The Biggest Sex Differences Between Men & Women - Steve Stewart-Williams

Why would we humans be confusing to be understood by an alien? How how would an alien scientist view our species, do you think? Um well, that's that's how I start the book, right? So, I start like that the framing device for the whole book is the idea that what how would an alien scientist, if it came to the earth, to try to explore these crazy creatures, human beings, what would it make of us? Um And the short answer is that it would be very very it'd be mystified by us. So, um so, I imagine that this is an alien that doesn't have doesn't have sexes, it doesn't have therefore doesn't have sex differences, um doesn't have families, doesn't have any of this kind of stuff that we take for granted. And so, it would be mystified by the fact that we are divided into two basic types, um that those two types differ from each other, um that we fall in love with each other, that we get jealous for some reason if the person that we're in love with gets involved with somebody else. Um that we that we're kinder typically toward our family members than to non-family members. Um that we uh that we listen to music that we have music and art and all these kind of strange strange things that don't have any obvious survival value, um but which we spend a lot of time just amusing ourselves with. Uh so, that's the framing device. They would find us very weird in many different ways. Yeah, it's very odd odd, I think I've had a lot of conversations about evolution, sex differences, sexual selection, etc. etc. But talking about culture and the role of culture evolutionarily, how how do you even begin to frame that integration? Yeah, and that's a maybe the big question. And and think I think possibly that's the thing that the alien would be most surprised about when encountering us. Cuz a lot of the stuff, you know, the sex differences and that kind of thing, they're kind of comparable to what we find in other species. But what really makes us unique, I think, is culture. That would be the thing that particularly mystifies the alien, I think. Um and I think the answer it's two-part answer, really, I think. I think the first part is that somewhere down the line, we we evolved the capacity for culture. And we're not the only species that has that, but we have just taken it further than any other species. So, we evolved the capacity uh to to basically make up tricks and learn tricks from each other. Um and uh we have the intelligence and the cultural capacity to do that, and it makes us a kind of open-ended system, so that um our culture can come kind of come off the leash, so to speak. And then that comes to the second part of the story, which is that once it's off the leash, um it starts evolving in its own right. Uh somewhat independently of biological evolution. So, you get um selection So, so, biological evolution is about selection for genes. Um cultural evolution is about selection not for genes, but for uh the elements of culture, which are often called memes. So, you get selection for for different memes, and the forces but the selective forces that act on memes aren't necessarily the same ones that act on genes. They can go in different directions. So, you can have memetic memetic evolution going off in completely different directions from what genetic evolution might favor. And we can be kind of torn between those two different options. Can you explain the fundamental dynamics of selection for us? Uh in general, selection Yep, sure. In general, it's about it's about replicators. So, it's about uh entities like genes or or like memes um that are capable of replicating themselves. And the nature of the selection process is that the replicators that are best at replicating themselves are the ones that are going to increase in frequency within the population. Uh in biological evolution, that's a question of genes, different gene variants becoming more and more common compared to competing versions of the same gene, competing alleles. Um in the cultural sphere, it's about different cultural elements becoming more and more common relative to competitors. Relative to competitors. Um and basically what you get is you get selection. So, like I said, selection for the variants that are best able to replicate themselves. And in the biological sphere, um you what what it does is that you get selection for genes that have effects on their owners, i.e. us, that um increase that increase the chances that they're going to be put forward into into future generations. Um and that turns us into what what I call in the book gene machines. So, into organisms that look as if we've been designed and look look as if our intention is to is to pass on as many of our genes as possible to the next generation. And just the rationale for that is that if you were a gene and you had an effect on your owner that meant that you were less likely to survive, less likely to have kids, less likely to help your kin, then you would pretty surely and pretty quickly go out of existence um compared to other genes that had the opposite effects, that boosted your survival, boosted your chances of having offspring, or boosted the extent to which you helped uh relatives. You kind of play a bait and switch, I think, six and a half times in the book where you try to explain what we might be as maximizing machines, and I think it ends up being like modified grandchildren maximizing machines. Can you can you explain why we're modified grandchildren maximizing machines? Yeah, yeah. Okay, so So, yeah, I go through a series of hypotheses basically about what we've evolved to do. What what human beings are for. So, so, the alien would see us where where like these biological machines, what are these machines designed to do? Let's see if I can remember them all. So, the first one is So, so, is it So, I ask are we designed to for the good of the species? And I rule that out when it's not for the good of the species. Uh the next one is are we survival machines? I rule that out because uh if you were to survive for 100,000 years, if you were never to have offspring, for instance, then you'd as soon as you actually die, your genes are going to go out of uh existence as quickly as if you'd lived for 20 seconds. So, then I think, okay, so maybe it's about offspring, right? So, are we just um machines designed to reproduce, to have offspring? Um That's that's a big step closer, I think. Um but I think that's not quite right, either, cuz if you if you had 100,000 babies, but none of those babies survived to have babies of their own, then uh you know, again, your genes are pretty quickly going to go out of existence um as if you'd never had any any babies. So, like a big jump in the right direction is that we're machines designed to ultimately have grandchildren. Um but actually I take it um a couple of steps beyond that as well, cuz there's also there's the inclusive fitness perspective. So, then um inclusive fitness brings in So, okay, so so, what I've said so far is like it's about surviving and making offspring that have their own offspring. Inclusive fitness brings in another element, which is kin altruism, which is that we can also spread our genes by helping our genetic relatives to survive and have offspring and those those offspring to have offspring of their own. Uh yeah. I heard uh I had a conversation a couple of months ago talking about twins and twin and twin studies. And I found it so interesting that if what you're saying is correct, which is basically the level of genetic similarity between us and the kin around us, whether that be children, grandchildren, brothers, aunties, uncles, cousins, etc., the closer that it is, the more affinity that we will feel, the higher level of investment that we will feel. And there was a study done that looked at uh levels of grieving of identical twins. And they found that the level of grief that was felt by the one remaining twin is potentially, hypothetically, the greatest amount of grieving that anyone could have for another person. Yeah, that's that's fascinating, right? So, people grieve more if they lose an identical twin than than if they lose a fraternal twin. Um it's fascinating. What is that Is that Nancy Segal's research? It was Nancy Segal. Yeah, she she came up to me at A Place. She gave said some very flattering things, and then shortly after I brought her on the podcast. Yeah, she's phenomenal. She is really great, right? And she's got research as well, I think, where when twins meet each other in adulthood for the first time, so they're separated at birth, grow up separately, when they meet each other, identical twins tend to have more of an affinity immediately than fraternal twins do. Even not having grown up with each other or anything. Is that because of Is that postulated that it's because of the visual similarity that they can quite quickly see or look at how close this person is to me? My guess is that it's it's that initially, it's the visual similarity, but then as they sort of interact and get to know each other a bit more, they're likely to be more similar. Oh, we use the same weird brand of toothpaste. Oh, you also drive a tan Chevy 85. Oh, you also married a woman called Stacy. Like that I know that this sounds to the people that haven't heard the Nancy Segal episode, this sounds like I'm just pulling stuff out of my ass, but like this is represented in like data. It's wild, right? This the similarity between between identical twins reared apart is just incredible. Yeah, it's wild. Uh I wonder whether that means that do we have an affinity for people who look like us? I think we do. I think we do, yeah. And I think um that that's probably one of the uh So, like that's nice on the one hand, right? Cuz if we're we're feeling an affinity with these people like us, but there's a dark side to that, of course, which I think is exactly It just is one of the things that makes uh I guess, put it back in the cultural evolution, it makes racist memes easier to accept just cuz we do have an affinity for people like us. And the flip side of that is the what whatever the opposite of an affinity is. Yes. People unlike us. Yeah, disaffinity. I I wonder whether one of the things that I've been parroting for a little while is we are more prejudiced against people with different accents than people with different skin colors. Yeah. Yeah. Yeah. Interesting. Yeah. What do you What do you make of that? Given that we also have My point being, ancestrally different skin colors would have been very novel, different accents would have been very common, therefore creating a tribal prejudice against different accents has more adaptive sense. But we also have this they look like us, they don't look like us thing which might be kind of further away and and and and deeper than the accent stuff. Yeah. No, I think I think you're right. I think that although we do have that disaffinity for people who look unlike us, it's it's not so deep that I mean we we can we can get past it. And I think the deeper trend is just a in-group out-group kind