The Uncomfortable Science Of Sex Differences - Steve Stewart-Williams

English

CChris Williamson

Mental HealthAdult EducationParenting

Transcript

00:00:00Do you think that you could have published this book six years ago?

00:00:03I think that I could have, but it would have been a less wise move.

00:00:06I think it would have gone down a lot worse six years ago.

00:00:10Things have kind of cooled off a little bit, I think.

00:00:13Why is talking about sex differences so controversial?

00:00:16Well, it's a good question, and I think that it's a few things.

00:00:19I mean, sometimes it surprises me, because sometimes I think a lot of the differences

00:00:23that we're talking about, they're really quite modest differences.

00:00:26They are often differences in preferences rather than cognitive abilities, so they're

00:00:31kind of neutral as far as I'm concerned.

00:00:33And if anything, I think probably they put men in a worse light than women.

00:00:37So sometimes it surprises me, but I think really the main reason is a long history of sexism

00:00:44against women.

00:00:45And I think that we've got quite a long, science as well has a bit of a sordid history in terms

00:00:51of how we've spoken about women, especially in the 1800s.

00:00:54I've got a quote, one of my favorite quotes, one of my favorite examples of this is from

00:00:58a scientist by the name of Gustave Le Bon, and he wrote that, sure, there are some women

00:01:05who are as intellectually accomplished as your typical man, but they're about as rare as

00:01:10a two-headed gorilla, and so therefore we don't really need to think about them.

00:01:15So with stuff like that in our background, it's, I guess, not surprising that people are a little

00:01:20bit nervous about talking about evolved sex differences, a little bit worried that if we

00:01:24start doing that, it's going to open the door to that kind of sexism.

00:01:28I think they're wrong to worry about that.

00:01:30I think that really the science of sex differences has disproved those kinds of ideas.

00:01:36And I think as well that we can treat men and women respectfully and humanely and treat them

00:01:44well, even if men and women are not identical on average, on every single train.

00:01:48Yeah, I suppose the history of science is to sex differences, what the Nazi party is to

00:01:56behavioral genetics.

00:01:57Right, right, exactly.

00:01:58Yeah, yeah.

00:01:59And I do think that science is the solution to the early sexism rather than a continuation

00:02:05of it.

00:02:05Yeah, that's a great way to put it.

00:02:07All right.

00:02:07Why is it important to study sex differences then?

00:02:10Why should anybody care?

00:02:11I think lots of reasons.

00:02:12The main reason for me is I think it's just deeply, deeply fascinating.

00:02:17It's the best.

00:02:18Yeah, it's the best.

00:02:19Me and you fell in love with the same book, The Moral Animal by Robert Wright.

00:02:22It changed my life.

00:02:23Yeah, likewise.

00:02:24It changed my life.

00:02:25It shaped the rest of my career.

00:02:27Just I think it's deeply fascinating.

00:02:30And yeah, I remember when I read that book, that's when I fell in love with evolutionary psychology

00:02:38and in particular fell in love with the evolutionary psychology of sex differences.

00:02:42And I got the same feeling that I did when I was a kid and I first understood how the phases

00:02:46of the moon work and everything just clicked into place.

00:02:49Suddenly the whole thing made sense.

00:02:50Oh, that is why it looks that way.

00:02:53Exactly.

00:02:53That is why people are different in that way.

00:02:56Exactly.

00:02:56Exactly.

00:02:56It all made sense.

00:02:57It was clear that it was true.

00:02:59And yeah, just sort of instant insight.

00:03:03And yeah.

00:03:04It's interesting, even as you're saying it, I can hear this sort of critic preparedness

00:03:10inside of my mind going, why would you, when you read a book, why would both of us, when

00:03:16we read a book, be so enamored by sex differences, dot, dot, dot.

00:03:19That must be because you are secretly a sexist who is looking to try and keep people in their

00:03:25place and not ever have any program.

00:03:27You know what I mean?

00:03:28Like the conversation around this has become so tarnished.

00:03:33And accusatory.

00:03:34Yes.

00:03:34Yes.

00:03:35Yeah.

00:03:35Yeah.

00:03:35You can't have an interest in something which is fundamental and fascinating and really important,

00:03:41right?

00:03:41So that you don't try and, people aren't trying to fight against something so that we

00:03:46don't fully account for and understand why behavior unfolds in particular ways that can allow

00:03:51us to have a better society, a society that's got outcomes that's more close to what we want.

00:03:56Yeah.

00:03:57Fascinating.

00:03:57Yeah, it is.

00:03:59Yeah.

00:04:00So I do, I agree with that.

00:04:02And I think, yeah, sorry, I just, I just meant blank.

00:04:08What was I going to say about that?

00:04:09Not at all.

00:04:09Just why is it important to study sex?

00:04:11Well, it wasn't important.

00:04:12Yeah.

00:04:12So that is, that points to another reason.

00:04:13So one big reason why it's important is just the fact that it's fascinating.

00:04:17Um, but I think also that, like you say, it is important in terms of staring society

00:04:21in, in positive directions and, uh, understand, understanding ourselves, uh, understanding

00:04:26interactions between men and women, um, in terms of, yeah, trying to keep people in their

00:04:31place and the like, that's certainly not the philosophy that I come away with, um, from

00:04:35having studied all this over the years.

00:04:38Um, I, instead of my basic philosophy, I think I can summarize.

00:04:41I can summarize in just four words.

00:04:43And those words would be let people be themselves.

00:04:46Uh, so if they, if they fit with traditional, uh, gender roles and expectations, that's great.

00:04:53Uh, but if they don't, that's great as well.

00:04:55It doesn't matter.

00:04:56The fact that something has evolutionary origin doesn't necessarily mean that it's good.

00:04:59Uh, it doesn't necessarily mean that it's bad either.

00:05:02I think that it's, it's morally neutral and that it's up to us to decide whether it's good

00:05:06or bad or somewhere in between.

00:05:08I think that's a big fear that people have that by looking at the evolutionary explanation

00:05:13for why certain traits show up the way that they do, why certain differences occur the

00:05:17way that they do.

00:05:18It sounds like you're excusing away that behavior.

00:05:20Indeed.

00:05:22Like a lot of people do worry that that's the case and that people will assume that it's

00:05:26the case.

00:05:26Naturalistic fallacy in your way through all of the bad behavior of men or all of the worst

00:05:31behavior of women or the most repressive ideas that we have for how people should behave.

00:05:35Yeah.

00:05:36Yeah.

00:05:36And I don't think that it does justify any particular behavior.

00:05:39Um, but I do think it's right to worry that people might assume that it does falsely assume

00:05:44that it does.

00:05:45So I do think when we discuss these issues, uh, that we should take into account the concerns

00:05:50that people have about this whole topic of sex differences, and we should discuss them

00:05:54carefully and we should always emphasize that most of the gaps are not huge.

00:05:57Most of the psychological sex differences are not huge.

00:06:00Um, that there's a huge amount of variation within both sexes, tons of overlap between the

00:06:04sexes, and also that there's no, um, normative implications of these generalizations.

00:06:10So no, um, sense of, uh, because something is evolved, because something is natural, that

00:06:16that therefore means that it's good or even permissible.

00:06:19Again, it's up to us to decide that.

00:06:22Right to say that the, the differences are modest at best, but when you start to stack them

00:06:27on top of each other, you end up with huge, you basically end up with two completely separate

00:06:31Venn diagrams, right?

00:06:32It's not just, um, uh, preference for violence and risk-taking and parental investment and

00:06:38dah, dah, dah, dah.

00:06:39It's when you put all of them together, you do have two very different groups of people.

00:06:43Yeah.

00:06:44Those are called multivariate sex differences.

00:06:46Yeah.

00:06:46When you sort of cluster, uh, the differences together.

00:06:48Um, I think that while that's statistically true, I think we need to be a little bit worried

00:06:54about the concept of multivariate statistic, uh, multivariate, um, sex differences, just

00:06:59because often we are thinking about single traits.

00:07:04So often we're thinking about sex differences in parenting, sex differences in sexual interests

00:07:08and aggression, risk-taking, uh, and, and so on.

00:07:11Um, but also if you were to divide up, take, take a group of people, divide them into two

00:07:19based on a flip of a coin, um, they're not going to be identical on every trait.

00:07:23There's going to be small differences between them, but then if you add up all those traits,

00:07:26you could just as well stack up the differences between these two randomly chosen groups of

00:07:30people, stack up the differences and you'd find that they equally, uh, massively discrepant

00:07:35from each other based on the multivariate statistical approach.

00:07:38Hmm.

00:07:38So, um, so I think that you need to be worried about exaggerating the magnitude of human sex

00:07:44differences based on that statistical approach.

00:07:46Yeah.

00:07:46So you could just as well exaggerate the sex differences between New Zealanders, New Zealanders

00:07:49and Australians or the British and the French, or, or like I say, two randomly British and

00:07:54the French do that enough already.

00:07:55All right.

00:07:55There's been a last few years, there's been a huge debate about what sex actually is.

00:07:59Yeah.

00:08:00What's the definition that you land on?

00:08:02Uh, well, there are a few definitions.

00:08:04The one that I land on is the traditional scientific definition, uh, via which sex is defined

00:08:10in terms of gamete size.

00:08:12So in the vast majority of sexually reproducing species, uh, you have two different gamete

00:08:19sizes and the small gametes are called sperm, the larger gametes are called eggs.

00:08:23Is that across the board?

00:08:24That is across the board.

00:08:25No way.

00:08:26Yeah.

00:08:26Okay.

00:08:27So every, every, almost every sexually reproducing male.

00:08:32Yes.

00:08:33Produces sperm.

00:08:34Yes.

00:08:34And sexually reproducing female produces eggs.

00:08:36Right.

00:08:37And I know this might, this might be like the most facepalm thing.

00:08:39I'm like, wow, I didn't know that that was, those are the only two currencies at play.

00:08:43Um, I mean, it seems like, so, so in biology, it's not like math, right?

00:08:46So in biology, there are very rarely, uh, generalizations that apply to every single species.

00:08:52Um, this is one of them, but the reason is that it's a definitional, it's a definitional

00:08:56truth.

00:08:56So we define males as the ones that produce the smaller gametes.

00:08:59Um, the.

00:09:02Empirical truth that in principle could have gone another way is the fact that in the vast

00:09:07majority of species you have where the gametes are not identical.

00:09:11You only have two different types and one is bigger and one is smaller, and that's true

00:09:16right across, uh, you know, all species except the minority where you, uh, you have, so that's

00:09:21called anisogamy where you have two different sizes and you have a few isogamous sexually

00:09:25reproducing species, but the vast majority anisogamous.

00:09:28Can you, what, what's an isogamous sexually reproducing species?

00:09:33What are some examples of them?

00:09:34Uh, there are some very, uh, I think no animals and no plants, but I think maybe some simple

00:09:40bacteria and things like that.

00:09:42And I think that w that would have been the starting position.

00:09:44So we all evolved from species that originally were isogamous.

00:09:47That's the first of all, sexual reproduction would have evolved.

00:09:50Then I saw, and they would have been isogamous.

00:09:52They would have produced the same gametes and mixed them, but then that's evolutionarily

00:09:56unstable and that tends to, um, fall apart into a smaller and larger gametes.

00:10:02Why is it unstable?

00:10:03Uh, because when you, when you have same size gametes, uh, this selection for any trait

00:10:10that will increase the chances of being one of the gamete or producing gametes that are

00:10:13going to, uh, produce offspring that survive.

00:10:16So that creates a selection pressure for maybe loading up your gametes with some extra,

00:10:20uh, supplies to help them survive.

00:10:22Um, so, so some gametes, uh, get a little bit bigger because of that, but as soon as they

00:10:27get big enough, the larger gametes, you have a selection for smaller gametes that,

00:10:32seek out the larger gametes and kind of ride on their coattails.

00:10:36And, uh, so, and you get this, it pushes them apart.

00:10:40And it's actually, uh, from a sexual survival or a gamete survival perspective.

00:10:46Yep.

00:10:47It's the gray area in the middle of the barbell is where you go to die.

00:10:51And the black and the white on either end are actually the ones that are most effective.

00:10:54Exactly right.

00:10:55Cause the ones in the middle, they're not big enough.

00:10:57They don't survive as well as the bigger ones that pack a picnic for their offspring.

00:11:00Um, but they're also motility, mobility by the, the smaller ones.

00:11:06Exactly.

00:11:06And, and just numbers, you know, so like if you are producing small gametes, you could

00:11:09produce many more.

00:11:10So individuals that produce the medium-sized gametes, they don't survive as well.

00:11:14Plus they don't produce as many.

00:11:15I can't remember what the stat is.

00:11:16There's some stat around.

00:11:17Jerry, can you look at Chachipi tea?

00:11:19Um, how many sperm are produced per day?

00:11:23Human sperm versus human eggs.

00:11:24It's a, it's such a hilariously big difference.

00:11:27Yeah.

00:11:28Um, okay.

00:11:29So broadly across the animal kingdom in almost every single sexually reproducing species,

00:11:36there's a binary.

00:11:38Yeah.

00:11:38There's a sex binary.

00:11:40There's a sex binary.

00:11:40Yeah.

00:11:41There's also a ton of variation in terms of the phenotypic characteristics.

00:11:45Within each of those sexes, but yeah, there is, there is a sex binary, you know, and you

00:11:49do get, um, intersex individuals.

00:11:51Yeah.

00:11:52What about the challenges to this?

00:11:53We have a hermaphrodites within sex variation, intersex conditions.

00:11:59Does that disprove this?

00:12:00Uh, it doesn't.

00:12:01Um, so I guess the easiest one is the within sex variation.

00:12:05There is tons of it.

00:12:06So the variation in terms of levels of masculinity, levels of femininity, um, just, uh, size dimorphism

00:12:13versus size monomorphism, where they're at the same size.

00:12:16Um, but nonetheless, they are all either producing sperm or eggs.

00:12:21Yep.

00:12:22The vast majority within each, within each group.

00:12:24You've seen that, uh, image, right?

00:12:26Of the bell curve graph.

00:12:27And you say, on average, something, something.

00:12:31Yeah.

00:12:31And then somebody says, well, I know a person who is actually more that than the other group.

00:12:36I know a woman who's six feet seven and, and, and she's actually taller than most men.

00:12:41Most men on average are taller than women.

00:12:43Well, my friend's six foot two.

00:12:44Yeah.

00:12:44And you go, right.

00:12:45Okay.

00:12:45But that doesn't necessarily disprove the way.

00:12:49The generalization.

00:12:50Exactly.

00:12:50The general, the fact that the generalization is there.

00:12:52And even more so the fact that the gamete size is definitional.

00:12:57As you say, oh, here we go.

00:12:58I don't even know what that number is.

00:12:59Is that sperm?

00:13:01Is that a billion sperm?

00:13:03A hundred to 300 million sperm per day produced by healthy adults.

00:13:06Oh, no, no, no, no, no, no.

00:13:07I want this globally.

00:13:08Total global sperm production, 200 quadrillion eggs released, 70 million.

00:13:13Step it up, ladies.

00:13:15So, so I think fucking lagging behind.

00:13:18We need to up the egg production.

00:13:20That's what I say.

00:13:21So much of the debate falls around nature versus nurture.

00:13:24Yeah.

00:13:25So much of it.

00:13:26How do you even begin to start to separate this out, right?

00:13:30No, almost no women have grown up in a society that hasn't had other women with the expectations

00:13:37of women and almost no men have grown up in society that doesn't have the expectations

00:13:41of men.

00:13:41How do we know that all of the sex differences aren't just socialization?

00:13:45It's a good question.

00:13:47And I think the first thing I want to say about that is that evolutionary psychologists don't

00:13:51deny that socialization has a very important impact on the nature of sex differences.

00:13:56in any given culture.

00:13:58We know that it does have a big impact because we know that sex differences, their size and

00:14:02the exact details of them, many of them, vary across cultures and vary across times.

00:14:08But in terms of how we know that it's not just socialization, there are various lines of evidence

00:14:12that point in that direction.

00:14:14None of them are perfect.

00:14:15None of them by themselves seal the deal.

00:14:17But the reason I'm persuaded is that they all point in, when you get a sex difference and

00:14:23they all point in the same direction.

00:14:25That just makes a very strong case, I think, that it's not just due to socialization.

00:14:29And in the book, I lay out six different lines of evidence for an innate contribution to any

00:14:34given difference.

00:14:35Let's see if I can remember the name.

00:14:37So the first one is that a lot of sex differences, they appear very, very early in the lifespan.

00:14:46So early, in fact, that even though it's conceivable that it could be a result of socialization,

00:14:50it just seems less plausible than that there's actually also an innate push.

00:14:53So the aggression sex difference and the risk-taking sex difference, both of those appear basically

00:14:59as soon as kids are mature enough that they can move around the place and are capable of

00:15:03risk-taking, capable of aggressing.

00:15:05You get that sex difference immediately.

00:15:09And a good example of that is that right from the get-go, right from early toddlerhood, more

00:15:15boys than girls end up in the ER from doing more risk-taking.

00:15:20And also, if it appears at puberty as well, like a lot of sex differences, innate, well,

00:15:26sex differences with an innate basis, they…

00:15:28What do you mean when you say innate?

00:15:30Unlearned.

00:15:31Right.

00:15:32Unlearned, yeah.

00:15:32Right, right.

00:15:33So there's an innate contribution, an unlearned contribution.

00:15:35And where that's the case, often you find that the sex difference, you may get it to some

00:15:40degree early in the lifespan, but then post-puberty, it just skyrockets and expands.

00:15:45Right, okay.

00:15:46Which would suggest that there is a biological basis, or else, why would this big change occur

00:15:51when puberty happens?

00:15:53Exactly.

00:15:53And do so right across cultures.

00:15:56Would the suggestion from social roles, socialization theorists be that while during puberty, culture

00:16:04ramps up its pressure on people, there's a greater expectation on young men and women to change

00:16:11their behavior?

00:16:12That would be the way that you would have to, you'd have to try to explain it, something

00:16:16like that, yeah.

00:16:17I think in the case of aggression.

00:16:19They're more absorbent, they're more…

00:16:20Yeah, more plastic at that age, perhaps.

00:16:22Yeah, yeah.

00:16:23Yeah, you could do that as well.

00:16:24I mean, that's sort of implying an innate contribution to the plasticity, I guess, but

00:16:30yeah, not for the specific sex difference.

00:16:32The reason I don't buy that, though, is that most cultures actually try to suppress male

00:16:37aggression, for instance.

00:16:38In every culture, male aggression, post-puberty, young male aggression, violence, risk-taking,

00:16:45homicide, is a big problem that the society has to deal with.

00:16:49And so usually they're trying to clamp down on it rather than trying to encourage it.

00:16:54And nonetheless, you get this increase in aggression.

00:16:58That's true.

00:16:58And actually, this is the second line of evidence, is that often these sex differences appear despite

00:17:02culture rather than just because of culture.

00:17:05Culture's trying to push down aggression right from early on.

00:17:08Parents, teachers early on, they actually tell off boys for aggression more than they tell

00:17:14off girls for aggression.

00:17:15Not because they disapprove of girls' aggression, but just simply because boys are more aggressive.

00:17:21They have more cause to do it.

00:17:24I think fMRIs of developing fetuses in the womb can detect sex differences at three months.

00:17:33They can, I think, even younger in some cases as well.

00:17:36What, are these boys and girls, these tiny minus six-month-year-olds, are they learning

00:17:44that their brains are supposed to develop differently?

00:17:47Yeah, they've been socialized to develop different brain structures.

00:17:49Inside of the womb.

00:17:50Yeah, it's not plausible.

00:17:52Okay, so early development.

00:17:53Early development, appearing despite culture rather than because of culture.

00:17:57Yep.

00:17:58Another one is that they persist often for a long time.

00:18:04So, for instance, sex differences and mate preferences were really consistent right throughout

00:18:08the entirety of the 20th century in the US.

00:18:12Sex differences and career preferences as well, or career-related interests.

00:18:16They were evident from the early 1900s when people first started measuring them, and then they

00:18:23just stayed the same.

00:18:23So, the average difference, the fact that men, for instance, on average, more interested in things and things-related jobs, whereas women, on average, are more interested in people and people-related jobs.

00:18:33That was the case right throughout the 20th century, despite the fact that there was quite a strong social, there was a lot of social pressure to try to get more women into traditionally male roles, and it persisted nonetheless.

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00:19:51So what are the sociocultural explanations that hold water?

00:19:55Well, I think a lot of them do.

00:19:58You know, it's tricky.

00:20:00So I guess we know because of cross-cultural differences in male-typical behavior, female-typical behavior, and the size of the differences, that something is making the difference.

00:20:10But it is actually quite tricky to figure out what it is that's making the difference.

