The Nature-Nurture-Nietzsche Newsletter

In Case You Missed It…

For years, we’ve been told that universities discriminate against women and racial minorities - and that White men are the chief beneficiaries of this biased system. A growing body of research suggests, however, that the reality is now closer to the reverse.

The latest example comes from a new paper by political scientist Scott Desposato. Desposato tracked more than 400 political science PhD students who entered the job market in 2023. His question was whether they’d secured a tenure-track assistant professorship by the following autumn.

Contrary to the conventional wisdom, female and underrepresented-minority candidates were considerably more likely to have done so than non-minority men. Was this because the former had better credentials? Apparently not; the disparity persisted even after statistically controlling for PhD-program rank, publication record, degree status, and academic subfield.

Based on Desposato’s findings, John Holbein on Twitter/X calculated the chances of four hypothetical individuals landing a position: a White man, a White woman, a minority man, and a minority woman. The candidates were identical in every respect, other than their sex and race. As shown in the graph below, the White man had around a one in four chance of getting the job, whereas everyone else had closer to a one in two chance.

Source: Holbein (2026).

How important was identity in determining who got hired? The answer seems to be “very.” Co-authoring a paper in the American Political Science Review - the discipline’s flagship journal - substantially increased a candidate’s chances of securing a position, just as you’d expect. But it didn’t increase their chances nearly as much as simply being female or an underrepresented minority. Only a solo-authored APSR paper was worth more on the job market than these demographic variables.

Source: Desposato (2026).

Desposato’s research doesn’t prove beyond a shadow of a doubt that the differences were due to discrimination. In principle, they could reflect unmeasured differences among candidates, differences in the positions they applied for or were willing to accept, or other confounding variables.

But it seems unlikely. Other research points in the same direction (see, e.g., here and here), and in any case, it’s an open secret that academia has been putting a thumb on the scale for women and underrepresented minorities for many years. The most plausible interpretation of Desposato’s data is that the relevant hiring committees were discriminating against White men.

Ironically, this was happening under the cover of the assumption that academia routinely discriminates in favor of White men. I was raised to think that discrimination is wrong, and I once assumed that most of my peers agreed. Apparently, though, many think it’s perfectly acceptable - as long as it’s against the right groups.

You can access Desposato’s paper here for free.

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Coming Soon to The Nature-Nurture-Nietzsche Newsletter…

Sex Differences in Cognitive Abilities
The Nature-Nurture-Nietzsche Linkfest for September 2026
Quick-Fire Responses to 18 Common Woke Arguments

How You Can Support the Newsletter

This post was free to read for all. If you like what I’m doing with The Nature-Nurture-Nietzsche Newsletter, and want to support my work, there are several ways you can do it.

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Upgrade to Paid: A paid subscription gets you:
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Thanks!

Steve

White People Hating White People

Steve Stewart-Williams — Tue, 15 Sep 2026 09:11:35 GMT

Photo by Christopher Ott on Unsplash

What’s Up With Self-Hating White Liberals?

In Case You Missed It…

Whatever else it is, wokeness is psychologically weird. A striking example comes from surveys of racial attitudes in the United States. Almost everyone feels warmer toward their own racial group than others - with one exception: White liberals. They do the opposite.

This was originally documented by in a 2019 article for Tablet, which included this viral graph:

Recently, the phenomenon was revisited in a fascinating post by fellow Substacker . The post runs through a series of questions about the finding, with the answers coming in the form of graphs. My kind of post.

First, was the original finding just a one-off? No. The basic pattern appears in every recent wave of the survey.

Second, is this a liberal thing, rather than a White liberal thing? That is, do liberals of every racial stripe favor other races over their own? No. Black, Hispanic, and Asian liberals all maintain a preference for their own race. It’s only White liberals who exhibit a racial outgroup preference.

Third, have White liberals always preferred other races? No. Until recently, they too preferred their own race. This flipped, however, during the Great Awokening of the 2010s. The reversal was evident by 2016 and intensified in the wake of George Floyd’s death.

And that’s just the tip of the iceberg! The post also explores whether the pattern varies with the strength of people’s liberalism; whether it reflects White liberals liking White people less, liking other races more, or both; whether it appears in other US datasets; whether it extends beyond the US; and whether it varies by sex, education, and income. You can read the full piece here.

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Coming Soon to The Nature-Nurture-Nietzsche Newsletter…

Is Academia Biased Against White Men?
Sex Differences in Cognitive Abilities
The Nature-Nurture-Nietzsche Linkfest for September 2026

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To help support my work, please consider upgrading to a paid subscription. A paid subscription will get you:

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Steve

How to Write Things People Actually Want to Read

Steve Stewart-Williams — Sat, 12 Sep 2026 09:35:15 GMT

Good writing looks like magic. The ideas seem to arrive in the right order; the jokes reliably land; and the sentences flow effortlessly from one to the next. Some people, it appears, possess the gift, while the rest of us are condemned to produce prose that reads like the terms and conditions of a software update.

Fortunately, appearances can be misleading. Writing well requires a certain amount of talent, sure - but it also rests on a collection of habits and learnable skills. Over the past few decades, I’ve written three non-fiction books, as well as numerous journal articles, lectures, essays, op-eds, and Substack posts. I’ve also written several million words of notes that have never seen the light of day. In the process, I’ve pieced together a toolkit of techniques and tactics that help turn serviceable prose into writing that people actually want to read.

In this post, I’ll share all my favorite tools. Among other things, I’ll discuss how to generate better ideas; how to escape the deadly gravitational pull of academese and pseudo-profound bullshit; how to switch between uninhibited-artist mode and pedantic-editor mode; how to give your prose rhythm and flow; and how to use AI without letting AI become a ghostwriter. I’ll also give you a step-by-step recipe for turning a germ of an idea into a polished final piece.