of thing. And it seems to be fairly easy to have people who look dissimilar to ourselves. We can we can put them into our in-groups pretty easily. And an accent is a good in-group marker, really. So that can trump any effects of physical dissimilarity and often does. So yeah, so the So we're not stuck with it. So we're not stuck with the um the disaffinity for people who look unlike us. It can be trumped by other things. And I do think you're right about the the accents. They do seem to serve as a tribal marker and often more so Yeah. skin color. Yeah, it's very very interesting indeed. So what do you think most people get wrong when it comes to understanding sex differences? I think that that that's a long list of things. I'm working on a new book actually and it's going to be focused on sex differences. Hell yeah. And I think So okay, so the the two big things I think that people get wrong and the one that probably people are going to be expecting me to say and that I do say in this new book is that people often think that there are no sex differences or that there are no that there's no innate push toward sex differences that it's to the extent they exist at all they come almost solely from culture. And I think that's one big mistake. But I do also think people make the opposite mistake as well. So there's also a tendency to exaggerate the magnitude of human sex differences. I think both of them are mistakes that people fall into. I think these days probably they more often fall into um the first mistake, the minimizing and denying mistake. But people do make both and I think both um potentially cause problems. Is it a uh narrow tightrope to walk along to actually get the amount of sex differences right? Is it? I think it is. I think it is very it is difficult cuz I think people it's just very easy to to swing to one extreme or the other. Um And then if you Okay, if you just sort of start opening the door, okay, there are some evolved sex differences and then I think we may be quite easily spin to the extreme of thinking that they're massive and that they're huge. And in some species they are. Um but I think that um where as mammals go we have relatively modest sex differences. And actually that's another thing I think that the alien would be puzzled by. He would say, okay, we've got these sex differences in this this weird species. Um but they belong to the big group called mammals and in a lot of mammals that the differences are much larger. What are your favorite psychological sex differences in humans? Um let me think. Okay, so let me start with with the one I think is the biggest one. The single biggest um psychological sex difference. I don't suppose you can guess what it might be. Desire for sexual novelty? That is that's usually about a medium effect size. Um so about 0.5, maybe a bit bigger. The one I'm thinking of is much much bigger than that. [ __ ] Uh I I I give up. Tell me. It's um it's one that as soon as I say it you'll you'll recognize it and you'll recognize that it's huge. I think we take it's so so obvious to us that we take it for granted and don't think about it. Um it's the fact that the vast majority of men are primarily interested sexually interested in women and the vast majority of women are primarily sexually interested in men. So it's interesting that that's a that is a massive difference. And that does show that natural selection can create huge sex differences in our species. And then most of the time it creates sex differences that are that are nowhere near that magnitude. Um it's interesting though if you look at summaries of sex differences and evolved sex differences, very often that one is just left out. And I just think it's just cuz we take it for granted so much that that's the case that we don't even really think of it when we're when we're listing them. That's like the physics of sex. Yeah. Yeah. Yeah. Yeah. Yep. Exactly. Um and there's a clear there's a clear evolutionary rationale of course for it as well. Um other ones on that list would be the desire for sexual variety. Like I said, it's a a medium sex difference. Uh the desire for casual sex is a large sex difference. That's one That one's actually larger usually than uh the desire for sexual variety. Um sex differences in aggression. Face-to-face aggression and and violence in particular. That's another big one. Uh sex differences in parental inclinations uh would be another. Yeah. It's interesting the Oh, what's the one in Tell me about jealousy. Uh sex difference in jealousy. This isn't this isn't a huge one, but that is the fact that um most uh so so men in general on average are more upset than women about sexual infidelity. So if their partner So So if you ask people, okay, so imagine your partner, you love your partner, your partner gets involved with somebody else, which would upset you more? Would you Would you be more upset if they had sex with somebody else or would you be more upset if they got emotionally close to someone else, kind of fell in love with somebody else? Um and obviously both of those things are upsetting to most people. But more men than women say that the sexual infidelity would be more upsetting to them. And more women than men say the opposite. They say that the emotional infidelity would be more upsetting to them. Yeah. Well, I mean, how many times has there been some on-street interview I I even remember this from like back in school I think about would you rather that your girlfriend kissed someone else or told you that they were in love with someone else or whatever. And just this asymmetry in terms of what it is that we're jealous about. So can you run through Can you go a layer deeper and talk about how those two types of jealousy are more and less adaptive? Yep. Um Let me start with the the commonality though. So just the I think the main function of jealousy for both sexes it's part of our pair bonding psychology. So we we fall in love with each other, but we also have jealousy and I think for both sexes the function the main function of that is to protect the pair bond. Um pair bonds were adaptive for us in the past as a setting for um having kids and rearing kids and so we've evolved a psychology to kind of protect them. Uh the differences though, the main difference um for men compared to women is is paternity uncertainty. So David Buss has a great way of putting this. He says there's never in the history of the world been a case where you have a woman who gives birth to a kid and then thinks is this my kid or is it some other woman's kid? I don't know. Um whereas for men, if their partner gives birth it's almost certainly their kid, but there is a possibility that's not their kid. And any any guy that ended up investing in a kid that wasn't his own biological kid um the all the paternal effort that he puts into that kid is putting it in effect into the genes of another guy. And so any any trait that would have come along that decreased the chances that that would happen, that trait would have a good chance of being selected. And jealousy I think is is one of those. Um so the kind of jealousy that makes the guy keep a kind of wary eye on his partner and on the good-looking mister neighbor and to take action if they start you know, or the or the guy at work maybe you know, she keeps talking about that guy at work. Uh he starts getting a bit worried about that, maybe takes action to try to make sure nothing happens. Maybe maybe he's a bit more attentive. Maybe he you know, handles it in a in a nastier way. But because paternity uncertainty is the main issue for guys um well well, paternity uncertainty is facilitated by by sex, not just falling in love, but but sex, the sex that sex act itself itself as well um leads to somebody having somebody else's kid, right? So um that's why that's the rationale evolutionary rationale for why guys are particularly focused on that. Uh with women on the other hand, emotional infidelity is like is less of a big deal. Obviously it's a big deal to people. A woman doesn't want her partner sleeping with somebody else. Um and she's going to be upset about that and it's a common cause of the end of relationships. But evolutionarily speaking, it doesn't have quite the catastrophic consequences that it does for for guys. Um what it can do though is if if she has a nice pair bond and they have a kid and I'm thinking sort of ancestrally more you have this investing dad, um if he were to fall in love with someone else then that would increase the chances that he's actually just going to split up the pair bond and go with somebody else. Uh and that would make it a lot harder for her to raise the kid. It would ancestrally increase the chances that the kid wouldn't make it for a start, but also it just increase the burden on her. So, it might be longer before she can have her next kid. It's this is going to be a a big hit to her fitness. Uh and so a a a bigger hit than if he just sleeps with somebody else. So, that's the evolutionary rational for why she might be more focused on uh love and fidelity as opposed to sex and fidelity, sexual infidelity. What is your favorite explanation for why women have concealed ovulation then? Uh I'm not sure I have I'm not sure I have one. It's a really interesting question why we we do have concealed ovulation. Um I've read the different theories and I don't find any of them hugely persuasive. So, so I'm not completely sure. Um let me let me highlight one though in particular that I guess is I I think maybe overlooked a little bit. And that's the idea that rather than ovulation being deliberately concealed, so to speak, deliberately by natural selection. Um that actually the default is just that you don't advertise it. And that in some species you have it advertised you have it advertised in chimpanzees and baboons and that kind of thing. They have the kind of swellings that they do when they're in estrus. Um but but the we just don't have that. So, there's been no selection for for advertising it as opposed to there being some definite adaptive rational for concealing it. If you see what How interesting. Yeah, that is uh I mean I've I've read a ton of theories as well about it. Is it that by concealing ovulation no one man knows when or no one male knows when him and that particular woman had sex, so therefore is this child mine? You kind of get this like dispersed male parental investment thing potentially. Is it that by making it more difficult to work out when you are fertile as a woman that it increases the amount of sex that you need to have with your partner, which means that you increase pair bonding, which gets both guy and woman to be more likely to stick around for this [ __ ] infant that needs 10 years of of looking after before it can be functional and independent on its own. Uh there was one where I think Mackin or William told me about it where it was an ever sort of escalating battle between the woman to work out how not to get pregnant and the system on telling her how when she was able to get pregnant. So, it was like reverse birth control Yeah, yeah, yeah, yeah. Um