The Prehistory of Men and Babies: On Sarah Blaffer Hrdy’s “Father Time”

TEN YEARS AGO, I wrote a postapocalyptic novel called The Mercy Journals in which I posed the question: could we change behaviors that, while they had allowed us to multiply and thrive in the past, now threatened our species’ future? One of the subtextual drumbeats in Sarah Blaffer Hrdy’s new book Father Time: A Natural History of Men and Babies is this same urgent question. Hrdy is one of the most renowned sociobiological thinkers of our time.

Hrdy had noticed, as many of us have, radical changes in fathering behavior during her lifetime. Her own father had been a supremely hands-off parent when she was growing up in Texas in the 1950s. Her husband Dan had been a committed father, but Hrdy was the primary caregiver to their infant children. Both her son and her son-in-law, by contrast, spent exponentially more time holding and caring for their infant children, taking observable pleasure and satisfaction from this involvement.

These observations got Hrdy curious about what prolonged exposure to babies might do to men’s brains and, at the same time, what the biologically based pathways to such behavior might be in the first place. When a scientist of Hrdy’s caliber gets curious about something, a deep dive into multifaceted research begins. In this book, she traces the origins of male nurturing across vertebrate, mammalian, primate, and hominid evolution, up to our current moment in history. Along the way, the reader learns about reproductive strategies in various creatures, including the poison dart frog, the cassowary, the meerkat, and the titi monkey, as well as our Homo sapiens selves.

Before she started working on Father Time, Hrdy’s career had concentrated on the female side of human evolution. For her second book, The Langurs of Abu: Female and Male Strategies of Reproduction (1978), she traveled to Mount Abu in India to research infanticide among our primate cousins, positing that when faced with such acts committed by males entering the group, females develop their own counterstrategies, one of which is mating with the strangers, who then cannot be sure if new babies are theirs or not. In her next book, The Woman That Never Evolved (1981), Hrdy examined the surprising variety of female reproductive strategies, starting with our early prehominid ancestors. Her 1999 book Mother Nature: Maternal Instincts and How They Shape the Human Species is a comprehensive study of how mothers and babies evolved in our species to accommodate high-cost infants who remain dependent far longer than those of any other primate, with Hrdy examining maternal ambivalence, cooperative breeding, infant strategies to promote attachment, and strategies mothers adopt in times of famine, hardship, and war. In her most recent book, Mothers and Others: The Evolutionary Origins of Mutual Understanding (2009), Hrdy examined the ways mothers attract and retain the help they need to successfully raise high-cost infants and how the need for “helpers at the nest” contributed to the development of empathy and cooperative breeding. Throughout her work, Hrdy doesn’t shy away from showing the built-in conflict between maternal and infant well-being, and how culture and class impact a baby’s chances of survival.

Many nonfiction books these days read like long, plumped-up magazine articles: after the first four or five chapters, you’ve basically gotten all the substance you’re going to get. Father Time is not like that. The reading is so nutrient-rich that you will want to pause, digest, reflect, delight, and then urgently read on. Because of the vast accumulation of knowledge and experience Hrdy knits together here, and the breadth of disciplines she draws upon, each chapter is more like a slice of pie, radiating around a central argument.

In an accessible style, Hrdy lays out the history of theories about the origins of male behavior—from Darwin to Dawkins, and including John Bowlby, Margaret Mead, Robert Ardrey, E. O. Wilson, Irven DeVore, Barry Hewlett, and Richard Wrangham. She connects this intellectual lineage with her own experience of growing up in a highly patriarchal, wealthy, white Texas family, starting a career in an androcentric academic discipline, then raising her own family as a working mother before, finally, observing the profound difference in the ways her children were raising her grandchildren.

Darwin, in adding sexual selection as one of the primary mechanisms by which natural selection works, concluded that, in Hrdy’s words, “human males were sexually selected to compete with rival males for status.” He had determined that “sexual selection was responsible not just for broad shoulders, beards, and baritone voices, but for men’s obsession with status and their competitive and potentially violent impulses, which Darwin termed man’s ‘natural and unfortunate birthright.’” In this view, men were genetically rigged for violence, dominance, and competition, and for having little involvement with infants and their care.

