What fatherhood will do to your body

As more and more men become stay-at-home parents, it’s time to question old assumptions about biology

432pp, Princeton, T £19.99 (0808 196 6794), RRP £25, ebook £17.99 ÌÌÌÌÌ

If there’s one feature of family life that has changed most visibly over the last few decades, it’s the sight of fathers with their children. Whether in London or New York, it seems I’m just as likely to see a man carrying his baby in a sling or pushing a buggy down the street as I am a woman. Fathers are involved in their children’s lives more than ever. It’s a subtle social revolution. But for American anthropologist Sarah Blaffer Hrdy, it also prompted a fascinating scientific question: why have biologists so neglected fatherhood?

Even now, despite abundant evidence of women hunters and warriors from prehistory onwards, there’s a lingering assumption in evolutionary biology that women’s bodies are geared for motherhood and that men have evolved to shoot and leave. In short, men are the hunters and women are the carers. In her remarkable new book Father Time, Hrdy’s compelling argument is that we have been misdirected.

Born in 1946 into a well-off, patriarchal family in Texas, Hrdy’s own father was stereotypically handsFATHER off. It was in her children’s generation that she witnessed a palpable shift. When her first grandchild was born in 2014, she recalls “watching a man totally immersed in nurturing a baby, and doing so entirely by choice”. And it wasn’t just her son-in-law. Fathers everywhere, she noticed, were being encouraged to bond with their babies and were enthusiastically seizing the opportunity. In 2021, almost one in five stay-at-home parents in the United States were fathers. Thirty years ago, it was closer to one in 10.

Should we be surprised? “Behavioural flexibility, after all, is a human speciality,” writes Hrdy. Fathers among the Aka people in Central Africa spend almost half their time with their infants. In the 1990s, one surprised Western anthropologist couldn’t help but notice how emotionally attuned these men were to their babies. Societies in which “men spend more time in contact with mothers and children are less bellicose and exhibit lower rates of violence.”

Recent studies confirm that men’s bodies respond viscerally to parenthood, just as women’s do. Hrdy notes that “men undergo remarkably similar endocrinological and neurological transformations” as women when they spend extended periods of time near children. Testosterone levels fall in men who are involved in looking

after their babies, just like the testosterone levels of women fall when they become mothers. Choosing to be a hands-on father unlocks the latent natural potential to be a better father.

This is a profound observation with far-reaching consequences. Too often, modern societies have been designed around the idea that our behaviour is fixed by biology, that old-fashioned gender roles are natural. But the scientific evidence suggests otherwise. When given social permission, we have the capacity to behave differently. Policymakers might do well to remember this when considering parental leave and other family policies.

Hrdy has taken one of the final big myths of human evolution – that childcare by men is peripheral or unimportant – and knocked it firmly on its head. Her 1981 book The Woman That Never Evolved, along with her influential later work, Mother Nature and Mothers and Others, placed females firmly in the evolutionary story as independent, strategic agents rather than the passive creatures that her male contemporaries often framed them as. In the vein of her earlier work, this book reminds us that human childrearing, unlike in some other species, is and always has been a communal activity involving people beyond the mother. Father Time will change minds, but more importantly, it points the way to a different type of science, one that takes into account how culture shapes biology and doesn’t stand apart from it.

It is also a reminder that Hrdy is, without exaggeration, one of the most important thinkers in evolutionary biology since Darwin. She was her Harvard professor’s first female graduate student in 1970, and her life since then has been spent blazing a trail. Her beautiful writing retains as much power to astound and educate as ever.

Angela Saini’s latest book is The Patriarchs: How Men Came to Rule

Pater familias: a father teaches his children in a late-Victorian lithograph