#786 - Steve Stewart-Williams - Why Are Differences Between Men & Women Being Denied?

This episode explores the evolutionary psychology behind differences between men and women, discussing why such distinctions are often denied or misunderstood in contemporary discourse.

1. Sex differences are often either denied or exaggerated in popular discourse, and understanding the balance is crucial.
2. Evolutionary psychology offers valuable insights into why certain behavioral patterns appear between sexes.
3. Cultural influences play a significant role in shaping perceptions and behaviors concerning sex differences.
4. There are significant misunderstandings and myths about sex differences that need to be addressed for a clearer understanding.
5. Insights from evolutionary psychology can challenge and expand our current understanding of gender roles.

1. Introduction and Background

Chris Williamson introduces Steve Stewart-Williams, discussing his background in evolutionary psychology and key themes of the episode.

• Chris Williamson: "Today we delve into why differences between men and women are often denied."

2. Evolutionary Background of Sex Differences

Discussion on the evolutionary explanations for sex differences and their manifestations in modern society.

• Steve Stewart-Williams: "Evolution shapes not just physical traits but psychological ones as well."

3. Cultural Impact on Sex Differences

Exploration of how culture influences and modifies inherent biological differences.

• Steve Stewart-Williams: "Culture can amplify or mute biological tendencies, complicating our understanding of sex differences."

4. Misconceptions and Public Perception

Addressing common misconceptions and the public's often polarized views on sex differences.

• Steve Stewart-Williams: "The debate often swings between denial and exaggeration, missing the nuanced reality."

5. Conclusions and Reflections

Summarizing the discussion and reflecting on the implications for society and science.

• Chris Williamson: "Understanding the nuanced truths about sex differences can lead to more informed societal discussions."

1. Seek out reputable sources on evolutionary psychology to understand the foundational theories.
2. Engage in discussions about sex differences with an open mind and readiness to challenge personal biases.
3. Consider both biological and cultural factors when discussing gender roles and differences.
4. Be critical of extreme views that completely deny or exaggerate sex differences.
5. Educate others about the complexities of sex differences using insights from evolutionary psychology.

Steve Stewart-Williams is an evolutionary psychologist, a professor and an author.
If you follow the thread of evolution long enough, you see that humans are simply a product of adaptations. So why are humans so peculiar? Does everything we do have a rational explanation, or are there aspects of our lives and psychology we have yet to understand?

Expect to learn how aliens would view our species if they were observing from above, what most people get wrong about understanding sex differences, Steve’s best explanation for the gender equality paradox, why humans have such strange sexual desires, why men tend to insult their intimate partners, how to deal with the discomfort of learning evolutionary psychology, my spicy new theory on dysgenic gene erosion and much more...

People

Steve Stewart-Williams

Companies

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Books

"The Ape that Understood the Universe" by Steve Stewart-Williams

Guest Name(s):

Steve Stewart-Williams

Content Warnings:

None

Chris Williamson
Hello, everybody. Welcome back to the show. My guest today is Steve Stewart Williams. He's a professor of psychology at the University of Nottingham, Malaysia, and an author. If you follow the thread of evolution long enough, you see that humans are simply a product of adaptations.

So how have humans become so peculiar? Does everything that we do have a rational explanation? Or are there still aspects of our lives and psychology that we have yet to understand? Expect to learn how aliens would view our species if they were observing from above what most people get wrong about understanding sex differences. Steve's best explanations for the gender equality paradox, why humans have such strange sexual desires, why men tend to insult their intimate partners, how to deal with the discomfort of learning evolutionary psychology, my spicy new theory on dysgenic gene erosion, and much more.

Steve is potentially one of my favorite authors of all time, and his book the Ape who understood the universe is in my list of 100 books that you need to read before you die and completely changed my worldview on an awful lot of things. And he is fascinating and his work is brilliant and this is just so much fun. I've been waiting a long time to bring him on the show. He is an underground hero. I'm confident that over the next few years you're going to see so much more of him.

Really, really happy to have brought him on. And yeah, it's just exciting, interesting, classic modern wisdom episode. So sit back and enjoy. Trust really is everything when it comes to supplements. A lot of brands may say that they're top quality, but very few can actually prove it, which is why I partnered with momentous.

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Why would we humans be confusing to be understood by an alien? How would an alien scientist view our species, do you think? Well, that's how I start the book, right? So I start the framing device for the whole book is the idea that 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? And the short answer is that it would be very, very.

Steve Stewart-Williams
It would be mystified by us. 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, 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, that those two types differ from each other, 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, that we're kinder typically toward our family members than to non family members, that we listen to music, that we have music and art and all these kind of strange things that don't have any obvious survival value, but which we spend a lot of time just amusing ourselves with.

So that's the framing device that would find us very weird in many different ways. Yeah, it's very odd. I think I've had a lot of conversations about evolution, sex differences, sexual selection, et cetera, et cetera. But talking about culture and the role of culture evolutionarily, how do you even begin to frame that integration? Yeah, and that's maybe the big question.

And I think possibly that's the thing that the alien would be most surprised about when encountering us, because 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. And I think the answer, it's a two part answer, really. I think the first part is that somewhere along the line, 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 to basically make up tricks and learn tricks from each other. And we have the intelligence, the cultural capacity to do that. And it makes us a kind of open ended system so that our culture can 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, it starts evolving in its own right, somewhat independently of biological evolution.

So you get selection. So biological evolution is about selection for genes. Cultural evolution is about selection, not for genes, but for the elements of culture, which are often called memes. So you get selection for different memes. And the forces like 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 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 in general?

Selection? Yep, sure. So in general, it's about replicators. So it's about entities, light genes or light memes, 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.