all those three I think I think the second of those I think is the one that I that rings truest to me. I've never been never been particularly persuaded by that last one. But yeah, so I'd sort of I'd either go I think if I if I had to bet on it right now, I'd either go for the non-adaptationist we just didn't evolve to advertise it. Mhm. Um one or or that the second one that it's to facilitate pair bonding. And males and females spend lots of time together all the time rather than just uh when the female is ovulating. Yeah, we're we're one of a very small number of species that have recreational sex, right? Yeah, yep, I think so. Um bonobos I guess would be would join us in that in that small club. Uh bonobos I think have quite a lot of sex and just with with everyone in the group. And with like rolled up handles of buckets and anything else that they can get their hands on as well. Yeah, yeah, indeed. And I guess I guess when you think about it that way that that dogs actually are quite um prolific in terms of the range of sexual interests to them. Yeah. Another spicy one, what do you make of the uh women purposefully starving themselves and making themselves anorexic is a vestige of ancestral birth control. Uh interesting. Um I think that's I think I don't know. That does That doesn't strike me as immediately particularly likely. Um I think I prefer some of the hypotheses that I that people are normally actually have come up with. Um his argument is that it's it's not an adaptation and it's not a sort of a like an extension of of an adaptation, but it's just a weird kind of cultural byproduct of just a just sort of status seeking intersexual competitiveness uh that you get you get within within each sex you have competition and different ways of like attracting a mate and that kind of thing. And it just seems to have in some societies wealthy societies have latched on to um being super thin. And that's that's not adaptive, but it's just taken to an to an extreme in a minority of people. And I think one reason I think that's more likely than an explanation like the the birth control explanation is that it's only really found in in wealthy societies. It doesn't doesn't really It's not typical of most cultures. It seems to be a weird quirk of the kind of societies that we live in today uh rather than something that's found in ancestral times. Yeah, I learned the environmental security hypothesis a couple of months ago. Have you heard this one? Yeah, yeah, what's that? I'm not sure. I'm not Male preference for female body size uh varies based on economic conditions. So, during heard that, yes. during times when the economy is more uncertain to men prefer uh fuller women and in times when the economy is safer they prefer thinner women. And they've done studies where they ask men to rate the relative attractiveness of women of various body sizes uh before and after they eat food. And the post eating food for men results in a uh thinner woman being preferred. right, right. And then when when they're hungry they prefer prefer thinner Yeah, well. Look at how robust she is. Look at how many famines she could handle. Look at Look at how many depressions and and high interest rates she would be able to put up with. Interesting. And what's the name of that? So, I have heard that I have heard Environmental security hypothesis. Hypothesis. Yeah, okay, cool. Yeah, that's interesting. Uh talk to me Okay, so just leaping back to the sex differences thing. What do you say to the people who would go that sounds fine, Steve, but how how do we not know that this is all just due to socialization? Well, I don't know. It's a I don't know. It's a good question and a perfectly reasonable question. And I think the first thing I'd say is that um that socialization does play a role. So, I certainly wouldn't be um arguing that these differences have nothing at all to do with socialization. One line of evidence that they do is that the magnitude of the differences uh is different across different cultures and is different within the same culture at different times. Um so, for me the question is really how how do we know that it's not just socialization? And I think that there are various lines of evidence that pretty strongly um very strongly actually I think do suggest that for kind of sex differences that I that I named earlier that they're not just down to socialization. Um so, I lay out six in the new book. See if I can remember what they are. So, one is that they tend to be really stable over time. So, they persist within a culture uh even when the culture changes quite a lot. Sex differences and mate preferences for instance um survived right throughout the 20th century uh in the US for instance. Um even though there were like quite radical shifts in the culture at that time. There was the sexual revolution and the feminist revolution and sex differences and mate preferences just persisted through throughout that time. Sex differences and and the preference for casual sex as well they they persisted throughout that time. Um you find them a lot of them appear quite early in development before it's sort of plausible that socialization could be involved. Uh the sex difference in aggression for instance appears really really early uh as soon as kids can basically move around and and be capable of aggression you see sex differences there. Uh and and and also like a lot of sex differences either appear appear in the wake of puberty or or they get bigger in the wake of puberty. Um so, the developmental timing there is you know, it's not it's not 100% proof, but that sort of suggests as well that it might be um uh have an have an evolutionary basis. Uh the third one is that uh often it resists often sex differences persist in the face of culture. So, it's I I think the usual story is okay, so these you have these differences and they're created by culture. Um but often they persist even when the culture is pushing in the opposite direction. So, so aggression is a good example of that actually. There's a sex difference in aggression. Males on average I mean I don't I don't need to say the the difference the direction the difference, but males are more aggressive and people might say well, it's because we encourage males to be more aggressive. Um but actually if you if you tabulate how often people are saying don't be aggressive to boys and don't be aggressive to girls, they're they're saying a lot more to boys. They're they're discouraging boys from being aggressive a lot more than they are discouraging girls. Um not cuz they want girls to be more aggressive, but just because boys are more aggressive and aggression is a problem and they try to clamp down on it. Uh and they clamp down on it in most cultures. There are some where they actively encourage it, but in most cultures they do clamp down on it. But despite that, you still have that same sex difference persisting anyway. Uh that was three, right? Four is uh hormonal um especially prenatal uh hormonal uh associations that you have between um uh levels of testosterone in the womb in particular and then the emergence of traits male typical and female traits female typical traits later on. So, there's a condition called congenital adrenal hyperplasia where you're exposed to very very high levels of testosterone, other androgens in the womb. Uh for guys that makes no difference cuz they already have very very high levels. Um but for um for for women who for for girls who are exposed to them, the high levels, it does have a big effect on them and it it sort of masculinizes their behavior in a lot of ways there. Uh more prone to aggression maybe, they have more male-typical um preferences, uh they're sort of shifted in the in the male direction. They're somewhere somewhere in between the female and the male norm as a result of testosterone. Number five is cross-cultural universality. So, if these things if the kind of sex differences we're talking about were just due to culture and culture alone, we'd expect them to vary quite a bit across cultures. Um So like in some cultures you might have uh men being more interested in porn for instance, uh and women being more interested in romance novels, in other cultures no sex differences in either direction, they they both like or dislike them just as much as each other. In others you'd find it reversed in some some cultures where women are more into porn and and women hire prostitutes and and and men are the majority of the prostitutes and men are reading the romance novels. Um and of course you you don't find that. Um you find that these differences are very very consistent across all depending on the trait every single culture that where we've looked or or the vast majority. It's a lot easier when you find that to explain it in evolutionary terms than to in terms of purely social cultural ones. And then the last one uh the last one maybe the most persuasive one is that you find the same kinds of sex differences in other species as well. You don't find them in all other species, but importantly you find them in in other species that are subject to the same selection pressures as our our species is. What do you mean when you say that? Well, the main selection pressure that creates most of these sex differences is the sex difference in reproductive variability or in other words, the sex difference in the maximum offspring number. So basically, men and a lot of male animals potentially can have many many more offspring than any female. If even the most successful female can have. Um the average has to be about the same has to be almost exactly the same as long as you have a an equal sex ratio, the average for both both sexes has to be the same, but the variance can be greater for males and females and and and often is. And when you have that, when you have um the greater variance in males, that means that there are more males than females having no offspring at one end, but then that the the important end is that you have more males than females having tons of offspring. And where that's the case, you have stronger selection on males for traits that are going to drag you up toward that end of having more offspring rather than than fewer. Uh so different selection pressure from what you have in females. So it selects for things like aggressive status seeking, stronger desire for status, a stronger desire for multiple sexual partners so that you can end up with multiple offspring uh you know or or would do in an ancestral past when we didn't have birth control and the like. Um all those kind of traits, uh lower level of parental investment so you can spend more time um seeking mates, all those kind of traits are selected and and not just in our species, but just in any species where you have greater reproductive variance among the males than the females. Um and and that's the that's the key thing, that's the key line of evidence is that where you have the greater reproductive variance, that's where you'd expect these sex differences if the theory is correct and that's where you do find sex differences. Yeah, so you've had