In Father Time, Hrdy has set herself the task of showing that this putative birthright paints only a partial picture of male behavior. Men, she argues, have a much broader biological legacy than has heretofore been imagined, having evolved to be nurturing fathers in various environments and to various degrees. This behavior is beneficial not only to the fathers themselves but also to the well-being of the infants, the group, and even our species as a whole. To build this argument, Hrdy’s acrobatic mind is able to draw on a wide range of disciplines, including anthropology, evolutionary biology, endocrinology, genetics, neuroscience, economics, technology, primatology, evolutionary psychology, and history, among others.

To trace the origins of a latent paternal neurological network in humans, Hrdy takes us back to the first vertebrates—fish, among which species only 28 percent give any care to their eggs or fry; of that 28 percent, however, almost all the care comes from males. Birds also have a high degree of paternal care, with about 80 percent of bird species being biparental. In mammals, it is the parent with mammary glands who has to stay close and nurture the offspring, while the father is frequently infanticidal.

Hrdy then focuses on primates, including our closest genetic relatives, chimpanzees and bonobos, to examine degrees and instances of paternal care. We are as closely related to bonobos as to chimpanzees—98.6 percent in both cases. Chimpanzees are quite violent, promiscuous, and infanticidal; males are thus rarely involved in caring for infants. Bonobos, on the other hand, are matriarchal, sexually adventurous, and easily aroused, and they use sexual activity for conflict resolution and bond strengthening. Bonobo males are less violent, more tolerant, and rarely infanticidal.

Hrdy covers new research into fathering, reporting on recent experiments with voles and hamsters to discover under what conditions infanticidal males might behave like nurturing fathers. She reports on studies comparing brain changes among fathers in heterosexual couples, where the male is not the primary caregiver, with fathers in same-sex relationships, where both fathers are primary caregivers. After examining the neurological and endocrinological foundations of nurturing behavior in men, Hrdy concludes, quoting evolutionary biologists Malin Ah-King and Patricia Gowaty, that “there is nothing so like a male as a female and vice versa.” Apart from sex chromosomes, all humans on the gender spectrum have the same genetic makeup, and those potentials can be activated in different environments and and at different moments in biological history.

Hrdy’s book is chock-full of fascinating details. She explains that during the Pleistocene epoch (2.6 million–11,700 years ago), other hominin species were alive and flourishing, but toward the end, all but Homo erectus had died off, and even that species only had about 20,000 reproducing adults. Hrdy asks what allowed our ancestors to survive over the next thousands of years in such punishing conditions. Other anthropologists, such as Owen Lovejoy and Richard Wrangham, have focused on the development of hunting tools and the harnessing of fire to cook meat, allowing precious calories to be consumed from animal kills. With her quest to understand the foundations for paternal nurture, Hrdy focuses on something else. She describes how, in hunter-gatherer as compared to herding societies, men spend quite a lot of time in proximity with women and babies, and that this produces endocrinological changes that result in less violent, more cooperative behavior. She proposes that changes in food-sharing behavior toward the end of the Pleistocene would have been enough to allow infants to survive through the hard times. If every hunter shares their kill, the risk of starvation is reduced for the whole group, which benefits the hunter’s kin also. A good hunter who shared with the group would have been highly valued, while a good hunter who was selfish would not. Social selection would have become a significant evolutionary factor on top of sexual selection. Hrdy concludes that “the priorities of these more accommodating, mellower fellows would have been socially selected in favor of men who strove to burnish their reputations in order to be chosen by others as partners, hunting companions, or groupmates.”

Hrdy’s work confirms that human behavior, while shaped by the environments in which we have survived and reproduced, is as culturally varied and flexible as a Cirque du Soleil contortionist. For those who would be prescriptive about what is natural to humans, Hrdy’s cupboard is full of rich illustrations of alternative behaviors. The social structures we live in today were never inevitable. Even with the same environmental pressures, and given the same raw genetic material, our societies could have evolved in any number of other ways. The biological imperative of our species is to be versatile, flexible, and highly adaptive.

Nurturing fathers may not be the probable outcome of our evolution, but they are an outcome nonetheless. In her epilogue, Hrdy expresses a hope. If fathers stay involved in early childcare, and are influenced by the brain chemistry changes that ensue, the result for our world could be positive. Once entangled with babies, they are more likely to push for the social changes necessary to deal with existential threats like climate change and nuclear warfare. They are also more likely to pressure other men within their spheres of influence to “father up.”