And biological evolution, that's a question of genesis. Different gene variants becoming more and more common compared to competing versions of the same gene, competing alleles. In the cultural sphere, it's about different cultural elements becoming more and more common relative to competitors. And basically what you get is you get selection. So, like I say, selection for the variants that are best able to replicate themselves.

And in the biological sphere, what it does is you get selection for genes that have effects on their owners, that is us, that increase the chances that they're going to be put forward into future generations. And that turns us into what I call in the book, gene machines, into organisms that look as if we've been designed and look as if our intention 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 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 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 explain why we're modified grandchildren maximizing machines?

Yeah. Yeah. Okay, so, yeah, I go through a series of hypotheses, basically about what we've evolved to do, what human beings are for. So the Alienwood cs, we're 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 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. The next one is, are we survival machines?

I rule that out because if you were to survive for 100,000 years, if you were never to have offspring, for instance, then as soon as you actually die, your genes are going to go out of existence as quickly as if you lived for 20 seconds. So then I think, okay, so maybe it's about offspring, right? So are we just machines designed to reproduce, to have offspring? That's a big step closer, I think. But I think that's not quite right either, because if you had 100,000 babies, but none of those babies survive to have babies of their own, then, you know, again, your genes are pretty quickly going to go out of existence as if you've never had any, any babies.

So, like a big jump in the right direction. Is that where machines designed to ultimately have grandchildren? But actually, I take a couple of steps beyond that as well, because there's also. There's the inclusive fitness perspective. So then inclusive fitness brings in, okay, so what I've said so far is like, it's about surviving and making offspring that had their own offspring.

Inclusive fitness brings in another element, which is can altruism, which is that we can also spread our genes by helping our genetic relatives to survive and have offspring, and those offspring to have offspring of their own. Yeah, I heard. 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, etcetera, 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 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 fascinating.

Right. So people grieve more if they lose an identical twin than if they lose a fraternal twin. It's fascinating. What is that? Is that Nancy Seagal's.

Chris Williamson
It was Nancy Segal. Yeah. Yeah. She came up to me at h best. She said some very flattering things.

And then shortly after, I brought her on the podcast. Yeah, she's phenomenal. Awesome. She is really great, Ryan. 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 postulate 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. 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 Stacey. I know that this sounds. To the people that haven't heard the Nancy Siegel episode, this sounds like I'm just pulling stuff out of my arse, but this is represented in data. It's wild, right? The similarity between identical twins reared apart is just incredible.

Yeah, it's wild. 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.

Steve Stewart-Williams
And I think that that's probably one of the. That's nice on the one hand, right. Because we're feeling an affinity, these people like us. But there's a dark side to that, of course, which is exactly. It just is one of the things that makes, I guess, put it back in the cultural evolution.

It makes racist memes easier to accept just because we do have an affinity for people like us. And the flip side of that is whatever the opposite of an affinity is to people unlike us. Yeah. Disaffinity. 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 make of that? Given that we also have.

Chris Williamson
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 deeper than the accent stuff. Yeah, no, I think you're right.

Steve Stewart-Williams
I think that although we do have that disaffinity for people who look unlike us, it's not so deep that, I mean, 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 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 disaffinity. For people who look unlike us, it can be trumped by other things. And I do think you're right about the accents. They do seem to serve as a tribal marker and often more so than skin color. Yeah, it's very, very interesting indeed.

Chris Williamson
So what do you think most people get wrong when it comes to understanding sex differences? I think that's a long list of things.

Steve Stewart-Williams
I'm working on a new book, actually, and it's going to be focused on sex differences. Hell, yeah. And I think. Okay, so 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 the first mistake, the minimizing and denying mistake. But people do make both. And I think both potentially cause problems. Is it a 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, because I think people. It's just very easy to swing to one extreme or the other. 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. But I think that 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. It would say, okay, we've got these sex differences in this. This weird species, but they belong to the big group called mammals. And in a lot of mammals, the differences are much larger. What are your favourite psychological sex differences in humans?

Let me think. Okay, so let me start with the one I think is the biggest one, the single biggest psychological sex difference. I don't suppose you can guess what it might be. Desire for sexual novelty.

That's usually about a medium effect size. So about 0.5, maybe a bit bigger. The one I'm thinking of is much, much bigger than that. Fuck.

Chris Williamson
I give up. Tell me. It's one that as soon as I say it, you'll recognize it and you'll recognize that it's huge. I think it's so obvious to us that we take it for granted and don't think of it. It's the fact that the vast majority of men are primarily sexually interested in women and the vast majority of women are primarily sexually interested in men.

Steve Stewart-Williams
So it's interesting. 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 nowhere near that magnitude. 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 because we take it for granted so much that that's the case, that we don't even really think of it when we're listing them. That's like the physics of sex. Yeah, yeah, yeah, yeah. Exactly. And there's a clear evolutionary rationale, of course, for it as well.

Other ones on that list would be the desire for sexual variety. Like I said, it's a medium sex difference. The desire for casual sex is a large sex difference. That one's actually larger usually than the desire for sexual variety. Sex differences in aggression, face to face aggression and violence in particular.

That's another big one. Sex differences in parental inclinations would be another. It's interesting. Oh, what's the one in. Tell me about jealousy.

Sex difference in jealousy. This isn't a huge one, but that is the fact that most. So men in general, on average, are more upset than women about sexual infidelity. So if their partner gets. So if you ask people, okay, so imagine your partner, you're in love with your partner, your partner gets involved with somebody else, which would upset you more.

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? 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.

Chris Williamson
Yeah, well, I mean, how many times has there been some on street interview? I even remember this from 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?

Steve Stewart-Williams
Yep. Let me start with the commonality, though. So just, I think the main function of jealousy for both sexes, it's part of our pair bonding psychology. So we fall in love with each other, but we also had jealousy. And I think the both sexes, the main function of that is to protect the pair bond.

