Father Time: A Natural History of Men and Babies Sarah Blaffer Hrdy Princeton Univ. Press (2024)

Primatologist Sarah Hrdy never questioned the idea that hands-on childcare was mainly women’s work — until her first grandchild was born. Then, while watching her son-in-law willingly care for his baby, she began to wonder whether the trend of fathers getting more involved with their children was merely down to cultural change in the decades since she had kids, or whether it could be explained by biology.

In Father Time, Hrdy takes us on a quest through vertebrate evolution and history to discover when and how men — unlike other male great apes — began to nurture their young. Ultimately, Hrdy finds that the idea of men caring for babies is not as evolutionarily unusual as she had initially surmised. She surprises herself by concluding that men can be every bit as protective and nurturing as the most committed mother.

Hrdy’s preconceptions of parenting stemmed from half a century studying the reproductive strategies of primates. Her graduate studies were steeped in Darwinian logic, which emphasized that male behaviour is driven by the need to outcompete rivals for mates — a way of being that requires little direct contact with infants. Her early fieldwork in India on Hanuman langur monkeys (Semnopithecus entellus) reinforced this view. Resident male langurs, she observed, paid little to no attention to the young in their group, but incoming males deliberately killed the babies of other males to hasten mating with resident females. Similarly, male apes generally shun infants, and are more likely to kill a newborn than nurture it.

A rare mammal

To explore what makes humans different, Hrdy begins her book by going back to our vertebrate origins. Parental care among fish and amphibians is just as likely to be done by males as by females. But in only 5% of mammalian species do males care for their young. Despite the differences in behaviours between fish and mammals, the hormonal and neurological mechanisms that promote parental care in the two groups are similar.

In mammals, pregnancy and feeding babies trigger the release of hormones, such as prolactin and oxytocin, in the mother’s brain. In humans, these then encourage nurturing behaviours and produce a feeling of bonding towards the infant. But, as Hrdy notes, historically it did not occur to scientists to study how caring for babies might affect male biology.

The author’s summary of the scant literature reinforces her argument that male nurturing is, like female care, a product of biology. In humans, men who care for infants experience profound biological changes. In the weeks before their baby is born, men experience a surge in prolactin. In the months after birth, their levels of testosterone levels drop and those of the bonding hormone oxytocin rise. Nurturing can also produce changes in the brain: scans of men who are the primary carer of an infant show that their brains light up in response to a crying baby, in much the same way as do the brains of mothers who are the main carers.

Cultural changes

Next, the author investigates the evolutionary events that set humans apart from other great apes. At the time of our last common ancestor with chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) — around five million to six million years ago — most other ape species had gone extinct, owing to cooling global temperatures and shrinking forests. Yet our hominin ancestors persevered, despite the fact that their large-brained offspring were weaned off milk earlier than those of other great apes, and required more food than mothers alone could provide through foraging. Male hunters, evolutionary anthropologists reason, must have learnt to share resources with children.

Some researchers have argued that this responsibility-sharing behaviour relied on males being sure of which children were theirs. But Hrdy points out that, among living hunter-gatherers, most of the meat is shared widely — it does not go directly to a hunter’s children. She posits that our ancestors became cooperative breeders, with groups of parents providing support, care and food for growing children together. And she argues that social selection — the subset of natural selection influenced by the behaviour of other individuals — had a central role in this change in parenting, with selection favouring men who had a reputation for cooperation and sharing food, making them more attractive as partners and group members.

The final chapters of the book focus on the cultural context of human fatherhood, and the ways in which men’s relationships with children have changed over the past few millennia. Hrdy argues that men were more involved in childcare before the invention of agriculture, and the ethnographic data from contemporary hunter-gather populations support her conclusion. Once agriculture was adopted — bringing with it the need to protect resources such as land and livestock — men tended to remain near their kin, whereas women moved away from their families when they married.

This led to patriarchal systems, increased segregation of men and women in domestic and social spheres, and thus fathers spending less time near their children. The trend continued in market economies, in which men adopted the role of breadwinner and worked outside the house. The most recent generation has seen some erosion of gender barriers, and men have actively been taking on childcare duties. But, as Hrdy discusses, those preferring more conventionally defined roles for mothers and fathers have been pushing back against these changes.

As always, Hrdy’s writing is a joy to read. Her previous books have focused on female care of offspring and on the broader role of non-parental (typically female) caretakers in shaping human evolution, some of which is rehashed in Father Time. But the focus on fatherhood and men’s biological responses to babies is new. And her model for how male care evolved in humans is plausible (if necessarily speculative).

Father Time will be valued by anyone interested in male care of infants and children. Hrdy’s broad, accessible writing will appeal to non-scientists, but her peers will appreciate her summary of current research on the hormonal and neurobiological aspects of male care. As a biological anthropologist focused on fatherhood and men’s investments in children, I certainly learnt a great deal.

After years of deliberation, US officials have released a policy that outlines how federal funding agencies and research institutions must review and oversee biological experiments on pathogens with the potential to be misused or spark a pandemic.