00:20:17Because we know, for instance, that, okay, so like a popular explanation is that it's how parents treat their kids.

00:20:22And that seems incredibly plausible that it's going to have an effect.

00:20:26There are a few reasons to think maybe that it has less effect than we might think.

00:20:29So one is that a lot of research in the West finds that parents don't particularly treat their sons and daughters differently in some important ways, but they're equally likely to encourage them to be successful, equally likely to encourage them to be independent.

00:20:46And another line of evidence against parents having a big role is what's called the second law of behavioral genetics.

00:20:54And that's the finding that when two people, okay, so take identical twins, two identical twins that grow up in the same home, you'd expect them to be more similar to each other than two identical twins who are separated at birth and reared apart.

00:21:07And in childhood, they often are quite a bit more similar than you would expect by chance.

00:21:13Um, by adulthood though, they're often not much more similar at all.

00:21:16And in some cases, no more similar than they would be, um, if they had grown up apart, which is a surprising finding, but a very consistent finding.

00:21:25And it suggests maybe that, uh, parental treatment affects individuals less than we might think that they would, which kind of pulls out the rug a little bit from the idea that parents are having a huge impact on sex differences specifically.

00:21:37What about the gender equality paradox?

00:21:40Uh, well, that, uh, undermines another kind of, uh, sociocultural explanation, which is the idea that, um, the sex differences that we see are products of the social roles of a culture and shaped by.

00:21:53Just social roles theory.

00:21:54Yeah, social roles theory.

00:21:55Right.

00:21:55Exactly.

00:21:56Um, and, and patriarchy theory, the idea that it's due to patriarchy, um, uh, that as well as undermined by the gender equality paradox.

00:22:05Um, cause both of those theories would predict that in like, like more patriarchal societies, societies that are more patriarchal, uh, societies that have stricter gender roles.

00:22:15Yeah.

00:22:15You'd expect that and predict that the sex differences would be bigger in those societies, uh, than they are in less patriarchal societies.

00:22:23And ones that have less strict social roles.

00:22:25What would be some examples of how that would play out if that was true?

00:22:29Uh, basically any sex difference you care to name, uh, aggression, sex difference, sex differences in masculinity versus femininity, all of those should be bigger.

00:22:37Sex differences in career related preferences, they should be bigger as well.

00:22:41And the gender equality paradox is the deeply counterintuitive finding and incredibly fascinating finding that often it goes the other way.

00:22:48It seems to go the other way that actually in more gender equal societies, societies that are less strict in terms of the gender roles, uh, and societies that are less patriarchal.

00:22:57You actually find larger sex differences often rather than smaller ones, uh, which is in the direction that you would predict as well.

00:23:05Uh, yeah.

00:23:06So, so opposite to the direction you predict if social role theory, right?

00:23:09Yes.

00:23:10Yes.

00:23:10Yes.

00:23:10But in the direction you would predict if you were taking an evolutionary perspective, I would imagine.

00:23:13Um, well, actually, you know, taking an evolutionary perspective, I, I didn't originally predict that.

00:23:18I, I thought that in more patriarchal societies, even given that there's an innate push towards certain sex differences, I still thought that patriarchy and stricter sex roles would pry the sexes apart even more.

00:23:29Right.

00:23:30So I was actually very surprised that it doesn't, and that it does the reverse is the real surprise.

00:23:35What are the rebuttals to socio, that sociocultural explainers have for the gender equality paradox?

00:23:43Uh, there are a few.

00:23:44One is that, um, people in more patriarchal societies, they tend to, the men and women have little to do with each other.

00:23:51And so they don't, they have a more sort of exaggerated picture of, uh, the other sex.

00:23:56And so when they fill out personality inventories, for instance, they, they're comparing themselves with, well, other men, if they're men or other women, if they're women, and they therefore see themselves as being more similar to the average for their comparison group.

00:24:11Right.

00:24:11Okay.

00:24:11Because they're just in, they're so siloed off in these patriarchal societies that they don't know what the fuck the other side's doing.

00:24:19Exactly.

00:24:19That's hilarious.

00:24:21It is, it is.

00:24:22You're just in a bunker so much that you don't know what's going on.

00:24:26It makes sense, it does, it does, but, um, there's also a plausible rebuttal to that rebuttal, uh, which is that, um, I love it.

00:24:34It's so good.

00:24:35This is my shit.

00:24:36This is my shit.

00:24:38So it doesn't just apply to self-report things like personality.

00:24:41You also find that for, uh, some cognitive abilities, I think spatial ability, for instance, you find it.

00:24:47Yep.

00:24:48Um, you find that as well for physical traits, like height.

00:24:53Are you saying that in more gender equal societies, boys get even better, better at throwing?

00:24:58Um, I don't know if that is actually the case, but that, that would be an example.

00:25:01Would be one of the examples.

00:25:02If there's research on that, I'm not sure if there is actually cross-cultural research on throwing.

00:25:04Throwing's my favorite one, dude.

00:25:05It's huge, huge difference.

00:25:07It's one of my absolute favorites.

00:25:08Did you ever look at that study where, um, so the, the, the difference in throwing, uh, uh, velocity, accuracy is a pretty big sex difference, but one of the, um, appropriate pushbacks was, well, uh, men's shoulders articulate differently, uh, the length of the forearm means that you've got more leverage, et cetera, et cetera.

00:25:28I think the, the sex difference at eight years old in throwing velocity and accuracy is basically the same as adult men and women being able to detect adult women and men just by their face.

00:25:40Right.

00:25:40It's a 90%.

00:25:42Yeah.

00:25:42It's a huge, huge, huge difference.

00:25:43So there was this, my favorite study on this was, uh, in order to negate the articulation argument, the issues of sort of biomechanics, uh, they got a tennis ball serving machine and fired tennis balls at students.

00:25:58Yep.

00:25:59And got the boys and the girls to see if they could get out of the way.

00:26:02And I don't think any of the males were hit.

00:26:05And I think that this is before you wouldn't have been able to get this past an ethics board.

00:26:09Um, but yeah, just the sort of spatial, uh, awareness, that spatial rotation stuff is, um, the sex differences is, is, is pretty large.

00:26:18And apparently maybe, maybe in a more gender equal society, even more would be women would be hit by the tennis balls.

00:26:23Well, that's possible.

00:26:23Yeah.

00:26:24Um, so the gender equality paradox, it doesn't apply to every trade.

00:26:26So it might not necessarily be bad, but, um, yeah, but, but you are right.

00:26:30I think that was probably a seventies, I think it was a seventies study.

00:26:32Yeah.

00:26:32I'm not sure you could do that.

00:26:33Yeah.

00:26:34In fact, you couldn't do that.

00:26:35You couldn't aim projectiles at, uh, participants in studies anymore, sadly.

00:26:39What's the largest sex difference between men and women?

00:26:43Um, well, the largest ones are physical differences, physical sex differences.

00:26:47So, um, the very largest, uh, sex differences and reproductive anatomy were basically all males have penises or females have vaginas and so on.

00:26:56Um, but other physical sex differences, um, are also very, very large.

00:27:01So the sex difference in upper body strength is, is huge and there's very little overlap, close to no overlap, uh, for that one.

00:27:10Um, the sex difference in voice pitch is another very, very large one as well.

00:27:14That's huge.

00:27:15Uh, which is quite interesting because, uh, the voice pitch sex difference in other apes.

00:27:21Isn't, is not as big, it's nowhere near as big and that's even the case for, um, for other species that are much more dimorphic than us in terms of size, like gorillas and orangutans.

00:27:31So that's a bit of a puzzle.

00:27:31I'm not quite sure why that is, why that's the case.

00:27:34Uh, when it comes to psychological sex differences, the vast majority of them are much more modest.

00:27:40Um, but there's one that stands out as being, as being almost as big as some of these physical ones.

00:27:46And I always ask people if they can guess what it is.

00:27:48I think last time I was on your show, actually, I asked you if you could guess and, and you didn't, but it'd be no one does.

00:27:53I've read the book now.

00:27:54You've read the book now, so you got a head start on that.

00:27:58Can you guess what it would be, Jared, the, the single biggest psych, psychological sex difference between men and women.

00:28:04Hmm.

00:28:05Is it aggression?

00:28:06Um, it's not aggression.

00:28:08I'll give you a clue.

00:28:09And that's that it is, it's related to reproduction pretty closely.

00:28:14What was that?

00:28:15Well, actually that is a big sex difference.

00:28:18Not as big as this one, you speak for yourself.

00:28:22It's the sex difference in which sex each sex is primarily attracted to.

00:28:27So men, most, the vast majority of men are primarily attracted to women.

00:28:31The vast majority of women primarily attracted to men.

00:28:34And when I say it, it's obvious, right?

00:28:36It's obvious that it's a big sex difference.

00:28:38And, um, but, but it's curious.

00:28:40People don't think of it.

00:28:42Even, um, scientists often don't think about it.

00:28:44I've read a bunch of papers that summarize evolved sex differences and they don't tend to mention that one.

00:28:49They often neglect to mention that, that very, very large one, but also that, uh, one that has quite a clear evolutionary rationale.

00:28:56Yeah.

00:28:56Yeah.

00:28:56Very interesting.

00:28:57Because if that wasn't the case, we wouldn't be here.

00:28:59Exactly.

00:29:00Literally.

00:29:01We literally wouldn't be here.

00:29:02Yeah.

00:29:02Uh, okay.

00:29:02So what are the biggest sex differences?

00:29:04Let's get down to some brass fucking tacks.

00:29:06What are the biggest sex differences when it comes to sex?

00:29:09When it comes to sex?

00:29:10Yes.

00:29:10Um, one of the largest ones is the sex difference and interest in casual sex and sexual variety.

00:29:17And, uh, so basically social, sociosexuality, the trait of sociosexuality, no strings attached to sex.

00:29:23Um, uh, do I need to mention which direction it is?

00:29:26Uh, people might be aware of it, right?

00:29:28Yeah, yeah, someone can intuit it, I guess.

00:29:30Yeah.

00:29:31So, so men on average, uh, score higher, uh, however you measure that trait, they score higher

00:29:36than women on that trait.

00:29:37Um, the differences there, maybe though, are not, not as huge as people sometimes assume.

00:29:43Um, we're looking usually at an effect size of, uh, you know, about Cohen's D equals one.

00:29:50So what, what that means is there's about one standard deviation between the average for

00:29:54men and the average for women.

00:29:56Uh, so, so yeah, between 0.8 and one.

00:29:59Um, and that is pretty big.

00:30:00That, that is big for human sex difference, but there is still quite a bit of overlap.

00:30:05So there are plenty of, uh, women who have a higher socio-sexuality than plenty of men.

00:30:10Uh, I guess an intuitive way to put it, a way to make it intuitive would be to say, if you

00:30:15imagine plucking two people at random, one man and one woman, with an effect size of 0.8,

00:30:210.1, probably two thirds to 70% of the time, the man will score higher than the woman on that

00:30:27trait.

00:30:28Um, so that is a majority, it's not an overwhelming majority though, in a significant minority

00:30:33of cases, you'd find that actually the woman scores higher than the man.

00:30:37Yeah.

00:30:38Why?

00:30:39Why is that sex difference?

00:30:40Uh, that is getting right into this, the central question of why there are any, any sex differences

00:30:45at all.

00:30:46We probably need to talk about like the evolution of sex differences, why they, why they exist

00:30:49in the first place.

00:30:50Yeah.

00:30:51Um, so we should jump to that.

00:30:52Uh, can I, just as an aside though, can I, we, we mentioned three of the six lines of evidence

00:30:58for innateness.

00:30:59Do we want to jump back and do the other three and then maybe get into the, sort of thing?

00:31:03Um, so what do we, what do we do?

00:31:07Do we had the developmental sex differences?

00:31:09We had the resistance, uh, cultural pressure.

00:31:12We had the, um, persistence across time.

00:31:16So another one is a hormonal correlates of sex differences.

00:31:21And in particular, um, you find associations between prenatal hormonal exposure and traits

00:31:28found later in life.

00:31:29Uh, so high levels of testosterone in the womb, for instance, are associated with high levels

00:31:34of aggression later, high levels of risk taking, lower levels of parental inclinations,

00:31:39um, and so on, so on.

00:31:42And that's regardless of sex.

00:31:43That is regardless of sex.

00:31:44Yeah, so you can look at within sex differences as well.

00:31:47Mm-hmm.

00:31:48And, uh, yeah, so one actually very strong line of evidence for that claim is the fact that,

00:31:52uh, women who, who, when they're in the womb are exposed to very, very high levels of prenatal,

00:31:59uh, testosterone, uh, due to having a condition called congenital adrenal hyperplasia or CAH.

00:32:05Uh, they, as girls and then as women, they, they exhibit a lot of, uh, male typical traits.

00:32:13Uh, for instance.

00:32:14Less interested in playing with dolls.

00:32:16Exactly.

00:32:17Yeah.

00:32:18Less interested in, uh, getting married and having kids, uh, more interest in things related

00:32:23professions as well.

00:32:24Mm-hmm.

00:32:25So that's pretty interesting.

00:32:26Does it make them more likely to be bisexual or lesbian?

00:32:27Yeah, yeah, it does.

00:32:28It makes them more likely to be interested in, in other women sexually as well, either as bisexuals

00:32:32or as, as lesbians.

00:32:33Yeah.

00:32:34Wow.

00:32:35So, so like a wide range of traits seem to be influenced by testosterone.

00:32:38Okay.

00:32:39So fourth one is, it correlates with hormones.

00:32:41Yep.

00:32:42Uh, the fifth one is, uh, cross cultural universality.

00:32:45So most of the key sex differences that we've been discussing so far, they are found either

00:32:51in every culture or in the vast majority.

00:32:54And if it were all just down to culture, you wouldn't expect that.

00:32:58You'd expect there to be more variation across cultures than what we found.

00:33:02Um, but you don't, you know, you just always have like in every culture, you find that men

00:33:07are more aggressive than women and you find, uh, at the extreme of aggression in particular,

00:33:11the differences are particularly big and you find that the vast majority of homicides are

00:33:15perpetrated by, by guys in every single nation for which we had data.

00:33:19Greater risk taking, more accidental, uh, fatalities among men than women.

00:33:23Uh, women across cultures are more involved in parental care and so on and so on.

00:33:28And then last but not least, and maybe this is the one I find most plausible on its own,

00:33:33is the fact that a lot of these sex differences, you find them as well in other species.

00:33:37You don't find them in all other species, but importantly, you find them in species, um,

00:33:42that were subject to the same evolutionary selection pressures as, as ourselves.

00:33:47Uh, and actually the selection pressures of question, uh, bring us to the, the ultimate roots

00:33:54of evolved sex differences.

00:33:56Uh, so basically most sex differences emerge from the sex difference in what I like to call

00:34:04the maximum offspring number that male animals versus female animals can produce.

00:34:09And in most species, uh, the males potentially can produce more offspring than females.

00:34:15Um, that, that average number of offspring has to be the same.

00:34:18At least in species where you have a similar sex ratio.

00:34:22The average has to be the same, but the variance in the number of offspring produced can be greater

00:34:27in one sex than the other.

00:34:28And it's usually greater in males.

00:34:30Why does the average need to be the same if the variance can be different?

00:34:33Uh, because it takes two to tango.

00:34:35Yeah.

00:34:36And so every, uh, offspring that's produced is produced by one male and one female.

00:34:42Mm-hmm.

00:34:43And then most species.

00:34:44But if you can have one male servicing 20 females, why not have a 20 to one ratio?

00:34:48Well, that'd be a 20 to one ratio in terms of the number of parents, but the average number

00:34:54for each sex would be the same.

00:34:55Right.

00:34:56Because you've got the one male with 20 times more, uh, than any female.

00:35:00Mm-hmm.

00:35:01And then nine, and that's a really high number, but then the other 19 bachelors who never get

00:35:05to have kids, uh, that brings the average for males down.

00:35:08Mm-hmm.

00:35:09And then it's the same for all the females.

00:35:10So you average out across all of them and, and the average is the same.

00:35:13I, I get that.

00:35:14I, sure.

00:35:15Maybe I'm being stupid.

00:35:16Why is it not the case given that men, given that males are able to produce more children

00:35:22than women can and females can?

00:35:26Yeah.

00:35:27Why is it not the case that there is a bias toward fewer males in the animal kingdom?

00:35:32Right.

00:35:33Right.

00:35:34That's a great question.

00:35:35Um, and that is one of the sort of early mysteries of evolutionary biology.

00:35:39And if it were for the, if selection acted for the good of the group, that is what we'd

00:35:44find.

00:35:45We'd find if you, if you only need one, one male for every 20 females and, uh, selection

00:35:51for the good of the group.

00:35:52You get that because if you have 20 of each, then the other 19 are surplus and they're using

00:35:57up each of resources and they're, uh, competing with each other and fighting with each other.

00:36:01It's not good for the species as a whole.

00:36:03Uh, but selection favors what's good for the individual.

00:36:06And for the individual.

00:36:07I could be the one.

00:36:08You could be the one.

00:36:09Exactly.

00:36:10And the, and the average is the same.

00:36:11So the, the, um, I guess useful to think about, think about it from the parent's point

00:36:17of view, like, is it better to have sons or daughters?

00:36:20Um, and if there were 20 females for every one male, it'd be much better to have sons.

00:36:28Because each son is going to just have, there's going to be tons of females.

00:36:30Yeah.

00:36:31And so that would mean that selection will slowly favor an increase in the number of

00:36:34sons.

00:36:35Motherfucker.

00:36:36You can't beat evolution.

00:36:37Exactly.

00:36:38And the reverse, if there's 20, 20 males and for every female, then it would be better for

00:36:42parents to produce daughters because then they get the pick the cream of the crop and, and

00:36:4620 males, probably they're going to have a low number.

00:36:48So it's better to have daughters.

00:36:49So the equilibrium point is 50, 50.

00:36:52Yeah.

00:36:53Obviously as well, there's survival and not just reproduction.

00:36:55Yep.

00:36:56We're not living in this perfect, hermetically sealed, safe environment.

00:36:59Yep.

00:37:00Males do other things than just reproduce, regardless of whether they can do 20 to one

00:37:05or not.

00:37:06Indeed.

00:37:07Yeah.

00:37:08Getting food, helping to protect, getting rid of other tribes, et cetera, et cetera.

00:37:14Yeah.

00:37:15Yeah, exactly.

00:37:16And you know, there are plenty of species where the male, uh, his, his role in reproduction

00:37:21is just the reproductive act.

00:37:23And then he, then he's off looking for other females, but we're not one of those species.

00:37:27I mean, that does happen occasionally.

00:37:28There's occasional male that will do that.

00:37:30Uh, but generally we're quite involved in childcare.

00:37:34Uh, yeah.

00:37:35So, okay.

00:37:36So the big difference there is you get this difference in the variance.

00:37:39Mm-hmm .

00:37:40Um, some males can have tons of offspring.

00:37:42Uh, and they can have many more offspring than any female can.

00:37:46Where that's the case though, there's going to be some males that had no offspring.

00:37:49Um, or maybe a few, a few or none.

00:37:52And where that's the case, you get strong selection on the males to be one of the lucky

00:37:57few males that has many offspring.

00:37:59Mm-hmm .

00:38:00Rather than one of the, the few that has none.

00:38:01Yep.

00:38:02One of the many that has none.

00:38:03Yep.

00:38:04Um, and so that selects for traits like greater aggression within sex aggression to try to beat

00:38:09up other males for either directly for females.

00:38:12Okay.

00:38:13Or for the territories, uh, the status or the resources that are necessary to attract female

00:38:18attention.

00:38:19Uh, a tendency to show off, a tendency to grow a great big tail.

00:38:23If you're a peacock, you might want to try that grow a great big flashy tail to seduce the

00:38:28peahens.

00:38:29Um, or just a tendency to seek multiple mates and, uh, and seek no strings attached sex basically.

00:38:36Right.

00:38:37So that's the answer to your earlier, earlier question.

00:38:38Is that what that's why you have selection for like stronger selection on males and females

00:38:43for an interest in multiple partners and sex with that commitment?

00:38:46Right.

00:38:47Yeah.

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00:39:43How does parental investment influence the evolution of sex differences?

00:39:48That is a major contributor.

00:39:50And the reason is that, so this variance sex difference is mainly a result of sex differences

00:39:57and parental investment.

00:39:59So the reason that some males can have many, many more offspring than any female in a lot

00:40:05of species is that females invest more in the young.

00:40:08So in mammals, for instance, to produce any one offspring, a female has to have a long pregnancy,

00:40:14has to give birth to the young, and then has to nurse the young for a while.

00:40:19Whereas a male, in order to produce an offspring, just in principle, only needs to engage in one sex act.

00:40:26So he can mate with multiple females and have tons of offspring because he invests potentially little in any given offspring.

