大衛·巴斯：性、約會、親密關係與性別差異

Lex Fridman Podcast #282 – David Buss: Sex, Dating, Relationships, and Sex Differences Machine transcription by Qwen3-ASR 0.6B (MLX, local, Apache-2.0). May contain recognition errors. The following is a conversation with David Bus, evolutionary psychologist at UT Austin researching human sex differences in mate selection. He's considered one of the founders of evolutionary psychology and has authored many exciting and challenging books, including The Evolution of Desire: Strategies of Human Mating, Bad Men: The Hidden Roots of Sexual Deception, Harassment and Assault, and The Murderer Next Door: Why the Mind is Designed to Kill. We talk a lot about sex, dating, relationships, and love. I take these at times controversial topics very seriously, but I also try to inject humor and ridiculousness throughout this conversation and all conversations I do. Please do not mistake my silliness for lack of seriousness, and my seriousness for lack of silliness. And above all, do not mistake my suit and tie or my PhD as a sign of intelligence or wisdom. I barely know what I am talking about on most days. I am simply curious and hoping to understand the way a child does. What the heck is going on in this weird and wonderful civilization of ours? If I say something stupid as I often do, I promise to learn and to improve. As Mark Twain said, "I do not want my schooling to interfere with my education." Open-minded curiosity, I think, is the best guide for proper and fun lifelong education. And now a quick few second mention of each sponsor. Check them out in the description. It's the best way to support this podcast. We got Notion for startups, ExpressVPN for privacy, Roka for style, Onit for supplements, and Indeed for hiring. Choose wisely, my friends. And now onto the full ad reads. As always, no ads in the middle. I try to make this interesting, but if you skip them, please still check out our sponsors. 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The team is what makes or breaks a business. Any kind of effort, anyway. Right now, get a free seventy five dollars sponsored job credit to upgrade your job post and Indeed dot com slash Lex. Get it at Indeed dot com slash Lex. Offer good for limited time terms and conditions apply. Go to Indeed dot com slash Lex. This is the Lex Friedman podcast, and here is my conversation with David Bus. What is more important in the history of the development of human civilization? Sex or violence? So mating strategies or military strategies. Oh well, both are important. I mean, first of all, humans are a sexually reproducing species, and so everything has to go through sex. You know, so in our mating psychology has to be very rich and complex because to succeed for us to be here now, all of our ancestors in an unbroken chain have had to succeed in selecting a fertile mate, attracting that mate, being mutually chosen by that mate, stay together long enough, do all the sexual things you need to do to reproduce, have the kids survive, et cetera. So everything has to go through mating, and in that sense I think it's I mean survival was really only a means to an end if you if you will. So so sex has got to be important and humans have a very rich evolved sexual psychology or an evolved mating psychology. Okay, but I wouldn't minimize the importance of violence either. There is a ton of evidence that humans evolved in the context of small groups and with a fair amount of small group warfare. So intertribal warfare, where and this is a harsh realization, but historically this is part of our bad evolutionary history. It has been advantageous from a purely reproductive standpoint to conquer a neighboring group, kill the males, and get whatever resources they have, including. Females and and sexual resources, tool as well as tools, weapons, territory, and so forth, and so and so I think that we have of course it's it's typically males who do that. I mean yes, some females are participated in warfare, but as far as I know, there is never been a single case in all of human recorded history of women forming a war tribe with other women to attack another group of women and kill them and capture the men as husbands. But these this phenomenon is common in the ethnographic record and small group studies. It's part of our common thing, so just one concrete example. Unfortunately, he's dead now. He passed away Napoleon Chagnon who studied the Onimamo for many many years. When he first started interviewing them, he he asked them, you know, why do you go to war? And they said, well, to capture women, of course, but it's the only sensible reason. And they said, you know, why do why does your culture go to war or however they phrased it and he said, well, we go to war for to spread democracy and ideas and everything. They basically fell off their logs laughing at such a stupid reason because why risk your life for anything other than women. Of course, it's more complex than that because some go to war for. Reputation reasons, they say if we if we don't retaliate because we've been attacked and they've stolen three of our women, if we don't retaliate, then we will get a reputation as exploitable and then other groups will start to attack us as well. And so they get into these cycles of you know like the Hatfield and McCoy's of attack, counter attack, retribution, and part of it is is reputation management. So that's that's between groups and and I think that's been the the primary source of. Violence, but not the only source. So there is also within group conflict, and so many ethnographies, many traditional societies have. Things