The policy, which applies to all research funded by US agencies and will take effect in May 2025, broadens oversight of these experiments. It singles out work involving high-risk pathogens for special oversight and streamlines existing policies and guidelines, adding clarity that researchers have been seeking for years.

“This is a very welcome development,” says Jaime Yassif, vice-president of global biological policy and programmes at the Nuclear Threat Initiative, a research centre in Washington DC that focuses on national-security issues. “The US is the biggest funder of life sciences research [globally], so we have a moral obligation to guard against risks.”

Balancing act

Manipulating pathogens such as viruses inside an enclosed laboratory facility, sometimes by making them more transmissible or harmful (called gain-of-function research), can help scientists to assess their risk to society and develop countermeasures such as vaccines or antiviral drugs. But the worry is that such pathogens could accidentally escape the laboratory or even become weaponized by people with malicious intent.

Policymakers have had difficulty developing a clearly articulated review system that evaluates the risks and benefits of this research, while ensuring that fundamental science needed to prepare for the next pandemic and to advance medicine isn’t paralysed. The latest policy, released on 6 May by the US Office of Science and Technology Policy, is the next stage of a long-running US balancing act between totally banning high-risk pathogen research and assessing it with standards that some say are too ambiguous.

In 2014, after several accidents involving mishandled pathogens at US government laboratories, the presidential administration announced a moratorium on funding for research that could make certain pathogens — such as influenza and coronaviruses — more dangerous, given their potential to unleash an epidemic or pandemic. At the time, some researchers said the ban threatened necessary flu surveillance and vaccine research.

The government ended the moratorium in 2017, after the US National Science Advisory Board for Biosecurity (NSABB), a panel of experts that advises the US government, concluded that very few experiments posed a risk. That year, the US Department of Health and Human Services (HHS) instead implemented a review framework for proposals from scientists seeking federal funding for experiments involving potential pandemic pathogens. This framework applied to proposals to any agency housed under the HHS, including the National Institutes of Health (NIH) — the largest public funder of biomedical research in the world.

Researchers raised concerns about the transparency of this review process, and the NSABB was asked to revisit these policies and guidelines in 2020, but the COVID-19 pandemic delayed any action until 2022. During that time, the emergence of the coronavirus SARS-CoV-2, and the ensuing debate over whether it had leaked from a lab in China, put biosafety at the top of researchers’ minds worldwide. The NIH, in particular, was scrutinized during the pandemic for its role in funding potentially risky coronavirus research. In response, some Republican lawmakers have — so far unsuccessfully — put forward legislation that would once again place a moratorium on research that might increase the transmissibility or virulence of pathogens.

Finding a balance

The latest policy aims to address concerns that have arisen over the past decade about lax oversight, ambiguous wording and lack of transparency.

It breaks potentially problematic research into two categories. The first includes research on biological pathogens or toxins that could generate knowledge, technologies or products that could be misused. The second includes research on pathogens with enhanced pandemic potential.

Research falls into the first category if it meets several criteria. For example, it must involve high-risk biological agents, such as smallpox, that are on specific lists. It must also have particular experimental outcomes, such as increasing an agent’s deadliness.

Research that falls into the second category includes pathogens intended to be modified in a way that is “reasonably anticipated” to make them more dangerous. That criterion means that even research on pathogens that are not typically considered dangerous — seasonal influenza, for example — can fall into the second category. Previously, pathogen surveillance and vaccine-development research were not subject to additional oversight in the United States; the latest policy eliminates this exception, but clarifies that both surveillance and vaccine research are “typically not within the scope” of research in the second category.

Layers of review

Scientists and their institutions are responsible for identifying research that falls into the two categories, the policy states. Once the funding agency confirms that a research proposal fits into either group, that agency will request a risk–benefit assessment and a risk-mitigation plan from the investigator and institution. If a proposal is deemed to fit into the second category, it will undergo an extra review before the project gets the green light. A report of all federally funded research that fits into the second category will be made public every year.

The directive also mandates that agencies outside the HHS that fund biological research, such as the US Department of Defense, must abide by the same rules. This is a huge step forward, says Tom Inglesby, director of the Johns Hopkins Center for Health Security in Baltimore, Maryland. But it applies only to federally funded research; the policy recommends, but does not require, that non-governmental organizations and the private sector follow the same rules.

Federal agencies and research institutions will now create their own implementation plans to comply with the policy before it goes into effect in 2025. Yassif says that the policy’s success will hinge on how these stakeholders implement it.

Nevertheless, the policy sets a worldwide standard and might inspire other countries to re-evaluate how they oversee life-sciences research, says Filippa Lentzos, a biosecurity researcher at King’s College London who chairs an advisory group for the World Health Organization (WHO) on the responsible use of life-sciences research. Later this month, at the World Health Assembly in Geneva, Switzerland, WHO member states will consider a proposal to urge nations to cooperate on developing international standards for biosecurity.