your uh hypothesis proven by the world around you. Exactly. Yeah. But by many different species and it's and it's very cool, right? Cuz there are some species where you don't find the sex difference in reproductive variance and in those species uh you don't really find much in the way of sex differences. So you find you have you have what are called monomorphic species. And in a few that it's it's actually flipped into reverse and females have greater variance and then all the usual sex differences are turned on their head and that the females are more aggressively seeking mates and beating each other up to try to get mates. And in jacanas, that's a that's a North American shorebird for instance, the jacana basically uh jacana females try to put together a little harem of of males and they have a bunch of different nests and they try to to get these little males um these these choosy little uh non-aggressive little males that try The shoe's on the other foot now, women. How do you like that? Exactly. My students do actually love this when I when I talk about the jacanas and I think it's for exactly that reason. It feels like the shoe's on the other foot. Yep. Yep. Eat some of your own medicine for a while. My favorite one, I think I think my learned this from David Geary yeah, and he was talking about um the preference that males have even uh male chimpanzees, other sort of primates um for reciprocal motion, reciprocating motion um in toys. So, you know, you would think the reason that young boys like trucks and young girls like dolls and fluffy things is that some socializationy thing. And he was like, you can give this to close sort of species relatives and the boys will pick that. There's something about the male brain which loves that res- I'm going to guess that you've looked at this as well. Yep. Yeah, I have and I think it's fascinating, right? You find that in vervet monkeys and macaques maybe, I think that's also both of yeah. Yeah, yeah. It's it's incredible, right? Cuz I cuz I have to say like this toy preferences, it does before seeing evidence like that, it does seem pretty plausible. Like what what could it that have to do with evolution? It's much more remote than things like aggression and sex drive and interest in casual sex. All that stuff is much more much more plausible, I think, basically. Well, what would be the adaptive reason for you wanting to have a toy that goes back and forth or you wanting to hold something that's soft and fluffy, but then you actually need to think sort of five steps down the line. Well, this reciprocal motion is your spatial orientation starting to lock in a little bit more because at some point in the future you might need to throw a stone and hit a snake or throw a spear. And this what are you doing? Well, you're kind of learning to keep something alive as a girl, you're you're learning to be able to care and nurture, to look something in the eyes and to be able to work out whether it's still alive or dead. And then, you know, you roll the clock forward and you look at like Joyce Benenson's work. What is it that children in primary schools are doing? Children in primary schools, if you're young set of boys, you're doing warfare. You're fighting Indians or aliens or or whatever it might be. And if you're girls, you're playing vet or nurse or doctor, you're keeping something alive, it's all interpersonal and yeah, whether it's macaques or vervet monkeys or toddlers, the the sort of rules seem to be very similar. Yeah. Yeah, it's amazing, right? And and like with the with the monkey research, the macaques and and the like, the the bit of that that I find most plausible is the um the caring for caring for dolls, caring for little things like that. That's I think it's pretty clearly an offshoot of a greater parental inclination in the females than the males. Um yeah, but it is it is really interesting, right? And and you know, that the toy differences it's like like I was saying it's hard to think of the evolutionary rationale, but despite that, it's among the largest sex differences other than sexual orientation that there is. It's a really big sex difference. Yeah, strange, right? Well, I saw David taught me about that study where you can raise you can you work out whether or not a child has been raised in a gender-conforming or a gender-nonconforming household, then you bring the children into the lab and you let them play with any toy that they want. You can play with trucks as a girl, you can play with dolls as a boy, and whether you've come from gender-conforming or gender-nonconforming households, you still see the same sex difference. Yeah, yeah. It's great, right? And and I think the big difference there is that um the ones in the gender-nonconforming household are just more tolerant of kids who want to be gender-nonconforming. Yes. Yeah, that's nice. That's a nice effect. All right, um your Substack apart from I'm just blowing you the entire entire episode. Uh your Substack is also fantastic and everybody should go and check that out. But what happened with the attempted debunking of the man the hunter theory? Please tell everyone the gossip. Yeah. Yeah, so that's one of my Substack posts, right? Is um there was a paper last year um by Abigail Anderson and colleagues where they ba- basically tried to debunk the idea that the they called it the man the hunter idea by which they meant the idea that um in hunter-gatherer conditions men did most of the hunting and women did most of the gathering and there was a pretty clear division of labor. Um and I remember when I read that I thought, I think I think that's quite unlikely just on the face of it, that's quite unlikely that uh anthropologists studying this issue for more than a century uh and not just male and you know, male and female anthropologists have looked at this issue is it really plausible that they have just kind of hallucinated the this massive sex difference and I think I I think it's muddled about this conclusion that men do most of the hunting, especially most of the big game hunting. And that women either do basically none or they just do a little bit and and more often small game hunting rather than big game. Um so so my my thought doesn't seem very likely and then this a preprint has come out uh in the last couple of months which has more systematically gone gone with that intuition and made a very what I think is a very strong case that they weren't right about that. That that that were wrong about this idea that hunting is a lot more even than we had thought. And and what they seem to they seem to make a number of mistakes. There there are coding errors in there where they were coding societies that didn't have female hunting as ones that did. That was one area one area rather. Another one was that they only included a relatively small subset of the available societies for which we had data. And if you plenty of others that they could have included that would have been which would have met their criteria but which they didn't include and when you include those as well they tend to show the traditional view that men do most of the hunting and women do a bit. Yeah, they didn't show frequency or like density of hunting as well, right? It was like a single instance of female big game hunting. You know, you you take your wife to work with you one day and and that kind of counts as her being there for a 50 year career. Yeah, and that's a way that you can make sex differences seem really really small is if you just have a yes no format. Like I've seen studies where they say for instance that interest in pornography is pretty even between the sexes cuz if you ask people have you ever watched it hardly any difference. But if you look at frequency the difference becomes huge and it's exactly the same for hunting. [ __ ] [ __ ] everywhere, Steve. So I I wrote a little theory off the back of this. You you have this really sort of lovely breakdown which is the male default, right? There's this assumption that male behavior is desirable in some way. And I call this the soft bigotry of male expectations. Nice. Which I think fits of male expectations. Yeah, so for instance you make this really great point which is no one is asking everybody was asking why are women not doing so much big game hunting. No one was asking why aren't men doing more berry collection. And there is implicit in you know what is I think supposed to be a not even thinly veiled completely transparent sort of pro-feminist boss [ __ ] moving forward kind of text. Well, are you not implicitly derogating the role that women mostly took which is that of being the carer, that of being the berry collector and the nut collector and the tuber tuber connector and all of that. Exactly. It does crucial tasks and and equally difficult tasks in their own kind of way and they're just considered to be not as valuable implicitly. Lesser. And and yeah, exactly. They are implicitly seen as lesser even though um yeah, even though it's it's supposedly a pro-feminist thing. It you know, you can read you can see in it it does have a sort of negative judgment about the things that are more common among females. I mean there's something so so satisfying about people that are self-righteous and self-aggrandizing sort of falling on their own sword and you know, reading that I I I'd be lying if I said it didn't give me a big sort of kick of satisfaction when I read your take down of it. Nice. I'm just going to write down just writing down soft bigotry of male expectations. I love that. Oh, yeah. Okay. So what are your best explanations for the gender equality paradox that we're seeing? Um so the gender equality paradox is the quite surprising and counterintuitive finding that for a lot of traits sex differences seem to be smaller rather than larger in less gender equal nations. So basically as nations become more gender equal in terms of who's involved in politics and equality under the law and equality of access to education etc. As they become more gender equal in those kind of ways traditional sociocultural theories and like social social role theory would predict that the sex differences would get progressively smaller as as gender equality increases. And for a few traits they do but for a lot of traits strangely enough it's the other way around. So gender equality increases and associated with that are larger sex differences rather than smaller ones. And and it's I find it I just think it's a very surprising finding. I would have even accepting that there was an innate contribution to a lot of sex differences I still would have thought that more patriarchal societies where men and women are treated very very differently and they're expected to do different stuff I would have expected that would amplify the sex differences and make them even bigger than the innate push. But often it's the opposite and and they actually get smaller. And then the question is why on earth is that the case? And I guess the first thing I want to say about that is that I don't think it's fully known. Uh but my best guess is that is that what's happening