Pair bonds were adapted for us in the past as a setting for having kids and rearing kids. And so we've evolved a psychology to kind of protect them. The differences, though, the main difference for men compared to women 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 this some other woman's kid?

I don't know. Whereas for men, if their partner gives birth, it's almost certainly their kid, but there is a possibility that it's not their kid. And any guy that ended up investing in a kid that wasn't his own biological kid, all the paternal effort that he puts into that kid, he's putting it, in effect, into the genes of another guy. And so 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 one of those.

So the kind of jealousy that makes the guy keep a kind of wary eye on his partner and on the good looking next door neighbor and to take action if they start, you know, or the guy at work, maybe she keeps talking about that guy at work, he starts getting a bit worried about that, maybe takes action to try to make sure nothing happens. Maybe he's a bit more tentative. Maybe he handles it in a nastier way. But because paternity uncertainty is the main issue for guys, well, paternity uncertainty is facilitated by sex. Not just falling in love, but sex.

The sex act itself is what leads to somebody having somebody else's care. Right? So that's why. That's the rationale, evolutionary rationale, for why guys are particularly focused on that. With women, on the other hand, emotional infidelity, this is a big deal.

Obviously, it's a big deal to people. A woman doesn't want her partner sleeping with somebody else and she's got 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 guys. What can do, though, is 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, if he would have fallen 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.

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 just increase the burden on her. So it might be longer before she can have her next kid. This is going to be a big hit to her fitness and a bigger hit than if he just sleeps with somebody else. So that's the evolutionary rationale for why she might be more focused on love and fidelity as opposed to sex infidelity.

Sexual infidelity. What is your favorite explanation for why women have concealed ovulation, then?

I'm not sure I have one. It's a really interesting question why we do have concealed ovulation. I've read the different theories and I don't find any of them hugely persuasive. So I'm not completely sure. Let me, let me highlight one, though, in particular that I guess is, 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, that actually that 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 anestrus, but we just don't have that. So there's been no selection for advertising it, as opposed to there being some definite adaptive rationale for concealing it, if you see what I mean. How interesting.

Chris Williamson
Yeah, that is. I mean, 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 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 fucking infant that needs ten years of looking after before it can be functional and independent on its own. There was one where I think Macken or William taught 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, in a way. Yeah, yeah, yeah. Of those three, I think.

Steve Stewart-Williams
I think the second of those, I think, is the one that I. That rings truest to me. I've 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 one or the second one, that is to facilitate pair bonding and males and females spending lots of time together all the time, rather than just when the female is ovulating. Yeah. We're one of a very small number of species that have recreational sex, right?

Yeah, yeah, I think so. Bonobos, I guess, would join us in that small club. Bonobos, I think, have quite a lot of sex and just 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 when you think about it that way, the dogs actually are quite prolific in terms of the range of sexual interests that they have. Another spicy one. What do you make of the women purposefully starving themselves and making themselves anorexic? Is a vestige of ancestral birth control.

Interesting.

I think that's.

I don't know. That doesn't strike me as immediately particularly likely.

I think I prefer some of the hypotheses that people like norm Lee actually have come up with. His argument is that it's not an adaptation and it's not an extension of an adaptation, but it's just a weird kind of cultural byproduct of just sort of status seeking intersexual competitiveness that you get within each sex, you have competition and different ways of attracting a mate and that kind of thing. And it just seems to have in some societies, wealthy societies have latched on to being super thin, and that's not adaptive, but it's just taken to an extreme and a minority of people. And I think one reason I think that's more likely than an explanation like the birth control explanation is that it's only really found in wealthy societies. It 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 rather than something that's found in ancestral times. Yeah, I learned the environmental security hypothesis a couple of months ago. Have you heard that? Yeah. What's that?

I'm not sure. Male preference for female body size varies based on economic conditions. So, yes, I have heard that, yes. During times when the economy is more uncertain, men prefer fuller women. And in times when the economy is safer, they prefer thinner women.

Chris Williamson
And they've done studies where they ask men to rate the relative attractiveness of women of various body sizes before and after they eat food. And the post eating food for men results in a. A thinner woman being pregnant. Right, right, right. And then when they were hungry, look.

At how robust she is. Look at how many famines she could handle. Look at. Look at how many depressions and high interest rates she would be able to put up with. Interesting.

Steve Stewart-Williams
And what's the name of that? So I have heard that environmental security. Environmental security hypothesis. Hypothesis, yeah. Okay, cool.

Yeah, that's interesting. Talk to me. Okay, so just looping back to the sex differences thing, what do you say to the people who would go, that sounds fine, Steve, but how do we not know that this is all just due to socialization? Well, I think that's a good question, a perfectly reasonable question. And I think the first thing I'd say is that socialization does play a role.

So I certainly wouldn't be arguing that these differences had nothing at all to do with socialization. One line of evidence that they do is that the magnitude of the differences is different across different cultures, and it's different within the same culture at different times. So for me, the question is really, how do we know that it's not just socialization? And I think that there are various lines of evidence that pretty strongly, very strongly, actually. I think do suggest that for the kind of sex differences that I named earlier, that they're not just down to socialization.

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 even when the culture changes quite a lot. Sex differences in mate preferences, for instance, survived right throughout the 20th century in the US, for instance, even though there were 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 throughout that time. Sex differences and the preference for casual sex as well, they persisted throughout that time.

You find them, a lot of them appear quite early in development, before it's sort of plausible that socialization could be involved. The sex difference in aggression, for instance, appears really, really early. As soon as kids can basically move around and be capable of aggression, you see sex differences there, and also, like a lot of sex differences, either a pair in the wake of puberty or they get bigger in the wake of puberty. So the developmental timing there is not 100% proof, but that sort of suggests as well that it might be have an evolutionary basis. The third one is that often it resists.