some of them are ritualized like wrestling matches or in the Onimamo they have these we're used to these chest pounding duels where so if we're in this match you challenge me and I have to of course chest pounding duel. I like this yeah yeah so it's not you are not hitting each other you are just it's like peacocking you oh no you are hitting each other oh sorry yeah so they they get twenty paces away and they they run up and you punch the other guy in the chest and he has to basically stand there. And then he does the same and everything oh wow and then it's basically last man standing. That's well I suppose that's better than the face. That's an interesting decision with the chest. Yeah, I mean I am sure if you get good at that kind of thing you could start breaking ribs. Yeah, and you can get loose about the rules of where exactly in the chest you can hit. What and and there is that guy who's always known for hitting not exactly in the chest accidentally missing. Right, right, the Mike Tyson of eating your ear off. So interesting. So there is like ritualized conflict, sort of purify the the competition. That that that resolves some kind of issue. Well, yeah, it's important to establish status hierarchies, you know, but but also and here is here is just another one more concrete point on on that the Onimamo we don't have this in our language we just have one word for kill or murder. But the Onimamo have you are either an Una if you are a male you are an Uno Kai or a non Uno Kai. The non Uno Kai are men who have not killed. If you are an Uno Kai, that means you have killed someone, and the Uno Kai among the Onimamo historically had higher status and more wives. So they're a polygynous society which is which has been true of something like eighty three to eighty five percent of traditional societies. Or actually, I was just corrected by a anthropologist. She said we no longer call them traditional societies, we call them small scale societies. So nothing can be called traditional. I don't know. I think here is the traditional society. Yeah, yeah, I think it's just one of these things. Language, the word, the the words that are deemed appropriate to use to describe things change over time. So yeah, so words can hurt people. They can inspire people. Words are funny, powerful things. You authored the textbook titled Evolutionary Psychology: The New Science of Mind in its sixth edition. What is the magic ingredient that gave birth to Homo sapiens? Do you think is it fire cooking ability to collaborate. Share ideas ability to contemplate our own mortality all that kind of stuff yeah well I think it's hard to isolate one factor I know I know you've had Richard Rangam on this podcast it was a wonderful wonderful interview and he used to be a colleague of mine when I was a professor at Michigan and I've stayed in touch with him. On off, he's brilliant brilliant guy, and he thinks fire and cooking have been one of the key things, but I think it's hard to isolate. I would trace at least part of our uniqueness to the uniqueness of our mating system. So we have in in mating. Unlike chimpanzees, who are our closest primate relative, and of which Richard Rangam is is a world's expert, but they have basically no long term pair bonded mating. Okay, the female comes into estrus, all the mating, all the sex happens, most of the sex happens during that window. But humans have evolved long term pair bonded mating, and it's it's only one mating strategy, but it's a really important one. And then you have with that. Male parental care, so basically again you go back to chimps and chimps with whom we share more than ninety eight percent of our DNA. Males don't do anything, so they inseminate the females. But then when the kids are born, they basically don't do much of anything in terms of provisioning and so forth. But human males do, we invest in the modern environment could be decades you know especially with the boomerang kids and everything. But we're not all males do, but compared to the vast majority of mammals, we are a very heavy male parental investment species. Could you if it's okay and I'll ask you a bunch of dumb basic questions because those are fun. Could you define mating here? How we is mating referred to the the the series of sexual acts that lead to reproduction? Is it include like dating and love and camaraderie, loyalty all those things. Yes, I you know yes yeah when I first started studying yeah I don't it's when I first started studying it I looked for the right term and obviously it's much broader than sex. So by mating I include things like mate selection, mate preferences, mate attraction, mate retention, mate poaching, mate expulsion, mate poaching. That sounds fun. So the early the the game theoretic strategy mate selection is primary. What mating what mating is about or do you include the long term ones? You agree that you are going to stick this out for a while and have multiple children. Is that also mating? Yes, I include that as well. So it's it's it's a broad category, broad definition and and absolutely includes the emotion of love. And of course there are many different types of love brotherly love, love parents for children, but love I think and this is one of the shifts in the social sciences. So when I was an undergraduate for example I was taught that love is this invention by some Caucasian European poets a couple hundred years ago, and and it turns out that's not the case. So you you there is been extensive cross cultural evidence now that that people not every person in all cultures of course but all some people in all cultures experience