Most important, though, I’ll share my ultimate writing secret: the single most effective technique I’ve discovered for improving the quality of your work. It’s simple and costs nothing, and I can virtually guarantee it’ll make your writing markedly better.

What Everyone Gets Wrong About Sex Differences

Steve Stewart-Williams — Wed, 09 Sep 2026 09:55:22 GMT

Buy A Billion Years of Sex Differences

I recently joined Donal O’Doherty on his Collective Wisdom podcast to discuss my new book, A Billion Years of Sex Differences.

We explored what science tells us about psychological differences between men and women, where those differences come from, and why the topic has become so politically charged.

Here’s some of what we discussed:

The largest sex differences in our species, and why most psychological differences are much smaller
The roles of evolution and culture
Why men and women are both choosy about long-term partners
Mutual mate choice and human equivalents of the peacock’s tail
The greater male variability hypothesis
The gender-equality paradox
Sex differences in STEM and whether they’re necessarily a problem
Dating apps, incels, and evolutionary mismatch
The evolutionary mystery of homosexuality
Whether there’s any such thing as objective morality

You can watch the full episode on Donal’s Collective Wisdom YouTube channel.

If you want to dive deeper into the issues we discussed, you can buy a copy of A Billion Years of Sex Differences here.

If you want to check out more of my podcast appearances, you can find them here.

Follow me on Twitter/X for more psychology, evolution, and science.

Coming Soon to The Nature-Nurture-Nietzsche Newsletter…

How I Write: My Top Tips for Writing Non-Fiction That People Want to Read
Sex Differences in Cognitive Abilities
How Some Dinosaurs Evolved Primate-Level Intelligence

How You Can Support the Newsletter

If you like what I’m doing with The Nature-Nurture-Nietzsche Newsletter and want to support my work, there are several ways you can do it.

Like and Restack - Click the buttons at the top or bottom of the page to boost the post’s visibility on Substack.
Share - Send the post to friends or share it on social media.

Upgrade to Paid - A paid subscription gets you:
- Full access to all new posts and the archive
- Full access to exclusive content such as my “12 Things Everyone Should Know” posts, Linkfests, and other regular features
- The ability to post comments and engage with the growing N³ Newsletter community

If you could do any of the above, I’d be hugely grateful. The support of readers like you makes it possible for me to keep running the newsletter.

Thanks!

Steve

The Evolution of Cuteness

Steve Stewart-Williams — Sat, 05 Sep 2026 09:27:50 GMT

Photo by Suke Tran on Unsplash

In Case You Missed It…

Why do we find babies and young children cute?

For decades, the standard scientific answer has been that we evolved to find them cute because they’re vulnerable, and perceptions of cuteness motivate us to protect them and keep them alive.

But a bold new paper by psychologists Alexis Garsmeur and Nicolas Baumard makes a compelling case that this explanation is fundamentally flawed. Among other things, it can’t explain why the cutest children aren’t the most vulnerable, or why older children, adults, and even romantic partners can also be seen as cute.

Garsmeur and Baumard’s alternative theory solves these lingering puzzles. And it also promises to explain much that the old theory can’t, such as why we want to squeeze or nibble cute things (so-called cute aggression), why cuteness has become so culturally prominent in modern societies, why we keep pets, and how cuteness helped shape the evolution of domesticated animals - and even of our own species.

Most importantly, the theory points to a fundamental distinction that generations of researchers overlooked: Parents do two very different things for their children, and cuteness evolved primarily to motivate the one we’ve largely ignored.

Sex Differences and Human Nature

Steve Stewart-Williams — Wed, 02 Sep 2026 08:32:42 GMT

I recently had the great pleasure of returning to The Good Fight podcast to chat with political scientist about my new book A Billion Years of Sex Differences. Yascha has kindly allowed me to reproduce the transcript here. If you’re not already familiar with his work, I highly recommend checking out his Substack and podcast.

Steve Stewart-Williams is a Professor of Psychology at the University of Nottingham’s Malaysia campus and runs The Nature-Nurture-Nietzsche Newsletter. His latest book is A Billion Years of Sex Differences.

In this conversation, Yascha Mounk and Steve Stewart-Williams discuss why women and men are more similar than is often assumed and what the real differences between them are, from casual sex to career choices.

This transcript has been condensed and lightly edited for clarity.

Yascha Mounk: Last time we spoke, you gave a really great introduction to how to think about the influence of evolution on human nature and human psychology. You are now out with a book that speaks more specifically about sex differences and how those are rooted in biology. Let’s go through some of the sex differences that the literature establishes relatively decisively.

One way you break this down is to say some sex differences are just completely dimorphic—women give birth, men do not—while others are more statistical variances. Tell us a little bit about how to think about the kinds of sex differences and what some of the most common ones are.

Steve Stewart-Williams: The new book is called A Billion Years of Sex Differences. I start by listing what I call the standard-issue sex differences: a list of very well-established sex differences in our species. As you say, they range from the very large and strictly dimorphic and categorical, to the not-so-large—at the other end, just statistical differences, relatively modest discrepancies in the average scores of massively overlapping distributions.

At the larger end of the spectrum, we generally just have physical differences between the sexes: reproductive differences, the reproductive organs, the capacity to nurse versus not, the capacity to give birth versus not—those are all very large differences. The difference in upper body strength is quite large—actually very large, with very little overlap. There is very little overlap in voice pitch either, so voice pitch is another quite large sex difference.