Often, sex differences persist in the face of culture. So I think the usual story is, okay, so you have these differences and they're created by culture, but often they persist even when the culture is pushing in the opposite direction. So aggression is a good example of that, actually, there's a sex difference in aggression. Males on average. I don't need to say the direction the difference, but males are more aggressive.

And people might say, well, that's because we encourage males to be more aggressive. But actually, if you tabulate how often people are saying, don't be aggressive to boys and don't be aggressive to girls, they're saying a lot more to boys. They're discouraging boys from being aggressive a lot more than they are discouraging girls, not because 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, 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.

That was three, right? Yeah. Four is hormonal, especially prenatal hormonal associations that you have between levels of testosterone, in the womb in particular, and then the emergence of traits, male typical and 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. For guys that makes no difference because they already have very, very high levels.

But for women, for girls who are exposed to that, the high levels, it does have a big effect on them and it sort of masculinizes their behavior in a lot of ways. There more prone to aggression. Maybe they have more male typical preferences. They sort of shifted in the male direction. They're 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.

In some cultures you might have men being more interested in porn, for instance, and women being more interested in romance novels. In other cultures, no sex differences in either direction that they both like or dislike them just as much as each other and others, you'd find it reversed. And so some cultures where women are more into porn and women hire prostitutes and men are, the majority of the prostitutes and men are reading the romance novels. And of course you don't find that. You find that these differences are very, very consistent across all, depending on the trade, every single culture that where we've looked, or the vast majority.

And it's a lot easier when you find that to explain it in evolutionary terms than in terms of purely sociocultural ones. And then the last one, 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 other species that are subject to the same selection pressures as 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, even the most successful female can have. The average has to be about the same, has to be almost exactly the same. As long as you have an equal sex ratio, the average for both sexes has to be the same. But the variance can be greater for males and females and often is. And when you have that, when you have the greater variance in males, that means that there are more males than females having no offspring at one end.

But then the important end is that you have more males and 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 fewer. 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 or with do. In our ancestral past when we didn't have birth control and the like, all those kinds of traits, lower level of parental investment so you can spend more time seeking mates.

All those kind of traits are selected, and not just in our species, but just in any species. We had greater reproductive variance among the males and the females. And, and that's the, that's the key thing. That's the key line of evidence. Evidence is that we had the greater reproductive variance.

That's where you'd expect these sex differences, that the theory is correct. And that's where you do find sex differences. Yeah. So you've had your hypothesis proven by the world around you. Exactly.

Yeah. By many different species. And it's very cool. Right? Because there are some species where you don't find the sex difference and reproductive variants and those species you don't really find much in the way of sex differences.

So you find you have what are called monomorphic species, and in a few that it's actually flipped into reverse and females have greater variance. And then all the usual sex differences are turned on their head and the females are more aggressively seeking mates and beating each other up to try to get mates. And jukanas, that's a north american shorebird, for instance, the jukkana, basically, jukana females try to put together a little harem of males and they have a bunch of different nests, and they try to get these little males, these choosy little non aggressive little males, shoes on the other foot. Now, women, how do you like that? My students do actually love this when I, when I talk about the chicanas.

And I think it's for exactly that reason. It feels like the shoes on the other foot. Yep, yep. Eat some of your own medicine for a while. My favorite one, I think.

Chris Williamson
I think my, I learned this from David Geary. And he was talking about the preference that males have, even male chimpanzees, other sort of primates, for reciprocal motion, reciprocating motion in toys. So you would think the reason that young boys like trucks and young girls like dolls and fluffy things is that some socialization 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.

I'm gonna guess that you've looked at this as well. Yep. Yeah, I have. And I think it's fascinating. Right.

Steve Stewart-Williams
You find that in vervet monkeys and macaques, maybe, I think. Yeah, yeah, yeah. It's incredible, right. Because I have to say, like, those toy preferences, it does. Before seeing evidence like that, it does seem pretty plausible.

Like, what could that have to do with evolution? It's much more remote than things like aggression and sex drive and interesting casual sex. All that stuff is 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.

Chris Williamson
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 young girl. 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 roll the clock forward and you look at Joyce Benninson's work. What is it that children in primary schools are doing? Children in primary schools, if you're a young set of boys, you're doing warfare, you're fighting Indians or aliens 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 sort of rules seem to be very similar. Yeah, yeah. It's amazing. Right.

Steve Stewart-Williams
And like, with the. With the monkey research, the macaques and the, like, the. The bit of that that I find most plausible is the caring for. Caring for dolls, caring for little things like that. I think it's pretty clearly an offshoot of a greater parental inclination.

And the females and the males. Yeah. But it is really interesting. And, you know, the toy differences, it's like, what I was saying is 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 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 non conforming household. Then you bring the children into the lab and you let them play with any toy that they want.

Chris Williamson
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 non conforming households, you still see the same sex difference. Yeah, yeah. It's great. Right.

Steve Stewart-Williams
And I think the big difference there is that the ones in the gender nonconforming household are just more tolerant of kids who want to be gender non conforming. Yes. Which other. Yeah, that's nice. That's a nice effect.

Chris Williamson
All right, your sub stack, apart from I'm just blowing you the entire episode, your sub stack 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 substate posts.

Steve Stewart-Williams
Right. There was a paper last year by Abigail Anderson and colleagues where they basically tried to debunk the idea that they called it the man the hunter idea, by which they meant the idea that in hunter gather conditions, men did most of the hunting and women did most of the gathering. And there was a pretty clear division of labor. And I remember when I read that, I thought, I think that's quite unlikely. Just on the face of it, that's quite unlikely that anthropologists studying this issue for more than a century, and not just male and male and female anthropologists have looked at this issue.

Is it really plausible that they have just kind of hallucinated this massive sex difference? And are they just 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 more often small game hunting rather than big game? So my thoughts doesn't seem very likely. And then a preprint has come out in the last couple of months, which has more systematically gone with that intuition and made what I think is a very strong case that they weren't right about that, that they were wrong about this idea that hunting is a lot more even than we had thought. And what they seem to.