is societies that are are more gender equal it comes with a cluster of different um cultural level variables. So they're more gender equal they also tend to be more individualistic on average. It also tends to be correlated with with wealth. Um greater human development of the societies that kind of thing and and where that's the case people have more freedom to pursue what they most want to do. Pursue the things that interest them most and nurture their own individuality. And the more people can do that the larger that individual differences get but also the larger the average sex differences get as well. Yeah, I mean it's so odd like from first principles to think that that would be the outcome that people are going to get. It is so strange. What do you have you got any idea what's actually happening with men and women in STEM at the moment? Um I yeah, I've got a I've got a few ideas about that. Um the first thing is so so we often hear that there are more men than women in STEM. And depending on how you define STEM there's not actually that's not actually necessarily the case. So um if you include the health sciences it's actually pretty pretty even at least among younger generations it's pretty even how um how many men how many women go into STEM. Uh overall really really close but the difference that that everybody notices and worries about is the fact that uh more men than women go to certain fields. Fields like physics and engineering and mathematics. Uh they got more going to philosophy as well. That's not STEM but but these are the ones that people worry about. Uh not not so worried about the flip side of this. Not so worried about the fact that more women than men go to the health sciences and that kind of thing. And I I do wonder if this is another example of the soft bigotry of male expectations. Is that people is that people um kind of assume that anything that tilts male is is superior and therefore that we need to get women into that and kind of implicitly downgrade the importance of the kind of areas in which uh more women than men men go into. Either way though um there's an interesting question about why those differences are there. Uh an interesting question and also it's quite a controversial question or at any rate there are controversial answers to that question. So I should probably the first thing I should say is that so so the main explanation that people like to give is that it's largely a product of discrimination and sex of socialization. And so I just want to point out that that I agree that that's part of it. Um that's part of the story. I would just say I just don't think it's the whole story though. I think that um some of the differences that we've talked about already actually the the difference in interest in people versus interest in in object plays into it as well. And and those differences they appear very very early on. They're found across cultures. Um in fact it's it's a massively consistent sex difference actually. Um there's one study I saw which I think had about 200,000 people in it. 53 nations and every single one of those 53 nations they found that sex difference. Then another study which which Dave David Geary actually was involved in they had half a million participants in the study. 80 nations and 80 out of the 80 nations you found that sex difference. So it is a huge sex difference and it's perfectly clear that it's a patriarchy going global. It's a patriarchy everywhere. Yeah, exactly. Um except that in less patriarchal nations some of those differences are are larger rather than smaller. That you do get a gender equality paradox for the sex difference in objects versus uh versus interest in people which is which is fascinating. And it just seems perfectly plausible to me that um that those sex differences in interests are a part of what's shaping the sex difference in which areas people go into which occupations. And actually I say I want to put this more strongly. I think that it would be implausible to think that those interests are not part of the story. Like how could they not be? If people are freely choosing what they want to do they have these interests even if we just ignore the question of where those interests come from. They do have those interests. It must be part of the story feeding into the into the difference in uh what's called occupational segregation. That's that's putting it too strongly I think that phrase cuz it's not segregation. Occupational segregation. What a great term. Occupational apartheid. Do you mean? Except that you know, it's it's the differences are much more modest than that and there's there's no field where one sex is present and one sex is absent. There's just uh you know, going away from a 50/50 ratio. So, there's a there's even where women are at least represented, there's a significant minority of of individuals in those fields are women. Mhm. And vice versa for men. What do you think was our typical ancestral setup for mating? When it comes to the way that we Yeah. got together, stayed together. Uh, I think that Let's come back to the alien, right? So, what the alien decides to look at our sexual behavior, I think one thing it would notice immediately is that we're pretty varied in what we do. Uh, as long as they're not really with a strict norm saying you absolutely can't do X, Y, or Z, we we do a fair amount of X, Y, and Z. Um, I think that that the most common reproductive pattern though that we engage in, um, is is pair bonding. That's the most common. So, we do some pair bonding that we have polygeny as well. Um, it's it's not too uncommon across the cultures of the world that some guys will have more than one wife. Uh, and there's some casual sex as well in every culture on record. Um, there's some casual sex as well. Pair bonding though does seem to be the the most common setting for sex and and reproduction. Even in societies that anthropologists classify as being polygynous, um, to say that a society is polygynous basically just means that um, polygyny is acceptable. You're you're allowed to do it. Um, if if you can if you you know, if everyone involved wants to. Um, actually that that's maybe it's it's not necessary for everyone what wants wants to do it necessarily. Sometimes there's coercion. So, I'll I'll take that back, but but you are allowed to do it. Um, but even in those societies the majority of of actual relationships are pair bonds. So, that that's our most common one. Yeah. How how do we get to a situation where people assume that a just free-wheeling, sleeping around, you you don't have sexual jealousy that is an actual innate problem. This is just your resistance that needs to be overcome through some combination of psychedelics and meditation. Like, how do we get from what seems to me to be quite an obvious setup of it takes like between 10 and 15 years to get a infant to maturity so that it can stand on its own two feet and look after itself. Therefore, you probably need people that stay together for at least a good portion of that. What like what's being missed? What's what what's modern dating sort of a modern mating done to that like innate understanding? Yeah. Yeah. Uh, that is a good question. Yeah. I don't know. So, I think so so people have argued quite a long time that that things like jealousy are just uh social inventions. And I think there's very good evidence that they're not. I do think though that people differ. I was thinking about this a while ago and I do wonder if there are maybe three three kinds of people. There there are some people who get jealous and just could you know, a pair bond suits them really well and they couldn't possibly contemplate uh or enjoy an open relationship or a um polyamorous relationship. And I think there are some people who are kind of the reverse of that, uh small number of people who just naturally um uh polyamorous and they don't particularly get jealous. And I think there may be some people in between who do get jealous and who do naturally feel that way, but who can if they decide to they can kind of hack their brains. And Or perhaps just in insanely high sociosexuality to the point where it kind of outweighs the potential sexual jealousy. Not that they don't feel it, but they're overclocked on their desire for sexual variety, etc. Yeah. Yeah. Yeah. Yeah. I think that's likely. Um, yeah. So, I think that so some people can hack hack it hack the system, so to speak. I think I think if they think that jealousy was just implanted by culture and culture alone, they're mistaken about that. But that doesn't mean that some of those tricks to get rid of it might they might work for some people. It's like a belief in belief in determinism, not believing in it means that you don't need to believe in it. Um, okay. So, how likely do you think it was that humans would have stayed together for life and how likely do you think that we're monogamous or serial monogamists? I think um that both happened, but um serial monogamy was more common. So, I've seen data for instance in uh hunter-gatherer societies that most first marriages don't last for life. So, most people um will have subsequent they will split up and have subsequent um marriages as well. But that that a small number do. So, I think maybe among I think it was the uh I think it was the Kung San. Maybe I shouldn't say actually cuz I'm not I think it was the Kung San or the Hadza or something like that. I I saw data on it and I think about 5% of marriages just lasted for life. Mhm. Um, but so the majority don't. And I and I think in our own culture we see this, right? Is that most people fall in love more than once in the course of their lifetimes. Um, you do get both, but just serial monogamy is is more common. I suppose the rarity ancestrally would have been a uh viable fertile couple staying together for a little while and not having children though. You know, we've decoupled having sex from producing babies now. Yeah. Yeah. And and sometimes that's to the detriment of like there's a theory um you've probably heard of that um that there's a sort of built-in tendency that you you partner up with somebody and if there are no if no kids come along that you just de-partner. That there's a built-in tendency to I got absolutely annihilated for dropping this theory about two years ago and we repurposed it into a I mean it's just it's very difficult. Like it's uncomfortable for people to hear, "Hey, if you and your partner have been in a relationship, you get together at 21, you're like, 'When we get to 30, we're going to start having our family, but we're going to enjoy our 20s first.' And over time due to no neither of your two faults, maybe you're on birth control, maybe you're just timing it right, I don't know, maybe you you know, cycle tracking, whatever. But ancestorally, the only reason that you and another partner would have been together for a long amount of time and not had children would have been that there was a problem with someone. Is it you? Is it them? You don't know, but what you certainly know is there is a 50% chance that if you stop being in love