Moving down the scale, when we are talking about psychological sex differences, the only one that is even remotely in the ballpark of those physical differences is the sex difference in the primary target of sexual attraction. Most men are primarily attracted to women, most women are primarily attracted to men—there are exceptions, of course—but nonetheless, that is a very large psychological difference. It shows, I think, that natural selection can create large levels of dimorphism.

Mounk: That is interesting, because in the first category—and we are certainly not going to get into the whole trans debate for purposes of this conversation, we are talking about biological sex—men can produce sperm, women can produce eggs. Those are just completely different biological processes: strictly dimorphic. Here, we are talking about how most men are attracted to women and most women are attracted to men, but then there are these subcategories of men who are strongly attracted to men and women who are strongly attracted to women. So that is a very different kind of distribution.

Stewart-Williams: It is a different kind of sex difference. Even though people attracted to the same sex are exceptions and a minority, they are not a trivial minority—there is a non-trivial number of exceptions. Whereas that is not the case for the first sex differences I named.

Mounk: Not to go down a rabbit hole, but a lot of people are going to have in their mind this idea of a Kinsey scale—that actually most people fall somewhere on a long spectrum between complete heterosexuality and complete homosexuality. So it’s not that most men are attracted to women and then some significant percentage of men happens to be very attracted to men, but rather that we all fall somewhere along that spectrum.

Is that compatible with modern science? Is that something that scientists today believe? How does what you are saying fit onto that kind of model of the Kinsey scale?

Stewart-Williams: I was thinking of the Kinsey scale when I framed the exact wording. My exact wording was that most men are primarily attracted to women, most women are primarily attracted to men—so that accepts the fact that it is not uncommon at all for there to be some degree of attraction to the same sex among people who are primarily attracted to the other sex.

There are differences in the degree of attraction to each sex that individuals have. One thing is that people often understand it to mean that there is a spectrum and that people are distributed fairly evenly across it, whereas you do actually have clustering toward the two extremes of the continuum—that is, primarily attracted to the other sex versus the same sex. That is especially true with men. With men you get quite strong clustering, either primarily attracted to the other sex or the same sex. With women, the distribution is a bit more even across that scale.

Mounk: So if you are picturing the scale from left to right, there is one big mountain on the left—attraction to the opposite sex—and then a smaller mountain on the other end of the scale, primarily attracted to the same sex, and then in between are all kinds of people who fall at all kinds of points, but those are not going to be big local maxima?

Stewart-Williams: That is exactly right, with just the one proviso that there are fewer men in the in-between category than there are women in the in-between category.

Mounk: So the peaks are going to look higher for men than for women for the same reason. Interesting. That was the second kind of category. The third category is where most of the interesting debates lie. The first category—the biological differences—is relatively straightforward and uncontested. The second category is super interesting and important, but perhaps applies to slightly fewer characteristics. A lot of the things that we really have big social debates about fall into the third category: is it true that men have an innate attraction to certain kinds of professions, to certain kinds of socializing, to certain kinds of ways of thinking about the world? All of that contested stuff lies in the third category—minor statistical differences that might nonetheless make a really significant impact on the world. So tell us about those.

Stewart-Williams: That is exactly right. The vast majority of psychological sex differences in our species are in that third category—statistical sex differences, or what I call fuzzy sex differences—where you have differences in the average of highly overlapping distributions. A big part of the reason there are so many debates about it is because they fall awkwardly into a middle ground where a lot of them are small enough that you can question whether they actually exist, but large enough that they trouble us. So they sit in that awkward middle ground where you can deny them, but they also have real-world effects to some degree.

They span a range of different magnitudes as well. Among the larger ones, you mentioned career-related interests—that is actually one of the larger sex differences in this category. There is usually about a standard deviation difference between the mean for men and the mean for women in career-related interests.

Mounk: Can you explain for lay listeners what that means—both in terms of how strongly a different professional preference drives professional choice, and roughly how big an effect a standard deviation is?

Stewart-Williams: On average, men tend to be more interested than women in things—how machines work, mathematical and formalized systems, impersonal subject matter—and more interested in careers involving those things. Whereas women on average tend to have a greater interest in people, how people work, and in people-related professions: professions that involve helping and interacting with people.

The difference is about a standard deviation between the means for the two scores, which is considered to be quite a large effect size. There is still a great deal of overlap. What it would mean in practice: if you were to choose two people at random, one man and one woman, for interest in things—where men score higher—there would be about a 75% chance that the man would score higher than the woman, and about a 25% chance it would go the other way. The converse holds for interest in people: in about 75% of randomly chosen pairs, the woman would score higher than the man, but there would still be a non-trivial minority of cases where the man scored higher than the woman.

Mounk: That is, I think, a little bit of what makes this awkward. Let’s cash this out with this relatively uncontroversial example, and then we can think about how it applies to more controversial ones.

What you are saying is that in the literal sense, stereotypes about this are right. There is a stereotype that men love their machines and their tools—they go into the man cave and potter around in the workshop—and that women gravitate toward more social professions, or, pejoratively, gossip, or whatever. You can make a negative caricature of each, or a positive one. The positive version: the man likes to build things and get things done, and the woman loves to be a connector in the neighborhood, making sure people are doing well and cared for. Or you can put a negative spin on each: the man locking himself away in his workshop, or the woman engaging in mean-girl gossip behavior. The point is that this is a stereotype we hold in society, and what you are saying is that there is some real empirical grounding for it.

And yet, of course, if you apply that to everybody—if you were hiring at an engineering firm and said, well, this is a female applicant, surely she does not actually like machines—you would not only be perpetrating an injustice towards that woman, but you would very often be wrong. A good number of women are interested in these kinds of things, and among women who are actually applying for such a position, probably most of them are.