00:40:34Whereas the females, on the other hand, they invest a lot in each offspring.

00:40:37That lowers the ceiling for the number of offspring they can produce.

00:40:40Therefore, you have to be choosier.

00:40:41You have to be choosier about your mates.

00:40:43Exactly.

00:40:44Sleeping with or mating with lots and lots of males, less useful for females than for males.

00:40:49So parental investment is really the core to…

00:40:54Is that the key driver?

00:40:56Well, I think the key driver is the difference in the maximum offspring number or the reproductive variance.

00:41:02Right.

00:41:03Because it's not just shaped by parental investment.

00:41:05Behaviourally, that shows up as parental investment.

00:41:07Well, that's a big part of it, yeah.

00:41:08So the parental investment is the major cause of the sex difference in maximum offspring number.

00:41:14But other things do come into it in different species.

00:41:17Well, gestation period too is like a biological imposition on parental investment.

00:41:22Indeed.

00:41:23Actually, is how long it takes to just make a baby considered part of parental investment?

00:41:30That is part of parental investment, yeah.

00:41:31Right.

00:41:32And parental care is, and nursing is…

00:41:33Obviously those two, but I wasn't sure whether or not it's classed…

00:41:36Parental investment is classed as actually the making of the baby.

00:41:39It is because it forecloses the option to make other babies.

00:41:42Understood.

00:41:43Yep, yep, yep.

00:41:44But ecological things come into it as well.

00:41:46So one example of a factor other than parental investment that influences the reproductive variance

00:41:51is ecological factors.

00:41:52So you'll have some species where the males, where they're quite solitary.

00:41:56So the males and females might pair up and there aren't many other individuals around.

00:42:01Even if the female invests a lot more in the young than the male does, their maximum offspring

00:42:09number is about the same because just simply because they're isolated from other members

00:42:13of the species, the males don't have many other opportunities to sow their wild oats.

00:42:18What's Bateman's principle?

00:42:19Bateman's principle?

00:42:20So that is the idea that reproductive variance is greater in males than females in most species.

00:42:26Right.

00:42:27And then Trivers' sort of refinement of that was that the main cause of that is parental investment.

00:42:31So Bateman put a lot of it on anastogamy.

00:42:35He explained the difference in reproductive variance in terms of the fact that females invest more per egg

00:42:44than males invest per sperm.

00:42:46Robert Trivers, who died recently, he said it's not just that.

00:42:50Actually, it's all kinds of investment that you put into the young, not just the gametes,

00:42:56but also gestation and parturition, which is giving birth, nursing, parental care, all those things are what matters.

00:43:04And I would just add that parental investment is the big one, but other things as well determine reproductive variance.

00:43:10What is the, it's about 40% of males, but with human males ancestrally reproduced and about 80% of females, is that right?

00:43:19I have heard that number bandied about.

00:43:21I actually think that probably in our species, my guess is that it's not, it's not that big.

00:43:27I've also seen other evidence suggesting that, um, it's called reproductive skew and suggesting that the reproductive skew in our species is quite a bit lower than you find in most mammals.

00:43:37And I think the reason for that is that.

00:43:40So the 4080 number you think is, is wrong.

00:43:42Yeah.

00:43:43Right.

00:43:44Okay.

00:43:45I think so.

00:43:46What's the reason?

00:43:47Because, uh, males in our species very often invest quite a lot in the, in the young.

00:43:52So it's not just the sex act.

00:43:54Um, they often typically help out with the young as well.

00:43:58Uh, and so we have, we have high levels of biparental care in our species that reduces the maximum offspring number for males relative to females and brings it down, brings it closer to what we have for females.

00:44:10So if other animals have less of a reproductive skew, but also have less, uh, male parental investment, how would the reproductive skew for us be so great if we have more male parental investment?

00:44:23Is that what you're saying?

00:44:24That is what I'm saying.

00:44:25There you go.

00:44:26I fucking know evolutionary psychology, dude.

00:44:27Don't test me on this.

00:44:28I fucking understand this.

00:44:29It's the only topic I understand.

00:44:31Um, yeah.

00:44:32So it's a very instant reproductive success.

00:44:34Yeah.

00:44:35What do you, what do you reckon it was then?

00:44:37If it's not 40, 80, feel free to just bro science it.

00:44:40I think I, um, I probably shouldn't put a number.

00:44:46I, I, uh, other than to say, I think it's smaller.

00:44:49I think it is.

00:44:50You said like an academic.

00:44:51I know, I know.

00:44:52That's why I'm in the room, dude.

00:44:53Let me just put this thing on for the rest of the conversation.

00:44:56Um, well, you've got these as well.

00:44:58That's also, that's if you want to say something insane.

00:45:00Okay, cool.

00:45:01Well, I'll keep it here.

00:45:02Yeah.

00:45:03Cause I may want to say something absolutely insane.

00:45:04You're allowed to put that on.

00:45:05It's actually saved me once already.

00:45:07I, uh, I, I got, I got clipped talking about a slightly highly postulated theory.

00:45:11Put that on.

00:45:12It's going to be interesting on you because you already have the mustache and the glasses.

00:45:15Yeah.

00:45:16Well, indeed.

00:45:17Yeah.

00:45:18Nothing's changed.

00:45:19Nothing's changed.

00:45:20Yeah.

00:45:21Okay.

00:45:22So we've got, uh, it's like an interesting, I guess an interesting, uh, pivot on what people

00:45:33think the, that sort of 40, 80 number, as far as I was aware, like actually.

00:45:38So you think the skew is different.

00:45:39What I thought might be true is that the overall number might be different too.

00:45:44Mm.

00:45:45That the whole, to me, like infant mortality.

00:45:48Right.

00:45:49Right.

00:45:50Fucking ruthless.

00:45:51So the only way that we can work out how many of our ancestors reproduced presumably

00:45:55is due to some kind of genealogy stuff.

00:45:58And that means that it's not how many reproduced it's how many survived.

00:46:03Yeah.

00:46:04Survived to reproduce.

00:46:05To reproduce.

00:46:06Yeah.

00:46:07The grandparent optimizing machine from yours, your previous book, which is fantastic.

00:46:10And everyone needs to go and look at, um, the April understood the universe.

00:46:1580% of women having grandchildren producing, 80% of women being grandchildren producing people.

00:46:25Yeah.

00:46:26Seems insanely high to me.

00:46:28Uh, I guess the thing is that they would have had a bunch of kids.

00:46:31Still though.

00:46:32And only about 50% would make it.

00:46:33About 50% would make it.

00:46:34And so if they, you know, have sex, for instance.

00:46:37That's what it is.

00:46:38Around about 50%.

00:46:39Yeah.

00:46:40That are born.

00:46:41To reproduce.

00:46:42Unbelievably high.

00:46:43Right.

00:46:44Uh, about 50%, um, infant mortality rate.

00:46:47So like half of them didn't make it.

00:46:49Yeah.

00:46:50One of the great things I think of our civilization is that we had lowered that number to very close

00:46:54to zero.

00:46:55Mm-hmm.

00:46:56Cause that was, I think a massive cause of misery throughout most of human history.

00:46:59Yeah.

00:47:00Yeah.

00:47:01Was it Darwin lost a bunch of kids?

00:47:02He did.

00:47:03Yeah.

00:47:04He had, uh, what was it here?

00:47:05He had 10 and three didn't make it to adulthood.

00:47:07I think that's the numbers.

00:47:08Yeah.

00:47:09Um, is it your book or was it, I think this might've been the moral animal.

00:47:14Yeah.

00:47:15Where.

00:47:16Robert Wright talks about the fact that Darwin lost multiple children.

00:47:20But the one that was the most psychologically painful.

00:47:24Yeah.

00:47:25Was his.

00:47:26Daughter who was 12 or 13.

00:47:28Yeah.

00:47:29And the reason for that, the evolutionary reason that Robert gives for it is that.

00:47:36Parents are able to detect the moment at which the life cycle of their child would have allowed

00:47:43them to just about become the grandparent optimizing machine that evolutionarily were driven to be.

00:47:51Yeah.

00:47:52And that if a child dies at two years old, that's horrible, but they weren't, they had a long way

00:47:59to go and many things could have occurred between now and being able to have kids.

00:48:03If a child dies when they're old, then they've had all of the opportunities to have had kids.

00:48:09And that didn't, you know, that didn't go well, or maybe it did go well.

00:48:12But if you are just on the cusp of being able to reproduce biologically and you die, that is from an evolutionary perspective, the most painful.

00:48:22Am I making that up?

00:48:23Or is that the story?

00:48:24No, that is the story.

00:48:25Yeah.

00:48:26Bingo.

00:48:27There's pretty good evidence on it as well.

00:48:28That grief tracks reproductive value of the individual.

00:48:31No fucking way.

00:48:32So this has been reproduced.

00:48:33Yeah.

00:48:34Because that book's 30 years old now.

00:48:35Yep.

00:48:36Yep.

00:48:37Yeah.

00:48:38The average grief levels go up and up and up.

00:48:40Reproductive value goes up as kids move from the very vulnerable, historically very vulnerable early infancy to childhood.

00:48:47It's kind of peaks at about the age that reproductive value peaks.

00:48:52So a couple of years after puberty, and then it starts coming down again as people get older.

00:48:57So fucking fascinating.

00:48:58How is everyone not obsessed with evolutionary psychology?

00:49:00I completely agree.

00:49:01It is so cool.

00:49:02It's fascinating, right?

00:49:03It's so fun.

00:49:04And sheds light on some of the most fundamental stuff in life.

00:49:06Yeah.

00:49:07I mean, obviously it's very bleak in some ways too.

00:49:11It's very stark.

00:49:12It doesn't paint a particularly flattering picture of human motivation.

00:49:15Yeah.

00:49:16The reason that Darwin was particularly sad about his 13-year-old daughter dying is that he had this weird algorithm running in the back of his mind.

00:49:23He said, "Oh, so you're just saying that all the children are, that's for you to be happy to do."

00:49:28Like, dude, you don't need to laud our ultimate evolutionary drives in order to understand and respect them and accept the fact that they are important influences on our behavior.

00:49:43I completely agree.

00:49:45And I do feel the pull to it.

00:49:47Like it is a bit bleak.

00:49:48I remember when I was first reading about that grief theory, it does seem a bit, a bit dark, but then when you think about it, it's not very flattering.

00:49:54Exactly.

00:49:55I mean, I guess one thing is that, um, we don't actually, we're not actually thinking about reproductive value.

00:50:00Uh, we just, we just have a built in tendency to react as if we are, but we're not actually thinking in the back of our minds.

00:50:06This is sad because I, this, this kid was close to having kids and then I would have been, yeah.

00:50:14This is sort of my least, I don't know, actually.

00:50:17I probably could write out a hit list of my least favorite internet rebuttals to anyone talking about evolutionary theory.

00:50:25But one of them is a lack of understanding about the difference between proximate and ultimate motivations for behavior.

00:50:32Yeah, exactly.

00:50:33So one of the big ones.

00:50:34Yeah.

00:50:35Like the misunderstandings, why you feel the desire to do a thing and the evolutionary advantage of you doing the thing.

00:50:45The fact that those two things are different.

00:50:47Um, you eat food because it tastes good, but the reason for eating food is to keep you alive.

00:50:54Uh, you have sex because it feels good, but the reason to have sex is not the reason that it feels good.

00:51:00Exactly right.

00:51:01And, and it's quite annoying, right?

00:51:02When people say, so you're saying that, um, like sex and, uh, having like short term relationships or long term relationships is just about babies.

00:51:11But that can't be true.

00:51:12Because often the last people, the last thing people want is to have kids.

00:51:15And they use birth control.

00:51:16I don't want to have kids.

00:51:17I love to have sex.

00:51:18Yeah.

00:51:19Yeah, yeah, exactly.

00:51:20So it doesn't make sense.

00:51:21But they've just misunderstood the idea.

00:51:22Yeah.

00:51:23Uh, like the, the genes I view explanations, the, the evolutionary explanations, those are not motivations.

00:51:29Those are just the explanations for why we have the, the proximate psychological drives that we do.

00:51:34Not the ultimate.

00:51:35Exactly.

00:51:36Yeah.

00:51:37Yeah.

00:51:38And you know, with the, the, what's it referred to as that theory of the sexual, not sexual value.

00:51:44Um, of, uh, Darwin's daughter dying.

00:51:49What's the.

00:51:50Oh, uh, yeah.

00:51:51Uh, reproductive value.

00:51:52Reproductive value.

00:51:53Yeah.

00:51:54No one is how horrible to say to a parent.

00:51:57Well, it's actually, um, Mrs. Thompson, the reason that your grief, Mrs. Darwin, the reason that your grief is so high is because of the reproductive value that your daughter almost didn't cash in on.

00:52:07Exactly.

00:52:08Like horrible, horrible thing to say.

00:52:09Yeah.

00:52:10But it, it doesn't need to, it doesn't need to be something that's in your mind to like go, how could you claim that this mother is feeling that, thinking that at the time and that's contributing to her grief?

00:52:21No.

00:52:22Yeah.

00:52:23She's not.

00:52:24She just loves the kid.

00:52:25It would be the same as going, um, why is it that people get depressed when they're lonely?

00:52:29Yeah.

00:52:30I'm not thinking about potentially being kicked out of the tribe.

00:52:32And you go, well, yeah, like we're in a modern environment.

00:52:36Why do you think it is that depression and anxiety correlate with isolation?

00:52:40Yeah.

00:52:41If it didn't matter?

00:52:42Well, it does matter.

00:52:43It doesn't matter anymore.

00:52:44Not in the same sort of a way, but that doesn't negate the fact that our system is basically ancient programming living in a modern world.

00:52:51Exactly.

00:52:52And even though it does seem bleak sometimes, I don't see that other explanations, sociocultural explanations would be any less bleak, you know?

00:52:59Oh, so you're telling me that I'm at the mercy of the memes and trends of the modern world?

00:53:04Well, exactly.

00:53:05And, you know, yeah.

00:53:06Some guy decides to start a new cool movement somewhere and then that completely sort of blows the wind of whatever it is that I'm supposed to care about?

00:53:14Exactly.

00:53:15Or you might say, okay, the reason that you grieve this individual is just because you've been socialized to do so.

00:53:20Yeah.

00:53:21And how is that any less bleak?

00:53:22It's the same.

00:53:23This is why I think there's a lot of similarities between evolutionary psychology and behavioral genetics, that if you start to strip away the science and the evidence underneath it, what you end up with is an equally or maybe even uglier perspective in the world.

00:53:39For instance, if you deny that there are genetic influences on outcomes in life, what you're left with is this world where everybody did start off equal and you are exclusively at the mercy of the entire world.

00:53:56Yeah.

00:53:57And injustices.

00:53:58Yeah.

00:53:59The only reason that this didn't come out is all on your shoulders.

00:54:01Yeah.

00:54:02It's all on your shoulders because you didn't try hard enough or your parents didn't try hard enough.

00:54:05Yeah.

00:54:06Horrid.

00:54:07Horrid.

00:54:08And I guess, though, the thing is that whatever horrid truth, and they're not all horrid either, but whatever horrid truth, ultimately we just got to accept what's true, whether we like it or not.

00:54:18And, you know, sometimes it is positive.

00:54:19So natural selection has given us a whole range of less than noble traits, but it's also given us some really lovely traits as well, like the capacity to fall in love and to love our children and to love our friends.

00:54:31You know, these are great things.

00:54:32To care for others, to do selfless things.

00:54:33Yeah, exactly.

00:54:34Okay, so I guess just to round out, we haven't even got into the sex differences yet, which is the meat and potatoes of this, but I don't care.

00:54:45Are humans unique in this regard?

00:54:48Because we've got mutual mate choice and we've got bi-parental care.

00:54:53So when we're talking about evolution of sex differences, parental investment, ability to produce children or volume of children across a lifespan, Bateman's principle, variance in reproductive success, but humans do seem to be somewhat of an outlier in mammals and especially in the animal kingdom.

00:55:12Yep.

00:55:13Yep.

00:55:14What wrinkle does that throw in?

00:55:16Well, yeah, so the question, are we unique?

00:55:20Sort of yes and no.

00:55:22So the way in which we are unique, we're very unique among mammals, like you say, and the fact that we have high levels of the tendency to pair bond.

00:55:29So to fall in love and form relatively durable pair bonds.

00:55:32And for both sexes, rather than just the females, to invest in the young.

00:55:36That is found in maybe five to 10%, 10% at the most of mammals.

00:55:43So the overwhelming trend among mammals is that the females do all the investment in the young and the males are basically deadbeat dads.

00:55:51And birds, on the other hand, they are an outlier family of animals among animals in general.

00:55:58And that around 90% of birds form pair bonds and have biparental care.

00:56:02And so this is a funny thing.

00:56:03I find this just very, very interesting is that in our primary reproductive behavior, humans are more like the average bird than like the average mammal.

00:56:12No way.

00:56:13No way.

00:56:13Yeah.

00:56:14That's because of our pair bonding and our biparental tendencies.

00:56:16Which is a reinforcement that the parental investment is the key driver of sex differences.

00:56:27Yeah.

00:56:28Exactly.

00:56:29And of the difference in the areas.

00:56:31Most birds are kind of like dinosaurs and humans are closer to birds than they are to most mammals.

00:56:41Yeah.

00:56:42Which means that humans are kind of dinosaurs.

00:56:43Yeah.

00:56:44That's my evolutionary logic.

00:56:45That's great.

00:56:46That's great.

00:56:47Do you want this?

00:56:48Yes.

00:56:49No, no, no.

00:56:50I don't need that.

00:56:51I don't need that.

00:56:52No, no.

00:56:53You don't.

00:56:54Because I agree.

00:56:55That's the primary reproductive arrangement of today's dinosaurs.

00:56:58Let's fucking go.

00:56:59It's wild, right?

00:57:00Let's fucking go.

00:57:01And so, yeah.

00:57:02So we're an exception among mammals in that respect.

00:57:04A way in which we're not an exception though, is that the same evolutionary principles that apply right across the animal kingdom apply to us as well.

00:57:13So the fact that sex differences emerge from the maximum offspring number, the level of sex differences and reproductive variance, that is true across the animal kingdom.

00:57:24And the rules about that apply to us as well.

00:57:28And the fact that we have, we do have a sex difference in reproductive variance.

00:57:33Men do have and have always had greater reproductive variance than women, but it's relatively low compared to most mammals.

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00:58:44Isn't there an interesting inversion of this in spiders where female spiders are bigger than the males?

00:58:50Actually, in most insects, it's that way around.

00:58:53And actually, there are more animals where the females are bigger than where the males are bigger.

00:58:57But that's not because of the difference in reproductive variants.

00:59:00It's because in a lot of species, the main driver of sexual dimorphism is just the number of eggs that you can produce.

00:59:10And bigger females can produce more eggs.

00:59:14So there's a selection pressure on them to get bigger and bigger and bigger.

00:59:16They're typically bigger than the males.

00:59:17The males don't need to be much bigger.

00:59:19They don't need that much room for sperm.

00:59:20Yeah, exactly.

00:59:21Yeah.

00:59:22So the gamete size difference, sperm are bigger than eggs, is reflected in the physiology of the species.

00:59:27Oh, that's so fucking cool.

00:59:29That's so cool.

00:59:30And we're the weirdos.

00:59:31We're so used to males being bigger than females, but actually mammals and other large vertebrates, we're the exception to the rule.

00:59:37Mm-hmm.

00:59:38And the main reason for it is that you still have the selection pressure on the females for producing more eggs.

00:59:44So, you know, they've got certain size, sort of push for them to be bigger.

00:59:49But you've got an even stronger push on the males to be bigger as a result of intersexual selection, which is selection for the ability to be able to beat each other up, basically.

00:59:57Right.

00:59:58So a lot of species, bigger males do better in fighting than smaller ones.

01:00:02Males get bigger, and sometimes they get even bigger than the females.

01:00:07All right, meat and potatoes.

01:00:08Yeah.

01:00:09Getting back to sex differences and sex drive.

01:00:10Yeah.

01:00:11What, casual sex, sexual variety, cheating, what's going on there?

01:00:16Yep.

01:00:17That's all about producing more offspring.

01:00:18So, a male that is equipped with those motivations is going to be sort of like a heat-seeking missile going out to seek multiple partners, and is therefore more likely to have more offspring, if he's successful than that, than he would if he just sort of sat back and wasn't interested in multiple partners.

01:00:40Right.

01:00:41And you do find that in many species.

01:00:43Now, I don't think that the difference is as big in our species as in many others, and I think that's a side effect of the fact that because we have biparental care, the level of reproductive variance among males in our species is somewhat constrained, still greater than among females.

01:00:57But because it's somewhat constrained, sex differences in our species have correspondingly come down as well.

