Editor's note: Earlier this year, I was delighted to interview David Buss, pioneer of evolutionary psychology about his new book When Men Behave Badly: The Hidden Roots of Sexual Deception, Harassment, and Assault. One of the first psychologists to apply Darwinian insights to humans, his research over the past three decades has focused on psychological sex differences, mating strategies, and sexual conflict. He is the author of several books including The Evolution of Desire, and The Murderer Next Door: Why the Mind Is Designed to Kill, and currently runs the Buss Lab at the University of Texas. What follows is a transcript of our discussion, lightly edited for readability.
CLAIRE LEHMANN: Well, it's a pleasure to finally talk to you Professor Buss! A pioneer of evolutionary psychology and sex differences research, how long has it been since you started researching sex differences?
DAVID BUSS: Boy, I think too long, maybe over 30 years. I've been researching sex differences since when I was in graduate school. I had multiple mentors, but one of my mentors was a woman named Jeanne Block. And, she had this theory that the reason that any sex differences existed whatsoever was because parents dressed up girls in pink and boys in blue.
She made a science documentary, The Pinks and the Blues. And, I just remember in graduate school feeling very dubious about these claims. There are sex differences, for example, in rough and tumble play, etc., and these emerge very early in life. Is it really because of parents dressing girls in pink and boys in blue?
So maybe that was the start of my questioning the orthodox interpretation of sex differences—which was largely sex difference denialism back then, and still to this day.
CL: So when did social constructionism become the orthodoxy? Was it around the 1960s or 1970s?
DB: Well, I think that, no. That label, maybe. But the extreme Blank Slatism emerged much earlier, at least in American psychology. So starting in 1920 with Watson, who claimed that if you gave him any child he could turn him into a physicist or a thief. And then B.F Skinner in 1938 who studied pigeons and rats, and then generalized his findings to all organisms. But this Blank Slate view, where humans come into the world equipped with basically nothing, and that the culture and parents write the script, that has been predominant in American psychology and social science for decades and decades. I think going back to those early times.
CL: It pervades the mainstream discourse around sexual conflict, which is what your new book is about. It’s called When Men Behave Badly: The Hidden Roots of Sexual Deception, Harassment, and Assault, and, I wanted to ask, were you inspired by the #MeToo movement to write this book?
DB: Well, no actually. I've been publishing on conflict between the sexes for more than 30 years.
Which is embarrassing to admit, but yeah, my first article on it was 1989. And so I had long planned on writing a book on conflict between the sexes. So I wrote the book proposal and my agents organised a nice contract for me, before the #MeToo movement happened. So this predated that, but it's a topic that has fascinated me. You know, that men and women seem to get into a lot of conflict on the mating market, within relationships, we get into conflicts even over our breakups, and we have stalking and revenge, and then revenge porn in the modern environment.
So sexual conflict is pervasive, and the evolutionary perspective adds a lot of clarity to where and why men and women get into conflict and the particular manifestations it takes in the human case.
CL: One thing that bothers me about the mainstream discourse on sexual conflict is this concept that all men are responsible for “gendered crimes” against women.
But the reading that I've done on criminal behavior suggests to me that it's a very small number of men who commit the vast majority of what you would consider sex offenses or criminal offenses against women. Does that show up in your research as well? Is it a small number of “bad men,” who commit most of the coercive or sexual crimes against women?
DB: Yes, absolutely. And this is one of the key themes of my work is identifying the subsets of man and the characteristics they have. Such as the men who are most likely to engage in things like sexual harassment, sexual coercion, intimate partner violence. It is not all men. So my book is not a male bash.
CL: I suppose it's important to clarify that sexual conflict is basically universal and we all have experienced sexual conflict in relationships and in our mating lives. But when we're talking about things that we would consider criminal behaviors, that's when a minority of bad men who commit offences are implicated. But if we're talking more broadly about sexual conflict, that's common. We all have arguments, we all have disagreements—that’s normal.
So it's important to separate those two things?
DB: Thank you, Claire. That's an important, a very important distinction. So in my book I talk about that. It’s kind of like there's a progression—starting with sexual conflict in the mating market and sexual conflict in relationships, which is pervasive, over sexual resources and financial resources.