Stewart-Williams: That is exactly right. A lot of stereotypes are on the right track—at the very least they are a response to something real. The danger is in exaggerating the magnitude of them, which is what you are doing if you say: this is a woman applying for a male-typical job involving machines, it is just impossible that she could be interested in them or good at working with them, and vice versa for men applying for people-related jobs. You would be exaggerating the strength of the sex difference.

I think that is a big reason why people are nervous about talking about sex differences: they worry that people are going to do exactly that. They worry that if there is any acknowledgement that there is some truth in these sex differences, people are going to misunderstand it, blow it out of proportion, and that it will become a justification for—or a cause of—discriminating against one sex or the other. I do take that concern seriously, and in the book I discuss it as something we genuinely need to concern ourselves about.

Nonetheless, I think it is really worth exploring this topic for two reasons. One is that whether we like it or not, there are average differences between the sexes in many different areas, and we cannot simply lie about that. The second reason is that even though there are dangers in talking about sex differences—dangers associated with exaggerating them and moralizing them—there are also dangers in the converse: in minimizing them, ignoring them, and moralizing the absence of sex differences instead. The only responsible solution to that conundrum is to look at what the data say, try to convey it accurately, and talk about sex differences carefully.

Mounk: Motivate where the dangers lie. The danger of the first kind of error is relatively straightforward: I am a hiring manager at an engineering firm, an excellent female candidate applies, and I say, well, she is a woman, she is not really going to want to be doing this kind of job, and I do not hire her even though she is an excellent, well-qualified candidate. That is a very straightforward danger. Where does the danger lie in not talking about these sex differences?

Stewart-Williams: There are quite a few, and there are actually other dangers with exaggerating sex differences as well—for instance, if we develop a mental image of what men and boys are supposed to do and what girls and women are supposed to do, we might pressure people to fall into stereotypical definitions of the sexes, which is bad for people who do not fit the norm.

Mounk: That is obviously related, but slightly different. In the first case, I am a hiring manager at an engineering firm—I may have no belief that it is wrong for women to want to be engineers. It would be great if women were super into engineering, but sadly not all of them are, so I am not going to take this candidate seriously. Now we have moved to a slightly different thing: because there are some statistical sex differences in the world, that is in fact what men and women should be like. So now let’s say I am a dad and my daughter is interested in engineering—well, that is not for you, you should really study psychology. Here we have moved to the danger of ignoring the is-ought distinction.

Stewart-Williams: There are dangers with exaggerating and moralizing sex differences, as I just mentioned. But there are converse dangers with minimizing sex differences and moralizing the absence of sex differences. One of these is directly symmetrical with the problem of trying to force men and women into traditional gender roles: there is a danger of trying to force them out of those roles—of not accepting the fact that, although there will always be exceptions, some people are simply going to fit with gender-typical norms, roles, and preferences. People sometimes have a tendency to think that that is a bad thing, a product purely of sexism, or—if it is their own kids—to feel guilty that they have done something wrong in parenting because their child falls into typical patterns: boys engaged in rough-and-tumble play, girls loving pink and dolls. That is one danger.

Another is that if we ignore sex differences in career-related preferences, then when we find discrepancies in the sex ratios of different professions, we will assume it is 100% due to discrimination and sexist socialization. While it is very probably partly due to those factors, it is not necessarily—and not even likely to be—the case that they are the only causes. Given that men and women do have, on average, these different preferences, it seems very likely that part of the reason we have different sex ratios in some professions is a result of those statistical differences in preferences. In fact, given that those different preferences exist, it seems very unlikely that they would not be one of the causes of the differences.

Mounk: There seems to be some preliminary evidence that men are not just more interested in tools generally, but also more interested in a specific tool: artificial intelligence. If that turns out to be the case, at a moment when it seems very likely that AI is going to fundamentally reshape our society, is that going to be to the detriment of women? Are we entering a technological age in which professions that many women occupy—like human resources—become relatively less lucrative, while professions involved in creating these new AI systems, in which men continue to be overrepresented, come to dominate?

Stewart-Williams: That is a very interesting question, and I think it is possible. One reason it is not necessarily going to turn out that way, though, is that the interface between people and AIs is quite a social activity—it does not feel like tool use in a traditional sense. You are interacting with something verbally; it can feel quite social.

I was recently at the HowTheLightGetsIn festival at Hay-on-Wye, and I met a few people who work in AI. One was , who is very interested in how AI can be used in medicine to help people. In that area, you might actually find a predominance of women over men being interested in the question. Someone else I met was very interested in the use of AI for psychotherapy—again, a field where women currently predominate over men. It is possible that if AI moves into that area in a big way, there will likewise be a predominance of women over men in AI applications of psychotherapy.

Mounk: Let’s make a simple prediction. If you think that professional choice is really down to socialization and social pressure—informal prohibitions on men becoming hairdressers or women becoming engineers—then you would expect that the more gender-egalitarian a country is, the less pronounced those gender differences in professional choice would be. So you would expect that in a more traditional society like Egypt, there would be a large difference, with very few women becoming engineers and very few men becoming hairdressers. And in Sweden, or whichever country is relatively gender-egalitarian, you would expect those differences to be relatively more minor. My understanding is that that is not in fact what the evidence shows.

Stewart-Williams: Your understanding is correct. I would have made that same prediction before I saw the data. Even accepting that there is an innate contribution to preferences, I would have thought that in cultures where men and women are treated more differently and gender roles are stricter, sex differences would be even bigger—so if there is an innate contribution, it would be amplified—and then smaller in more gender-egalitarian, more individualistic, and wealthier societies where people are freer to pursue their own interests.