01:01:03Mm-hmm.

01:01:04So, we still have all the traditional sex differences that you find in most mammals and many other species, but they're somewhat muted.

01:01:11So, you have the sexuality, sex differences, but they're somewhat muted.

01:01:15The aggression differences, but they're somewhat muted.

01:01:18The parenting differences is the main source of this.

01:01:23So, the discrepancy in male investment in kids versus female investment has been massively reduced.

01:01:30And that's the driver.

01:01:31And that's the driver.

01:01:32That's the driver.

01:01:33Yeah.

01:01:34The biparental investment is the nerfing, the reason for the nerfing of all of the others.

01:01:39Okay.

01:01:40Again, I'm only going to make this fucking disclaimer once.

01:01:43But we said it, we said it previously, but I think it's worth saying again.

01:01:46Just because we can explain using evolutionary logic, the reason why men might be driven to cheat more than women is not the same thing as excusing why it happens.

01:01:57No, not at all.

01:01:58Any more than a socio-cultural explanation would excuse it.

01:02:02That's a funny asymmetry.

01:02:03People seem to think if you explain it in evolutionary terms, that excuses it.

01:02:07But there's no more reason to assume that than to assume that if you explain it in socio-cultural terms, it excuses it.

01:02:11Because with both of those, you are outsourcing the culpability of the individual to something else.

01:02:18Yeah.

01:02:19In one, it's evolution and ancestors, and in the other, it's culture and influence.

01:02:22Yeah, exactly.

01:02:23And all our behavior must have causes, right?

01:02:25So, if we're going to say that if we can identify the cause of a behavior, and it's an evolutionary cause, we're going to have to not hold people to blame.

01:02:34We're going to have to say that for any cause, and we're going to have to say that for all behaviors.

01:02:37Because all behaviors have some kind of cause, whether or not we know what it is, they have some kind of cause.

01:02:41Whether it's evolutionary or cultural.

01:02:43Or most likely a combination of both.

01:02:45Yeah.

01:02:46And so I think that basically the institution of holding people responsible, we have to keep that institution because it's useful, regardless of the fact that, of course, people's behavior has causes and it's not inexplicable.

01:02:56That's so good.

01:02:57Ashley Madison, The Cheating Website, had 20 million active male users and 1,492 active female users, despite women getting free lifetime membership and men having to pay.

01:03:08Yeah.

01:03:09That's wild, right?

01:03:10That's a massive difference.

01:03:1120 million to 1,500.

01:03:14Yeah.

01:03:15It's probably similar to that ratio we had up there before.

01:03:17It's probably, it's almost exactly the same, yeah.

01:03:19Yeah.

01:03:20What about men being more turned on by visual triggers?

01:03:23Yeah, that's another big sex difference.

01:03:26Both sexes are to some degree, you know, both sexes are interested in good looks in a mate, but it's stronger in men than in women.

01:03:33And the main reason for that is that the traits that we consider good looking are associated with youthfulness and fertility for both sexes.

01:03:41Um, but men place a greater weight on those traits because of menopause basically.

01:03:46So the fact that, um, they place more weight on youthfulness in a mate because youthfulness is more closely linked to fertility in women than men because of the fact that women's fertility shuts off about, you know, two thirds of the other way through the lifespan.

01:04:00Mm-hm.

01:04:01Yeah.

01:04:02Yeah.

01:04:03So, yeah.

01:04:04So men are much more interested in visual sexual stimuli, as psychologists call it.

01:04:07It's part of the explanation for the fact that, um, men are much more avid consumers of porn than women are.

01:04:13What is the reason that women are much more avid consumers of romantic and romance novels than men?

01:04:20It's an interesting one, isn't it?

01:04:21So that's the standard sort of differences in consumer preferences that we hear about.

01:04:26Men are much more into porn than women.

01:04:27Women are much more into romance novels.

01:04:29Um, now, now it is interesting.

01:04:34We've, we've talked about the fact that men on average are more interested in casual sex than women.

01:04:39And people often assume that the flip side of that is true as well, that women are more interested in long-term relationships than men.

01:04:45But actually that's not the case.

01:04:47Uh, typically what we find is that men and women are about as interested as, as each other in long-term committed relationships and falling in love and falling in a committed bond with, with a partner.

01:04:57So you haven't re-apportioned the sex drive, relationship drive, desire from short-term to long-term for women.

01:05:06No.

01:05:06It's just that they don't have this addition that men do of the one night stand.

01:05:11Exactly right.

01:05:12But bearing that in mind.

01:05:13To the same degree.

01:05:14Yeah, yeah, yeah.

01:05:15Uh, bearing that in mind, uh, the, the fact that women are so much more interested in romance novels is interesting and sort of slightly unexpected.

01:05:24You would, you might expect that both sexes would be interested in them.

01:05:27Um, so, so why it is the case that women are more interested in them?

01:05:31I guess, evolutionarily speaking, I don't know.

01:05:33They, they do seem to be, despite the fact that actually men do seem to be very invested in long-term relationships.

01:05:39Bunch of papers have come out recently actually saying that in a lot of ways, men are kind of more, more romantic than women.

01:05:46They are more likely to suffer after a breakup.

01:05:48Fall in love more quickly.

01:05:49Say I love you more soon.

01:05:50Exactly.

01:05:51Exactly.

01:05:52Exactly.

01:05:53So why aren't they more into romance novels?

01:05:54I don't know.

01:05:55Maybe they're just too busy with the, with the porn, but.

01:05:57Yeah.

01:05:58True.

01:05:59I did.

01:06:00I mean, I, I sat next to a lady, lovely lady, floral dress, slightly, slightly older lady on a flight a few months ago.

01:06:05And, uh, she had a iPad up resting it and it was a big, big fuck off font.

01:06:10Yeah.

01:06:11And she was reading some romantic-y thing and she was getting to the good stuff.

01:06:15And, uh, I mean, I couldn't, I was like, we have legalized, we have legalized women reading porn.

01:06:22In public.

01:06:23In public.

01:06:24Yeah.

01:06:25And it's not, I, I mean, I, it was, I, she was having a, she seemed to be having a wonderful flight.

01:06:29And I got my, when someone sits next to me and they've got an iPad, I think, oh, that's, that's great.

01:06:34Cause it's going to, or whatever the kindle or something, it's going to influence me to be, not be a degenerate.

01:06:39Yeah.

01:06:39All I wanted to do was put a pair of blinkers on.

01:06:42I'd like to focus on some brain slop stuff.

01:06:45I've never, I've never, um, I've been meaning for ages as a sort of anthropological study.

01:06:50Excuse it however you want dude.

01:06:52Excuse it however you want.

01:06:53I haven't got around to doing it.

01:06:54I'm going to do it.

01:06:55I'm going to read a romance novel at some point.

01:06:56I have heard that the general theme is.

01:06:58Boy meets girl.

01:06:59Boy is a bit of an asshole.

01:07:01Uh, girl tames boy.

01:07:03And then they live happily ever after.

01:07:05And they do involve sex, right?

01:07:06Well, yeah.

01:07:07I mean, there, there is some sex in them.

01:07:08At least there was in hers.

01:07:09And the one that she was reading.

01:07:10Yeah, exactly.

01:07:11Um, I mean, there's some interesting stuff, right?

01:07:13The number of, uh, if you have a single, a sexual fantasy, mental sexual fantasy, men will cycle through.

01:07:19I think it's between four and six different partners on average during.

01:07:24Is that four and six or 46?

01:07:26Four and six, I think, but it depends who you are.

01:07:28Um, whereas for women, they tend to have fewer.

01:07:31Yeah.

01:07:32Or maybe, maybe just one.

01:07:33Now I don't know, but I'm going to guess that this would be reflected in romance novels.

01:07:37Uh, in fact, I know that this is the case because I've been on the cover of a bunch of them.

01:07:41And during those novels, at least I would say on average, most.

01:07:46Yeah.

01:07:47Yeah.

01:07:48The women who are the protagonists aren't cycling through multiple male suitors.

01:07:54And if they are, even if you look at movies, movies like the notebook or Titanic or whatever, it tends to be a, a pivot between two different life directions.

01:08:04Yeah.

01:08:05Um, it's not a kind of ruthless conveyor belt that is closer to sort of the, the typical male fantasy.

01:08:12Uh, but yeah, the, the men being more turned on by visual triggers thing, I think make, makes, makes an awful lot of sense.

01:08:19I remember in, uh, bad men buses book, he talks about how there is an area of the brain that exists in men that lights up when they just see something that's remotely sexual, a pair of rocks that look like boobs.

01:08:33Pulling a coin into a vending machine.

01:08:35Putting a coin into a vending machine.

01:08:36Yeah.

01:08:37You're fucking kidding me.

01:08:38Although that was a joke.

01:08:39I'm not sure there's actually research on that.

01:08:40That honestly wouldn't surprise me.

01:08:41Yeah.

01:08:42No, no.

01:08:43Likewise.

01:08:44Yeah.

01:08:45About gambling and it was on top of the risk taking on top.

01:08:47Yeah.

01:08:48That's it.

01:08:49Um, over perception bias as well.

01:08:51Yes.

01:08:52Another great example that I learned from, uh, bad men by David.

01:08:55Yeah.

01:08:56Yeah.

01:08:57And that's, um, uh, researched by him and, and spearheaded by, uh, his former student, Marty Hazelton.

01:09:01Yeah.

01:09:02Sexual over perception bias.

01:09:03Yeah.

01:09:04That refers to the fact that, uh, men are more likely to infer sexual interest on the part of a woman.

01:09:12Falsely, like falsely inferred than women are in the case of men.

01:09:16They're more likely to think, yeah, she's into me when actually they're just, uh, in a little dream world.

01:09:21And that's not actually true.

01:09:22Men are more likely to think that women are interested in them than they are.

01:09:27And women are more likely to think that men aren't interested in them when they are.

01:09:31Yeah.

01:09:32And I think that the data shows the level of attraction that men assume a woman has toward them is roughly equal to the amount of attraction that the man has toward the woman.

01:09:44Right.

01:09:45Right.

01:09:46Yes.

01:09:47Right.

01:09:48Yeah, exactly.

01:09:49So it seems to be maybe some kind of, uh, projecting yourself into the world kind of bias.

01:09:51Yeah.

01:09:52So it's a failure of cross-sex mind reading.

01:09:53Yep.

01:09:54But it's also specifically in a, in an over perception bias here too.

01:09:57Yeah.

01:09:58And this is smoke detector principle.

01:10:00If you, as a man had the opportunity to potentially bag an available and attractive woman.

01:10:07And because you weren't sufficiently vigilant and detecting it because you underplayed your potential success likelihood as opposed to overplayed it.

01:10:15Yeah.

01:10:16You are going to have an error of missing the opportunity as opposed to the error of an awkward and clumsy rejection.

01:10:22Exactly.

01:10:23And this again, fuck, I'm just going to have to keep saying it does not excuse guys in the workplace with the receptionist in the printing room.

01:10:31Yeah.

01:10:32Having an awkward fumble that she absolutely didn't give off signals for.

01:10:35Indeed.

01:10:36Uh, however.

01:10:37Yeah.

01:10:38This does explain how you get to that situation or why it is that on average men seem to be,

01:10:45unless you're the CEO of, who was it?

01:10:47Procter and Gamble.

01:10:48Who was the one that that Indian dude made the whole fucking, um, uh, conspiracy theory about.

01:10:53It went insanely viral.

01:10:55I bet your fish head Asian wife doesn't have these cannons.

01:10:58Do you remember that?

01:10:59Golden.

01:11:00Goldman Sachs.

01:11:01Yeah.

01:11:02Goldman Sachs.

01:11:03Yasmin's mum works at Goldman.

01:11:04We should get the inside scoop.

01:11:05Um, uh, yeah, my guest book is mum is like real, real high up at, uh, at Goldman Sachs.

01:11:12And then there was that huge.

01:11:13Did you see this thing kick off a couple of months ago?

01:11:15I don't know.

01:11:16Or about a month ago or so?

01:11:17No.

01:11:18Uh, it just, it was a, a guy me too-ing a very, very high up, um.

01:11:21Right.

01:11:22Okay.

01:11:23Yeah.

01:11:24Bit of a role reversal.

01:11:25Goldman.

01:11:26But as soon as the proposed accusations came out, there was no, it was so rare.

01:11:32It was like the most, it would have been incredibly extreme.

01:11:35Yeah.

01:11:36For a guy to do.

01:11:37Yeah.

01:11:38Yeah.

01:11:39And the fact that everybody intuited like really?

01:11:41Yeah.

01:11:42Sex differences.

01:11:43Yeah.

01:11:44Yeah.

01:11:45All right.

01:11:46How do, um, how do gay men and lesbians reveal what each sex wants?

01:11:49They do so in a very interesting way, which is that, um, gay men have more casual sex than

01:11:55straight men and lesbians have less casual sex than straight women.

01:11:59Uh, and the reason is that gay men and lesbians don't have to compromise with the typical sexual

01:12:04inclinations of the other sex.

01:12:06Mm-hmm.

01:12:07And they can, therefore their behavior is like a clearer window onto the, the sexual motivations

01:12:13of men and women in general.

01:12:15Unsullied by the other sex.

01:12:16Exactly.

01:12:17Yeah.

01:12:18So men are compromising by having less because basically women are thwarting their plans.

01:12:22Yep.

01:12:23Whereas.

01:12:24There's no gatekeeper.

01:12:25Exactly.

01:12:26And, uh, yeah.

01:12:27Whereas straight women are compromising with men and maybe having more than more, uh, casual

01:12:31sex than they would choose, uh, at least as revealed by them.

01:12:34Yeah.

01:12:35Lesbian behavior.

01:12:36There's a, an interesting study that Rob brought up, which was, uh, inside of marriages.

01:12:41Typically men say that they would like to have twice as much sex as they are having.

01:12:46And women say that they are happy with the amount of sex that they are having.

01:12:49Yeah.

01:12:50Which suggests that there is a compromise going on.

01:12:51Yeah.

01:12:52Uh, but that the compromises.

01:12:53The guy going, okay, fine.

01:12:55And she's setting, she's setting the level.

01:12:57She's setting the level with that regard.

01:12:59Uh, I do think that there's kind of a, and this is, I mean, like, are we really going

01:13:06to say boo hoo, poor men not getting exactly what they want?

01:13:10But I do think that it's a, a kind of compromise that might be invisible to women because sexual

01:13:17entitlement comes wrapped in some really ugly, uh, paper.

01:13:22But there is an argument that you can make that to say something like, look, men are doing

01:13:30a type of containment, a type of desire containment there.

01:13:33That isn't a burden that is, that they are paying.

01:13:37That isn't being paid in the same way inside of a marriage by the women.

01:13:41And ha that's well done.

01:13:43Well done for doing that for compromising what it is that you want.

01:13:46Yeah, indeed.

01:13:47And I guess, uh, I guess it's more, it's more, I guess that, um, men are doing that more often.

01:13:55Like some women are doing the same thing, no doubt, but there's just fewer women than men

01:13:59in that situation.

01:14:00Yeah.

01:14:01Uh, there's also more dead bedroom in lesbian relationships.

01:14:05I've heard that.

01:14:06Yeah.

01:14:07What is it?

01:14:08Um, there's some, some phrase like that, isn't there?

01:14:09The, uh, lesbian dead bed or something.

01:14:11Yeah.

01:14:12Yeah.

01:14:13Okay.

01:14:14So, mate preferences.

01:14:15Yes.

01:14:16When it comes to mate preferences, is it surprising how similar men and women are when it comes

01:14:22to what they look for in a partner?

01:14:24Uh, well, I guess it fits with the generalisation that in a lot of ways we are quite similar,

01:14:31that we, that sex differences in our species are not as huge as, as in some others.

01:14:35And I guess also just on a, um, everyday level, when, when you hear about some of the sex differences

01:14:40that we have in common, they're all things that I think it's obvious why we like them.

01:14:45Uh, people tend to be, men and women tend to want somebody, uh, who's pretty intelligent

01:14:51and who's kind and who loves them and who is attracted to them and who is pretty good looking,

01:14:57uh, and who's not, uh, like, mentally unstable.

01:15:01Uh, both sexes want that, not just men, not just women.

01:15:05Um, there are some areas though, where you do find sex differences in the strength of different preferences.

01:15:11So, uh, both sexes want someone who's pretty good looking, for instance.

01:15:14Um, but on average in long-term relationships, that's a bigger deal for men than for women.

01:15:19Uh, men put more weight on looks in a mate, um, than, in a long-term mate than, than women do,

01:15:24for the reasons that I mentioned, that I mentioned earlier.

01:15:26Uh, women on the other hand, tend to put more weight on resources and status in a long-term mate, uh, than men do.

01:15:36Um, now, now, in neither of those cases is, is that the, it's not like looks are the most important thing to most men.

01:15:43For most men, it's, it's important, but other things are equally important or even more important, traits like kindness.

01:15:49And likewise with women, um, resources and status in a mate, they're important.

01:15:54But other things like, again, like kindness, uh, tend to top the list of the things that are most important for women.

01:16:00Mm.

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01:16:55What's the evolutionary logic of non-physical mate preferences, like wealth and status?

01:17:00It all comes down, I think, to the fact, well, there are two main explanations for it.

01:17:04So one is that it's part of our evolution of a pair-bonding biparental species.

01:17:09So a guy who is able to access resources, you know, bring in food, and also has good standing within the group,

01:17:18that's going to be someone who is better able to invest in the young, to co-rare the children.

01:17:24And that's the explanation I think is most popular and most likely.

01:17:28There is also an explanation, though, that it's primarily a human equivalent to the peacock's tail.

01:17:34So that any male that is capable of bringing in resources and climbing the status hierarchy,

01:17:40that's a male who's got good genes and he's going to pass on whatever traits enabled him to do that to his male offspring.

01:17:46They're going to be able to do the same.

01:17:48They're going to attract more mates.

01:17:50So those are the two main explanations.

01:17:52I think it's quite possible that both of them shed light on it, that it's both a fitness indicator,

01:17:58but also is actually useful in the context of biparental care.

01:18:01You mentioned this is to do with long-term relationships.

01:18:05Yeah.

01:18:06How does this change when it comes to short-term relationships?

01:18:08Do women place more or closer to equal weight on physical attractiveness in men?

01:18:15They do.

01:18:16They do, yeah.

01:18:17So that's sex difference in good looks.

01:18:19We sometimes hear it discussed as if that's the difference between men and women right across the board in every context.

01:18:24But actually it does just apply to long-term relationships.

01:18:27And when it comes to low-commitment relationships, then that difference basically evaporates.

01:18:33And women are at least as interested in physical attractiveness in a mate as men are.

01:18:39If not, you know, some research suggests they may be even more interested in physical attractiveness.

01:18:43Why would that be the case using evolutionary logic?

01:18:45Because, well, the best explanation is that in a short-term context,

01:18:50there's going to be no further investment probably, likely no further investment.

01:19:00The only investment is the genes that the male is going to be passing on.

01:19:04And therefore traits that are indicative of good genes are much more important.

01:19:09They take center stage in terms of what women are looking for.

01:19:13And yeah, with the basic evolutionary logic that when you're reproducing, you are finding somebody to mix your genes with.

01:19:21If you want your genes to go on in the gene pool, you've got to mix them with a good set of genes from another individual.

01:19:29And what you want, if you have a short window to do this assessment in, you want the most obvious representation of those good genes as you can.

01:19:36Exactly. And physical looks at that.

01:19:39I'm sorry, your ability to do non-kin altruism and reciprocal care and kindness and your ambition over time.

01:19:48It's like, yeah, great, but I don't have time to assess that in the same way as I do your status and your resources.

01:19:55I suppose it's another one of the reasons and both men and women, if this sex difference didn't exist, if this preference didn't exist, why would it be the case that both men and women seem to play into a caricature of that in an attempt to get sexual access?

01:20:08Yeah.

01:20:09Why is the caricature of dudes in Miami nightclubs wearing a Rolex and having a fast car outside?

01:20:15Yeah.

01:20:16Well, that's a way to turn wealth, ambition, and status, buying a VIP booth, status, into an immediately transactable and obvious advertisement in case there is some of this short-term mating that's going on.

01:20:34Why is it that women do more beautification when they go on a night out, et cetera, et cetera?

01:20:39Like, because you're playing into, even if you don't intend on doing it, it's always nice to sort of be window shopped against, I suppose.

01:20:45Totally.

01:20:46And it's interesting, right?

01:20:47Because these are human equivalents of the peacock's tail.

01:20:50And whereas in peacocks and every other species, basically their peacock's tails are non-negotiable.

01:20:57That's just how they do it.

01:20:58Whereas we, because we're a cultural animal, we always have our peacock's tails.

01:21:01We always have our way of showing off status and whatever else, resources.

