what you just read. You might call out to friends and family nearby, maybe even to wounded skateboarders and hungry, video-gaming 13-year-olds, “Can you believe this?” and read out a mind-blowing passage. And then you might say, “If that’s true, then that means,” suddenly seeing some part of your day-to-day life in a completely new way. 

Just one example, the classic complaint of women over 50 that they eat less, exercise more and still gain weight. After reading Mothers and Others, you’ll realize that this is because their biological role is to gather food with all the stamina, resourcefulness and expertise of their years, yet eat little so there is plenty left over to share with children and nursing mothers. Who knew?

As our species embarks on the third millennium, with climate change, war in both its nuclear and corner-store varieties, and overpopulation exerting new evolutionary pressures on our survival, it has never been more important to understand human evolution. Without this understanding, we can never fully understand our limitations or our strengths as a species, or hope to separate what is probable in our future from what is possible or impossible.

Sarah Blaffer Hrdy has added another enormous building block to our thinking about our origins with this new book. Our species is lucky to have her.