They seem to have made 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 error. Rather another one was that they only included a relatively small subset of the available societies for which we had data, and there were plenty of others that they could have included that would have been, which would have met the 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 just do that. 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 take your wife to work with you one day, 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, because 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. Fuckery. Fuckery everywhere. Steve. So I wrote a little theory off the back of this.

Chris Williamson
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.

I like that. That's great. Which I think fits of male expectations. Yeah, that's great. 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, pitchy, moving forward kind of text. Yeah. 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 connector and all of that?

Steve Stewart-Williams
Exactly. Just crucial tasks and equally difficult tasks in their own kind of way. And they're just considered to be not as valuable, implicitly lesser and. Yeah, exactly. They are implicitly seen as lesser.

Even though. Yeah, even though it's supposedly a pro feminist thing. You know, you can read, you can see, and 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 reading that. I'd be lying if I said it didn't give me a big sort of kick of satisfaction when I read your takedown of it.

Nice. I'm just going to write down, just writing down soft bigotry of male expectations. I like that. Oh yeah. Okay, so what are your best explanations for the gender equality paradox that we're seeing?

So the gender equality paradox is the quite surprising 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, etcetera, as they become more gender equal in those kind of ways, traditional socio cultural theories and like social role theory would predict that the sex differences would get progressively smaller 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 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 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, but my best guess is that, is that what's happening is societies that are more gender equal. It comes with a cluster of different cultural levels variables. So they're more gender equal. They also tend to be more individualistic on average. It also tends to be correlated with wealth, greater human development of the societies, that kind of thing.

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. Have you got any idea what's actually happening with men and women in STEm at the moment?

Yeah, I've got a few ideas about that. The first thing is, so we often hear that there are more men than women in STEm. And depending on how you define stem, that's not actually necessarily the case. So if you include the health sciences, it's actually pretty even. At least among younger generations, it's pretty even.

How many men, how many women go into stem overall? Really, really close. But the difference that everybody notices and worries about is the fact that more men than women go to certain fields, fields like physics and engineering and mathematics. They got more going to philosophy as well. That's not stem.

But these are the ones that people worry about. Not so worried about the flip side of this. Not so worried about the fact that more women and men go into the health sciences and that kind of thing. And I do wonder if this is another example of the soft bigotry of male expectations, is that people. Is that people kind of assume that anything that tilts male 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 more women than men, men go into.

Either way, though, there's an interesting question about why those differences are there. 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 the main explanation that people like to give is that it's largely a product of discrimination and sexist socialization.

And so I just want to point out that I agree that that's part of it. That's part of the story. I would just say. I just don't think it's the whole story, though. I think that some of the differences that we talked about already, actually the difference in interest in people versus interest in objects plays into it as well.

And those differences, they appear very, very early on. They're found across cultures. In fact, it's a massively consistent sex difference. Actually, 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 David Gehry 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. Goddamn patriarchy going global everywhere. Yeah, exactly.

Except that in less patriarchal nations, some of those differences are larger rather than smaller, that you do get a gender equality paradox for the sex difference in objects versus interests in people, which is fascinating. And it just seems perfectly plausible to me that those sex differences and interests are part of what's shaping the sex difference, in which areas people go into which occupations, and actually I say I'd 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 difference in what's called occupational segregation. That's putting it too strongly, I think, that phrase. Because it's not segregation.

Chris Williamson
Segregation. What a great occupational apartheid. Except that, you know, the differences are much more modest than that. And there's no field where one sex is present and one sex is absent. There's just, you know, going away from a 50 50 sex ratio.

Steve Stewart-Williams
So there's. Even where women are least represented, there's a significant minority of individuals in those fields of women, and vice versa for men. What do you think was our typical ancestral setup for mating when it comes to the way that we got together, stayed together? I think that. Let's come back to the alien, right?

So the alien decides to look at our sexual behaviour. I think one thing I would notice immediately is that we're pretty varied in what we do. As long as they're not really, really strict norms. Say, you absolutely can't do x, y or z. We do a fair amount of x, y and z.

I think that the most common reproductive pattern, though, that we engage in is pair bonding. That's the most common. So we do some pair bonding that we have polygyny as well. It's not too uncommon across the cultures of the world that some guys will have more than one wife. And there's some casual sex as well.

In every culture on record, there's some casual sex as well. Pair bonding, though, does seem to be the most common setting for sex and reproduction, even in societies that anthropologists classify as being polygynous. To say that a society is polygynous basically just means that polygyny is acceptable. You're allowed to do it if you, you know, if everyone involved wants to actually, that maybe it's not necessary for. Everyone wants to do it, necessarily.

Sometimes there's coercion. So I'll take that back, but you are allowed to do it. But even in those societies, the majority of actual relationships are paired bonds. So that's our most common one. Yeah.

Chris Williamson
How. How do we get to a situation where people assume that are just freewheeling, sleeping around, 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. How do we get from what seems to me to be quite an obvious setup of it takes like between ten and 15 years to get an infant to maturity so that it can stand on its own 2ft and look after itself.

Therefore, you probably need people that stay together for at least a good portion of that. What's being missed? What's modern dating, sort of modern mating done to that innate understanding? Yeah. Yeah.

Steve Stewart-Williams
That is a good question. Yeah.

I don't know. So. I think so. People have argued for quite a long time that things like jealousy are just 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 kinds of people. There are some people who get jealousy and just could, you know, a pair bond suits them really well and they couldn't possibly contemplate or enjoy an open relationship or a polyamorous relationship. And I think there are some people who are kind of the reverse of that. A small number of people who just naturally are 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.

