August 18, 2023   7 mins

Once upon a time, Darwinian theory was regarded as anathema to feminism. It presents gender stereotypes as inherent and predetermined, rather than as a production of socialisation and implies that women should fulfil “traditional roles”. No wonder it found a natural home among social conservatives. More surprising, though, is how a new generation of feminists have embraced evolutionary theory, using it to explain the current sexual disenchantment they see in the world.

Women, as they see it, are losing in our overly casualised, hook-up-oriented sexual marketplace because it is not how natural selection meant us to be. We were sold a lie that promiscuity was empowering, and we have come up against the constraints of an evolved psychology that tells us to lock down a man and have a baby. As a result, women are single, childless and unhappy. The solution? Variations on abandoning contraception, practising abstinence, embracing marriage and prioritising traditional family structures. The illiberalism of “there are no differences between men and women” is met with the illiberalism of “these differences are insurmountable”.

The evolutionary logic behind human behavioural sex differences, first theorised by the evolutionary biologist Robert Trivers in 1972, goes like this: because men can hypothetically father as many children as women they could sleep with, whereas women are limited in the maximum number of children they can have, men have evolved to be promiscuous, competing among themselves for a limited number of women. It also led men to become jealous, and in some instances violent, to avoid being cuckolded.

Women, by contrast, who are at risk of being left holding a demanding and vulnerable baby, have evolved to be picky and to prefer monogamy. This package of behaviours is sometimes called “sociosexuality” (high = promiscuous, low = chaste), and is borne out by our experience that men tend to desire more sexual partners and seek out casual sex to a greater degree than women.

But then we get to the question of the size of this difference — and in a debate about the sexual revolution, size matters. Is the disparity really that big? Is it even biological? Or does it vary between cultures?

In The Case Against the Sexual Revolution and Feminism Against Progress, Louise Perry and Mary Harrington both lean on Trivers’s theory, with Perry citing research that shows large sex differences in sociosexuality across 48 countries. The study, carried out in 2005 by a psychologist at Bradley University in Illinois, asked university students how many sexual partners they had had in the last year, how many of these were one-night stands, and whether they thought sex without love was acceptable, among other things. Putting aside that the sex lives of students are wholly unrepresentative of the general population and are unlikely to reflect how older individuals approach sex, and, in the words of the author of the research himself, that to extrapolate from this data to populations as a whole “would be inappropriate”, the research also showed that the sociosexuality gap varied a lot between these same 48 modern states, narrowing considerably in more gender-equal countries. If you keep in mind that men tend to overstate their promiscuity while women tend to understate theirs, then these differences are likely to get significantly smaller. They will still exist, but presenting them as entirely biologically caused, universally large and culturally invariable is a misleading first step in a logic that is defeatist about social change. If we were to look a little wider, outside of our rich and industrialised countries, we would find that the story of male and female sexuality gets a lot more complicated.

Consider the following statement: “I don’t like it when her boyfriend is here in the morning when I come back from being away.” This line might seem plucked from a conversation about sexual jealousy in a polyamorous chatroom, but in fact it comes from a Himba man, a semi-nomadic pastoralist group from Northwest Namibia.

With an estimated population of 50,000, the Himba still “marry”, in the sense that there are socially recognised unions between two or more individuals. There is also widespread acceptance of infidelity for men and women, leading to the highest rate of extra-marital children ever recorded, with 48% of all children fathered by someone other than the husband. It’s no secret when this happens, and parents tend to know with high accuracy whose child is whose. Moreover, Himba men place great value on being good fathers, even when they suspect the child is not biologically theirs. Jealousy still exists, as the above quote demonstrates, as does violence, and there is a degree of informal concealment around these affairs: to reduce the risk of run-ins, husbands are expected not to come home if they are out after dark, while lovers should leave before they hear the roosters crowing.

The Himba are an extreme example, but stories of relationship fluidity and female promiscuity crop up again and again in the anthropological record. As Paul Riesman has observed, among the Fulani of West Africa, a man knows that a woman has lovers and that “if he is away, whether on a trip… or out looking for women himself, ineluctably his wife will have visitors and that it depends on her wishes alone whether she will go into the bush with them or not”. Meanwhile, many lowland indigenous populations of South America believe in partible paternity, whereby multiple men “contribute” semen to the gestation of a child, leading to most children having several fathers. In the Maqu region of Tibet, trial marriage is practised, where men and women live together before formal marriage, and prior to this cohabitation, may have multiple sexual partners. For the Mosuo and Zhaba farmers of China, husband and wife don’t ever cohabit, instead practising a “walking” marriage in which husbands visit at night, and help raise their sisters’ children during the day. In many traditional hunter-gatherer societies, the environment in which we have spent most of our evolutionary history, there is little stopping lovers from wandering into the forest together.