with them and go off with somebody else, that maybe you're going to be sweet. And I said that and it got re-clipped. And I it's a an uncomfortable thesis for people to hear, especially people who are maybe in relationships that are eight years long and have been intending on holding off having children for a little while. Uh, so Yeah. Yeah. But I love it I love it as a theory. Yeah, it works. And one of the reasons I take it seriously is that there is pretty good evidence I think that you find the same thing in pair bonding birds. That if birds pair up and if they one or other is infertile and actually there's a third option, which is that the couple together But just they Yeah. Yeah. Yeah, exactly. And they could both have kids with somebody else, but for some reason it's just not uh the right match. But in birds, yeah, the same thing. If they don't um if there's no offspring, little chicks coming along, uh you know, in the in the breeding season, they will they will split and and try again. What do you make of the fact that if what you've said is correct, uh maybe 95%ish of unions ancestrally would have not lasted for life. What should we make of the fact that we have a culture and a relationship setup system ingrained that looks down on and disparages uh unions that do end up in a way that may be more sort of ancestrally aligned? Um, in the sense of not lasting for for life, right? Yeah. Um, that is an example where the culture is kind of pushing against our nature to some degree. And I think that uh I don't know. Like like especially in the past, right? There was massive stigmatization of divorce. Couples who divorced, that was just like a really really big deal. And I think that would have made it a lot harder for them and I think it probably made it a lot harder for the kids as well. It's hard enough for kids when the parents split in general. But if your culture is strongly stigmatizing it and therefore it's very very rare, um then that's just going to make it twice as hard for the kids. And I think um I think it was probably the cause of quite a lot of needless misery where people who were miserable couldn't could couldn't split up. If they were forced especially in the past, forced to stay together, I think it caused a lot of needless misery and um you know, splitting up too easily, especially if you have kids, that's a that can be a problem as well. But I think there's got to be a there's got to be a balance somewhere, a middle ground somewhere in between those extremes. You know how many divorces were registered in the year that that uh Charles Darwin was born? How many divorces? Uh, no. I'm not sure. Four. Four? Is that right? Four. That's fascinating. Nationally. Yeah, wow. That's how many That's not four per thousand. That's not four per county. Four. Four in total. For all the UK. Correct. Yes, four in total. Yeah, so funny. It's just a That's another Robert Wright-ism from Oh, interesting. Yeah, the That's from The Moral Animal, isn't Yeah, The Moral Animal, sorry. Oh, yeah, okay. Interesting. Um, what can we what can we tell about our mating preferences from our testicle body size comparison? Um, can you imagine how how surprising that question would sound? How is it going? who had Exactly. It's um Yeah, it's a it's a bizarre fact, but the relative size of males' testicles is related to the mating system of of a species. And so and our friends the bonobos who we discussed earlier and chimpanzees as well, basically everybody mates with everybody. And in that context, the best way that males can boost the number of offspring that they're going to have is to produce more sperm. So it's a on exactly the same principle that the best way to win the lottery is to buy more lottery tickets. Um if lots and lots of people are mating a lot and lots of chimps rather are mating with the same female, produce more sperm, you boost your chances of um of uh of being the one that actually fertilizes the egg and size the offspring. Um so yes, so they've evolved huge testes relative to their their body size. And in fact, their testes are almost as big as their brains. I've seen I've seen a photo of a chimp a chimp brain and chimp testes and the testes are only a little smaller. that you're being led around by your penis or by your genitals not by your brain, it actually goes through. Totally. Uh and that's and chimps are quite smart too, so they have pretty big brains, so Terrifying testicles. Absolutely terrifying. Uh at the other end of the spectrum among the primates, we have gorillas for instance. So gorillas uh they're massive massive creatures, they're massive males. They have a harem of females. And although the males mate with all of the females, each of the females while while they're in that particular harem, each of the females only mates with one male, which is the harem master, the the big guy. Um and therefore you don't have sperm It's called sperm competition when you have lots um when you have the sperm from multiple males in the female's reproductive tract um at the same time. So but you don't have that in gorillas because the males are the only ones that mate with the females. Um and so they have very very small testes. So they're they're massive muscular huge scary uh creatures with tiny only tiny testicles. Don't tell him. He's like I don't know. He'll come and get you. Always. Singapore, he'll come and get you. Um And then and then there's the question that everyone wants to and I'm sure everyone's thought of this already. Okay, so where do where do humans fit within the scale from bonobos and chimps at one end to gorillas at the other? And the answer is that we're somewhere in between. So we're closer to the gorillas, but we are we're somewhere in between. And a lot of people have interpreted that to mean that we have walked somewhere down the path toward chimpanzee level promiscuity. We haven't gone anywhere near as far as them, but we have walked somewhere down the path to that. Um and I don't I don't know if that's necessarily wrong, but there's an added bit of information that you need I think to properly interpret that, which is to look at gibbons. So gibbons are another primate, they're a pair-bonding primate. And actually they're their relative testis size is very very close to ours. So we're we're closer to the pair-bonding gibbons than we are to the promiscuous chimps and bonobos. And so the moral of that story I think, combined with what we know about human behavior, is that there's possibly been some degree of sperm competition in our ancestral past, but not a huge amount. So some degree of promis- promis- promiscuous mating in other words, but um not a huge amount and and and again I think that pair-bonding is our most common uh format. What do you think about the mutual mate choice model? Are you familiar with this? Uh I named it. No way. Yeah, yeah. So um Uh me me and Andrew Thomas did it actually. So we worked on a paper called For the people who don't know, Andrew is a horrible horrible Welshman uh that that I I love dearly. He's a great guy and and he's a great researcher, right? And he's produced heaps and heaps of great work. Uh he was my PhD student and and while he was my PhD student, we did this hear that for you. Um we did this we did this paper called uh The Ape That Thought It Was a Peacock uh in which we argue for this um idea that humans are sexually dimorphic, but that it's easy to exaggerate the extent to which we are dimorphic. Um And and in that we coined the terms mutual mate choice model, MMC model we called it, and MCFC model. So uh males choose, females compete. Other way around. Males compete, females choose. Uh and the idea is the these are two different ways that you can construe human sexual behavior. One way is the MCFC model, so males compete with each other for access to females. Uh and females choose from among the competing males. And males do all of the competing, females do all of the choosing. The mutual mate choice model on the other hand, the MMC model, uh that's the idea that both sexes uh compete for desirable mates and that both sexes are choosy to some degree about about their mates. Um and we argue that we fit more with the MMC than the than the MCFC model. Um You do still have the same you have the same sex differences, but they're in a muted form. So although both sexes are choosy in our species rather than only the females being choosy, at least both sexes are choosy at least about long-term mates. Um but females are choosier. So you do have the same sex difference, but it's just it's muted. Um and likewise with competitiveness um for mates and intersexual competition, intersexual competition in both sexes, but it's it's ramped up in males compared to females. Especially especially when it comes to risky and and um uh risky competitive tactics and aggression uh and the like, that's much much stronger in males than females. But but both sexes do it rather than just males competing and females just not competing at all. Why? Why is this the setup that you think that humans have? Because of our big brains is the short answer. So basically as we evolved our our big brains and our high intelligence and our cultural capacity, um that led to all the culture that we have that will so confuse the alien, as that happened, it became more and more intensive to look after kids. So for most apes, uh the females can do it alone. The females can look after the kids all by themselves uh and they don't need help from anybody else. And that's not the case with our species for a number of reasons. So one of one of them is that when um babies are born, they're they're completely dependent. Uh they can't they can't even grip onto anything like uh the young of most primate species. Um and that's because they're in effect born prematurely because it's the only way to get a big-brained baby uh out of out of the reproductive tract is to be born in effect prematurely. And if basically if we if we appeared on the scene if babies appeared on the scene in the same developmental stage um as most primates, pregnancy would last about uh I think it's closer to 2 years maybe. Uh a hor- horrifying prospect. Yeah, and then and then rip a person in half when it's Exactly. Exactly. Yeah. And as as I mean presumably that happened in the process of selecting for Oh, wow. Of course. Yeah. Which is a really horrible thought. Yeah, how many proto-human females died during child birth because their genetic mutation was like, "Ah, we'll test it. 12 months. Who cares?" Yeah. All for the sake of our intelligence and cultural capacity. Um so that's the first thing, so they're completely dependent at birth. And then um just takes a lot longer to get a human being to be nutritionally independent. Is that the is that the the the uh barometer? Nutritionally independent? Yeah. Yeah. So um not not being in the red in terms of of nutrition, not not being uh you know, making at least as much as you're receiving. Uh and that can take up to 18 to 20 years even even in a traditional non-state society. Uh so for both of those reasons, um women can't do it alone. So