this emotion that we call love. And for the word love, are we going to in this conversation try to stick to sort of romantic love for the for the meaning of the word love? Well, there that's that's a great question, but I mean there it's pretty well established that there are these different phases of love. So there is this infatuation phase where our psychology we we get obsessional thoughts. It's hard to focus on work when we're not with the person we're thinking about the other person constantly. So there is kind of like ideological intrusion into our psychology, but you you can't sustain that. I mean it would be and then of course there is a pardon the phrase but what I describe is the fucking like bunny's phase of of this you know intense sexuality, but people have other adaptive problems they have to solve, and so you can't stay in that state for too long and so that subsides over time and and drops into. At least in many cases, this warm attachment, cuddling bunnies, the long term cuddling bunnies, yes, phase of the relationship, but still romantic, not like brotherly love or. You know, because I talk about a love a lot, love a lot, and for me, you know, love is a broader experience of just experiencing the joy and the beauty of life. So like just looking out of nature, yeah, that's a kind of love like whatever the chemicals that lead to a feeling that at least echoes the same kind of feeling that you get with romantic love. You can experience that with even inanimate objects. That sounds weird to say, but just a gratitude and appreciation, not in some kind of weird Zen way, but just in a very human way. Just it feels good to be alive kind of. Yeah, yeah, yeah. I guess I would. I mean, that's an interesting thought. I hadn't thought about that. I guess I would use other terms to describe that. So like the term of awe, for example, when you see a beautiful sunset, you know that's why kind of started out by saying I think there are different types of love and and I am focusing on the mating type. And we'll talk about that, but so yeah, there is a sense of beauty and there is a sense of sexual appeal, maybe that's a good and those intersect in fascinating ways. We'll we'll talk about that. Okay, we'll talk about all of that, but you are saying mating strategies, not that we've kind of placed ourselves. What we mean by mating mating strategies is one of the cool features that made humans what they are. One of the initial inventions is is the weird, weird and wonderful ways that we mate. Yeah, and I mean if you go to even things like how we compete for mates, and this is another kind of strange for some people angle on it, but mating is inherently a competitive process. In that desirable mates are in scarce supply relative to the numbers of people who want them, and so even even post mating after that is after mate selection, mate attraction, and mutual mate choice. Desirable mate, that's why there is mate poaching. Mate poaching is one of the strategies that we in my lab with David Schmidt have studied. And so okay, but one of the unique aspects of humans is that we compete using language, and that is we have reputations and humans devote a lot of effort to maintaining the reputations, to building the reputations, to. Trying to recover reputations after a loss of reputation for various reasons, but we we compete for mates using language, and that includes. Sending signals to the person that we're trying to attract using language, verbal fluency and you know obviously some more recent things like poetry, but also we use language to derogate our competitors. So one one of the papers I published very early on was a research project on derogation of competitors, the the ways in which people impugn the status, character and reputations of their rivals. With the goal of making them less desirable to other people, and humans do that, and women and men both do that. So it's an interesting thing that we're male competition who we are talking about the onomama earlier in some of these overt physical or what what animal biologists call contest competition where there is a physical battle. Males do that, and so a lot of the early attention on mate competition was focused on these sort of ostentatious overt battles in contest competition, but we compete through language. And and so there is this big overlooked domain of women, the ways in which women compete with each other using language, and one of the things that astonished me is how. Observant women are about the subtle imperfections in their rivals and take pains to point them out. So just just this is random examples. I went to a party. This is back in in my youth, but went to a party with my girlfriend at the time, and and I got into this conversation with another woman who happened to be very attractive. But but then we leave the party and she said something just casually offhanded like she said, "Did you notice that her thighs were heavy? " And I hadn't, but next time I saw her, this other woman, I found my attention being drawn to check out her thigh. Well, and originally it puzzles me why women would derogate other women on appearance. Well, they do it of course because men prioritize appearance, but I thought well the man can see. The woman directly with his own eyes. Why would verbal input alter his perceptions of how attractive he was? And I think that part of it is I think there are actually two quick answers to that. One is the attentional one. So our attentional field when they draw attention to it, the those what could be very small deviations from perfect symmetry or whatever they are become