These examples are not meant to disprove the “naturalness” of long-term monogamous relationships, nor are they “better” ways of being. Many of them are also evidence of the essential existence of “pair bonding” in human relationships, where most individuals do form long-term monogamous relationships. But what they are meant to disprove is a notion of women as inherently chaste and of men as inherently promiscuous. If the elaborate cultural constraints and shame we usually put on women’s sexual behaviour are proof of anything, it is that, without them, women will, and often do, engage in promiscuous behaviour. If the predominance of pair-bonding in humans is proof of anything, it is that men will, and often do, stick around to raise the kids.

But are these examples, interesting as they are, relevant to those of us who departed down a different cultural route a long time ago? Well, is Tibetan “trial marriage” so different from a young couple living together but deciding to part ways? Is a Himba father investing in children he knows are not his, so different from the love and care that many receive from stepparents? Is Donald Trump marrying three times, albeit consecutively, so different from a rich polygamous pastoralist having three wives? We may no longer legally allow polygamous marriage, but the evolutionary nuts and bolts of having a man rich enough that he is able to support multiple wives and children is the same whether it is Trump or a Kipsigi man. We may not require that a man raises a stepchild under his own name like the Himba, but we would still expect him to treat them with kindness and care. There are, of course, still differences, but they are differences of degree, not kind, and much like the gaps in sociosexuality, they are often considered to be larger than they are.

So, what are the commonalities among the environments in which we find the Himba, the Maqu, the Mosuo, the Fulani, one of the 53 South American societies with partible paternity beliefs, or indeed our own society, where sexual behaviour is more relaxed, where women are freer, and where children are still raised to become happy and healthy adults? Often, women live close to their extended family members, who can help her raise her children and come to her defence if mistreated. Women inherit, and they also control some means of wealth generation. Most crucially, women are less dependent on their husband.

It is in these situations where research has shown that male jealousy is lower, as men are less concerned with becoming a “cuck” whose resources are unwittingly going to non-biological children, since wealth is instead passed through women. As Perry and Harrington note, this does weaken marriage bonds, because both men and women are able to walk away more easily. But compare this with societies where men control all the wealth, or where women make a lesser contribution to the economy, and male jealousy becomes high, the sexual culture less permissive, and strict controls emerge over women’s behaviour as paternity once again becomes an issue. Socially imposed monogamous marriage did not emerge in the West because it was better for society (though it might well be), as Perry states. It emerged to protect the wealth of a man being inherited by a non-biological son. Virginity and chasteness became highly valued, and women traded their promiscuity in exchange for their sons to be the sole heirs of a man’s estate, for they had no estate of their own.

Despite this, many “feminists” today propose solutions that would return women to once again being highly reliant on husbands. “Get married and do your best to stay married” is Perry’s parting advice. Harrington tells us to reject the contraceptive pill. Both propose that women wait to have sex, possibly until after marriage. “There was a wisdom to the traditional model in which the father was primarily responsible for earning money while the mother was primarily responsible for caring for children at home,” Perry states. All of these solutions are aimed at controlling the two male evolutionary strategies that Perry describes — cad and dad — as by being chaste you force men to make themselves marriageable. Yet, she denies women the same multitude of sexual strategies, instead reducing the female evolutionary story to a battlefield of male-on-male competition where our only active role is one of containing male promiscuity.

But can any of this tell us how to live? I’m not convinced. Natural selection doesn’t care much for your long-term happiness and doesn’t provide us with the means to build a moral and sexual ethics. The dissatisfaction individuals express about our contemporary sexual culture is more complicated and individualised than the sweeping conclusions provided by evolutionary theory. We should acknowledge that weakening monogamy leaves some women vulnerable, particularly if they cannot replace support from husbands with family or the state; just as we should also acknowledge that reinstating a forceful emphasis on monogamous marriage with sexual divisions of labour would limit women’s freedom. What we should not do, however, is use evolutionary theory to make superficially convincing narratives of gender stereotypes, which are a distraction, and do a disservice to the multitude of ways that humans can and have evolved to live.

Olympia Campbell is a PhD student in evolutionary anthropology at UCL.