Chris Williamson
Or perhaps just insanely high sociosexuality, to the point where it kind of outweighs the potential sexual jealousy. Not that they don't feel it, but that they're overclocked on their desire for sexual variety, et cetera. Yeah, yeah, yeah, yeah. I think that's likely. Yeah.

Steve Stewart-Williams
So I think that. So some people can hack the system, so to speak. 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, they might work for something else. It's like a belief in determinism.

Chris Williamson
Not believing in it means that you don't need to believe in it. Okay, so how likely do you think it was that humans would have stayed together for life? And how likely do you think that were monogamish or serial monogamists? I think they both happened, but serial monogamy was more common. So I've seen data, for instance, in hunter gatherer societies, that most first marriages don't last for life.

Steve Stewart-Williams
So most people will have subsequent, they will split up and have subsequent marriages as well. But that a small number do. So I think maybe among. I think it was the.

I think it was the Kung San, maybe I shouldn't say, actually, because I'm not. It was the kongsang or the haza or something like that. I saw data on it and I think around 5% of marriages just lasted for life, so the majority don't. 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. You do get both, but just serial monogamy is more common.

Chris Williamson
I suppose the rarity, ancestrally, would have been a 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. Yep. Yep. And sometimes that's to the detriment of, like, there's a theory you've probably heard of, that there's a sort of built in tendency that you partner up with somebody and if there are no. 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 twenties first. And over time, due to know neither of your two faults, maybe you're on birth control, maybe you're just timing it right. I don't know, maybe, you know, cycle tracking, whatever.

But ancestrally, 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 reclaimed. And it's 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.

Steve Stewart-Williams
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, a 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 can be. Yeah, yeah, exactly. And they could both have kids with somebody else, but for some reason, it's just not the right match.

But in birds, yeah. The same thing. If they don't, if there's no offspring, little chicks coming along, you know, in the breeding season, they will split and try again. What do you make of the fact that if what you've said is correct, 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 unions that do end up in a way that may be more sort of ancestrally aligned.

In the sense of not lasting for life. Right. Yeah. That is an example of where culture is kind of pushing against our nature to some degree. And I think that, uh, I don't know, 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, 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 split up if they were forced, especially in the past, forced to stay together.

I think it caused a lot of needless misery and splitting up too easily, especially if you have kids, that can be a problem as well. But I think 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 Charles Darwin was born?

How many divorces did. No, I'm not sure. Four. Four, is that right? Four.

That's fascinating. Nationally. Yeah. Wow. That's how many?

Chris Williamson
That's not four per thousand. That's not four per county. Four. Four in total. All the UK.

Steve Stewart-Williams
Four, correct. Yes. Four in total. Yeah. So funny.

Chris Williamson
It's just. That's another Robert Wright ism from. Oh, interesting. Yeah. That's from the moral animal.

Yeah, the moral animal. Sorry. Oh, yeah. Okay. Yeah.

What can we do? What can we tell about our mating preferences from our testicle body size comparison.

Steve Stewart-Williams
Can you imagine how surprising that question would sound?

Someone who had. Exactly.

Yeah, it's a bizarre fact. But the relative size of males testicles is related to the mating system of a species. And so in 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 moss sperm. So on exactly the same principle, that the best way to win the lottery is to buy more lottery tickets.

If lots and lots of people are mating, lots, lots of chimps, rather, are mating with the same female, produce more sperm, you boost your chances of being the one that actually fertilizes the egg and size the offspring. So, yeah, so they've evolved huge testes relative to their body size. And in fact, their testes are almost as big as their brains. I've seen a photo of a chimp brain and chimp testes, and the testes are only available when you say that. You'Re being led around by your penis or by your genitals, not by your brain, it actually comes through.

Totally. And that's. And chimps are quite smart too, so they have pretty big brains. So terrifying testicles, absolutely terrifying. At the other end of the spectrum, among the primates, we have gorillas, for instance.

So gorillas, the massive, massive creatures, they're massive males, they have harm of females. And although the males mate with all the females, each of the females, while they're in that particular harem, each of the females only mates would one male, which is the harem master, the big guy. And therefore you don't have sperm. It's called sperm competition. When you have lots, when you have the sperm from multiple males in the females reproductive tract at the same time.

But you don't have that in gorillas because the males are the only ones that mate with the females. And so they have very, very small testes. So they're massive, muscular, huge, scary creatures with tiny, only tiny testicles.

Chris Williamson
Don't tell him, he's listening. He'll come and get you. All the way to Singapore, he'll come and get you.

Steve Stewart-Williams
And then the question that everyone wants to, and I'm sure everyone's thought of this already, okay, so 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 close to the gorillas, but 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 then, but we have walked somewhere down the path to that. And I don't know if it'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, their relative testis size is very close to ours. So 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 promiscuous mating, in other words, but not a huge amount. And again, I think that pair bonding is our most common format. What do you think about the mutual mate choice model? Are you familiar with this? I named it.

Chris Williamson
No way. Yeah. Yeah.

Steve Stewart-Williams
Me and Andrew Thomas did, actually. So we worked on a paper, Andrew. For the people who don't know, Andrew is a horrible, horrible welsh man that I love dearly. He's a great guy and he's a great researcher, and he's produced heaps and heaps of great work. He was my PhD student and while he was my PhD student.

Chris Williamson
So sorry to hear that from you.

Steve Stewart-Williams
We did this paper called the ape that thought it was a peacock, in which we argue for this idea that humans are sexually dimorphic, but that it's easy to exaggerate the extent to which we are dimorphic. And in that we coined the terms mutual mate choice model. MMC model. We called it an MCFC model. So males choose, females compete.

Other way around. Males compete, females choose. And the idea is these are two different ways that you can construe human sexual behavior. One way is the NTFC model. So males compete with each other for access to females, and females choose from among the competing males, and males do all the competing females do all of the choosing.