I think as our big brains were evolving, they must have co-evolved with various forms of what's called allo-maternal care. So in other words, care from individuals other than the mother. And that can come from different sources. Uh it often comes from the woman's mother, so maternal grandmother of the kid, uh siblings, uh especially sisters of of the mother, uh various other sources, paternal uncles, etc. Um very often though, it comes from the father. So often uh fathers are the key investors, which which makes a lot of sense, right? Because the father's the only other adult in the world who's as closely related to that kid as as the mother is. So it makes sense that in many many cultures and we do find that in in most cultures, maybe all cultures, that men invest a lot more than most male mammals. So the evolution of male parental care and then the key thing is that um as as we started forming these pair bonds, as we started having male investment as well as female investment, um that reduced the sex difference in reproductive variance that we were talking about earlier. So the maximum offspring number for humans, other than a few exceptions who would have had heaps, but but in general, it would have come down quite a bit. And as it came down, that would select for a lower level of dimorphism in our species than is typical of mammals. One other paper I didn't realize cuz I went on your Google Scholar and a big deep dark rummage around. You've done a good bit of stuff about men insulting intimate partners. Why or when do men do that with their significant other? That is going way back into the past. That's That's not research that I led, so I shouldn't say too much about that other than other than the gist. Um but the gist of the idea was that uh men sometimes use derogation of the their partner basically as a tool for believe it or not for keeping their partner. So So David Buss talks about this quite a bit, right? He talks about the ways in which men keep a partner. And and they fall into two main categories, the carrot and the stick. So the carrot's the nice stuff, so people are more attentive, they give gifts, they're kind, all the good stuff. Sometimes though um men will uh forget about the carrot and uh go with the stick instead and use uh various ways unpleasant ways to try to keep a partner under their under their thumb, you know? And and the rationale for all that research was that one of those ways is kind of insulting them. So if you could persuade somebody that you know, they're not so great then they're less likely to think, "Well, maybe I could do better than this guy." Uh that's the the main rationale. And it's not a recommendation, by the way. I'm always nervous talk talking about this stuff. Yeah, it's not a prescription. No, we have a unreasonably reasonable audience, so and you know, moving from uh benefit affording to cost inflicting mating strategies, everyone's seen that. And everyone's seen it on the reverse side as well. You know, they've seen it with with women too, that this fear that maybe your partner is slipping away from you. So when he says that he wants to go and hang out with the boys, it triggers a little bit of a jealousy or uncertainty. Is he actually spending time with the boys? So then you make him feel guilty for spending time with the boys, which means that if he doesn't spend time with the boys. I mean, one of the worst ones that Buss talks about is that like I can't remember the term for it, the isolation from male kin and support. Yeah. I can't remember the name, but I know I know what you mean. Yeah. Yeah, where basically if you if a woman has fewer males that are not brothers, uncles, father, etc. around, then it's going to be harder for her to leave. You know, like resource independence is basically going to be tougher for her to get to. So Yeah, it's wild, man. I mean, when I think when I think about just how many of the impetuses and impulses we have as humans that we assume are either of our own making or at the very least under our control, I'm a huge fan of agency. I love the idea of being the author of my own desires and direction in this world. And you know, it's the Jonathan Haidt thing of the rider atop an elephant, but it's not the elephant that's got the blinkers on, it's the rider. And um how have you learned or how would you describe or advise the audience of how to fold evolutionary psychology thinking into their view of what it means to live a good life, of how to feel like the architect of of what they're doing. Cuz I think people can learn about how their desires and and defaults are highly preset and highly disposed in in a variety of directions. And it can feel disempowering. It can I I once tweeted Geoffrey Miller asking how to deal with like the discomfort of learning stuff from evolutionary psychology. So have you got any advice of of how you've done that? Yeah, um well, I do agree that it it can feel disempowering. I agree, but I I think actually that um longer term that it can be empowering. Um for a few reasons. So one is if you have a a good understanding of where these impulses come from um they can stop seeing they they can stop seeming like like your your emotional reactions and and your desires and that kind of thing can stop seeming like uh direct perceptions of the nature of things. You know, like it's really really it really just objectively is very very important for me to do this and this is this is really good and this is really bad. It can allow us to take a step back from that and potentially deflate those feelings to know where they come from and to know that a lot of the feelings that we have we have uh in our minds because they on average let our ancestors to pass on their genes in ancestral environments. And so we can think, "Well, my goal isn't to pass on my genes. I've got these other things that I think are more important and therefore I'm not going to take these emotional reactions as seriously as as I would otherwise." And and I do think it works. I do think it can deflate uh our feelings. Uh one example that I think I wouldn't I think it was one of Steven Pinker's books. He was talking about how uh you know, when people are feeling high status kind of people who strut around and that kind of thing. When when you see that chickens do the same thing um and and the males puff up, it doesn't make you think, "Oh, cool. Well, this this uh this is even more important than I thought." It deflates it. It makes you think, "Oh, this is just a silly animalistic tendency." Um so I think I could pick it That's one way I think that it can help. It can deflate things so you can more easily choose like what do I really want to do? Uh rather than just going with your gut instincts. And the second thing I think relates to what we were talking earlier about jealousy and whether people can hack their brains to get rid of their jealousy. And I do think a lot of people can't do that. And I but I but I think that if people think that they can they might think, "Okay, this this jealousy I do feel this jealousy. I'm you know, I've got I've got this partner who wants to have a polyamorous relationship." Um I don't like the idea, but that's just cuz of society. It's It's I can cast it off just as easily as as it was taught to me. And if they know that quite possibly that's not the case, that that there is an evolutionary origin to that emotion and that therefore quite possibly they're not going to be able to cast it off they might they can make a more informed decision, I think. They can They can think, "Well, I'm probably not going to cast it off. This probably is going to be unpleasant for me whether I want it to be or not. So I just think that this is this is perhaps not the relationship for me." And they can steer clear of it cuz they they might realize that it's unrealistic that they can just reprogram reprogram themselves so easily. Not to say there's anything wrong like polyamory does work for some people. Um but having those kind of thinking tools can can help you think through whether it's going to actually work for you or not. Certainly for me letting go of castigating myself for thinking a thing or feeling a thing very difficult, right? Because we we want to hold two competing thoughts in our mind at at the same time. One being I am in control of my outcomes. The other being I did not get to design my source code. And like these two things are just going to continue to clash up against each other. And you know, David David Hawkins wrote a great book, Letting Go. And that happens to be the thing that you try to do with emotions when they arise in meditation. It's the thing that you are trying to do with this also. Look, I I can I can try and leave it all on the field of play and control my destiny and at the same time know that I don't have full control. I don't really even have partial control. Yeah. Yeah. And and that kind of thing, letting go and and meditation, that's those other ways that we can hack our brains. There are there are ways like we there's a definite evolutionary push in certain directions from our genes, but our genes aren't the only thing the only things that are shaping us and therefore we can sometimes push back at least to some degree. Uh uh which is nice. I I know one reason that people resist evolutionary psychology is that um is that they dislike the idea that they're dislike the idea that they're just puppets of their genes. And um I do think though that uh well well well, first of all, an evolutionary perspective doesn't say it's just genes, right? So it it would say that you're puppets of the the genes and the environment, really. But but that would be my other thought is that um if being a puppet is the problem uh rejecting an evolutionary perspective isn't a isn't a solution, right? It's just um choosing an alternative puppeteer because the environment if it's just the environment, well, then it's just the environment that's shaping our um shaping our source code instead. Which is even more ruthless. I mean, you recently did a great post about uh behavioral genetics. Plomin's been on the show. And you know, if you were to get to a world where uh all genetic differences between people had been flattened out or gotten rid of or accounted for the entirety of the difference in your outcomes in life would be laid at the feet of your environment. And that's seems like even more [ __ ] brutal. That's like Exactly. Exactly. Pick pick what it is that you want. Pick pick your poison, right? Yeah, exactly. Um so Yeah, sorry. Go ahead. Just I'm kind of thinking about whether or not we are fated to fail at discovering a greater reason for our existence if all that we are are just propagators for our genes. Like is it all just futile, this trying to trying to get something more out or is there a a realistic path to enlightenment here? Nice easy question. Um uh I mean, what what sort of what sort of higher things are you thinking of? Meaning beyond the immediate. Like trying to find a way to contribute to things. Like it it seems especially upon you your book and most evolutionary psychology, I