But as you say, there is this phenomenon called the gender equality paradox, which reflects the fact that for many traits, including career-related preferences and job choices, it is the exact opposite: the more gender-equal, wealthy, and individualistic a nation is, the larger those sex differences become rather than smaller. Very counterintuitive.

Mounk: Really interesting finding. I had an interesting episode that touched on that with Alice Evans on the global gender paradox, among other things.

One of the things that makes these conversations often unproductive—and I think this is true not just of this conversation but of many conversations—is that different people have different audiences in mind, and that drives them to talk about things in slightly different ways. Let me give a totally different example.

A lot of social science disciplines, like sociology, love to make the move of saying: this thing actually turns out to be socially constructed. I find that useful for an introductory undergraduate class, in the sense that a lot of 18-year-olds come in thinking that something like the United States Constitution is a God-given thing that is objectively correct and beyond question. To say: these are particular people who built this at a particular moment—brilliant people doing something important, but with their own shortcomings and blind spots—is a helpful corrective. I am not sure how many 18-year-olds still arrive at college with that kind of naive view, but I can see where it comes from. There is a danger, though, in inflating what it means for something to be socially constructed, which is a general pet peeve of mine, and also in making your whole academic career invested in pointing out that this or that thing is not natural or God-given—speaking to an audience that already agrees with you.

I think something similar happens when people talk about gender differences. A lot of people, for understandable reasons, think: there are stereotypes and prejudices in society that coerce men and women into gender roles and obstruct women from advancing in certain professions—that is really what we need to be on the lookout against. From that perspective, writing a book about sex differences seems actively unhelpful. Then there are others who say: the mainstream has become so concerned about that real danger that it has overshot the mark and gone in the other direction, producing all kinds of other confusions—and that is what we should be setting ourselves against. We can call these alpha bias and beta bias. Talk us through that.

Stewart-Williams: Those are not my terms, but they are very useful ones. The alpha bias is the tendency to exaggerate the magnitude of sex differences, and the beta bias is the opposite—the tendency to minimize, downplay, and perhaps deny them. There is quite a strong tendency toward the beta bias in media and academia, in the mainstream and among the chattering classes. The alpha bias is perhaps the historical starting point, and it does exist in some small areas of academia and probably journalism as well. I would have to say the tendency to exaggerate sex differences sometimes exists in my own field of evolutionary psychology—perhaps because we are responding to the beta bias we find elsewhere in academia, and it may have swung to the opposite extreme to some extent.

What I am trying to do with the book is respond to both, critique both, and steer a middle course between them. I would love to think that people on both sides will agree and perhaps come to a truce—but of course another possibility is that I’ll simply annoy people on both sides of the debate. That is nonetheless what I am trying to do: strike a balance.

Mounk: Let me pose the question so we can address this directly. To make things more complicated, you then add two further biases—the gamma and the delta bias. What are those?

Stewart-Williams: The gamma bias is the tendency to highlight sex differences that put women in a better light than men, while downplaying those that put men in a better light than women. I think it is a response to historical anti-female sexism—basically an attempt to set right the reverse tendency, where differences were highlighted in ways that cast men as superior and women as deficient. It is a kind of overcorrection that aims to be protective of women.

The delta bias, on the other hand, is a tendency to highlight and favor sex differences that go in the opposite direction to traditional sex differences. For instance, devoting everything to your career and placing family lower down the list might be frowned upon if a man does it, but celebrated if a woman does it. Sleeping around is sometimes considered a bad thing if men do it, but a good thing if women do it. I think that is a response to traditional social norms.

Mounk: That reminds me of one of the very early viral internet controversies—the Duke “Fuck List,” if you remember that. A senior at Duke University had made a joking PowerPoint, styled like a senior thesis, about all the men she had slept with in college. In a way you can see how it was a fun, charming idea, though the slides themselves were quite demeaning and objectifying—ranking all of these men in various ways. Some people thought it was a mean way to interact with and write about other people. But Jezebel and the early internet feminists defended it as a great act of female empowerment. It was obvious that the same people, had it been a man ranking and grading the genitals of women he had slept with in similar ways, would have found it to be terrible. But because this was typically something men did and not women, when a woman did it, it was considered empowering.

Stewart-Williams: That is a good example of the delta bias, and also a good example of where I think it comes from—different standards are applied because of the history, because it is turning the tables. Those are the four biases that I think make the discussion harder and make it trickier to research and talk about sex differences without it getting heated. There are these biases and preferences that people have for what kind of sex differences they want to see or not see.

Mounk: We have done a lot of the preparatory ground for thinking about how to approach these questions. Let’s go a little deeper into how we should think about particular sex differences in light of all this. Why don’t you tell me the three most juicy ones we should talk about for the next twenty or so minutes?

Stewart-Williams: How about the sex difference in interest in casual sex, in choosiness about sexual partners, and in aggression?

Mounk: Let’s start with casual sex.

Stewart-Williams: The difference here—and you will be very surprised to hear this—is that on average men are more interested in casual sex, no-strings-attached sex, and sexual variety than women are. That is a pretty big difference as human sex differences go. Depending on exactly what you ask about, the difference is about 0.8 standard deviations between the means for men and women, with men scoring higher. To use the analogy of plucking two people at random, one man and one woman, for that sex difference you would find about 70% of the time that the man would be more interested in casual sex than the woman. Again, there is a significant minority where it would be the other way around. So it is a real sex difference and it is pretty substantial as human sex differences go, but it is not quite as big as people sometimes make it out to be.