The mutual mate choice model, on the other hand, the MMC model, that's the idea that both sexes compete for desirable mates and that both sexes are choosy to some degree about their mates. And we argue that we fit more with the MMC than the. Than the MCSC model. 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, but females are choosier. So you do have the same sex difference, but it's just, it's muted. And likewise with competitiveness for mates and intersexual competition. Intersexual competition in both sexes, but it's ramped up in males compared to females, especially when it comes to risky and risky competitive tactics, integration and the like. That's much stronger males than females, but both sexes do it rather than just males competing and females just not competing at all.

Chris Williamson
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 big brains and our high intelligence and our cultural capacity, that led to all the culture that we had that was so confused, the alien. As that happened, it became more and more intensive to look after kids.

Steve Stewart-Williams
So for most apes, the females can do it alone, the females can look after the kids all by themselves 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 them is that when babies are born, they're completely dependent. They can't even grip onto anything like the young of most primate species. And that's because we're, in effect, born prematurely, because it's the only way to get a big brained baby out of the reproductive tract is to be born, in effect, prematurely.

And basically, if we appeared on the scene, if babies appeared on the scene in the same developmental stage as most primates, pregnancy would last about, I think it's close to two years, maybe. A horrifying prospect. Yeah. And then rip a person in half when it. Exactly, exactly, yeah.

And presumably that happened in the process of selecting. Oh, wow. Of course. Which is a really horrible thought. Yeah.

Chris Williamson
How many proto human females died during childbirth because their genetic mutation was like, ah, we'll test it, twelve months, who cares? Yeah. All for the sake of our intelligence and cultural capacity. So that's the first thing. So they're completely dependent at birth and then just takes a lot longer to get a human being to be nutritionally independent.

Is that the barometer? Nutritionally independent? Yeah. Yeah. So not being in the red in terms of nutrition, not being, you know, making at least as much as you're receiving, and that can take up to 18 to 20 years, even.

Steve Stewart-Williams
Even in a traditional non state society. So for both of those reasons, 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 alloy, maternal care. So in other words, care from individuals other than the mother. And that can come from different sources.

It often comes from the woman's mother. So maternal grandmother of the kid, siblings, especially sisters of the mother, various other sources, maternal uncles, et cetera. Very often, though, it comes from the father, so often fathers, key investors, 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 the mother is. So it makes sense that in many, many cultures, and we do find that 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 as we started forming these pair bonds, as we started having male investment as well as female investment, that reduced the sex difference in reproductive variants that we were talking about earlier. So the maximum offspring number for humans, other than a few exceptions who would have had heaps. 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 because I went on your Google scholar and had a big, deep, dark rummage around, you've done a good bit of stuff about men insulting intimate partners.

Chris Williamson
Why or when do men do that with their significant other that is going. Way back into the past? That's not research that I led. So I shouldn't say too much about that other than the gist. But the gist of the idea was that men sometimes use derogation of their partner, basically as a tool for, believe it or not, for keeping their partner.

Steve Stewart-Williams
So David Buss talks about this quite a bit, right? He talks about the ways in which men keep a partner. 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, men will forget about the carrot and go with the stick instead and use various ways, unpleasant ways, to try to keep a partner under the thumb. The rationale for all that research was that one of those ways is kind of insulting them. So if you could persuade somebody that they're not so great, then they're less likely to think, well, maybe I could do better than this guy. That's the main rationale. And it's not a recommendation, by the way.

I'm always nervous talking, talking about this stuff. Yeah. It's not a prescription. No. We have unreasonably reasonable audience.

Good, good. Moving from benefit, affording to cost, inflicting mating strategies. Everyone's seen that. And everyone's seen it on the reverse side as well. They've seen it with women, too.

Chris Williamson
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 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 bus talks about is that I can't remember the term for it. The isolation from male kin and support.

Steve Stewart-Williams
Yeah. I can't remember the name, but I know what you mean. Yeah. Yeah. Where basically, if a woman has fewer males that are not brothers, uncles, father, etcetera, around, then it's going to be harder for her to leave.

Chris Williamson
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 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 what they're doing, because I think people can learn about how their desires and defaults are highly preset and highly disposed in a variety of directions. And it can feel disempowering.

I once tweeted Jeffrey Miller asking how to deal with the discomfort of learning stuff from evolutionary psychology. So have you got any advice of how you've done that? Yep. I do agree that it can feel disempowering. I agree.

Steve Stewart-Williams
But I think actually that longer term that it can be empowering for a few reasons. So one is if you have a good understanding of where these impulses come from, they can stop seeing. They can stop seeming like your emotional reactions and your desires and that kind of thing can stop seeing direct perceptions of the nature of things.

It really, just objectively is very, very important for me to do this, and 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 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 I would otherwise. And I do think it works.

I do think it can deflate our feelings. One example that I think I read, and I think it was one of Steven Pinker's books, he was talking about how, you know, when people are feeling high status kind of people who strut around and that kind of thing, when you see that chickens do the same thing and the males puff up, it doesn't make you think, oh, cool, well, this is even more important than I thought. It deflates it. It makes you think, oh, this is just a silly animalistic tendency. So I think.

I think that's one way. I think that it can help. It can deflate things so you can more easily choose, look, what do I really want to do? Rather than just going with your gut instincts, then? 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. But I think that if people think that they can, they might think, okay, just this jealousy. I do feel this jealousy. I've got this partner who wants to have a polyamorous relationship. I don't like the idea, but that's just because of society.

I can cast it off just as easily as it was taught to me. And if they know that, quite possibly that's not the case, 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 can make a more informed decision. I think 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 perhaps not the relationship for me, and they can steer clear of it because they might realize that it's unrealistic that they can just reprogram themselves so easily.

Not to say there's anything wrong, like polyamory does work for some people, but having those kind of thinking tools 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 want to hold two competing thoughts in our mind 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 these two things are just going to continue to clash up against each other.