think speaks to you in the mood or the vibe that you're in at the time. Like if you read something about reciprocal altruism when you're feeling full of serotonin and and everything's going well, you think God, how great that I love my mom. How fantastic that I rang her last week. But if you read it when you're feeling a little bit more zero-sum and like the world's out to get you, you just see it as a thinly veiled mask for selfishness masquerading as selflessness. And I I I'm trying to work out whether or not how we can take more pleasure in the things that we want to take pleasure in beyond this is just a transaction for my genes to get themselves toward the next generation. Interesting. So I wrote a bit about this in my first book which was called Darwin and God and the Meaning of Life. And in the Meaning of Life section of that book, I looked at the question of is there is there any ultimate meaning to life? Is there is there any meaning to life in any sense? And I concluded that I concluded with a message that initially might seem a bit of a downer which is that there's no there's no no ultimate meaning to life. So no meaning to life imposed on us from outside of ourselves from from from a god or from or any kind of meaning imprinted into the basic nature of existence. But I don't think that is necessarily terminally a downer. I think that once you get used to that idea it in a way it gives us a kind of freedom and the freedom is that we can choose our own meanings in life rather than having a meaning imposed on us from outside of ourselves. So we can choose a meaning. And our genes may be to push us into the into a direction that we can quite easily feel cynical about. It's just just in interest of the genes and yeah, some of the stuff is kind of nice but ultimately it's just about gene propagation and but having turned us into a cultural animal and an intelligent animal and made us an open system, I think we can think beyond that. And that's what we're doing when we learn about evolutionary psychology and step back from looking at our evolved nature and thinking, okay. Well, what do I what do I actually want my life to be about? What do I think is more valuable? If I don't think transactional this that and the other thing, what are bigger goals that I do think are important that I can choose for myself? And for some people that might be like effective altruism and dealing with existential risks and for other people it might be something you know, something more modest. But I do think that the fact that we are evolved creatures doesn't preclude doesn't preclude being able to go beyond our evolved nature via culture and and to do other things that uh and choose other values beyond what's been bequeathed to us by natural selection. Yeah, you do get to be the architect in that way, I think. It again it it as it comes down to with many things, it's holding conflicting ideas or at least slightly sort of uh tensionary ideas in in your mind at the same time. Before we finish up, I I learned something John Tooby passed away last year. I was very fortunate that I got to meet him. Yeah, great great guy, right? Phenomenal. I think David Buss says one of only two people he's ever met in his entire life who justifies the title of genius. And um I I agree and also really nice guy. Phenomenal dude. Also also most importantly subscriber of Modern Wisdom. So that was that was that was the best thing. Um someone sent me a article looking at a quote of his and deconstructing it and we're an hour and 20 minutes into the episode. So anyone that's not reasonable has already left. So I wanted to have a quick chat with you about it. Um it's the crumbling genome theory of population dysgenics. Crumbling genome theory of population dysgenics, right? Yeah. So basically Tooby's argument is that each time that a new generation comes along, there's some genetic mutations that get fiddled with. Every time that that happens, some of them are better and some of them are worse. Some of them are more optimal and some of them are more suboptimal. When selection pressures in an environment get released through things like health care and the ability to improve medicine and a germ theory of disease and so on and so forth, you relieve some of the selection pressure. You know, somebody that was blind in both eyes probably didn't last very long ancestrally. Somebody who was born without legs probably didn't last very long ancestrally. In the modern world we have technology that can thankfully keep those people alive. The problem being that you are accumulating mutational load that ancestrally would have been suboptimal making no judgments about the people that are alive today. But that his the balance the genome balance needs to be you discarding suboptimal mutations at the same rate as you acquire optimal mutations. And if you roll this forward over a long enough time that basically a reduction in selection pressure results in an increase accumulation of all of this stuff. Now here was the really spicy bit that someone put it if that wasn't spicy enough right? The really really spicy bit that someone put toward the end of this article was perhaps this explains birth dearth which is if you as a human who has a genetic mutation even like you just normal person walking around all over the place. Uh if you make it to reproductive age and you're for some reason there's just something about you that shouldn't go on to the next generation who's to say that your desire for children wouldn't just be nerfed a little bit or maybe your desire for sex wouldn't just be tuned down a little bit. Perhaps enough so that you don't end up making children and taking them forward. So when you think about you know, the ever-increasing rates of depression, anxiety, like antisocial behavior, all of that the maladies that people are dealing with mentally at the moment and the ones that people are dealing with physically like obesity, etc. How many of those would have been selected out ancestrally and how much is the decline in desire for children and subsequent birth rate collapse a population-wide prophylactic or a filtration net stopping those particular individuals from going to the next next generation? Interesting. So a lot there spicy like you say. Uh And so I guess the first thing is that that's all that's all perfectly possible, right? So I do think that um So one example, right? Is that in ancestral times myopia was probably a much bigger problem for survival than it is today. And people who had genes that predisposed them to myopia and couldn't really see so well probably were less likely to uh put forth their genes. That's been released for quite a long time. We have glasses and things. Now we have cultural ways of mean that that it's just no longer a problem. And I think it's quite plausible that the average genetic quality of eyesight could have deteriorated to some degree for that reason. And and that would just be one example that could be others along those lines. And then that's tricky to know like how do you deal with that, right? So but you couldn't say, okay, well, we're just going to ban glasses so that this doesn't happen anymore. So that people people that have got myopia die at a higher rate. Exactly. So they just wander randomly into traffic and take take their myopic genes out of the gene pool. So we couldn't do that. I think what could happen is that the more that these kind of technologies evolve culturally the more dependent that we will dependent will become on them not just habitually but also biologically as well. I think it's it's possible you know, people are looking at ways of so to speak men mending the genomes for like major health So genes that contribute to major health problems, it's not implausible that the time will come when it's possible to filter those out or to if if you have offspring, you can choose to uh to go to go with I don't know like I fertilize the eggs and choose the ones that don't have the problem. for Yeah, yeah, that's that's the phrase. Yeah, exactly. Yeah, I think that Well, actually I think it's embryo selection against negative traits. I think it's the main one that people Yeah, yeah, yeah. Um I'm not the prophylactic idea I'm not so sure about cuz that sort of seems like a like a good of the group explanation. So like it would be good for the species as a whole if we were to have that kind of dulled down sexual desire or desire for kids. But what would that be What would be in it for the individuals with those desires? not just roll why not just roll the dice anyway? What do what do you care about resource depletion? Like there's no tragedy of the commons baked into our genes. Yeah, yeah, yeah, exactly. Exactly. I do know though that with with things like the Well, actually most mental illnesses so depression, schizophrenia the vast majority um of of mental illnesses are actually associated with lower number of offspring. So there certainly I think there is some filtration going on in some areas. Yeah, that's a really good that's a really good point. Uh the the fact that you don't have this God's eye view population-wide coordination thing, what like give me the mechanism through which your genes would just be like just have a crack. Like see what we don't know what's going to happen. Maybe maybe you were a blip and they're going to be they they can fly like the next your kids can fly. Like who knows? Um Yeah. That's really really interesting. Steve, I'm a huge fan of your work. I'm a huge fan of your Substack. Your book's fantastic. Uh I'm excited for whatever the next thing is. Where should people go if they want to keep up to date with everything that you do? Uh well, my Substack is is my favorite thing at the moment. I really I really love Substack. Um it's taken over from Twitter in terms of my favorite uh you know, social social media outlet. So, that's called um uh it's called the Nature Nurture Nietzsche newsletter. And it's stevestewartwilliams.com. Um I am still on Twitter as Sorry, go ahead. Go ahead. Nothing. Just I wanted to know where Nietzsche came in. I haven't seen you write about Nietzsche yet. Yeah, I'm not sure it's the greatest name for a for the Substack because I I love the clever play on words and I love philosophy. And that's what it is. So, I love nature nurture issues and I love philosophy and it's kind of Mhm. Nietzsche stands in for for philosophy as a whole. I do quite like Nietzsche's writing style. I'm not a huge I'm not actually a huge fan of of Nietzsche. So. Maybe it's not the perfect title. People probably think I'm a Nietzsche nut, but um but I'm a philosophy nut uh instead. And I'm I'm on Twitter as well. It's um @stevestewells, so s t e v e s t u w i double l. Oh, yeah. Steve, I mean, you're you're fantastic. I I can't wait to see what you do next. Oh, awesome. Thank you very much, man. It's been It's been a lot of fun. I really enjoyed this conversation. If you enjoyed that episode, you will love a selection of the best clips from the podcast over the last couple of months and it's available right here. Go on. Give them a watch.