01:21:06But it varies from culture and culture and time to time.

01:21:09Why isn't it that women aren't turning up in a fast car with an expensive watch outside?

01:21:13That's a very interesting question.

01:21:14And I guess because that's more indicative of resources and resources are more important to women than men.

01:21:22I don't know, there was this study where this guy, it wasn't a study actually, this guy in his class, his evolutionary psychology class.

01:21:32He was showing a photo of this amazing Rolex and people saying how great it was and what a great way of attracting a mate that it would be.

01:21:41And then he revealed the trick was that actually it was a woman's Rolex rather than a man's.

01:21:46And, uh, and, and his point was that actually this goes both and in both directions more than we kind of think it does.

01:21:53Yeah.

01:21:54Have you seen, I think it's Andrew Thomas that did this study.

01:21:58Have you seen the preferences that women state when it comes to sperm donors?

01:22:07Yeah.

01:22:08So this is fucking fascinating.

01:22:10Cause what's interesting is when you run a, a kind of a split test or you're able to separate out certain motivations from, uh, a behavior that people are typical with.

01:22:20So in order for you to do the, I want to have kids with this person, typically you need to go through courtship phase and get to know them.

01:22:29And even if it's a one night stand, be seduced by them.

01:22:32Yeah.

01:22:32But that means that you're optimizing for two different things.

01:22:35You're not just optimizing for the genes that your kid gets.

01:22:37You're also optimizing for the expression of traits that make you want to get into bed with somebody.

01:22:45Right.

01:22:46But if you get rid of the seduction side of this, all you're optimizing for is what do I want my kids to have from a trait perspective.

01:22:52Yeah.

01:22:53And that difference of when you get rid of the need to actually be attracted to somebody and you can just optimize for what do I want my kids to be like.

01:23:01Yep.

01:23:02Kind of fascinating.

01:23:03It's really fascinating, right?

01:23:04And, and just the same mate preferences emerge in that context as emerging and actual, uh, interactions, social interactions.

01:23:11Yeah.

01:23:12There's that Clark Hatfield study as well, right?

01:23:14The on the street interview.

01:23:16Yeah.

01:23:17Yeah.

01:23:18That's the one where, um, uh, basically they got a bunch of good looking guys, good looking gals to go around, uh, campus on a nice day.

01:23:27Uh, walk up to random people on the campus and just say, hello, how you doing?

01:23:31Um, I've noticed you around the place lately and find you very attractive.

01:23:35And I was just wondering whether you wanted to dot, dot, dot.

01:23:38And then they would finish that sentence was one of three options.

01:23:41Option number one was, I was wondering if you wanted to go out with me tonight.

01:23:44Option number two was, I was wondering if you wanted to come up to my room.

01:23:48And option number three was, I wondering, wondering if you want to go to bed with me.

01:23:51And they got men to ask women, women to ask men.

01:23:54And for the, um, for the first question that go out with me question there, and the first study they did, there was basically no sex difference.

01:24:02So it was about 50%, 50, 50 likelihood of saying yes in both cases.

01:24:06Uh, other replication studies have found that it's not a huge difference, but that actually men are more likely to say yes than women are.

01:24:13But then with the other two questions, the gaps get bigger and bigger with question number two, which is, would you want to come up to my room?

01:24:20Um, what was it, it was basically 60, in the first study about 67% of men said yes.

01:24:27So actually higher than the date rate.

01:24:30More likely to go up to your room than I am to go on a date with you.

01:24:33Exactly.

01:24:34Hilarious.

01:24:35Uh, with women on the other hand, it, uh, sank down to, I believe it was 6% said yes to that.

01:24:41Uh, and then the gap was even bigger for the last question, unsurprisingly.

01:24:45So would you go to bed with me?

01:24:4775% of men said yes, uh, to that offer.

01:24:51So at even higher rate of men, whereas, uh, exactly 0% of women said yes to the kind offer.

01:24:58And not only that, but actually the, the manner of the refusal differed between men and women.

01:25:03So of the, um, 25% of men who said, thanks, but no thanks.

01:25:08Well, they kind of said that they were like polite about it.

01:25:10And, uh, some of them said, I'm really sorry.

01:25:12I'm, I'm meeting my fiance or whatever.

01:25:14A bunch of them even asked for a rain check.

01:25:16Apparently they said, I can't, I'm not very busy.

01:25:18I'm meeting my phone or whatever, but maybe we could postpone the sex tour later.

01:25:22Whereas, uh, none of the women, uh, who were refusing were polite about it at all.

01:25:27They were more, they were more like, are you crazy?

01:25:30Um, how, how dare you ask me that?

01:25:32None of them, um, apologize and ask for a rain check.

01:25:36Why do you think that the manner of refusal was so different?

01:25:40Uh, I think that it reveals, uh, two reasons.

01:25:44So one is there's this average difference in interest in casual sex.

01:25:48And because men are more interested in it, they are more likely to be flattered by the request.

01:25:53Uh, because men are much more likely to approach women than vice versa.

01:25:57Traditionally, uh, women are much more likely to get sick of it and, and to have to, you know, uh, push guys away.

01:26:05Whereas guys are much, it's a rarer event for them.

01:26:07So they are more likely to be flattered and, uh, and hugely grateful on the rare occasions when it happens.

01:26:14Uh, the other thing though.

01:26:16And the reason I think the difference is quite so big is because it's not just a reflection of sex differences and interest in casual sex.

01:26:24I think also in that situation, like, like if a woman were to go off with a guy that she doesn't know, she's at a greater physical risk than if a guy goes off with a woman that he doesn't know.

01:26:36Mm-hm.

01:26:37So the fact that the difference was massive is partly due to that as well.

01:26:42It feels like a danger.

01:26:43Exactly.

01:26:44Some of that emotional activation of, hang on, I'm going to go with this person who I don't know, who is physically stronger than me.

01:26:51Yep.

01:26:52Explosion.

01:26:53Exactly.

01:26:54As opposed to, this is just way less of a, it feels less of a physical threat to me.

01:26:58Exactly.

01:26:59Those both make, those both make complete sense.

01:27:01Yeah.

01:27:02There's a, an interesting wrinkle in this.

01:27:05Now I'm going to guess that when they did this, the Clark Hatfield study, they must have done some sort of rated assessment of the attractiveness of the man or the men versus the women to ensure that they were similarly high in terms of physical attractiveness.

01:27:19Yeah.

01:27:20Right.

01:27:21So something that I learned that I think is absolutely fucking hilarious is one of the reasons why women, and I presume men would be too, if women approached men at the same rate.

01:27:32One of the reasons why women are sometimes quite rude when guys come up to them is if they feel like there's too big of a disparity in mate value between them and the person doing it.

01:27:42Right.

01:27:43Because they go, hang on, you think that you've got a chance with me.

01:27:47Yeah.

01:27:48Oh my God.

01:27:49It's basically an insult.

01:27:50Yeah.

01:27:51Yeah.

01:27:51It's essentially an insult.

01:27:52If you as a woman think that you're an eight, nobody thinks like this.

01:27:56Yeah.

01:27:57It's not the whatever podcast.

01:27:58You as a woman think that you're an eight.

01:28:01Yeah.

01:28:02And a guy that you think is a three comes up to you.

01:28:05That is.

01:28:06Yeah.

01:28:07It tests your own self-perception and you go, fuck, maybe this is how the world sees me.

01:28:13Yeah.

01:28:14I think I'm an eight as well.

01:28:15Yeah.

01:28:16Yeah.

01:28:17Yeah.

01:28:18And I think that it feels like an insult.

01:28:19And the same thing, like, fucking no, get away, because rightly so, you're kind of pissed that this thing happened.

01:28:25I wonder if guys would feel the same in reverse.

01:28:28See, my hunch is that they would be less likely to take it as a huge insult if the guy felt he was an eight and approached by a three.

01:28:35Yeah.

01:28:36Well, preference for casual sex.

01:28:37Yeah.

01:28:38Uh, rarer approach in any case.

01:28:42Indeed.

01:28:43And because women are less likely to approach.

01:28:46Yeah.

01:28:47I think that most guys would actually see it as closer to, you know what?

01:28:51I'm so good looking that I got that girl to overcome her non-approach predisposition.

01:28:59Yeah.

01:29:00That's the power of my attractiveness.

01:29:02I think that's, I think that's how a lot of guys would take it.

01:29:04I agree.

01:29:05And that's why it is, it is flattering.

01:29:07It's like, um, somebody running for a bus fast that they really, really want.

01:29:11Yeah.

01:29:12You're like, well, you must really want this bus.

01:29:13Cause look at how fast they're going.

01:29:14Yeah.

01:29:15Yeah.

01:29:16And guys tend to be more overconfident than women.

01:29:19Mm.

01:29:20Yeah.

01:29:21What about sex differences in aggression?

01:29:23Sex differences in aggression are very, very consistent.

01:29:26Um, especially for direct aggression.

01:29:28So face to face aggression and guys predominate.

01:29:31And a really interesting fact about the aggression sex difference is that it's for like verbal aggression.

01:29:37It's there and it's significant.

01:29:39It's fairly modest though.

01:29:40So the effect size might be about like a 0.5 effect size.

01:29:43So half a standard deviation between the mean for men, men and women, and maybe, you know, pluck two people at random, uh, guy and a gal.

01:29:52Two thirds of the time, the guy is going to be higher in verbal aggression.

01:29:55But as you go further out to more and more intense forms of aggression, the size of the sex difference gets bigger and bigger with every step.

01:30:02So when you go to low levels of physical aggression, slapping, pushing, that kind of thing, that you have a larger sex difference, men doing it more than you get into serious physical aggression, violent crime.

01:30:14That's much more men than women.

01:30:16Independent of who the victim is.

01:30:18Independent of who the victim is.

01:30:19Yeah.

01:30:20Um, and then when you get to the extreme of one-on-one aggression, which is homicide, uh, men vastly predominate.

01:30:28So across different, uh, cultures, every single nation, uh, every data set I've ever seen 90 plus percent of homicides are perpetrated by men.

01:30:36Men are also the majority of the victims as well.

01:30:38And, and almost all data sets that I've seen.

01:30:41Um, but, but yeah, the 90% plus perpetrators very, very strong effect.

01:30:47Yeah.

01:30:48Uh, men commit more than 90% of homicides in every society on earth where data is available in this gap is remarkably invariant across cultures, not just the absolute rates in humans.

01:30:56In humans, males commit 95% of homicides and the 70 to 80% of homicide victims.

01:31:02In chimpanzees, male commit 92% of chimpicides and are 73% of victims, virtually identical numbers to humans.

01:31:09It's wild, right?

01:31:10Yeah.

01:31:11Now they are more aggressive than us.

01:31:12I think some, sometimes people hear that and they think that the claim is that we're just as aggressive as chimps, but they are more.

01:31:18But the size of the sex difference in lethal aggression is the same and the size of the, the targets, the sex difference in the targets of aggression is about the same as well.

01:31:27Why?

01:31:28Uh, that is a direct offshoot of the fact that, um, it's the selection for getting to be one of the few males that has many offspring rather than the many that have few or none.

01:31:42And one of the ways that males do that is they compete with each other, uh, for status and resources, uh, which increase their mating opportunities.

01:31:52And so you get selection in many, many species, not just humans selection for greater aggression in the males and, and particularly for greater male, male aggression, which is why you have this, the skew toward.

01:32:03And not only the other males more aggressive, but the targets of their aggression tend to be same sex individuals as well.

01:32:09For women and for female animals in general, they are capable of aggression in many species, but there's just less of a selection pressure.

01:32:16It's less, it's less useful for them evolutionarily to engage in same sex combat for status and resources because of the fact that the, the ceiling offspring number that they have is lower.

01:32:28So they can't vastly increase the number of offspring they have by fighting each other and getting lots of status resources.

01:32:35And ultimately mates, you know, that, that won't boost the number of offspring they have because the ceiling is lower.

01:32:40So it's, it's costlier for them.

01:32:42The costs aren't worth the risks.

01:32:44Yeah.

01:32:45Plus more fragile.

01:32:46Yeah.

01:32:47More easy, more easily killed.

01:32:49Like just generally.

01:32:50Yeah.

01:32:51Um, but that's, that's possibly just an offshoot of the fact that there's been less selection on them for aggression.

01:32:56Right.

01:32:57So there's been more, more of that on males.

01:32:58So you don't need to build up the defenses in order to be able to, that's why we have a brow ridge.

01:33:01That's why we've got bigger hands.

01:33:03Exactly.

01:33:04Yeah.

01:33:05Tell you what's interesting.

01:33:06Again, talking to Andrew Thomas about this, he said, why is it the case if violence is rightly so such a huge fear that most women have that lots of women are attracted to powerful men who are able to be violent.

01:33:23And Andrew's theory is that it's a perspective that a guy who is violent is able to turn it on and turn it off in service of the family unit.

01:33:39Yeah.

01:33:40As opposed to violence being a trait that just is more global across the board.

01:33:44Yeah.

01:33:45I think.

01:33:46Has Andrew done Krav Maga?

01:33:47He's into martial artsy type stuff.

01:33:48I swear.

01:33:49I think so.

01:33:50Yeah.

01:33:51Yeah.

01:33:52And, uh, he was explaining how many Krav Maga, this Israeli martial art, very lethal, supposedly martial art.

01:33:59Um, a lot of the guys that he trained with unbelievably lethal physically.

01:34:04Yeah.

01:34:05And a lot of the training was them learning to turn it off, not turn it on.

01:34:10Interesting.

01:34:11Yeah.

01:34:12And that, that.

01:34:14The number of men who are physically imposing and might seem like somebody that would be really great to be able to protect the family unit.

01:34:22Yeah.

01:34:23That have done the work to be able to learn to turn that off.

01:34:26Yeah.

01:34:27To the trigger that makes this person likely to be a flash in the pan.

01:34:32You don't want to fuck with me, bro.

01:34:34Guy.

01:34:35At least non-zero Lee are also going to have some triggers that will be more sensitive when it comes to interpersonal communication and domestic disputes.

01:34:46Yeah.

01:34:47And things around the house.

01:34:48Indeed.

01:34:49Uh, interesting, isn't it?

01:34:50Having, uh, that kind of temperament, violent temperament and the capacity for physical aggression is a, uh, it's really a mixed blessing for women.

01:34:59Yeah.

01:34:59You know, it's great if the guy's going to protect them, protect the family, but it's not so great because he can potentially turn that against them as well.

01:35:06Yeah.

01:35:06And so, you know, you get the evaluation of those traits.

01:35:10It can increase attract, like aggression itself.

01:35:13I don't think increases attractiveness.

01:35:15Protectiveness does.

01:35:16Yeah.

01:35:17Uh, muscularity and the like can increase attraction somewhat, but because it's a mixed blessing, I think women are also interested in the guy's character.

01:35:24Muscularity seems pretty reliable at improving attractiveness.

01:35:26Yeah.

01:35:27Yeah.

01:35:28It's probably the most easily modifiable thing that guys can do.

01:35:31Right.

01:35:32Yeah.

01:35:33In fact, I think William said that this is exactly the case because he's, he's looking at his incel stuff.

01:35:37Yeah.

01:35:38Did you see now I bro science this, I put the, I put the, the captain of bro science hat on, uh, when Mackin came through last time.

01:35:46Yeah.

01:35:47And I said, I'm pretty sure that I've seen a study that says a woman would be, uh, would lose more attraction if her partner didn't protect her during a physical altercation than if he cheated on her.

01:36:02Right.

01:36:03And then the guys went and replicated it and.

01:36:05And you were right.

01:36:06I was right.

01:36:07Excellent.

01:36:08I was right.

01:36:09Um, I mean, it wasn't my original insight because I found it in a study that I couldn't discover again, but this, this, this, the same insight being true, the protectiveness, the ability to protect.

01:36:16In fact, do you know what it is?

01:36:17Yeah.

01:36:18It was the willingness to protect.

01:36:19Yes.

01:36:20Wasn't even the ability to protect.

01:36:21Yes.

01:36:22But I suppose willingness to protect is the most important part of protectiveness because you can be the biggest guy in the world, but if you're not prepared to step in between your missus and this potential assailant.

01:36:31Yeah.

01:36:32It doesn't mean anything.

01:36:33You might as well not be.

01:36:34You know, yeah, exactly.

01:36:35I wonder, do you know what it is?

01:36:36I wonder if this would be, this is another new skew that the guys should do.

01:36:39Yeah.

01:36:40Is it more or less attractive for a guy who could protect you to not than a guy who couldn't protect you to not?

01:36:49That's an interesting one.

01:36:50You know what I mean?

01:36:51We're trying to separate out here.

01:36:53But in terms of the character trait, it would be less attractive for the guy who could protect you, but doesn't, right?

01:36:59Mm-hmm .

01:37:00That shows a worse character.

01:37:01Yep.

01:37:02Um, but I guess it does also matter.

01:37:05If they're not going to do it anyway.

01:37:06I just need to train him to be able to in future.

01:37:08Well, right.

01:37:09There is that.

01:37:10There is that.

01:37:11Yeah.

01:37:12But if they're not going to do this.

01:37:13I need to teach him to be able to, like, be strong enough to be protective.

01:37:15Yeah.

01:37:16Or I need to be able to change his character in order for him to use his strength of potential protectiveness.

01:37:20Yeah.

01:37:21Yeah.

01:37:22But if he's definitely not going to do that, that's going to be very off-putting.

01:37:25And you might just want the person who is not quite so good at protecting, but is willing to do it.

01:37:29Mm-hmm .

01:37:30If they, if they can do it.

01:37:32Fascinating.

01:37:33Yeah.

01:37:34Why is it, why is it that women care more about a man's height than women do?

01:37:37Is it playing to this?

01:37:38Uh, I think it probably is.

01:37:39I think it must be.

01:37:40I think it's within a cluster of traits that determine protectiveness and the like.

01:37:44Muscularity, height, they, they're all part of the same package.

01:37:48Mm-hmm .

01:37:49And it's interesting, right?

01:37:50That does seem to be really, really high on the list for women.

01:37:52It seems to be very important.

01:37:53You know why this makes the most sense?

01:37:56It makes the most sense.

01:37:57And it's the probably, yeah, I would, I would go as far as to say it's the most commonly cited.

01:38:06Well, you bitches internet kind of rebuttal that guys have around.

01:38:11I think, uh, Tinder released as an April fool's joke about 10 years ago, a height filter that people could use.

01:38:18Wouldn't it be funny if we gave you a height filter?

01:38:20Yeah.

01:38:21That's now an actual feature.

01:38:22It's an actual feature, right?

01:38:23Yeah.

01:38:24Um, and many women don't need to date or don't want to date men that are under six feet.

01:38:30Uh, especially not men when you get sort of like five, seven, five, six, five, five, very few would.

01:38:35And I had this insight, the tall girl problem, uh, and it was born out of a friend whose sister is five foot two.

01:38:44Uh, sorry, her sister's five foot 11.

01:38:46Um, so if she wants to wear heels on her wedding day, she's looking at professional athletes.

01:38:50Yep.

01:38:51And they were going around the supermarket and she saw this guy who was like six, five, like tall dude, like you, tall guy.

01:38:58And she sort of nudges her sister and says, like, I might go up, I might go up and talk to him.

01:39:04And they round the corner and they say, see him with this five foot two Latina bombshell.

01:39:11And she kicks off at her sister quietly, uh, and says like this fucking bitch.

01:39:17Like she could date five foot five, five foot six, five foot seven.

01:39:20Why'd you have to take a guy that's a foot and a half taller than her?

01:39:23But the point here is if we're talking about protectiveness as the driver.

01:39:29Yeah.

01:39:30The fact that your chick is a five, two Latina, not a five 11 American does not make your height any more or less useful when it comes to protectiveness.

01:39:42I don't need to protect you less just because you're smaller.

01:39:44Yeah.

01:39:45Yeah.

01:39:46Indeed.

01:39:47And this is why I think you don't see much of a height compensation effect.

01:39:53Yeah.

01:39:54Other than, I guess if you're five foot two, you can't really tell the day.

01:39:58Like I don't, above probably five, 10, it's all just up there.

01:40:01Yeah.

01:40:02It's just like, it's over there, you know, in the clouds.

01:40:04Exactly.

01:40:05Yeah.

01:40:06Yeah.

01:40:06My cousins, my cousins are quite tall because I'm from a tall family and I know they were

01:40:10complaining often.

01:40:11I remember then complaining, female cousins, uh, about guys, taller guys dating much shorter

01:40:16women.

01:40:17But I guess, I guess how tall my wife is.

01:40:19She's five foot four.

01:40:21So.

01:40:22These bloody bitches.

01:40:23How dare they take the toll, man?

01:40:25Uh, all right.

01:40:26Sex differences in stalking.

01:40:27What about that?