But the more extreme forms like sexual harassment, sexual assault, stalking and so forth—the more extreme you get, the more that males have a monopoly on it and the more women are the victims. But as you rightly point out it’s [only] a subset of males that do this.
We know empirically who that subset of males are. And they are men high in Dark Triad traits. These are narcissism, psychopathy, and Machiavellianism. Narcissism is a sense of grandiosity, a sense of entitlement, these are the guys who think that they're hot, but they're not—is one way to phrase it. They overestimate their intelligence, their attractiveness, etc. They think they’re god's gift to women.
And then Machiavellianism describes people who pursue an exploitative social strategy. So these are the liars, the cheaters, and the deceivers. And then psychopathy is marked by a lack of empathy.
For most normal humans, 95 percent of us—or 96 percent of us—have this empathy circuit—where if someone gets harmed, we feel some sense of compassion for the harmful experience that the harmed person has going through. Psychopaths don't at all. They don't care. They will laugh if someone gets harmed. Or they're just totally indifferent to it.
So that moral circuit is absent in psychopaths. So if you combine the Dark Triad with a short-term mating strategy, that is what proves to be a deadly combination. So these are guys who are serial sexual harassers and also serial sexual assaulters.
CL: And it's important to point out that these individuals can be very charming, and socially slick. When you say psychopaths are people who are low on empathy, we're not talking about autistic traits. We're talking about people who can potentially understand what you're feeling, but just don't care.
DB: Yes. That's exactly right. But psychopaths—these are very bad dudes. These are the serial criminals and they're not responsive to punishments, that is one of the hallmarks of those who are high in psychopathy. But this gets to the point where you get to these extreme forms of sexual conflict and sexual violence, which from an evolutionary perspective, bypass female choice, which is like the first law of mating (it comes from Darwin's theory of sexual selection, circa 1871). Sexual violence against women bypasses female choice. And these guys are indifferent to that.
And I think that back to your point about “not all men,” most men I think would find the bypassing of female choice to be morally abhorrent. But high Dark Triad guys don’t. They don't care. And it's that combination of narcissism Machiavellianism, and psychopathy, with a short-term mating strategy that predicts it, then combined with social circumstances that allow them to get away with it.
These men deploy strategies that I think women need to know about which includes various forms of disabling evolved female defenses against sexual violence. I go into it in a whole chapter in the book, that is, in identifying about a dozen or so female defenses against [sexual coercion] because I knew that [these defenses] go back into deep time.
If you look at the molecular genetic evidence, the paleo-archeological evidence of the written record, sexual violence has a deep, deep history. It has occurred over human evolutionary history. So it would be astonishing if women had not evolved defenses to try to preserve female choice and defend against these sexually treacherous men.
CL: You would also think that healthy societies would have developed mechanisms for mitigating the damage caused by these men. And we have, you know, the legal system, the justice system, we shame and stigmatise sex offenders and so on. We have all sorts of methods by which we try and mitigate the damage that these individuals cause. Because psychopaths indeed cause a very large amount of harm. If you look at recidivist defenders, it's something like a very small percentage of criminals who commit the vast majority of crime. So in terms of damage done to innocent victims, their contribution is vast.
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CL: Going back to understanding sex differences - would you say the most fundamental theory in understanding them would be Parental Investment Theory?
DB: Well, yeah. I mean, sexual conflict started with the evolution of sexual reproduction. So we're talking about one to two billion years ago when sexual reproduction evolved. That's when the two sexes evolved—where the sexes are defined from a biological perspective—by the size of the gametes.
Males are defined by the small gametes, a small packet of DNA with an outboard motor on it, to get to the valuable egg, and females are defined as the ones with large gametes—in the human case the nutrient rich egg. So you start with this sexual division: two sexes, and what's optimal from a male perspective differs from what is optimal from a female perspective.
So you have what biologists call a sexually antagonistic co-evolutionary arms race, which I know is a mouthful, but it is accurate. In that what you have is very much like predators and prey, you have adaptations in one sex that try to manipulate or influence the other sex to be closer to its own optimum. Then counter-defences or adaptations from the other sex to prevent that from happening. Much like predators and prey, this is a co-evolutionary arms race which is perpetual. And we understand it when it comes to cheetahs and Gazelles—predators and prey—but exactly the same process or an analogous process happens between the sexes, within the species.