This raises an interesting point about sex differences in general: even when you have a sex difference that is fairly modest at the mean, when you go out to the extreme of the distribution, the difference will typically get a lot bigger. If you go out to the extreme of the distribution for interest in casual sex, you will find that even though it is about 0.8 or one standard deviation at the mean, out at the extreme there are many more men than women. I think a lot of our stereotypes come from thinking about those extremes rather than about people closer to the mean.

Even small differences at the mean are associated with large differences at the tails of the distribution. Source: Steve Stewart-Williams (2026), A Billion Years of Sex Differences.

Mounk: It is just a function of how normal distributions work. If you have a relatively small difference at the median—where the top of the distribution is—that relatively small difference can mean that once you are three or four standard deviations out, where you are talking about people at the extremes—the most or least intelligent, the most or least interested in casual sex, the most or least violent—that small difference in the mean can translate into a four, five, or tenfold difference at those extremes. Now that we have established those statistical properties, how does that shape social behavior—and things like casual sex in particular?

Stewart-Williams: It is often going to be the case that men are pursuing casual sex to a greater extent than women are. One mistake people often make when they hear about that sex difference is thinking that the claim is that men are more interested in casual sex whereas women are more interested in long-term relationships. But actually men and women have similar levels of interest in long-term committed relationships—it is really only within the domain of casual sex that we find this sex difference.

There are actually two differences here. One is that men are more interested in casual sex on average. The second is that when it comes to casual sex and low-commitment relationships—and also early courtship—women tend to be choosier about their mates: choosier about who they are willing to have a short-term thing with.

Mounk: On the first topic, before we get to mate choosiness—what do lesbian and gay relationships tell us here? Obviously there may be ways in which lesbian women’s sexual behavior differs from heterosexual women’s, and gay men’s sexual behavior differs from heterosexual men’s—not just in terms of the object of attraction, but presumably this is at least a suggestive field of study: what happens if you take two people with male sexual preferences and put them in a relationship together, versus two people with more female sexual preferences in a relationship together? Obviously there is going to be a huge range, from very monogamous gay couples to very open ones. But do we see systematic differences between lesbian and gay couples, and what does that tell us?

Stewart-Williams: We do see differences, and they stem from the fact that in same-sex relationships, people are not having to negotiate with the preferences of the other sex. They can typically express their own preferences to a greater degree, with less compromise. Looking at the sexual behavior of gay men and lesbians can therefore provide a clearer window into the sexual preferences of men and women in general.

What you find is that gay men typically engage in a lot more casual sex than straight men, because they are interacting with other men who typically have similar preferences. Lesbians, on the other hand, typically have less casual sex than straight women—again, because they are not having to accommodate the average preferences of the other sex. It fits very nicely with the idea that there are these average differences between the sexes when it comes to interest in casual sex, and it is a good piece of evidence for that idea.

Mounk: You were saying that men do not necessarily have less interest in long-term committed relationships, but they do have a much greater interest in casual sex. If you just know those two things, you would predict that you would end up with a lot of couples that are open to each partner having casual sex—which is certainly not the universal norm among gay couples, but is true of many of them.

Stewart-Williams: It is true of more gay couples than straight couples. In straight couples, some men do want that, but sexual jealousy often gets in the way—a man might think: it would be great if I could sleep with other people, but I do not want my partner sleeping with other people, so I will content myself with monogamy. That seems to be less often the case with gay men. I am sure many do fit that description, but there do seem to be more gay couples where jealousy is not quite such a big issue as it is in straight couples—that is the impression I have, anyway.

Mounk: Just to up the level of intrigue here—I have read, though I am not sure if this is true, that there are significantly higher rates of divorce among lesbian couples than among gay couples. Why is that?

Stewart-Williams: I have read the same thing—there are good data on that. Why that is, I am really not too sure. It could be a selection effect, or it could be related to the fact that among straight couples, around two-thirds of divorces are initiated by the woman rather than the man. Maybe it is an offshoot of women’s greater choosiness about their mates—our next juicy topic. But I am not 100% sure about that.

Mounk: Let’s go to choosiness about mates. Two things here are striking. The first is that evolutionary theory would suggest that women are choosier about mates than men because they invest more in offspring—if only through pregnancy, and often well beyond that. That is true throughout the animal kingdom and is true for humans as well. The other thing that is often forgotten—and you will have to remind us of the Greek designation for it—is that actually the difference between the two sexes in humans is relatively smaller than it is in most other animals in this regard.

Stewart-Williams: At least for long-term relationships it is smaller. When we think of women being choosy and men being not choosy, that has some truth in the short-term context.

Mounk: So at 2 a.m. in a club, the man is happy to go home with whatever woman, but the woman says: even though I might enjoy casual sex, I am still going to be quite picky. But when it comes to long-term relationships, suddenly the men become picky too.

Stewart-Williams: Both sexes tend to be pretty picky in long-term relationships—and maybe similarly picky. So you get the alpha bias, the exaggeration of sex differences, when it comes to the long-term context. It is a general truth, actually, that sex differences in sexual psychology are a lot smaller when it comes to long-term committed relationships than to short-term relationships, casual sex, and early courtship. It is in early courtship and low-commitment relationships that the sex differences are a lot bigger.

Mounk: Is this a challenge for evolutionary theory? Or is it simply downstream from the fact that humans procreate in very different ways from most other animals, because they invest in offspring for so much longer?

Stewart-Williams: It is not a challenge to an evolutionary perspective—I think it fits very nicely with one. According to the evolutionary perspective, the greater female choosiness we see right across the animal kingdom follows directly from the fact that female animals in general invest more in each offspring they produce than male animals do. Because they invest more, they can have fewer offspring in their lifetimes. Males, on the other hand, typically invest less in each offspring, and therefore in principle could have many more offspring than any female could. That creates different selection pressures on both sexes, and produces a range of traits in males that increase their chances of being one of the few males that has many offspring, rather than one of the many males that has none or just a handful. That is where most sex differences come from: the difference in the maximum offspring number each sex can produce.