01:40:28Uh, women do a lot more of it.

01:40:30Joke.

01:40:31Men do a lot more of it.

01:40:35Uh, men do a lot more of it.

01:40:36It's, I think it's just, um, an example of the fact that men are more, you know, proactive,

01:40:42seeking out mates, seeking out multiple mates, uh, and stalking is the subcategory of that

01:40:46when it gets into extremely inappropriate examples of that.

01:40:50Um, and also I guess, uh, yeah, it's also, it's not just mate seeking.

01:40:54It's also when people get fixated on somebody and both sexes can do that.

01:41:00They can get fixated on somebody.

01:41:02Sort of limerence type thing.

01:41:03Yeah, yeah, exactly.

01:41:04Limerence.

01:41:05Yeah.

01:41:06So sort of falling in love, except that we call it limerence because it's an inappropriate

01:41:10circumstance, i.e.

01:41:11a circumstance where the other person does not reciprocate.

01:41:13Both sexes can do it, but men are more prone to aggression and risk taking and just

01:41:19bad behavior.

01:41:20And so they're more likely to do more of those kinds of behaviors in the context of, uh, of

01:41:24limerence and being fixated on somebody.

01:41:26What about surveillance, surveilling of a partner checking in?

01:41:31Because I could see two, two reasons why either side might be doing it more.

01:41:36Uh, male parental uncertainty, which we haven't talked about yet, but is super important that

01:41:41no woman has ever given both to a child and wondered whether it was hers.

01:41:44Yeah.

01:41:45But many men have looked at maybe even all men to some degree.

01:41:49In fact, it would be evolutionary, uh, useful for you the first time that you look at your

01:41:53kid to be so beautiful.

01:41:55And those my eyes.

01:41:56Yeah.

01:41:57Yeah.

01:41:58I think they're my eyes.

01:41:59Um, uh, but given the fact that you have high male parental uncertainty.

01:42:02Yeah.

01:42:03Because you've got concealed ovulation and you don't have the same kind of sort of harem,

01:42:07hermetically sealed sphere when it comes to men and women.

01:42:12Yeah.

01:42:13Um, stalking.

01:42:16I can see a surveilling surveillance behavior, uh, make God could be a part of mate guarding.

01:42:21Totally.

01:42:22Uh, to try and counteract that.

01:42:24But I could also see how it would be useful for women in order to ensure that their partner

01:42:30doesn't leave them high and dry because there's more of a dependency, especially if we are going

01:42:36to have a kid or do have a kid.

01:42:38Yep.

01:42:39Um, the, the man doesn't need the woman as much for survival.

01:42:43Uh, but the woman doesn't need to check on the man as much to ensure female parental uncertainty.

01:42:49Yeah, that's exactly right.

01:42:51Um, and both sexes do get jealous, uh, paternity uncertainty or, uh, you know, parental uncertainty

01:42:58is uniquely an issue for guys, but you're absolutely right that there is, uh, the danger of desertion

01:43:04for women.

01:43:06And so for different reasons, both sexes have evolved to be, to be jealous and prone to jealousy.

01:43:09And one way that that manifests.

01:43:11So, so jealousy drives mate guarding behavior.

01:43:13And one subset of mate guarding behavior is surveilling and just keeping, keeping an eye

01:43:18on what the person is up to.

01:43:19And are they getting on too well with that good looking next door neighbor or the good

01:43:23looking guy or woman at work?

01:43:25Um, and then if you take that to an extreme, that's where it becomes surveilling behavior.

01:43:30Isn't it interesting that you have a, an extreme insight of men about other men and an extreme

01:43:39insight of women about other women, but the failure of cross-sex mind reading still occurs

01:43:43even when you add other individuals in.

01:43:45Yeah.

01:43:46So when we're talking about surveillance, jealousy, mate guarding, et cetera.

01:43:51The, I mean, William put these stats up recently about how, what the percentage is of men who

01:43:58would sleep with a female friend.

01:44:00It's huge.

01:44:01Yeah.

01:44:02It's like 50% of relationships used to be friendships.

01:44:06Yeah.

01:44:07Yeah.

01:44:08Yeah.

01:44:09Yeah.

01:44:10Uh, so that's like 50%.

01:44:11Yeah.

01:44:12That's a huge amount.

01:44:13And I think, uh, when you put all of this together, you end up with a world where inside of a

01:44:21relationship, men are trying to explain to women what they see in other men that are around

01:44:26them.

01:44:27And women are trying to explain to men what they see in the other women that are around

01:44:30them.

01:44:31Just because it's not them talking about themselves doesn't mean that they can explain it.

01:44:36A woman is no better at understanding another man than her own husband.

01:44:40And a man is no better at understanding another woman than his own wife in these sort of, uh,

01:44:45more subtle, uh, hard to detect motivations and behaviors.

01:44:48Did you say what?

01:44:49Um, that, those data that, uh, that William was talking about.

01:44:53Um, so, so yeah, so like a lot of guys would be interested in sleeping with friends that

01:44:58they have, right.

01:44:59Um, it's not true in the other direction, like fewer, uh, some women, but fewer of them,

01:45:03um, are particularly interested in sleeping with, uh, male friends that they have.

01:45:07Mm-hmm .

01:45:08But because of the sexual over-perception bias, the male friends in question would probably,

01:45:12uh, assume otherwise.

01:45:14Mm-hmm .

01:45:15What's the sex difference around sexual violence?

01:45:18Sexual violence, uh, men are much more likely to do it.

01:45:21Um, and that is just partly just an offshoot of the fact that men are more aggressive,

01:45:25uh, more aggressive.

01:45:26Mm.

01:45:27Um, yeah.

01:45:28And the numbers are pretty big.

01:45:30So sexual violence, um, is much more often perpetrated by men than by women.

01:45:35It's not, it doesn't only go in the one direction though, but it is just much more common for

01:45:40men to do it.

01:45:41Do you have any idea what the numbers are?

01:45:42Uh, I probably do.

01:45:43Let me have a think.

01:45:44Um, okay.

01:45:45Um, okay, so I do have a few numbers coming to mind, but I'm not actually sure if they're

01:45:48the right numbers.

01:45:49So I'm going to, I'm going to again, do the annoying academic thing.

01:45:52Directionally correct, specifically vague.

01:45:54Indeed.

01:45:55So directionally correct.

01:45:56And, and I'll, you know, I've got to say that it is a big difference.

01:45:59Yep.

01:46:00Um, I think the effect size might be something like, uh, two.

01:46:06So like two standard deviations between the mean for men and women for the extreme forms

01:46:11of, um, of sexual violence and sexual assault and harassment and the like.

01:46:15Yeah.

01:46:16Yeah.

01:46:17Yeah.

01:46:18Another situation where it's kind of hard to talk about evolutionary explanations for bad

01:46:21behavior, like the worst behavior, right?

01:46:23Yeah.

01:46:24Between this and homicide without sounding like you're excusing it is natural, but.

01:46:26Exactly.

01:46:27But again, natural doesn't mean good.

01:46:28Yeah.

01:46:29I mean, you know, you can explain bad stuff without saying that actually the bad stuff is

01:46:33not good stuff.

01:46:34It's still, uh, bad, even if it has an evolutionary explanation.

01:46:37Yeah.

01:46:38Yeah.

01:46:39Yeah.

01:46:40It's that, uh, analysis is not justification.

01:46:41Yeah.

01:46:42Yeah, exactly.

01:46:43Uh, you know, that's a fucking Hassan Abi quote.

01:46:45That's like a Hassan Piker quote.

01:46:46Is that right?

01:46:47Yeah.

01:46:48He got canceled.

01:46:49He got canceled for talking about some stuff to do with the right wing.

01:46:50Yeah.

01:46:51That is an absolute slammer of a line.

01:46:52Analysis is not justification.

01:46:53Yeah.

01:46:54Uh, but you know, we can see sexual violence.

01:46:57If men are able to procreate without having to do any investment, the ultimate form of that

01:47:08is to not even have to ask for consent as well.

01:47:10Yeah.

01:47:11Yeah, indeed.

01:47:12And, you know, it has been argued that the tendency in some men to do that, to take that

01:47:18path does have evolutionary roots.

01:47:20Um, and I guess really you just have to have two things.

01:47:24You have to have men's greater interest in sexual variety and casual sex, uh, coupled

01:47:32with their willingness to use violence in certain, uh, you know, certain situations.

01:47:38So because men are more interested in casual sex, it's going to be not uncommon for a man

01:47:42to want to have sex with a woman who doesn't want to do so.

01:47:45Yep.

01:47:46And because men are willing to use violence, uh, sometimes to get what they want.

01:47:49Mm-hmm.

01:47:50Every now and then you are going to have that situation where those, those factors add up

01:47:54and the man is going to try to force the woman to have sex.

01:47:57Mm-hmm.

01:47:58That's not as found in our species.

01:47:59Uh, males and many species try to coerce women, uh, females rather, into sex.

01:48:05Yeah.

01:48:06It happens in our species.

01:48:07It's also been argued though, that because, uh, preserving female choice is so important

01:48:13across the animal kingdom, including in our own species.

01:48:15So important to women, uh, that, that helps explain why sexual coercion and rape is so upsetting

01:48:22to women.

01:48:23You know, it's not, we haven't just been socialized for it to be upsetting to women.

01:48:26It's very, very deep in, uh, females nature to be upset by it because it compromises female

01:48:32choice.

01:48:33Oh, that's interesting.

01:48:34Yeah.

01:48:35That's interesting.

01:48:36Because not, not only, not only is it fucking heinous, but you know that because somebody,

01:48:46because this male committed that behavior, they've had to disregard the entire female wide

01:48:55value that is supposed to be, uh, universally, uh, uh, protected.

01:49:01Well, right.

01:49:02Well, I mean, she's evolved this tendency to be choosier about her mates than men have.

01:49:07And she's got these mate choice criteria and, uh, that that's because she can have fewer

01:49:12offspring and therefore each offspring counts for more.

01:49:14So she's got to be, uh, wiser in every mating decision that she makes.

01:49:18And this other male has come along and has just taken that away from her, taking that choice

01:49:25away from her, uh, has gone against the, the, the, she's evolved to be more, to be choosier.

01:49:31And I think this, I think that the inability of men to fully understand what fear of sexual

01:49:41violence must feel like is one of the reasons why any guy who's seemingly sort of flippant

01:49:51or callous about any type of male, female aggression, even non-sexual violence.

01:49:56Yeah.

01:49:57Yeah.

01:49:58Is treated with a very strong antibody response from, from women.

01:50:04Indeed.

01:50:05Yeah.

01:50:06And guys do, you know, uh, guys, the idea of going to prison and being raped in prison,

01:50:09obviously is, is terrifying for a lot of guys.

01:50:11So they, they do get it to some degree, but, um, uh, and I guess particularly when it comes

01:50:16to the sort of lower level stuff, like, like I think in buses, bad men book, he talks about

01:50:21research suggesting that men often will underestimate just how upsetting it is to women to be, to be

01:50:26sexually harassed and to have stuff done to them against their will.

01:50:29And that's another, uh, very good example of a, and a very important example of a failure

01:50:33of cross sex mind reading where the guy just doesn't really appreciate just quite how upsetting it is for

01:50:38that to happen, because if it would happen in reverse, if it would happen to him, he might

01:50:43not like it, but he on average is not going to be quite so upset by him.

01:50:47Mm.

01:50:48Mm.

01:50:49It's interesting that people who denied sex differences seem to sort of not want to argue

01:50:52for parity that if women weren't so held back, they'd want to commit just as much violent crime

01:50:57as men do.

01:50:58Indeed.

01:50:59Yeah.

01:51:00It's a good example of, um, how equality is not necessarily a good thing in itself.

01:51:01Yeah.

01:51:02So, so men are more aggressive than women.

01:51:03The solution to that is.

01:51:04So, so, so we want to kind of.

01:51:05Um, we want to kind of, um, you know, um, how equality is not necessarily a good thing in itself.

01:51:06So, so men are more aggressive than women.

01:51:07The solution to that is.

01:51:08So, so we want to kind of, um, um, how equality is not necessarily a good thing in itself.

01:51:09So, so men are more aggressive than women.

01:51:10The solution to that is.

01:51:11So, so we want to kind of, um, um, um, how equality is not necessarily a good thing in itself.

01:51:11So, so men are more aggressive than women.

01:51:12The solution to that is.

01:51:13So, so we want to kind of, um, um, um, how equality is not necessarily a good thing in itself.

01:51:14Mm-hmm .

01:51:15And, and that has been kept down the fact that they're not doing it.

01:51:17Yeah.

01:51:18The patriarchy, the damn patriarchy.

01:51:19And I guess the thing is that they, and, and we all would want it all to come down.

01:51:23Mm-hmm .

01:51:24And it's a good example of, um, how equality is not necessarily a good thing in itself.

01:51:28So, so men are more aggressive than women.

01:51:30The solution to that is.

01:51:32So, so we want to kind of, um, reduce male violence.

01:51:37And in the process of doing that, we're going to reduce the size of the sex difference.

01:51:41Mm-hmm .

01:51:42And, and that's a, that's a very good thing to do.

01:51:44But the reason it's a good thing to do is not because there's anything inherently wrong with the sex difference.

01:51:48It's because the violence is bad.

01:51:50It's not because the sex difference is bad.

01:51:51It's because the violence is bad.

01:51:52Mm-hmm .

01:51:53And we know that because another way to get rid of that sex difference and violence would be to increase the female level of violence.

01:51:58And that would be big thumbs down on that, right?

01:52:02That is going to make the world a worse place rather than a better place.

01:52:05So the point is, yeah, equality is not a good thing in itself.

01:52:10Yeah, yeah, yeah, yeah.

01:52:11Okay.

01:52:12What about the differences in parenting?

01:52:13Differences in parenting.

01:52:14That's quite a controversial one, actually.

01:52:15Um, that's one of the ones that people like least.

01:52:19The aggression sex difference, no worries about the parenting sex difference people aren't so keen on.

01:52:23And that refers to the fact that in every culture, again, where we have good data, women do more of the direct parenting than men do.

01:52:33Uh, and they invest more in the young.

01:52:36They do more parental care.

01:52:37Um, men in every culture do more than your average male chimpanzee or male walrus, but they do less than women in every single culture.

01:52:46Um, and it doesn't seem to just be because men are forcing women to do it.

01:52:49They do seem to be average differences in terms of parental inclinations with women being more interested in doing it, uh, than men are on average.

01:52:57And yeah, I guess the reason that it's controversial is that there's a concern that people are saying, making up an excuse why you should do it.

01:53:06So, so like the guys are using it as an excuse.

01:53:09It's just, it's just natural that you should want to be changing the nappies and doing these things that coincidentally, I would rather not have to do.

01:53:16Um, so that, that I think is the concern, but in a way it's ironic.

01:53:20So the fact that people consider it to be kind of an insult to say that on average, women are more interested in parenting than men, um, implies a negative valuation of parenting or doing more of the parenting.

01:53:34Because if it didn't imply a negative valuation of that, it would not be an insult to say that women on average are more.

01:53:40This has been one of my most, one of my, one of the best ideas that I think I've come up with over the last couple of years, which was the, the soft signal of male expectations.

01:53:48Yeah, yeah, yeah.

01:53:49I think you mentioned that when we met the first time, right?

01:53:51Yeah, yeah, yeah.

01:53:52The soft bigotry of male expectations.

01:53:54Soft bigotry of male expectations.

01:53:55It's like as if we treat the, the male standard, whatever men do, that's the standard of what, what is right.

01:54:00And if women do it less, that's a bad thing and we should make them more like males, but not so much, not so much the reverse.

01:54:06Um, yeah.

01:54:08And it is very ironic because it's really misogynistic worldview.

01:54:11It is really, isn't it?

01:54:12It is.

01:54:13It is.

01:54:14And so if we're taking a negative valuation of, uh, of parenting, which is what we are implicitly doing.

01:54:20If we say that it's an insult to say women are more parental, we're implicitly, uh, and if it is actually true that women on average are more parental by nature, then we're taking a negative valuation of a more female typical trait.

01:54:32And that is really sexist.

01:54:34Yeah.

01:54:35Yeah.

01:54:36What's the kibbutz experiment?

01:54:37Uh, the kibbutz experiment that, so there, there, uh, um, there, there were these kibbutzim that they had in, in, uh, Israel.

01:54:44So these were these communes, uh, like highly Egeritarian, uh, communes where they wanted to get rid of all traditional kind of structures, including traditional male, female ways where the woman is expected to do all of the childcare.

01:54:59And the guy is out, out in the public doing the public stuff.

01:55:02She's at home doing the private stuff.

01:55:04So what they did was they would, um, they would get all the kids and they would house them in communal houses.

01:55:12And then they would have dedicated adults within the group who would be the primary, primarily in charge of looking after all the kids.

01:55:18So the kids weren't living under the, the roof of their biological parents.

01:55:22They didn't think, you know, the idea was everyone should care for everyone rather than having this traditional, what they sort of saw as bourgeois, uh, approach where people are specifically interested in their own biological children.

01:55:36They want to get rid of them.

01:55:37Um, they tried it, they did manage to make it work for awhile, but what happened was that just the parents hated it.

01:55:45Basically the parents hated not having their own kids living with them under their, under their roof.

01:55:50And they agitated and complained about it.

01:55:52And eventually it broke down.

01:55:53And the interesting thing was that, um, although both parents hated it, most of the, the mothers particularly hated it.

01:56:00And a lot of the agitation came from the mothers more than the fathers.

01:56:04And it's a great example, a great case study, because we often hear that, um, that women are placed in the primary caregiver role by men.

01:56:13They may have kind of forced them into the, into that role, but here was a case where actually, uh, the women in particular were rebelling against the male leaders to try to put themselves into that role instead.

01:56:26So it's, so it's a, another example of a very common phenomenon where you see certain behaviors and certain aspects of human nature that emerge and persist despite culture, rather than because of culture.

01:56:40Culture's pushing the opposite direction.

01:56:41They're actively going against it.

01:56:42Exactly.

01:56:43Yeah.

01:56:44Yeah.

01:56:45I saw this really heartbreaking video of a woman on TikTok.

01:56:48She was at work in a cubicle, looked like a sort of normal office cubicle.

01:56:52And she had a screen up of maybe the daycare that her kid went to.

01:56:59And she was seeing, watching her kid say its first words or take its first steps.

01:57:07And the, it was just one of those ones with the caption over it that said, uh, like me being devastated that I'm at work while my kid is going through one of the most meaningful experiences at the start of its life.

01:57:19And I'm missing it.

01:57:20It's tough, right?

01:57:21There's a real, that's the, uh, the, the work family, um, you know, clashing roles, uh, that, that both sexes do experience, but it does seem to be, um, still a bigger deal to women than men.

01:57:33Yeah.

01:57:34It's not, it's not, it's certainly not something that people are happy to talk about maternity leave and the lack of maternity leave as being kind of barbaric.

01:57:41And I agree.

01:57:42I think, I mean, the UK gives nine months, which is still not enough, but it feels at least remotely humane.

01:57:47Yeah.

01:57:48Uh, in the U S is basically once you're out of the hospital, you're back to work.

01:57:53Yeah.

01:57:54Uh, but very few people, I think it's not a big cultural conversation around what is missed by either the need to go back to work to keep yourself financially stable or the desire to go back to work because of expectations that have been adjusted on women about where their value comes from this soft bigotry thing.

01:58:14Yeah.

01:58:15I don't want to be just a mum.

01:58:16Yeah.

01:58:17Uh, but by being not just a mum, I'm also missing out on a lot of the joys of motherhood.

01:58:21Yeah.

01:58:22Uh, it's a, it's a kind of, it's kind of hard to win that situation.

01:58:26Yeah.

01:58:27Women really don't have a good, a good outcome there.

01:58:29Yeah.

01:58:30And people in general, I mean, in a way, you know, there are, there are these kinds of trade-offs for everybody always.

01:58:35And, and choosing one option always does mean, uh, not choosing another one.

01:58:40Yeah.

01:58:41I know that a lot of people solve that problem to some degree, to the extent that it is solvable.

01:58:45A lot of women do by taking some time off, you know, more time off, taking a career break, in other words, when the kids are young.

01:58:52Yeah.

01:58:53But then particularly when they go to school, then, you know, getting back on the, uh, career, career horse.

01:58:58Yeah.

01:58:59What about differences between men and women in sexual jealousy?

01:59:02Um, that's an interesting one.

01:59:04So both are prone to it, like I mentioned, but for the reasons that, uh, you mentioned already, um, men, men's jealousy is more focused than women's on sex.

01:59:15So a sexual infidelity, like, like if you ask men, which would upset you more, uh, your partner who you love going off and sleeping with somebody else or just forming a close emotional bond with somebody else.