And so, yes, that's your point that parental investment from the very start. To produce a single individual in the human case, it takes not only the sperm and the egg but the nine months of pregnancy by the woman in contrast to one act of sex in the minimal case for the man. Unfortunately, men do more than the minimum, as I'm sure you're aware of, which is a good thing (laughs). But not all men do. But you take this fundamental sex difference in human reproductive biology, and it would be miraculous and astonishing and defy all scientific wisdom and knowledge if there did not evolve sex differences in our sexual psychology, sexual strategies, and consequent behavior. And there is of course, abundant evidence that humans have. [Arguing that we don't have different sexual psychology] would be like saying we have evolved the anatomy and physiology for bipedal locomotion, but we don't walk.
So all these sex differences in anatomy and physiology have psychological correspondence.
CL: If you look at other species whether it's a mammalian species or not, where the female has less parental investment or fewer opportunity costs inflicted by pregnancy do you see the mating strategies equalize a bit? Is there less sexual dimorphism if there is less investment on behalf of the female?
DB: Well there is variation across species in magnitude of sexual dimorphism, absolutely.
It really hinges on the power of the components of sexual selection. So there are some aspects of sexual selection where for example—elephant seals or gorillas as a primate example—where it's basically male-on-male combat that determines the outcomes. There you see the males are like four times the size and weight of the females. Although even in those species—like elephant seals—females do exercise choice. They don't want to mate with the beta males or the gamma males. So if either of those males try to mate with them, they put out this bellow, and alert the alpha male who comes bounding and beats off the mate poacher.
But one of the things about the human case of sexual dimorphism is that some people have argued that “well, humans are not really all that dimorphic.” But in fact, it really hinges on which aspect of dimorphism you’re looking at. So if you’re talking about some of the upper body strength humans are as dimorphic as gorillas are on these dimensions.
If you talk about our sexual psychology, the magnitude of the effects are enormous by psychological standards. They dwarf the typical effect sizes in psychology.
CL: And what are the most robust and reliable sex differences that are found in the psych literature? I mean, we know about the career preferences one.
But what are some of the ones that you've discovered in your lifetime of research?
DB: Well, so one of the largest ones that I think causes the most problems is sex differences in desire for sexual variety, meaning a variety of different sex partners.
So how many sex partners would you like to have in the next 10 years? Men will give an answer with five times as many desired partners as women. Is sex without love OK? Men tend to agree with that attitude, women tend to disagree. Sex with total strangers? Men are more comfortable with that than women.
Or even sexual fantasies. The nature of male and female sexual fantasies are dramatically different. I actually recently got an email from a guy who's 85 years old. And he said:
You know, I'm 85 years old, and every time I walk down the street, my brain punishes me by evaluating the sexual attractiveness of every female that walks by.
This guy, I mean he's 85 years old—he probably has zero sex life, but his male brain is still attending to those cues and finding them attractive. So that’s the biggest one. And it's also the one that causes the most havoc because it not only promotes males to deceive women in the mating market, but also in relationships, as it drives men into having affairs.
In one section of the book I talk about the sex differences in the motivations for why men and women have affairs. For men it is the desire for sexual variety—that's what they cite, at least 70 percent of them anyway. They say they have affairs for the “novelty,” or because “the opportunity presented itself.” Whereas for women, it was more like, “I fell in love with someone else,” or “I became emotionally involved with someone else.”
Then something like 70 percent of women who have affairs do fall in love with their affair partners. So it tends not to be the casual, impersonal sexual conduct that it is for the males. And so these sex differences in what I broadly describe as desire for sexual variety play themselves out in multiple contexts.
CL: It's probably useful for young women in particular to understand that there is this difference in orientation to variety. And would you say that one of the more deceitful mechanisms that men have developed is lying or not being honest about their intentions in engaging in a sexual relationship?
DB: That's a classic one (laughs). I mean, we found this in research I did with Martie Haselton, a former student of mine, who's now a very well-known professor at UCLA. We looked at the ways in which men and women deceive each other. And I should say that women deceive men as well. So we're not letting women off the hook. No. (Laughs). But that's one of the things that we found, and it's a very replicable finding, and it's that men exaggerate the depths of their commitment. They exaggerate how similar their interests are, and they also feign a long-term mating strategy in the service of pursuing a short-term mating strategy.
