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7 July 2021

The science of sexual conflict

How evolutionary theory explains why men and women seduce, deceive, abandon and hurt each other.

By Louise Perry

There was a time, near the beginning of this century, when the wacky behaviour of creationists was the subject of intense media interest. People who believed that the Earth was less than 10,000 years old were intent on teaching schoolchildren a religious alternative to the theory of evolution by natural selection, and every right-minded atheist was intent on stopping them. Leading the charge was Richard Dawkins who, in a 2009 review of a book titled Why Evolution Is True, condemned the folly of those who, rather than “working out that they have probably misunderstood evolution… conclude, instead, that evolution must be false”.

An under-acknowledged truth, however, is that hostility towards evolutionary theory is not confined to religious fundamentalists. Many secular liberals, for instance, find the notion of a divergent mark left by evolution on male and female brains to be a source of intense discomfort. Most feminists prefer to explain differences in male and female behaviour as a consequence of socialisation, particularly during childhood, and are sceptical of any account that presents these differences as innate – fearing, I suspect, that toxic male behaviour would be harder to challenge if it were found to be natural in origin. In fact, the very idea that there are evolved psychological differences between the sexes has become so taboo in some circles that even voicing the possibility is taken to be an indication of anti-feminist sentiment.

[See also: The baby bust]

In 2017, the Google engineer James Damore fell afoul of this taboo when he circulated an internal memo which suggested that the under-representation of women at the company might partly be a consequence of “differences in distributions of traits between men and women”. Damore cited legitimate scientific research, but he was nevertheless fired for violating Google’s code of conduct, provoking a media storm.


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The problem Damore encountered is that the socio-political ramifications of evolutionary theory can upset everyone, because “nature red in tooth and claw” is grisly, and not only among non-human animals. Evolution is a blind, amoral process that essentially depends on two things: random gene mutations and a huge amount of death. It doesn’t care about human well-being or 21st-century niceties. And sometimes digging down into the research reveals things that we’d rather not know.

But David M Buss is one of those rare people who is able to look Darwin straight in the eye without flinching. Professor of evolutionary psychology at the University of Texas, Buss is the author of a long list of popular titles, the latest of which – Bad Men: The Hidden Roots of Sexual Deception, Harassment and Assault – returns to his favourite academic topic: human mating.

Buss is interested in conflict between men and women, both as groups and as individuals. We are all engaged, he argues, in a “co-evolutionary arms race” in which the weapons are beauty, deception, charm, coercion and aggression, often deployed subconsciously. Buss understands male and female interests to be fundamentally misaligned in important ways, and Bad Men is thus dedicated to “everyone who has suffered from sexual conflict” – which is, as he points out, all of us.

The book, organised lightly by theme, is a recitation of decades of accumulated research, conducted mostly, though not exclusively, on heterosexuals. Fortunately for Buss, his subject is gripping enough to carry what could otherwise have been a rather dry format. Delivered in the cool tones of an eminent scientist, each page nevertheless manages to evoke equal parts titillation and horror. Examining human mating from an evolutionary perspective turns out to be as disgusting, compelling and unnervingly intimate as watching someone burst a pimple.

Although his subject is “bad men”, Buss also introduces us to a lot of bad women. Sexual conflict has a way of bringing out the worst in humans: we learn about deception in online dating, treachery within marriage, stalking in the aftermath of break-ups and harassment in the workplace. Buss’s thesis – which is extremely well supported by the research data – is that male and female sexuality is, in general, different, and that these differences produce conflict, sometimes in strange and subtle ways.

We start from the recognition that reproduction places more physical demands on women than it does on men. Pregnancy lasts more than nine months, and concludes with a dangerous labour, which is followed by many more years of breastfeeding and childcare. Men, however, only really need to expend the amount of effort it takes to orgasm in order to reproduce. This foundational physical difference has led to average psychological differences between the sexes that are sometimes profound. As Buss writes,

[S]ex differences in reproductive biology have created selection pressure for sex differences in sexual psychology that are often comparable in degree to sex differences in height, weight, upper body muscle mass, body-fat distribution, testosterone levels, and oestrogen production… [they] show up in mating motivations, such as sex drive and the desire for sexual variety… in the emotions of attraction, lust, arousal, disgust, jealousy and love… in thought processes, such as sexual fantasies and inferences about other people’s sexual interest.

Buss is keen to stress that these differences are average ones, just like differences in height between the sexes. You cannot confidently predict an individual’s preferences or behaviour if the only thing you know about them is their sex. At the population level, however, even minor average differences can produce striking effects.

The dynamics of the sex trade reveal this particularly starkly. Women make up the overwhelming majority of sex-sellers, for the simple reason that almost all sex-buyers are men (at least 99 per cent across the world), most men are straight, and the industry is driven by demand. Sex-buyers are people who seek sex outside of a committed relationship, usually with a person they have never met before, and this kind of sexual encounter is far more likely to appeal to those who score higher on the inventory of what psychologists term “socio-sexuality”: a desire for sexual variety.