Chris Williamson
And 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 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.

Steve Stewart-Williams
Yep, yep. And that kind of thing, letting go and meditation, that's those other ways that we can hack our brains. 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, which is nice. I know one reason that people resist evolutionary psychology is that they dislike that they dislike the idea that they're just puppets of their genes.

And I do think, though, that, well, first of all, an evolutionary perspective doesn't say it's just genes, right? So it would say that your puppets are the genes and the environment, really? But that would be my other thought is that if being a puppet is the problem, rejecting an evolutionary perspective isn't a solution, right. It's just choosing an alternative puppeteer. Because the environment, if it's just the environment, well, then it's just the environment that's shaping our source code instead, which.

Chris Williamson
Is even more ruthless. I mean, you recently did a great post about behavioral genetics. Ploman's been on the show, and if you were to get to a world where 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 seems like even more fucking brutal. Exactly. Exactly.

Pick what it is that you want. Pick your poison. Right. Yeah, exactly. Yeah, sorry, go ahead.

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 get something more out? Or is there a realistic path to enlightenment here?

Steve Stewart-Williams
Nice easy question.

I mean, 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 seems especially upon 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 everything's going well, you think, God, how great that I love my mom and how fantastic that I rang her last week.

Chris Williamson
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'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, God and the meaning of life.

Steve Stewart-Williams
And in the meaning of life section of that book, I looked at the question of is there any ultimate meaning to life? 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 ultimate meaning to life, so no meaning to life imposed on us from outside of ourselves, from a God 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, 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 maybe do push us into the. Into a direction that we can quite easily feel cynical about. It's just distant 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 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 a fact of 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 to do other things that, and choose other values beyond what's been bequeathed to us by natural selection.

Chris Williamson
Yeah, you do get to be the architect in that way, I think. Again, as it comes down to with many things, it's holding conflicting ideas, or at least slightly sort of tensionary ideas in your mind at the same time. Before we finish up, I learned something. John Tooby passed away last year. I was very fortunate that I got to meet him.

Steve Stewart-Williams
Yeah, great guy, right? Phenomenal. I think David Bussay is one of only two people he's ever met in his entire life who justifies the title of genius. I agree. And also a really nice guy.

Chris Williamson
Phenomenal dude. Also, most importantly, subscriber of modern wisdom. That was the best thing. 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.

It's the crumbling genome theory of population dysgenics. Crumbling genome theory of population dysgenics, right. Yeah. So basically two B'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 healthcare 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 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 increased accumulation of all of this stuff. Now, here was the really spicy bit that someone put. 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 death, which is if you, as a human who has a genetic mutation, even like just normal person walking around all over the place, if you make it to reproductive age, and 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, etcetera, 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 generation? Interesting. So a lot there.

Steve Stewart-Williams
Spicy, like you say.

So I guess the first thing is that's all perfectly possible, right? So I do think that. 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 predispose them to myopia and couldn't really see so well, probably were less likely to put forth their genes that's been released for quite a long time. We have glasses and things now.

We have cultural ways of meaning 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 that would just be one example. There could be others along those lines. And then it's tricky to know, how do you deal with that?

But you couldn't say, okay, well, we're just going to ban glasses so that this doesn't have any people. People that have got myopia die at a higher rate. Exactly. So they just wander randomly into traffic and 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 possible people are looking at ways of, so to speak, 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 you have offspring you can choose to go. To go with, I don't know, like fertilized eggs and choose the ones that embryo selection for. Yeah, that's the phrase. Yep, exactly. Yeah, I think that.

Well, actually, I think it's embryo selection against negative traits, I think is the main one that people. Yeah, yeah, yeah. Now, the prophylactic idea I'm not so sure about, because that sort of seems like a good of the group explanation. So, like, it would be good for the species as a whole if we would have had that kind of doled down sexual desire or desire for kids. But what would that be?

What would be in it for the individuals with those designs? Yeah, why not just roll the dice? Anyway, 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 things like, well, actually, most mental illnesses, so depression, schizophrenia, the vast majority of mental illnesses are actually associated with lower number of offspring. So I think there is some filtration going on in some areas. Yeah, that's a really good.

Chris Williamson
That's a really good point. The fact that you don't have this God's eye view, population wide coordination thing. 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 you were a blip and they're going to be. They can fly like, your kids can fly like, who knows? Yeah. That's really, really interesting. Steve, I'm a huge fan of your work.

I'm a huge fan of your sub stack. Your book's fantastic. I'm excited for whatever the next thing is. Where should people go? They want to keep up to date with everything that you do.

Steve Stewart-Williams
Well, my substack is my favorite thing at the moment. I really love substack. It's taken over from twitter in terms of my favorite social media outlet. It's called the nature nurture nature newsletter, and it's stevestuartwilliams.com. I am still on twitter as.

Sorry, go ahead. Go ahead. Nothing. Just. I wanted to know where nietzsche came in.

Chris Williamson
I haven't seen you write about nietzsche yet. Yeah, I'm not sure it's the greatest name for the sub stack, because I love the clever play on words, and I love philosophy, and that's what it is. I love nature nurture issues, and I love philosophy. And it's kind of. Nietzsche stands in for philosophy as a whole.

Steve Stewart-Williams
I do quite like nietzsche's writing style. I'm not a huge. I'm not actually a huge fan of nietzsche, so maybe it's not the perfect title. People probably think I'm a nietzsche nut, but I'm a philosophy nut instead. And I'm on Twitter as well.

It's Eve stew. Well, so. Stevestuwi, double L. Hell, yeah, Steve. I mean, you're fantastic.

Chris Williamson
I can't wait to see what you do next. Awesome. Thank you very much. Man, it's been. This has been a lot of fun.

Steve Stewart-Williams
I've really enjoyed this conversation.