CL: So they will mimic being in love to get sexual access to a woman, and then potentially that all falls away or drops away after the relationship is consummated.
DB: Right. Indeed. And I think that there's probably some triggers—the original parental investment theory also has a theory of self-deception. And I think that in this aspect, [Trivers] is probably right. Because just based on the men that I’ve interviewed, and the studies that we've done, men sometimes truly believe that they feel this depth of feeling for the woman and then post orgasm they realize, “I don't know what I was thinking. I actually don't feel that way.” So this is a post-orgasm affective shift in their feelings. And I think part of that might be self-deception in the service of deception.
CL: Wow. That's so interesting. Is that called the negative effective shift? Is that the term that’s used?
DB: Yeah. We published an article on precisely that. What we found is that it's only men and it's only men who are high in the pursuit of a short-term mating strategy that experienced this—this affective shift from pre-orgasm to post-orgasm.
CL: And that’s the desire to sort of get away, or run away, or not have anything to do with the woman?
DB: “The get outta Dodge adaptation.” We have hypothesised that it's an adaptation to minimize commitment in entangling and involvement because those entanglements will interfere with the successful pursuit of short-term mating strategy.
CL: Yep. And there's also sex differences in terms of the experience of sexual disgust?
DB: Oh yes. Those are huge.
CL: And are women more sensitive to sexual disgust?
DB: Yeah absolutely—which makes sense. I think that's part of female choice. So although both sexes take a risk by having sex with someone else—you risk acquiring pathogens and infections, diseases, and so forth. But the costs to women are much greater, and the benefits much less. From a male perspective, they are willing to down-regulate their sexual disgust in the pursuit of short-term mating. Women are much more easily sexually disgusted. If the guy doesn't smell right, you know, body odour can be a sexual killer for women.
So yeah, these are again high magnitude effects. Very replicable.
CL: We have to emphasize that these emotions aren't necessarily occurring on some rational, conscious level. They're very animalistic or, you know, instinctive.
DB: Yeah. A woman doesn't sit down and say, “let's see, rationally, this guy doesn't smell good. And therefore he has a high pathogen load.” No, it's just a gut level reaction.
CL: And then we might rationalize our reactions after the fact, but it's that gut level response that happens first.
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CL: A term that is often used in evolutionary psychology papers is “opportunity cost,” and sometimes I think that term is thrown around a little bit, without it being explained.
Can you explain what opportunity costs are? And would you say that opportunity costs are different for men and women? And if so, is this a predictable source of tension and conflict?
DB: I think it's part of our evolved sexual psychology, but it's actually an economic concept. It's basically this concept that we have limited time, energy and resources. And in every moment in time, we have to allocate those resources to one thing versus another.
And so at every point there’s a number of decisions—and a decision to do something is also a decision not to do something else. And so the opportunity cost structure is different for males and females, where, for males, for example, the cost of missing out on a sexual opportunity historically over evolutionary time have been much greater for men compared to women.
From a woman's perspective, there's never been any shortage of men who were willing to have sex. But from a male perspective, there has been. Especially since ancestrally women have often been either pregnant or lactating. And so the actual number of fertile days over a woman's reproductive career ancestrally were much lower than they are in the current environment.
And so missing out on the sexual opportunity from a male perspective would have been extraordinarily costly from a fitness perspective, and from a female perspective, not at all costly, since there’s a line of guys out there.
CL: That then ties in with sexual regret. So men tend to regret missed opportunities, whereas women regret opportunities they have fulfilled.
DB: That's one of the fascinating things. When we have asked “so looking back, what sexual things do you regret?” Men would really regret those missed opportunities:
So there was that one time back in high school, or back in college when I had this chance to have sex with this woman. And I, I was too shy. I wasn't bold enough to move.
Whereas women are more likely to say:
Well, I just, I had a couple of glasses of wine and I slept with this guy and it was just, it was a disaster, and he's lower in mate value than I am.