magnified in our attentional field. But the other is that. Who we have as a mate is also a reflection of our own status, and and and you saw this in a kind of overt and way in the earlier the last presidential not the last the the 2016 presidential election where. Donald Trump was saying, "This was when he was in competition with Ted Cruz. I think in the primaries, look look at my wife, look at Ted Cruz's life and what wife and he really impugned the appearance of Ted Cruz's wife. " So using language, you can alter the the dynamics of the social hierarchy, the status hierarchy. Sorry, so like you can change the values subtly or if you have a large platform in big ways, you can move things around just with your words. Yeah, yeah, that's right, right, and fascinating humans, yeah, because it's all socially constructed anyway. So this I mean the question I have is you said there is the interesting thing about mating strategies is there is a small. Pool of desirable mates, and what the word desirable means is socially defined almost by on purpose to make sure the pool always stays small. I would have a couple thoughts on that. It's an interesting issue set of issues you raise. Okay, one is that we I think we have evolved adaptations. Part of our psychology is to detect differences, and so this is why like a I don't know a a Martian or an alien coming down. They might look at humans and say, "Boy, they all look alike as one just like we look at I don't know zebras or whatever and we think they all look look alike. " But what's important in decision making, especially in the mating domain or even friendship domain or or coalitional selection domain, is the differences. And and so I noticed this just a concrete example of this. I was sitting around this is again ages ago watching a a something like a Miss America beauty contest and people with a bunch of other people and they were saying, "Boy, did you see Miss North Carolina? What a dog! " and and so this is astonishing. So here are like 50 contestants who are selected as the most attractive in their state, presumably. Although they claim it's based on talent, but but we notice the differences. And and and this is why I would push back a little bit on the term socially constructed because I think it's. There are many different meanings of that of that phrase, and one meaning that some people have one interpretation is that it's arbitrary, and I don't think it's arbitrary. So this has another been another shift in understanding standards of beauty where it used to be believed in the in the social sciences. You can't judge a book by its cover. Beauty is only skin deep. You know, don't judge people on the superficial characteristics, but in fact, physical appearance provides a wealth of information. About the health status of someone, their in the case of males, their physical formability. And we have formability assessment adaptations, and then fertility as well. So there are a very predictable set of cues to fertility that have evolved to be part of our standards of attractiveness and and they're not arbitrary. There are some culturally arbitrary ones. So like. You go to the the Maori in New Zealand for example, and they find tattoos on their lips to be very attractive. So there are some culturally arbitrary things, but standards of beauty like. Cues to youth, cues to health in women: clear skin, full lips, clear eyes, lustrous hair, a small waist hip ratio that is circumference of the waist relative to the hips. Is a cue to youth and fertility and and a cue to health. Symmetrical features, so we are a bilaterally symmetrical species, but we all have we all have deviations from perfect symmetry that are due to different things. Mutation load, environmental insults, diseases during development, and so forth. All right, but that's kind of deeply biological. Like there is cues that indicate something that is biologically true about a particular human. So we will talk about both men and women. So we're now talking about what men want. In the mating strategies when they look at women, so you are saying small waist to hip ratio, right? Is how much of that is our deep biological past on top of which we can build all kinds of different standards of beauty. So you know we have many. Things going on in our brain, our value of other humans in selecting a mate might incorporate a lot more variables as we get into the 21st century. So how quickly does our. Evaluation of a mate evolve relative to the evolution of the human species. They're using evolve in the sense of culturally culturally evolved and then relative to biologically evolved. Yeah, well I think that there are there are some things that are biologically evolved some standards standards of attractiveness. And there are some of the things that I mentioned. So in male evaluation of females, let me back up and just say what is the underlying logic? Why would we have standards of attractiveness? So here is the interesting thing and this gets back to your earlier question about what is unique to humans or what distinguishes us or what set us off on the path that we did. Is chimpanzee males do not have any difficulty figuring out when a female is fertile. She signals that like crazy with the bright red genital swelling, olfactory cues she goes into estrus. In humans, we have and this was actually a third thing that I wanted to add earlier we have concealed ovulation, okay, relatively concealed ovulation which is remarkable given how close we are, primatologically to to chimpanzees. And so there is there is a little bit of evidence that there are subtle changes that occur