01:59:28That both of those are upsetting to most men, but men are more likely to say that the sex is more upsetting than just the bond.

01:59:35And you pose the same question to women.

01:59:39And again, it's both of them are upsetting to, to the vast majority of women, but they're more likely to say that the emotional bond, the sort of falling in love, maybe falling in love with the other person, um, that that's more upsetting than just sex per se.

01:59:52Hmm.

01:59:53It's interesting, right?

01:59:54And it comes out of the fact that, uh, men had this, this problem of paternity uncertainty.

02:00:00Like you say, no man in the history of the species has ever, um, no woman in the history of the species ever given birth and thought, now, how do I know that this is my kid and not some other woman's kid?

02:00:11Whereas, you know, for most men, more than likely it is their own kid.

02:00:14Um, but there is always some non-zero chance that actually it's not, that it's the, uh, the good looking next door neighbor's kid instead.

02:00:21So yeah, that's why sex is more important issue for men than women.

02:00:25Women are more likely to be left holding the baby and that is not good for their fitness because it's going to reduce the time before they can have another kid and, uh, just make things a lot more difficult for them.

02:00:37And so it's obviously not great if their partner sort of sleeps with somebody else.

02:00:43It's not great.

02:00:44They'd be very, very upset about it.

02:00:45Very often it destroys the relationship, but it's even worse for most women.

02:00:51If the partner gets emotionally involved with somebody else, because then the, whether, whether they want the relationship to end or not, it's going to end because they're going to leave, very likely going to leave and, uh, set up shop with the other woman.

02:01:03I have an example that I heard about from a while ago that a, uh, a friend was on 23andMe or ancestry.com and one day in their thirties got an email notification saying you've got a new half sister.

02:01:20Right.

02:01:21And she says, how the fuck have I got a new half sister?

02:01:23What it turns out was that 32 years ago, the dad had had a one night stand affair.

02:01:30That kid had never met the father, never been involved again.

02:01:34Right.

02:01:35But three decades later, this situation unfolds and, uh, obviously awful, awful to try and live through.

02:01:45But I would have been fascinated to have done a study to work out what happens to, what happens to sexual jealousy and intimacy jealousy and the fear of, uh, resources, resource provisioning needing to be split.

02:02:01Yeah.

02:02:02You've gone past all of those things because you have this, you know, three decades, assuming that there's not been more infidelity, this three decade example of someone committing to the family and raising the kids and doing the rest of this stuff.

02:02:15And also the person that would have been the dependent is no longer in need of any of the provisioning.

02:02:21It's really interesting.

02:02:22Yeah.

02:02:23You understand what I'm getting at?

02:02:24I do.

02:02:25To like separate out all of the typical areas.

02:02:27Yeah.

02:02:28Now trust, infidelity, all of those things, like obviously horrible, but kind of, kind of fascinating too.

02:02:35It is really fascinating.

02:02:36And I wonder if this could be an example where proximate and ultimate, uh, like thinking about the proximate and ultimate might solve the mystery.

02:02:46Cause it's possible that, cause we don't necessarily think about, we don't necessarily think it through, right?

02:02:51We're not really necessarily thinking, well, I'm going to lose this partner.

02:02:54He, he's going to fall in love with her and he's going to go away.

02:02:56And then I've got this baby and I'm going to have no one to help me with it.

02:03:00That's the evolutionary rationale, but it could just be a gut reaction.

02:03:03Like he's getting close to somebody else.

02:03:05I hate that.

02:03:06I feel jealous.

02:03:07I feel bad about it.

02:03:08And so that could kick him just as strongly 30 years down the line when it doesn't matter anyway.

02:03:13You know, like you say, trust issues and those kinds of things are going to kick him.

02:03:16Could kick him just, just as strong, even though evolutionarily the circumstances, it doesn't matter anymore.

02:03:22Hmm.

02:03:23The gut reaction that evolved might be, might not discriminate those, those details.

02:03:29Hmm.

02:03:30What do we know about sex differences in personality?

02:03:32Uh, well, there are some, and they're pretty consistent.

02:03:35They're not huge.

02:03:36Two of them are bigger, uh, bigger than the rest.

02:03:38Now if you're thinking about the big five personality traits.

02:03:41So, so the ocean acronym, right?

02:03:43So openness to experience, neuroticism, extroversion, agreeableness, uh, and, uh, conscientiousness.

02:03:51I got that in the wrong order.

02:03:52That wasn't ocean, but, but those are the, those are the five.

02:03:56So, um, the two sex differences that are largest and most consistent, uh, the sex difference in neuroticism, which is proneness to negative emotions like depression and anxiety.

02:04:07Plus emotional volatility, so ups and downs.

02:04:10Um, and that is about a medium effect size.

02:04:13So I guess it's usually estimated between about 0.2 and 0.5, um, a standard deviation between, between men and women.

02:04:20There's that one.

02:04:21And then the other consistent one is the sex difference in agreeableness.

02:04:25Uh, and women on average score higher.

02:04:28Again, it's not a massive difference, heaps of overlap, but, but again, it's 0.2 to 0.5.

02:04:33I would say it's, um, it's a medium, small to medium sex difference, uh, as well.

02:04:38There are some sex differences in the other, uh, three big five traits.

02:04:42Um, often, not always.

02:04:46You sometimes find that women score a bit higher in conscientiousness, but, but not always.

02:04:51Some studies don't find that.

02:04:52Uh, extroversion on average, women slightly higher on extroversion, but, but again, not always.

02:04:58And it's, it's a smaller difference if it is one.

02:05:00Uh, and then, uh, uh, what's the other one?

02:05:06Conscientious.

02:05:07Openness.

02:05:08Openness.

02:05:09Yeah.

02:05:10Openness slightly higher for, for women as well.

02:05:11All no difference.

02:05:12What's the explanation for why those would be the case?

02:05:15Uh, well, I, I don't think we know for sure, but my best guess, so then neuroticism, sex

02:05:21difference.

02:05:22So that's proneness to things like anxiety and depression.

02:05:24And I think women, there's a general trend where women seem to be more self protective

02:05:29than men, which is kind of the flip side of the fact that men take greater risks than women.

02:05:34They're more risk takey.

02:05:35I think that that evolved because that is, um, about trying to propel yourself up the status hierarchy.

02:05:41You've got to take risks in order to do so.

02:05:43Uh, and men have evolved to do that more than women because they have a higher maximum offspring

02:05:47number.

02:05:48But yeah, the flip side of risk taking is to be more self self protective.

02:05:52Part of that is to be more prone to anxiety.

02:05:54Anxiety.

02:05:55The function of anxiety is to, it's the same as the function of the, of the turtle shell.

02:05:59It's to protect yourself.

02:06:00It's about protection.

02:06:01It's about protection.

02:06:02So I think that's why women are more neurotic.

02:06:06Now the agreeableness, sex difference.

02:06:08So women on average are more agreeable.

02:06:10Um, I don't have quite as strong an idea about that.

02:06:14I do think that, well, I guess, I guess it could be the flip side of the fact that men

02:06:18are, um, sort of more, more aggressive, more, more pushy.

02:06:22Um, and that evolved like, like we've discussed to try to, again, get up the status hierarchy,

02:06:27uh, beat rival males to, to go up in the world and achieve status and resources.

02:06:32Uh, women have evolved to do less of that.

02:06:34And one manifestation of that is the fact that they're more, more agreeable, more friendly,

02:06:39more compassionate.

02:06:40Um, and just the way that women have evolved to form social bonds, it does tend to, uh,

02:06:46have a higher level of compassion and, and understanding the other person.

02:06:51Um, that seems to be more common in women than men.

02:06:54What about the people versus things divide?

02:06:56Hmm.

02:06:57So that's an interesting one, right?

02:06:58Um, that is a bigger difference.

02:07:01That's actually quite a big difference.

02:07:03It's one of the bigger psychological sex differences.

02:07:06And the effect size there is, is like one standard deviation or even, even a bit more when it

02:07:10comes to people, people versus things.

02:07:12Right.

02:07:13Very, very consistent.

02:07:14I think there's a good case that it is not just due to socialization.

02:07:18So, so one thing is that, like I mentioned earlier, it has persisted for as long as we've

02:07:22been measuring it.

02:07:23Very, very consistent.

02:07:24Even when the culture is trying to push against it and, and get women more interested in things

02:07:28related professions, traditionally male professions.

02:07:31It seems to be related, as we also mentioned, seems to be related to prenatal hormonal exposure.

02:07:36And one thing I haven't mentioned already is that it's also very, very cross-culturally

02:07:41consistent.

02:07:42So there was one study that had about 200,000 people in it and found that sex difference in

02:07:47career related interests, found it in 53 out of 53 nations.

02:07:51And another one had half a million people and found it in 80 out of 80 nations.

02:07:56Wow.

02:07:57And that level, it's amazing, right?

02:07:58That level of cross-cultural uniformity, you just hardly ever find it in the social sciences,

02:08:03but you do find it for that difference.

02:08:05And this has been around for a hundred years.

02:08:06Yep.

02:08:07Yeah.

02:08:08First documented in 1911.

02:08:09Yeah.

02:08:10Yeah, that's right.

02:08:11Yeah.

02:08:12First documented it and it's been consistent ever since.

02:08:14It's one of the biggest differences.

02:08:15And I always find that pretty interesting really, because the kind of careers that we have today

02:08:20are evolutionarily novel.

02:08:22So you might not necessarily expect that to be one of the biggest sex differences.

02:08:26You know, interest in careers that just haven't existed throughout the vast majority of evolutionary history for our species.

02:08:31Yeah.

02:08:32Yeah.

02:08:33But it's there and very consistent.

02:08:34And there's been some deliberate effects, attempts to try and close it as well.

02:08:38Indeed.

02:08:39And they're ongoing and it just doesn't seem to, doesn't seem to budge really.

02:08:43Yeah.

02:08:44It's interesting that the soft bigotry of male expectations happens with get more women into STEM as well.

02:08:49Yes.

02:08:50Yeah, indeed.

02:08:51As opposed to get more men into traditionally female dominance.

02:08:54Exactly.

02:08:55Richard Reeves, who has been on the show, right?

02:08:58And that he's trying to get more men into those kinds of professions.

02:09:02He's trying to do it.

02:09:03Yeah.

02:09:04But again, I think the reason that there is a publicly lauded push toward getting more women into STEM is because of that soft bigotry.

02:09:15Agreed.

02:09:16And if you look, I'm going to guess that if you look at the gender equality paradox, you're going to find that in more gender equal nations,

02:09:24fewer women end up going into things-based roles.

02:09:28Yep.

02:09:29And more men go into things-based roles.

02:09:31That is exactly right.

02:09:32Yeah.

02:09:33And just the interest in it gets bigger in those cultures as well.

02:09:36Regardless of what you do.

02:09:37Exactly.

02:09:38That's an interesting one to have.

02:09:39To separate out what jobs are available to you and can you get from what ones you're interested in.

02:09:43Yep.

02:09:44Exactly.

02:09:45And both expand.

02:09:46And it's interesting.

02:09:47Now, I think that you're right that it does reflect the soft bigotry of male expectations.

02:09:51I think people who want to close those gaps also will typically point out that those kinds of professions pay more as well.

02:09:59And that's another reason to try to close the gap.

02:10:01But that doesn't change the interest.

02:10:03It doesn't.

02:10:04It doesn't change the interest.

02:10:05I mean, some people are interested in things because I went to university and did business.

02:10:09Yeah.

02:10:10Because I thought I could get a job in it.

02:10:12Yeah.

02:10:13It became interested, but it was a very transactional type of interest.

02:10:18Interesting.

02:10:19Yeah.

02:10:20So, yeah.

02:10:21How many people develop an interest in a thing because it's functionally useful for them to acquire resources in it?

02:10:28It might depend.

02:10:30I would say that in a pretty wealthy society that more men than women do that.

02:10:35Now, in poorer societies, I think it's more common for everybody to do that.

02:10:40You know, in poorer societies, you just think, well, I would love to do whatever it is, impressionistic dancing or whatever.

02:10:45But you get some, in high inequality and high poverty environments, you get some really interesting outcomes.

02:10:52You've seen Candace Blake's work on the female beautification.

02:10:55I have.

02:10:56Yeah.

02:10:57Remind me.

02:10:58Remind me of the details.

02:10:59They analyzed, it was either Instagram posts or tweets, and correlated them with the level of income inequality in the local ecology.

02:11:05Yeah.

02:11:06And in areas with higher income inequality, women did more self-sexualization and more beautification.

02:11:10Yeah, yeah, yeah.

02:11:11Interesting.

02:11:12And supposedly, the proposed mechanism for that is when you see not only how high you could climb, but how low you could fall, you try to maximize your ability to be assisted in being dragged out of that.

02:11:21Interesting.

02:11:22From a resource provisioning perspective.

02:11:23Yeah, yeah.

02:11:24It's cool research there, right?

02:11:25It's really cool.

02:11:26But basically, it's just when material restrictions are in place, stuff gets warped and squirrely because people are concerned about survival.

02:11:38Yeah.

02:11:39I mean, you've seen the environmental security hypothesis as well about men are more attracted to bigger women in times of poor economy and more attracted to skinnier women in times of bad, in times of good economy.

02:11:54But yeah, it's interesting, right?

02:11:55And there does seem to be pretty good data on that.

02:11:57I am not 100% persuaded of the evolutionary arguments for it, though.

02:12:01You could survive a famine.

02:12:02There's a famine imminent.

02:12:03Yeah.

02:12:04You couldn't survive a famine, but it doesn't matter because we've got loads of food.

02:12:06Indeed.

02:12:07And I mean, it does make sense.

02:12:08But the logic there does make sense.

02:12:10But I mean, is it the case that for a long enough fraction of human evolutionary history, we had feasts and famines.

02:12:18Feasts and famines.

02:12:19I'm sure we did have that.

02:12:20But were the feast periods big enough that people were actually getting big?

02:12:23I mean, my impression is that hunter-gatherers, they just didn't really get big enough that there would have been selection.

02:12:29See, a fat person would have been very, very, very rare.

02:12:31Exactly.

02:12:32It would have been almost impossible.

02:12:34Indeed.

02:12:35Before, what, 13,000 years ago?

02:12:37Yeah.

02:12:38It would have been almost exactly impossible, definitionally, because you could only eat what you could carry.

02:12:43Exactly.

02:12:44There was no surplus at all.

02:12:46That's interesting.

02:12:47So I sort of feel like it couldn't have-

02:12:48Well, I can see it today.

02:12:49We can fucking grill him about it.

02:12:50We can talk about that, yeah.

02:12:51Because he's a fan of that, right?

02:12:52Yeah, he is.

02:12:53Well, he likes the sort of behavioral ecology approach to things.

02:12:56He likes humans as plants as well as humans as animals.

02:12:59So we grow toward the sun and how is the local ecology imposing and warping.

02:13:04But definitely the self-sexualization in high income inequality makes sense.

02:13:11Yeah.

02:13:12And I do agree with the general principle that we've evolved to respond to the ecology.

02:13:18I'm just not sure in that case it could have evolved because there weren't, you know, fatter people around the place for long enough.

02:13:25What about cognitive abilities?

02:13:27Is there a sex difference?

02:13:28Cognitive abilities.

02:13:29That's, if anything, I would say that's probably the most controversial topic that I deal with in the book.

02:13:36Sick.

02:13:37Let's bury it two hours into the episode.

02:13:38Yeah.

02:13:39So there are some, I guess, a few things to say to avoid, try to avoid getting cancelled.

02:13:46It's first of all that there are no sex differences in the cognitive ability that matters most to most people, which is IQ or general cognitive ability.

02:13:54Um, there is basically zero sex difference in the average there.

02:13:58Um, now people, when you say that some people will say, but that's because IQ tests have deliberately been constructed to create equal averages.

02:14:08Um, and that is true.

02:14:09Have they?

02:14:10Some of them have, some of them have, but there are some IQ tests.

02:14:12What, to offset the sex difference?

02:14:15Well, that, that's the, that's the theory.

02:14:17And so some, some of them have been deliberately, um, created that way, but some haven't.

02:14:23But even those ones that haven't been created specifically to give the same, the same outcome and balancing spatial versus verbal and that kind of thing.

02:14:30Um, even when they haven't, they, they give basically the same averages with representative samples of people.

02:14:37Now, sometimes you'll get, uh, some studies that will have males doing slightly better on average, but, uh, I'm persuaded by the argument that that is because the very low IQ males are more likely to fall off the map, fall through the cracks and kind of disappear and, and not end up in the samples.

02:14:53Right.

02:14:54Than the low IQ women bringing down, bringing down the female average.

02:14:58Because we do have a higher variance.

02:15:00Yeah.

02:15:01Right.

02:15:02Yeah.

02:15:03Yeah.

02:15:04Yeah.

02:15:05Yeah.

02:15:06Yeah.

02:15:07And cognitive abilities, there's higher variance.

02:15:08Yeah.

02:15:09Average is the same.

02:15:10The variance is slightly greater in men than in women.

02:15:11More male geniuses and more male retards.

02:15:12That is exactly right.

02:15:13But, uh, important, um, uh, note that that's quite a small effect.

02:15:16Um, and that is, this is the controversial area.

02:15:19And that's maybe the most controversial claim within that controversial area.

02:15:22Um, so I always like to follow that up by saying.

02:15:25Um, so that, that people hate that cause it's a cognitive advantage that gives an advantage

02:15:30to guys, but there are also other cognitive, um, ability sex differences that give the advantage

02:15:35to women.

02:15:36Um, so women on average, um, are better verbally.

02:15:39Um, that is one.

02:15:40And another one is that among the minority people who are really, really gifted at maths, the

02:15:46women are more likely than the men to also be gifted verbally.

02:15:49So they're more likely to be a double threat.

02:15:52That's cool.

02:15:53Uh, so that's, so no average differences in IQ where you do find differences.

02:16:00They're just as likely to favor women as men.

02:16:02Some of them, in some cases, men are slightly better.

02:16:05Spatial abilities, uh, best example.

02:16:08Verbal abilities though, women tend to be somewhat better.

02:16:11And then most of the differences are small.

02:16:14So the personality, they're smaller than the personality differences.

02:16:17They're much smaller than the differences and interests.

02:16:19So when it comes to cognitive abilities, we're much more alike than different.

02:16:23Mm.

02:16:24But having said all that, there are these average differences in these specific abilities.

02:16:29Um, and that like it or not, that just is the, the fact of the matter.

02:16:33And that's been measured for a hundred years as well.

02:16:36There's, there's tons and tons of data on it.

02:16:38Typically found across cultures, very likely, I think to be, to be partly innate, you know,

02:16:44that, uh, it's shaped by culture as well.

02:16:46You can, you can minimize it.

02:16:48Uh, and, and I guess also in principle, you could increase it as well.

02:16:52But yeah, I would be surprised if it's just due to socialization.

02:16:55What about physical health?

02:16:56Physical health.

02:16:57Um, there are some definite sex differences there.

02:17:01Uh, one of them.

02:17:03And the one that's probably best known is that men are more prone to cardiovascular disease

02:17:07than women, more prone to heart attacks in particular.

02:17:09Um, at least among, you know, like, like in fifties and sixties until, until very old age,

02:17:16men are more prone to those.

02:17:18Women are more prone to immune system disorders.

02:17:21They're more prone as well to, to pain disorders.

02:17:24Uh, men are more prone to most forms of cancer other than sort of reproductive cancers that

02:17:31only strike one sex or the other.

02:17:32Uh, men are somewhat more prone to cancers as well.

02:17:35And actually one of the big ones is that men die younger on average than men in the vast

02:17:39majority of cultures.

02:17:40Uh, including even most cultures where women have high rates of death during childbirth.

02:17:45Hmm.

02:17:46Hmm.

02:17:47So we drew the short straw there.

02:17:49Unix in the Korean chosen dynasty lived longer than intact males of identical social standing.

02:17:55Yep.

02:17:56Unix in the wild.

02:17:57Unix in the wild.

02:17:58Yeah.

02:17:59Unix in the male lifespan.

02:18:00That is very true.

02:18:01So I touched on that in the book in a billion, a billion years of sex differences.

02:18:05I write about how actually most people probably don't know this, but we do actually already

02:18:09have an intervention that we could in principle do, which would completely obliterate the,

02:18:14the average difference in lifespan between men and women and would extend men's lifespan.

02:18:18And that is castration.

02:18:19It's gotta be, um, castration before you hit puberty though.

02:18:23So, you know, sadly enough, if anyone wants to take that approach, if you've already hit

02:18:27puberty, it's too late.

02:18:28Uh, but yeah, the fact that it would work is, it's interesting does show that it's testosterone

02:18:33that is making us bigger, stronger, more aggressive, but also shortening our, our lifespan as well.