Not necessarily in these terms. But women tend to regret acts of sexual commission, and men regret acts of sexual omission.
CL: Interesting. And so what are some of the ways that we can reduce the conflict between sexes perhaps in our own relationships, or in our dating lives?
I can't imagine we can get rid of the conflict altogether. That would be impossible, but is there some way that we can be aware of the other sex having different interests than we do, and perhaps finding some equilibrium? Is that possible?
DB: So in my book I talk about two different things. One is an evolutionary recipe for harmony between the sexes. What I mean is harmony in the context of a long-term mateship. If you have monogamy, any deviation from monogamy does cause the interest of the sexes to depart.
The second thing though, is education about the scientific facts about sex differences. One of the trends that I find appalling that occurs these days is what I call sex differences denialism, where some argue as if there are no sex differences in the brain, or that there are no sex differences at all. I mean really? The evidence is just too overwhelming. But I think that education about what these sex differences are will at least help bridge the gap.
Because we live inside the interiors of our own brains, and we use our introspection about our own minds to infer what's going on in another person's mind. And when men infer what's going on in women's minds, they're going to make errors and vice versa. And so knowledge about these sex differences I think will help both men and women.
For example, one of the things I talk about in the book is the sexual overperception bias.
That’s when a woman smiles, or looks at the man in the eyes and the man makes an inference that “she absolutely wants my body.” And the woman actually thinks “no, I'm just being friendly and polite, and this guy's creepy and he's making me nervous.” So knowledge that men tend to err in inferring sexual interest when it's not there, can help men to maybe curb their approaches. But also help women to understand that men have this psychological tic—which I think is an evolved design feature—and perhaps guard against it. And so I think that education about sex differences is critical in reducing conflict between the sexes.
Even the scientific knowledge about these sex differences should infuse our legal system as well. Even things like sexual harassment laws, they're written in the generic reasonable person standard. So would a reasonable person view this pattern of conduct to be sexually harassing? Well, it turns out my research and others have shown that reasonable men and reasonable women differ in what they consider to be sexual harassment, where women perceive the same pattern of conduct to be more sexually harassing, and more upsetting than men do.
So I think that even knowledge of these sex differences should influence our laws about these forms of criminal sexual activity.
CL: I wonder what feminist scholars would say about that because it would sort of run against our conventional wisdom to have two separate standards of law for the sexes. But that's a whole other debate.
DB: I'm not a legal scholar and so I don't know how the scientific knowledge could be implemented, but I think that it should, it should influence the laws in some way. It gets back to the issue of sex difference denialism.
CL: Something that also seems relevant is sex differences in personality. One trait that is more predominant in women is agreeableness. From my point of view, this causes some misunderstandings and conflict in mating as well.
DB: I think you're right about that because agreeableness will be interpreted by some men as sexual interest.
CL: I think it's possible that agreeableness can make it more difficult for women to say “no.”
DB: Not only is it more difficult to say no, but puts women in a very awkward bind in [places like] the workplace where a sexual approach of let's say by a boss or even a coworker puts women in this situation where they want to decline the sexual advance, but they also want to do it in a way that does not jeopardize or evoke revenge. Rage has no fury like a spurned man. And so part of that is women do what I call in the book a “soft rejection,”
Thank you for your interest, but I have a boyfriend or I'm married, or, you know, I'm busy this weekend.
Women do these rejections but in a way that tries to minimize the costs that he might inflict on her from being rejected. I think that might be an element of the agreeableness component that you're talking about.
CL: So what are some of the strategies that women have evolved to detect the liars and deceivers?
DB: Well one is to delay sex, to impose a longer courtship time, in part because the qualities that women desire in potential mates are often not discernible on immediate observation, or on first glance. They take time to judge. Is the guy reliable? Is he emotionally stable? Does he come with entanglements or commitments? Is he married with three kids? These things take time to assess. And so that's partly why women delay sex. But it’s also about assessing whether or not he's pursuing a short-term or long-term mating strategy. And the short-term maters basically tire more quickly and move on to explore the more sexually exploitable.
CL: I suppose the sex ratio is one key aspect of an environment which might push men towards a more short-term meeting strategy.
DB: Yeah. When there's a surplus of women, it pushes both men and women to a short mating strategy because basically the rarer sex is the more valuable sex.