when women ovulate non women not on hormonal contraceptives but it's mostly concealed. But it is it is largely concealed. I think that's a feature of bug in like do we evolve that is that is that a cool a powerful invention for the human species. I think it's it's an adaptation in women that women have evolved concealed ovulation, and I think it's a feature not a bug. It gives more would it give more power for women to select. A mate. There are a couple different hypotheses about it, but the one that I think is most plausible is that. You know if again comparing it to chimps, Thema goes into estrus. The male just has to try to monopolize her while she's in that estrus phase, and then they basically ignore the females after that. If you can't know when a when a woman is fertile, then you have to stick around a lot longer. And so I think long term pair bonding co evolved with concealed ovulation. And with that also a very different form of sexuality which is that we have sex throughout the the ovulatory cycle. And chimps don't you know there is there is little bit of mating little bit of sex toward the edges of the estrus cycle but but very little. So that that actually makes mating a more fundamental part of interaction between humans than it does for chimps. So meaning like year round every day constantly selecting mates in terms of biologically speaking. So what what else what what else do men want? Today in the 21st century versus in the cave man days. A wonderful question to answer it though I have to distinguish between long term mating and short term mating. And in long term mating it gets very complicated. So as as a one way to put it yeah. Well, so I teach a course in in human sexuality at at University of Texas at Austin and one of the things this is back in the days when there were chalkboards and you and you taught with a piece of chalk and wrote things on the board. And what I would do is I would ask the class I teach this large class one to 200. I'd say, "What do women want? Tell me all the things women want in a long term mate. " And so I would start at one end of the blackboard. There were like five blackboards and they say, "Well, I want a mate who's who's kind, who's understanding, who's intelligent, who's healthy, who's got a good sense of humor, who shares my values, and and I just go and I saw five blackboards and then run out of space. " And and so the first this large number of characteristics that people want and then specific magnitudes of those characteristics or amounts. I say you you want a mate who's a generous with their resources and they say yes, I want mates generous with the resource. So I said so like a guy who this is a women's mate selection a guy who at the end of every month gets his paycheck and gives it to the local wino on on the drag. And I said well no not that generous. Okay, generous toward me not not indiscriminately generous and so you want a mate who's ambitious you know who's a hard worker yes but but not a workaholic you know. And so and so then you get to interactions among different characteristics. So there is a lot of characteristics, a lot of variables in this very complex optimization problem for women. Yes, that's right, and more so for women than for men. So and then I turned to the men and I say, "Well, what do men want? " And then I I run out of space after about a blackboard and a half because they they can't think of anything else. So the women I think there is a lot of explanations for that besides the lack of the number of variables. It's also you know I mean it's that's interesting. So what what's the difference between the variables? So on the men side, what are the variables? Well, there in long term mates selection there there is a lot of overlap. Sure, okay, um. So things like intelligence, good health, sense of humor, an agreeable personality, someone who's not too neurotic or moody or or emotionally volatile. But there are key differences as well, and the differences stem from you basically fall on the delimited number of domains. So for men, it's physical attractiveness, physical appearance, and youth are the two real big ones. Okay, men prioritize those more than women do, and so that's why you have phenomena such as this quote love at first sight, where sometimes men can walk into a party and they see a woman across the room and they say that I'm going to marry that woman. That's the woman for me. Women very rarely do that. I most men don't don't do that either, but men are much more inclined to fall in love at first sight. That's because they prioritize physical appearance. Why? Because physical appearance provides that this wealth of information about a woman's fertility status, and this is from from an evolutionary perspective from a purely reproductive perspective. In in business school, they would call it job one. Job one is you have to select a fertile mate. So those who in our evolutionary past who selected infertile mates, so postmenopausal women for example, did not become our ancestors. So we are all the descendants of this long and unbroken chain of ancestors who all of whom succeeded in selecting a fertile mate. But fertility cannot be observed directly. It can use some cues exactly, and and there are cues that are probabilistically related to this underlying quality of fertility that we can't observe directly. And we're doing that computation in our heads. What about men? What do men want for short term mating? Well, so for short term mating, for both sexes, physical appearance looms very large. So so in so women are no physical attractiveness and appearance they're