We have some of the same thing in our species, but because of the great dependence of our young, we have evolved a reproductive system where we fall in love, form pair bonds, and engage in high levels of biparental care—much higher than you see in most mammals. When males are investing heavily in their young as well as females, that reduces the sex difference in the maximum offspring number each sex can produce. It brings down the ceiling number of offspring that men can produce—a few exceptional historical examples notwithstanding—and as it brings it down, it has led to the evolution of reduced sexual dimorphism in our species. One area where that is evident is in the sex difference in choosiness.

The sex difference in choosiness is a result of females investing more, but in a long-term context both sexes are typically going to be investing quite heavily—in the relationship and in any offspring that result from it. For exactly the same reason that females evolved to be choosy when they can only have a relatively small number of offspring, men likewise evolve to be choosy in a context where they are only going to have a relatively circumscribed number of offspring.

Mounk: I once leafed through a book arguing that when we compare humans to other animal species, we fall somewhere towards the middle of the range on the extent to which we are wired to be monogamous—that some species are strongly monogamous, and many species, perhaps most, are not monogamous at all.

When you look at a whole set of physical characteristics of humans, they tend to fall somewhere in the middle between those extremes. The book was arguing that we are semi-monogamous, and that this is how to think about us and how to explain a lot of conflict in social life—the fact that we have both a tendency towards pair-bonded long-term committed relationships and a tendency beyond that. Do you find that a helpful way of thinking about this topic?

Stewart-Williams: We have a strong tendency toward pair bonding and biparental care, but it is not like gibbons or some birds. We also have an interest in sexual partners other than our main partner, which is not uncommon, and that nudges us toward arrangements other than strictly monogamous pair bonding. Men have a desire for sexual variety—some members of both sexes do, but men typically have a stronger desire for it—and that sometimes translates into polygyny, where one man has more than one partner. Pair bonding is the most common relationship type found in basically all human societies, including polygynous ones. Even in societies where men can take more than one wife, it is a minority activity. It is not like gorillas, where a male either has a harem of females or is a bachelor—with humans, most men who have more than zero mates have only one. There are a small number who have multiple mates. Pair bonding is our main reproductive approach, but we are very flexible and do all sorts of other things as well.

On to the third topic: aggression. At least when it comes to direct or face-to-face aggression, men on average do more of it. That includes verbal aggression, where the effect size is medium—about half a standard deviation between the means for men and women, so not a massive sex difference. But as you go up the scale toward more intense forms of aggression—physical violence, pushing and shoving, more extreme forms of physical violence—the gap gets bigger and men come to predominate more. At the extreme of one-on-one violence, which would be homicide, men predominate massively: around 90% of homicides worldwide are perpetrated by men. Only a minority of men commit homicide, but among those who do, it is massively skewed toward men.

When it comes to indirect aggression—the mean girls phenomenon, gossip, spreading rumors, where you are trying to harm someone but not to their face—we find either no sex difference, with both sexes doing it about evenly, or we find it is slightly more common among women than men. But for most forms of aggression, men predominate.

Mounk: There is another area where stereotypes seem to hold up to some degree. When you talk about the extreme forms of violence, that difference is very obvious in the statistics and easy to understand—men are more likely to murder, more likely to be soldiers, more likely to be in criminal gangs, and prisons are much more full of men than women. But when you are not talking about the extremes, when you are talking about people towards the middle of the distribution, how big is that difference in standard operating procedure? Is it that the average man is not particularly violent, but perhaps once or twice in his life has gotten into a small scuffle at a bar? The average woman is not particularly violent, but when she engages in social aggression, it takes the form of rounding up a few people to ostracize somebody in the friend group they have a grievance with?

To what extent are those stereotypes about the middle of the distribution true? Is that a helpful lens for understanding society? As an evolutionary biologist and psychologist, do you feel like you can watch Cruel Intentions or whatever high school movie and check off the behaviors—that your training helps you understand what is going on in ways it would not for someone without it? Or do you think it does not in fact illuminate social reality in that kind of way? Is the alpha bias or the beta bias more tempting here?

Stewart-Williams: That is a good question. I think with low-level aggression the alpha bias comes in more, and people exaggerate. People are maybe a little surprised when they hear that the difference is not larger for verbal aggression and the like. The way you describe it is pretty accurate for modern Western societies: most men are not especially aggressive—they may get into an occasional scuffle over the course of their lifetimes, or more commonly the odd verbal altercation—and likewise women are not especially aggressive either.

Women may have as many verbally aggressive interactions, but with less of a sense that there is a physical threat and that it could turn into actual violence. I think that is accurate in the West. We have successfully tamed our aggressive impulses to a considerable degree in the West, and in more traditional cultures there have often been higher levels of violence—especially among men. Culture brings it out more in some contexts, while simultaneously suppressing it somewhat in modern Western populations, which I personally think is a good thing. I imagine most people would agree. It is an example of a case where we have a natural tendency that society pushes against—but it is a tendency that is generally a bad thing, so it is a good thing that we are able to engineer unnaturally low levels of aggression.

Mounk: One benefit of thinking about the world in evolutionary terms is that it helps us see where the dangers lie for society. One very fundamental insight from evolutionary biology and evolutionary psychology is the human tendency to split into in-groups and out-groups. You could fall into the naturalistic fallacy and say: therefore we should encourage people to stick to their tribe and hate the other. But we have learned from history that that is a disaster. The whole point of civilization, the whole point of building positive institutions, is to mitigate the impact of the in-group and out-group tendency. The way to do that is to channel it—not to deprive people of any outlet for it, but to redirect it.