One of the most well-supported findings within the cross-cultural study of human sexuality is that men are, on average, higher in socio-sexuality than women. This makes intuitive sense within an evolutionary framework since, while it may be advantageous for fathers to hang around after conception to increase the mother and baby’s chances of survival, it isn’t always necessary. A man who can game the system by abandoning a woman after impregnating her, and then ride off into the sunset to impregnate more women is successfully spreading his genetic material. He carries the risk of retribution, including violence from the woman’s male kin, but the benefits may sometimes outweigh the risks.

Our female ancestors had to bring up their children in a dangerous environment, which usually meant keeping a male partner around, both for material support and for protection from other men. Our male ancestors, meanwhile, “recurrently faced an adaptive problem no woman in the history of human evolution has ever faced – investing resources in the mistaken belief that a child has sprung from his own loins and not from those of an interloper”. In our evolutionary history, men who unwittingly devoted themselves to raising children who weren’t genetically related to them were at a selection disadvantage, while those who practised what biologists call “mate guarding” could be certain that their children were their own.

[See also: The Good Girls investigates violence against women in Modi’s India]

Although women experience jealousy just as often as men do, the male expression of this emotion is most destructive: 50 to 70 per cent of female murder victims are killed by men motivated by sexual jealousy, whereas only 3 per cent of male murder victims are killed by romantic partners or ex-partners. The disproportionate institutional power that men have historically held means that male sexual jealousy is also embedded in cultural and legal systems. In much of the Middle East and West and Central Africa, men are permitted to take multiple wives, but women must remain monogamous. Even in the modern West, where this sexual double standard is no longer formalised in law, it still shows up in myriad ways.

The invention of hormonal birth control may have reduced the biological necessity of mate guarding, but it can’t undo evolution. If you take a group of married men, hook them up to machines that monitor heart rate and other physiological responses, and ask them to imagine their wives having sex with another man, they are sure to show an intense physical stress response, whether or not their wives are imagined to be on the contraceptive pill. Although cultural variation demonstrates that it is possible to encourage or discourage an instinctive emotion like jealousy through the use of social pressures, it is very hard to override adaptations that are deeply embedded in the human mind – this, in the end, is the core tenet of evolutionary psychology.


Bad Men is a popular-science book, rich with lively detail, but it can also be read as a self-help book informed by evolutionary research. Plenty of Buss’s insights will be useful to anyone attempting to navigate the modern dating landscape. For example, it apparently really is true that men who own sports cars are more likely to cheat on their partners, as are women who wear a lot of make-up. It is also true that a man who is reluctant to introduce a partner to his friends and family is probably attempting what Buss coyly terms a “short-term mating strategy”, or what others might refer to as a “fuck and chuck”. Most stereotypes about human mating are borne out by the data.

But there are also more important insights to be gleaned from the second half of the book, which is concerned with violence, overwhelmingly inflicted by men on women. An unfortunate effect of the feminist rejection of evolutionary psychology is that most feminists have stepped away from the discipline and so play only a minor role in shaping it. Yet the discipline can still be put to feminist ends. Refusing to acknowledge the existence of psychological differences between the sexes is not only hard to justify scientifically, it also denies us the opportunity to take advantage of a body of knowledge that could be truly useful, particularly for the young women who are most at risk from sexual violence.

[See also: Reconsidering violence against women]

Bad Men is well worth reading for its practical advice, which includes – among much else – strategies for victims of stalking, as well as a lengthy description of the psychological characteristics of men most likely to rape (impulsivity, disagreeableness, promiscuity, hyper-masculinity and low empathy). Buss makes a scientifically informed case for recruiting more female police officers to investigate sexual crime, and explains why women’s intuitive fear of strangers in dark alleys is perfectly rational, demonstrating that, at a policy level, evolutionary psychology could be used to argue both for major reforms to the criminal justice system, and for minor changes, such as improved street lighting.

Despite these helpful recommendations and his attempts to signal friendliness by quoting icons such as Kimberlé Crenshaw and Susan Brownmiller, Buss is bound to be either condemned or ignored by most feminists, given that recognising the natural origins of male violence is such a dismaying prospect. Nevertheless, while this might not seem an obvious choice of feminist reading matter, I would press this book into the hands of any teenage girl. “Men’s sexual violence toward women remains the most widespread human rights problem in the world,” writes this unlikely feminist ally. “A deep understanding of the co-evolution of sexual conflict in humans will not magically solve all problems. But I am convinced it is the light and the way.”

Bad Men: The Hidden Roots of Sexual Deception, Harassment and Assault
David M Buss
Robinson, 336pp, £18.99

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This article appears in the 07 Jul 2021 issue of the New Statesman, The baby bust