important for women in long term mate selection. So I don't want to mislead anyone on that. They're just not as important as they are for men. And so a lot of characteristics come for women before physical appearance, physical attractiveness. So women, so if we switch to women, what do women want? They want. Also physical appearance for short term mating, yeah physical attractiveness. What else? Well, some cues that represent physical attractiveness that maybe represent health. Well, here is this is your. I am learning a lot here. Yeah, well, so but you are also asking a very interesting question about what is controversial within the evolutionary psychology. Field right, right and not totally resolved, so that's why you are on the sixth edition of the book and there could be a lot more editions come. Yeah, I revise it every four years or so because there is four years of new interesting work and so it deserves updating but. The traditional I should say, answer to your question is that women go for good genes cues to good genes in the short term and cues to resources in the long term and this has been the hypothesis that advocated. I didn't come up with this this one by Steve Gangsted, former student of Marty Hayles and Randy Thornhill and some other very smart players in the field. And and what they used as markers of good genes are things like symmetrical features and masculine features so strong jawline high shoulder to hip ratio. You know other other sorts of masculine features, but I started to doubt this explanation for what women want in the short term because of some other findings. So for for women a lot of short term mating is not one night stand mating so but rather it's a fair mating. So so if you ask the question why do women have affairs so let's restrict the question for the moment. My colleagues would argue well women have affairs because they're trying to get good genes from one guy while they're getting investment from the regular partner the husband. Okay, but the problem is that when women have affairs, seventy plus percent tend to fall in love with or become attached to their affair partner. Now it's like what percentage seventy yeah seventy some large majority yeah seventy or more in contrast to men where it's more like thirty percent of men who have affairs fall in love with or become attached their affair partner. So but from a design perspective, an engineering perspective if you will, that's a disastrous thing if you are just trying to get good genes so you are trying to retain the investment of one guy while getting good genes surreptitiously from this you know guy who presumably has more. Falling in love with them becoming attached that's that's not a feature you want. Yeah bad engineering. Yeah exactly bad engineering and so and so I developed an alternative hypothesis that I call the mate switching hypothesis which is that affairs are one way in which women. Divest themselves of a a cost inflicting partner or a partner who things aren't working out well with and it's a way to either transition back into the mating market or to or to trade up in in the mating market. And and so and anyway so these are these are probably the two leading hypotheses about why why women have affairs and I am putting my money on the mate switching hypothesis. My esteemed colleagues are putting their money on the good genes hypothesis but I think. The evidence for the good genes hypothesis is starting to look shakyer than initially. Well this is a heated debate I mean mate switching sounds like a so from a game theory perspective from an engineering perspective seems to make a lot more sense unless you put a lot of value in life long sort of in the long term mating. Some kind of value in the lifelong singular relationship like monogamy. Yeah and maybe we do psychologically maybe there is a big evolutionary advantage to that and we we do but we also know that divorce is you know and breakups are are also common and occur in all cultures so. We're just not very good at this thing. Well either we're not good at the mate selection such that maybe we're we're not incorporating all the variables well or we're just not good at monogamy period. From an evolutionary perspective. Well I think there that's raises a debate. No that raises an interesting set of questions so I think that I mean one issue is is longevity so I mean we didn't live to be seventy eighty years old. And over ninety nine percent of human evolutionary history and so we didn't necessarily evolve to be mated monogracy with one person for decades and decades and decades. But I also think that long term peer bonding is a critical strategy but mate switching is also a critical strategy. So if you have a mate for example who. Becomes cost inflicting or becomes sufficiently debilitated or who suffers an injury such that like in hunter gather societies where the mate can no longer hunt can no longer provide resources for their kids and and the woman. This becomes this becomes a problem and so and so I think that we have adaptations to mate switch and to divest ourselves from some partners and trade up in the mating market under certain conditions. So okay and those conditions will differ for men and women. What are some of the cues in terms of what women want? You know go to the gym. So a hotly contested debate you said evolutionary psychology and this is in the bro psychology forums that I visit multiple times a day no I am just kidding. What what what's the most important cue of appearance. For guys, what muscle group is the most important to work on? Do women care about biceps is what I am asking