02:18:38If male mortality rates were lowered to female rates, Randy Nessie, who did the evolutionary

02:18:43medicine studies calculated, we would save more years of life than if we cured cancer.

02:18:49Male mortality were at female rates.

02:18:52We would save more years of life than if we cured cancer.

02:18:55Yeah.

02:18:56So we're so used to it.

02:18:57So used to the fact that men die younger that we don't really think about it, I think.

02:19:01But then when you do think about it, yeah, you find that that is a, it's just a massive,

02:19:05massive difference.

02:19:06We've got 88% of Darwin award winners, which are people who die through spectacular self-inflicted

02:19:11stupidity, are men.

02:19:12Yep.

02:19:13But 90% of Carnegie hero awards, which are given to people who risk someone's life in order to

02:19:17save a stranger, also go to men.

02:19:19Indeed.

02:19:19So the risk sort of cuts both ways.

02:19:21It's almost exactly the same.

02:19:2288% of people who die through stupid self-inflicted ways are guys.

02:19:27Yeah.

02:19:28And 90% of people who risk one's life to save a stranger are also guys.

02:19:32Yeah.

02:19:33So that is the trade off there of risk taking, right?

02:19:36In fact, almost by definition, taking risks can pay off big time, but can also kill you.

02:19:41Winners and losers.

02:19:42Yeah, exactly.

02:19:43And because men do more of that risk taking.

02:19:45I mean, that's one of the reasons I think that, um, that you get more males than females will

02:19:51start a business that does really, really well.

02:19:53Uh, and people focus on that and they think it's, it's unfair.

02:19:56I'm going to guess more will go bankrupt too.

02:19:57Exactly.

02:19:58Exactly right.

02:19:59Yeah.

02:19:59They're more likely to go in both directions.

02:20:00So they're more likely to succeed because they take bigger risks, more likely to fail because

02:20:04they take bigger risks.

02:20:05Uh huh.

02:20:06Some people, when they hear about that, they think, well, we should encourage women to take

02:20:09bigger risks.

02:20:10But the problem is that they are then, to the extent that they do that, they're opening themselves

02:20:14up, not only to greater chances of success, but also to greater chances of failure.

02:20:18Yeah.

02:20:19Risk doesn't just cut one way.

02:20:20Totally.

02:20:21Exactly.

02:20:22And so my solution there, I think would be just tell everybody all the facts, tell men and

02:20:24women all the facts, this approach to life, this risky approach, uh, cuts both ways.

02:20:29You could go up, you could go down, uh, do, do what you want with that, with that knowledge.

02:20:34Uh huh.

02:20:35And that's my approach to just, uh, a lot of gender gaps in general, right?

02:20:38So like workplace gender gaps, tell people all the facts, try to get rid of, I mean, just

02:20:42do everything we can to get rid of bias and barriers.

02:20:45Uh huh.

02:20:46But then having done that, um, respect people's choices about their own lives and how they want

02:20:52to live them and what careers they want to do.

02:20:54You know what's really interesting about that is if you try to.

02:20:59Compartmentalize the information that people see.

02:21:02Hmm.

02:21:03And you don't give them full access to the information.

02:21:06Yeah.

02:21:07What you end up with is actually a world in which there's more likely to be resentfulness and

02:21:15you need to do more compensation on the backend because people have made decisions under imperfect

02:21:20information.

02:21:21Yep.

02:21:22Yep.

02:21:23That's exactly right.

02:21:24And, um, some of the steps I think that people take to try to balance out gender gaps in the

02:21:28workplace, I think can have exactly that effect, creating a resentment.

02:21:32Um, there's one of the dangers really, I think of overstating the extent to which gender gaps

02:21:39in occupations are due to bias and barriers.

02:21:42Um, you know, I do think it's absolutely essential to look at the extent to which they are due to

02:21:49those facts, but I think we just, to bias and barriers.

02:21:52I think we also don't need to look at, um, the extent to which they're due to preferences, uh, as well.

02:21:57Uh, cause if we don't, first of all, if, if we say any kind of gaps that you see are products of discrimination,

02:22:03first of all, it's going to create unnecessary resentment.

02:22:07Cause you're going to say, look, look at these gaps.

02:22:09That's because of, uh, men mistreating women.

02:22:11Uh, second, it's going to lead to, uh, like, like costly interventions to try to eliminate the gaps.

02:22:17Uh, and those interventions are probably not going to work because they're targeting things that are not

02:22:23the causes, the primary causes, uh, of the gaps in the first place.

02:22:26Then what happens is cause they don't work.

02:22:29We start doing more and more coercive things to try to eliminate the gaps.

02:22:33Yep.

02:22:34Um, in some cases we do anti-male discrimination, kind of inadvertently just trying to eliminate the gaps.

02:22:40We get a bit more coercive and end up instead of getting rid of discrimination,

02:22:45which is what I think we should do.

02:22:46We end up reversing the direction of discrimination, uh, which I think is just creating.

02:22:51It's not, it's not undoing past injustices.

02:22:53It is just adding to the.

02:22:55Additional injustices.

02:22:56Exactly.

02:22:57Exactly.

02:22:58And reverse, reverse ones.

02:22:59Uh, and then that can create a backlash among guys.

02:23:02Um, and then also if we, if we exaggerate the extent to which discrimination is behind those

02:23:07gender gaps, um, like in STEM, for instance, we say there's the, the, had these gaps in STEM,

02:23:15more men than women go into it.

02:23:16And it's just because, uh, STEM is just riddled with sexism as a horrible, horrible, hotbed of sexism.

02:23:22That's going to put a lot of women off girls and women off who might otherwise go into it.

02:23:26So ironically, this effort to try to, to fight it could actually be, you know, create the reverse.

02:23:33Hmm.

02:23:34You touched on it earlier on.

02:23:35What about differences in mental health?

02:23:36Yeah.

02:23:37Mental health.

02:23:38Um, so there's the neuroticism, sex difference.

02:23:41First of all, women are more prone to depression and anxiety, just sort of day to day depression and anxiety, um, rather than clinical levels of it.

02:23:48But at the extreme of that distribution, they are also more prone to clinical depression and clinical anxiety disorders.

02:23:56Hmm.

02:23:57Uh, men are slightly more prone to schizophrenia.

02:24:00Men are much more prone to like antisocial personality disorder, sociopathy, psychopathy, uh, more likely to be psychopaths.

02:24:09Hmm.

02:24:10What else is there?

02:24:11I'll tell you one that where you don't find a sex difference is bipolar disorder.

02:24:15That is, I'd say in the book that that's the, the least sexist disorder on record, because it's basically the same, uh, across cultures.

02:24:24It's about the same frequency of both sexes.

02:24:26What's your explanation for why we would have these differences in mental health?

02:24:31Well, with the depression and anxiety, I think that's just a, um, side effect of the neuroticism, sex difference.

02:24:38So at, at lower levels, it's adaptive for women to be, girls as well, but especially women to be somewhat more anxiety prone because they, they protect themselves more and they're not taking risks, uh, in a way that is more adaptive for males, um, because of the higher maximum offspring number.

02:24:56Um, I, so it's adaptive at that level, but I think that cause you have a distribution, it, it means that inevitably some people are going to be the extreme that distribution.

02:25:06And I don't think it's actually adaptive out there.

02:25:08So I don't accept adaptive explanations for clinical depression or clinical levels of anxiety disorders.

02:25:14Hmm.

02:25:15I think that there is a sort of, uh, non-adaptive or actually maladaptive often by-product of sex difference.

02:25:22Spandrel type thing?

02:25:23Kind of a spandrel, yeah.

02:25:24So just a side effect, um, exactly of differences that closer to the mean are adaptive.

02:25:29Hmm.

02:25:30The schizophrenia difference.

02:25:31I don't have a theory about why that is.

02:25:33And I don't think there is that there is a theory yet about why that is more common among men than women.

02:25:38Hmm.

02:25:39Uh, some that I didn't mention actually, autism is more common among boys and girls.

02:25:42Uh, ADHD is more common among, uh, boys and girls as well.

02:25:47Um, so yeah, ADHD, I think that again, that's just a sort of offshoot of the fact that boys are kind of more active on average than girls and sort of less attentive and more likely to get distracted and running around the place.

02:26:01Uh, and it's not a problem in the usual.

02:26:04I mean, it might be irritating for parents and teachers, but it's not a big problem in the normal, uh, range, but at the extremes, it is a quite a problem.

02:26:13And it's a problem more often suffered by males than females as an offshoot of the differences that the mean.

02:26:19Hmm.

02:26:20I think going through all of this, doing all of the, the research, obviously you've been deep in this for a long time.

02:26:26Yeah.

02:26:27And then doing the book, what happens or what's your fear when people don't respect sex differences or they deny them?

02:26:36What, what's the sort of world that we live in if that happens?

02:26:39It's a good question.

02:26:40And I think it's a particularly good question because we're always focusing on the dangers of exaggerating sex differences and, and moralizing sex differences.

02:26:48And I think there are lots of problems with doing that and we need to be careful not to do it.

02:26:51Um, but where I think I disagree with a lot of folks is that I, I think that there are also problems with doing that.

02:26:57I think there are also problems with minimizing sex differences and denying them.

02:27:01Um, so one thing is that just as in exactly the same way that some people who exaggerate and moralize sex differences, they try to push people into traditional gender roles.

02:27:10People who deny the differences or, or like massively minimize them, they're in danger of trying to push people out of gender roles.

02:27:19So kind of replacing one gender straight jacket with, with another unisex gender straight jacket, or like a maybe reversed gender role, reversed, uh, straight jacket.

02:27:28Um, and then we've actually touched on another of the big problems, I think with minimizing the differences, which is the fact that trying to explain gender gaps in society, like occupational gender gaps.

02:27:38There's just a whole host of problems with doing that, that we, that we discussed, um, uh, other problems, uh, with minimizing sex differences is that there are certain, uh, physical health problems and mental health problems.

02:27:54Um, that, so, so not only did the frequency of the, of different problems differ between the sexes, sometimes the, um, symptoms differ as well.

02:28:03They, they present differently.

02:28:04Right.

02:28:05So like cardiovascular problems present differently for women than men.

02:28:09Women are more likely than men to have shortness of breath as, as a, as a, uh, as a symptom rather than sort of shooting pains down the arms and the other kind of classic problems like that.

02:28:18And if you don't focus on sex differences, you might be more likely to overlook the symptoms of heart attacks in women.

02:28:24Traditionally doctors and people themselves have been, have overlooked it for that reason, because they've underestimated the sex differences.

02:28:31Uh, mental health wise, same deal.

02:28:33So even though autism is more common among boys than girls, there is a strong case that it's underdiagnosed in girls.

02:28:40And part of the reason for that is that it presents somewhat differently in girls.

02:28:45It's less likely for instance, to involve repetitive behaviors.

02:28:49So people might not know if they, if they're not aware of that sex difference, they might overlook it in girls.

02:28:53And that means girls won't get the help that they need.

02:28:56Uh, and yeah, likewise with, um, social problems.

02:29:00Uh, if we're looking at social problems, like intimate partner abuse, um, if we assume that all intimate partner abuse only goes in one direction, uh, like male to female.

02:29:12Uh, then we're going to like underestimate the center, which is sometimes goes in the, in the other direction.

02:29:18Um, yeah.

02:29:19The vast majority of it is bi-directional, right?

02:29:22Uh, at, at low levels it is.

02:29:24Yeah.

02:29:25Sort of low levels, um, verbal, uh, abuse, pushing and shoving.

02:29:28And actually in the West, there's even some data suggesting that like verbal abuse might be more common women toward men.

02:29:34Uh, other cultures, that's not the case.

02:29:37Um, and, and it's more likely men to women.

02:29:40And when it comes to severe.

02:29:41Damn gender equality paradox.

02:29:43Indeed.

02:29:44Uh, when it comes to severe aggression though, even, even in the West, uh, men do predominate.

02:29:49Yeah.

02:29:50But you know, uh, it's not a hundred percent.

02:29:53And what are the harms of exaggerating sex differences?

02:29:55Uh, so one of them is trying to push, push people into, um, traditional gender roles.

02:30:02And like, if you just let people do what they want, probably a majority are going to kind of gravitate in the direction and traditional directions, but not everyone does.

02:30:11Um, we, cause we don't have massive, massive sex differences, somewhat modest sex differences.

02:30:17There are always going to be some folks who, uh, are not going to want to go into the traditional directions.

02:30:21And my view, my let people be themselves view would say, well, that's fine.

02:30:26Just let them, let them be themselves.

02:30:28It doesn't matter.

02:30:29But if you exaggerate and moralize sex differences, you're unlikely to think that you're going to think, well, no, no, this is the way of nature.

02:30:35Any exceptions to the rule that is by definition, a problem.

02:30:38And we need to push people into, into those roles.

02:30:41Um, what else, uh, other problems with exaggerating differences.

02:30:46Um, if you exaggerate the frequency of cardiovascular health problems, uh, you will say, well, you find them in men, not women.

02:30:53So that's another reason that you might overlook them in women.

02:30:56Uh, just because you just, it doesn't occur to you that, okay, she's got these symptoms.

02:31:02What would that be?

02:31:03Well, it's not going to be cardiovascular problems because those are men's problems.

02:31:06Um, get the same thing with, with mental health problems.

02:31:09Uh, if you're really fixated on the fact that depression, for instance, is more common among women than men, you might overlook it in men, uh, because you're exaggerating the size of the sex difference.

02:31:19And, you know, like a significant minority of people who suffer depression are men, you know, about a third of cases are guys.

02:31:27Um, so if you exaggerate that difference, uh, you might not be on the lookout for them.

02:31:32Anxiety disorders as well.

02:31:33So, and social problems.

02:31:35Yeah.

02:31:36So social problems like, um, and interpersonal violence, sexual harassment.

02:31:40If you exaggerate the extent of those, you are more likely to focus on just the cases where men are doing it to women.

02:31:47And those are the majority of the cases, but there are cases, the majority of extreme cases anyway, but you do find the reverse.

02:31:54And the reverse is a problem as well.

02:31:56And it's a problem though that we overlook if we exaggerate those sex differences.

02:31:59There's an irony there though, um, which is that, uh, the sex difference in sexual harassment, sex difference in interpersonal, uh, intimate partner abuse.

02:32:11The people who are most likely to exaggerate that and say, it's all men tend to be gender role progressives.

02:32:17So people who generally trying to minimize and deny sex differences in those cases, they actually funnily enough flip to the reverse and, and, and adhere to them.

02:32:27And in fact, just reverse it and massively exaggerate those differences.

02:32:31Fascinating.

02:32:32Steve, you're the best.

02:32:33I appreciate you, man.

02:32:34You've done a wonderful job with this book.

02:32:35Everyone should go and buy it.

02:32:36Billion years of sex differences.

02:32:37What else, what else do you want to plug?

02:32:39Could I plug, uh, my sub stack.

02:32:41So that's the, the thing I'm most excited about.

02:32:43Nature, nurture, Nietzsche newsletter.

02:32:45Dude, I am a, I'm a Steve Stewart Williams Stan, bro.

02:32:49I mean, you're the April understood the universe is in the five books that everybody needs to read from my first reading list.

02:32:54And had this one have been out, it would have been in the second one.

02:32:57Uh, yeah, your, your sub stack rules and everyone should go and check it out.

02:33:01I love it.

02:33:02My favorite thing that you do is the link fest.

02:33:05Yeah.

02:33:06Breakdowns once a month.

02:33:07You just send like 40 or 50 different studies or insights that you found.

02:33:11You're the best man.

02:33:12I really appreciate you.

02:33:13Thank you so much for coming.

02:33:14Chris.

02:33:15Thanks very much for, for making this happen.

02:33:16This is great.

02:33:17I got you.

02:33:18All right.

02:33:19Goodbye everyone.

02:33:20Okay.

02:33:21Later folks.

02:33:22Dude.

02:33:23Yes.

02:33:24All right.

02:33:25Nailed it.

02:33:26Nailed it.

02:33:27Nailed it.

02:33:28Nailed it.

02:33:29Congratulations.

02:33:30You made it to the end of a full podcast episode.

02:33:31You are not so tick tock brain that you've completely dissolved into nothingness.

02:33:33Why not watch another one?

02:33:35Right.

02:33:36Go on.

02:33:37Press it.

02:33:38you

Key Takeaway

Evolutionary pressures resulting from anisogamy and differential parental investment drive biological and psychological sex differences, which persist even in gender-equal societies despite socialization influences.

Highlights

Biological sex is defined by anisogamy, where males produce small gametes (sperm) and females produce large gametes (eggs).
Men commit over 90% of homicides globally, a sex difference that persists across cultures and is also mirrored in chimpanzee aggression statistics.
Parental investment is the primary driver of sex differences, explaining why reproductive variance is generally higher in males than in females.
The gender equality paradox shows that in more gender-equal societies, psychological sex differences often expand rather than shrink.
Men score higher on sociosexuality, with an effect size of approximately 0.8 to 1.0 (Cohen's D), meaning men are more interested in casual sex on average.
Prenatal testosterone exposure is associated with increased male-typical traits, such as aggression and decreased interest in people-related professions, in both sexes.

Timeline

Defining Sex and Evolutionary Drivers

Sex is defined biologically by anisogamy, the production of differently sized gametes (sperm vs. eggs).
The sex binary exists in the vast majority of sexually reproducing species due to the stability of these two gamete types.
Reproductive variance is typically higher in males, creating different selection pressures.

Sex is defined by gamete size, an empirical constant across almost all sexually reproducing species. Isogamy, where gametes are identical, is evolutionarily unstable, leading to a split into small, mobile sperm and large, resource-packed eggs. This divergence creates different reproductive strategies and higher variance in male reproductive success, which forms the basis for evolved sex differences.

Evidence for Innate Sex Differences

Sex differences appear early in the lifespan, often before extensive socialization occurs.
Aggression levels in young boys increase post-puberty across cultures, despite society frequently attempting to suppress this behavior.
Sex differences in career interests have remained consistent throughout the 20th century.

Evolutionary psychology accounts for both nature and nurture, noting that while socialization impacts sex differences, it cannot explain all observed variations. Evidence includes early-life appearance of traits like risk-taking, consistency over time despite social pressure, and cross-cultural universality. Furthermore, biological markers like fMRI scans of fetuses suggest neurological development differences exist pre-birth.

Sociocultural Theories and the Equality Paradox

The gender equality paradox demonstrates that sex differences often increase, not decrease, in more gender-equal societies.
Social role theory predicts smaller differences in gender-equal societies, which is contradicted by empirical data.
Physical sex differences, such as upper-body strength and throwing velocity, show massive, non-overlapping gaps.

The gender equality paradox challenges traditional social role theories. Counter-intuitively, societies with higher gender equality often exhibit larger, not smaller, psychological and occupational sex differences. This suggests that when social constraints are removed, innate preferences become more pronounced, though these differences remain statistically modest in many psychological domains compared to physical ones.

Evolutionary Roots of Behavior

Men exhibit significantly higher interest in casual sex and sexual variety than women.
Parental investment theory, refined by Robert Trivers, explains that differences in offspring production capacity drive sexual selection.
Humans are unique among mammals for high levels of biparental care, making them more similar to birds in reproductive strategy.

The sex difference in maximum potential offspring and parental investment drives sexual selection. Men face stronger selection to compete for mates and resources, leading to higher aggression and risk-taking traits. Humans are an outlier among mammals, showing high levels of biparental investment, which effectively reduces the magnitude of sex differences compared to other highly polygynous species.

Mate Preferences and Aggression

Women place greater emphasis on long-term partner resources and status, while men weigh physical attractiveness more heavily.
In short-term mating contexts, women's preference for physical attractiveness increases, aligning with gene-quality indicators.
Males commit over 90% of homicides globally, a pattern reflected in chimpanzee lethal aggression.

Mate preferences are shaped by long-term and short-term reproductive goals. Men prioritize youth and fertility indicators, while women prioritize resource-provisioning capabilities for offspring. However, in short-term contexts, women's preference for physical traits that signal good genes increases. Lethal aggression is similarly male-skewed, stemming from competition for status and mating opportunities.

Parenting, Health, and Conclusion

Women exhibit higher average interest in direct parenting, a trend seen even in the highly egalitarian kibbutz experiments.
Men have a shorter average lifespan than women across most cultures, a difference largely mediated by testosterone.
Minimizing or exaggerating sex differences can lead to clinical blind spots in medical diagnostics and social policy.

Parenting and health differences reflect biological and evolutionary trajectories. Women demonstrate higher levels of direct parental care, a trait that persists even in social experiments designed to eliminate gendered roles. Health disparities, such as male-skewed cardiovascular disease and shorter lifespans, are linked to hormonal impacts. Accurate recognition of these differences is essential for effective medical diagnosis and social intervention.

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