I gave a talk a few years ago at Texas Christian University, and they have a sex ratio of about 60 women for every 40 men. And the women described it to me—they said—the guys who are normally say a “five” on the mating market are an “eight” at Texas Christian University. And one thing I noticed when I was there was that women were dressing in skimpy clothing and with a very sexualizing appearance.
When there's a surplus of men, you have the opposite. You have very stable long-term relationships, lower divorce rates, etc. So sex ratio is indeed a context that shifts the mating game quite substantially.
CL: So, if you were a young, single woman who wanted to get married and start a family, it might be a good idea to look at the sex ratio in the city that you live in, or the city that you wanted to move to, potentially.
DB: Yeah, absolutely. Or the universities, or even within universities in the majors. This is one the things that I wrote an essay years ago called “The Mating Crisis Among Educated Women” where in universities throughout many countries there is a surplus of women getting higher education degrees.
With the exceptions being very predictable, such as engineering. There's always a surplus of men in an engineering school, so MIT and Caltech have more men. But if I were either sex, I would look at the sex ratio or the environment that you're moving to. You want to move to a social environment where the sex ratio is in your favor rather than working against you.
CL: Which means that you want to be the rarer sex in the ratio. So there's more demand than supply of your sex.
CL: The issue of more and more women becoming educated and there being a smaller pool of men with the same credentials is a real issue. That doesn't seem to be slowing down does it?
DB: No. It's accelerating. And I think you have to combine that with the fact that women are less willing to settle for guys who are less educated, less intelligent, or lower in status than they are.
And so you are combining evolved mate preferences with this subsequent issue of imbalance in the hierarchy. People say, well, there's an easy solution. Women should just mate down, with guys who are lower than they are on these qualities. But it's hard to go against these evolved preferences. People desire what they desire.
CL: Or it's also an argument for potentially finding your long-term mate at a younger age before you become very successful, if you're a woman.
DB: Well, yeah, that's a possibility, but I would push back against that a little bit, just in the sense that, there is a statistical relationship between younger age at marriage and a higher risk of divorce.
One of the problems for young women is that when they enter the mating market they are not necessarily aware of their mate value. And so sometimes they are exploited by older guys and sort of snapped up before they realize their true mate value. Then over time this causes a problem because then they come to realize that they're higher in value than their current partner. And then the guys are very reluctant to give her up. They realize they're not going to be able to find a woman of equivalent value should a break up occur.
CL: This brings us back to the more extreme end of the sexual conflict spectrum, where you get stalking and that kind of thing.
Is it one of your findings that the younger the woman is the more likely she is to suffer stalking or harassment after a break up?
DB: Yeah, indeed. Younger women are stalked more frequently. But of course, women of all ages are stalked. And this is again, is one of these things where there's a sharp sex difference, when you talk about criminal stalkings, it’s about 80 percent of men who are the stalkers, and most of their victims are women. And for most of them, stalking is mating related. The woman wants to break up and the guy does not.
CL: This sometimes can spill over into spitefulness and violence where the aggrieved ex-partner wants to actually hurt the woman.
DB: I have a section in the book, where I talk about the aftermath of break ups and stalking and revenge porn. And one of the very first studies done on revenge porn was done in Australia, and it found that about 10 percent of women had been victims of revenge porn.
So these are basically where the guy is posting photos. On revenge porn websites and so on. Of course, this is very traumatizing for women. Comparable studies haven't been done in other countries, but revenge porn is one of these modern manifestations where technology is exploited for displaying this form of sexual conflict.
CL: I didn't realize it the rate of revenge porn was that high—that's a worrying statistic.
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CL: Your new book synthesises the insights that you've gained over 30 years of research into sex differences and sexual conflict. And I'm glad to hear that there's a chapter in there on promoting sexual harmony between the sexes, because that's what we need more of today.
DB: Yeah. And that's really what the goal is—to expose the forms of sexual conflict that exist and how best to deal with them. So my hope is that the book will be ultimately be used to reduce conflict and produce harmony between the sexes.
When Men Behave Badly: The Hidden Roots of Sexual Deception, Harassment, and Assault by David Buss is available now on Amazon and in all good book stores.
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