That is why you have sports rivalries in high schools. That is why, if you think of Harry Potter, you split a boarding school into different houses so that they can compete with each other. There are dangers with that—sometimes they come to blows—but the main point is to make people within each house aspire to work hard and take pride in it. The city of Siena is split into around twenty contrade—parts of the city that compete against each other in a huge horse race—as a way of instilling solidarity within each neighborhood. They hate each other and compete fiercely, but it has historically strengthened Siena’s ability to work together as a whole, because it instills a strong civic identity. In terms of aggression, you might think sports work similarly: when you are playing American football, rugby, or even a less violent sport like basketball, that is a way of channeling aggression into something socially harmless.

Stewart-Williams: A way of, as Freud would have said, sublimating those potentially destructive desires. I think that is true and interesting. When you study the fact that we are so prone to in-group and out-group biases, evolutionary biology and psychology, rather than saying it is natural and therefore good, can equally well puncture it. You might genuinely think your in-group really is great and that the out-group really is terrible. But if you realize that we have this built-in tendency in human nature to divide the world into in-groups and out-groups, it can make you challenge that. It can make you think: maybe I am just falling prey to this evolved illusion, and it is not actually true that we are superior and angelic and they are genuinely terrible and demonic.

In the rest of this conversation, Yascha and Steve discuss how society should respond to sex differences, why there are more female double threats than male ones, and to what extent the predominance of men in certain disciplines is due to sex differences versus discrimination. This part of the conversation is reserved for paying subscribers…

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The Science of Ticklishness, Declining Student IQs, and How New Music Causes Car Crashes

Steve Stewart-Williams — Sat, 29 Aug 2026 09:05:55 GMT

Photo by Moritz Kindler on Unsplash

Why does hearing a new album make you more likely to crash your car? Why are humans the only animals that cry? And why are today’s university students measurably less bright than yesterday’s? This month’s N³ Newsletter Linkfest provides answers to all three questions, plus much, much more:

The opposite of déjà vu
Sex differences in A-level choices
A $10 million dilemma
How money changes your personality
How AI can impair learning but reduce political polarization
How anti-racism can increase racism
New drugs that cause you to lose weight without eating less - or even actively boost muscle growth

Around half the items are free to read for everyone; the rest are for paid subscribers. I tend to put the spicier content behind bars, so if you’ve got a high spice tolerance, maybe consider a paid subscription. Check out the other benefits here.

You can access the complete collection of Linkfests here.

The Science of Ticklishness

Here’s some recent research that’s not only interesting but useful. The figure below shows the most ticklish parts of the human body. Notice that the same body parts are ticklish for people from three very different cultures, hinting at the universality of the finding. Needless to say, this is crucial information for anyone planning a tickle attack - and as far as we can tell, you can use the same tickle strategy regardless of your victim’s cultural background. [Link.]

Source: Xiong and Kilteni (2026).

The Opposite of Déjà Vu

You’ve heard of déjà vu, but what about its opposite? Jamais vu happens when something familiar - a face, a place, or even a word - suddenly seems unfamiliar, strange, or wrong. You can often induce it by saying or writing the same word again and again until it seems like it couldn’t be real. [Link.]

The Declining IQ of University Students

University students aren’t what they used to be, at least when it comes to IQ. As higher education has gone from an elite pursuit to something more common, the average IQ of US undergraduates has fallen from around 120 in the mid-20th century to around 102 today - barely above the population average. [Link.]

A relationship between mean IQ adjusted for Flynn Effect and year of assessment for the US u/g samples (k = 102). The figure includes the meta-regression line with 95% CI bands. Source: Uttl et al. (2024).

Sex Differences in Academic Interests

Boys and girls are interested in different stuff. This can be seen in the gender breakdown of A-level choices in the UK. Boys massively outnumber girls in computing, physics, further mathematics, and economics, whereas girls outnumber boys in English literature, sociology, psychology, and art. [Link.]

Source: The Telegraph.

Guaranteed True Love or Ten Million in Cash?

Which would you choose? Give your answer in the poll below.

When 1,635 people from 38 countries were asked this question, they split almost perfectly down the middle: 50% chose love; 50% chose the money. At the same time, there were interesting differences by country, age, and occupation. [Link.]

Source: wisehumans.

New Album Drops, Car Crashes Rise

The release of a major new album is associated with a 15% increase in fatal car crashes. A probable culprit is distracted driving: Finding and streaming unfamiliar new music may demand just enough extra attention to make driving notably more dangerous. [Link.]

Source: Patel et al. (2026).

The Deep Primate Origins of Pet Keeping

Our furry monkey cousins sometimes interact with other species in ways that resemble human interactions with their pets: They play with them, groom them, cuddle them, nurse them, and even adopt them long-term. These interactions vary predictably by age and sex: Youngsters are more likely than oldsters to play with members of other species, females are more likely than males to care for them, and adult males are more likely than females or juveniles to ignore them or treat them aggressively. [Link.]

Frequency matrix of interspecific social interactions by behavioral subtype and age–sex class of the primary species. Each cell shows the number of recorded interactions for a specific behavioral subtype (e.g., grooming, playing, food sharing) initiated by a particular age-sex class (adult male, adult female, juvenile, infant). Source: Grueter et al. (2026).

Why Do Humans Cry?

How I Learned to Stop Worrying and Love Sex Differences

Steve Stewart-Williams — Wed, 26 Aug 2026 10:30:27 GMT

I recently sat down with Australian boxer and podcaster Tiffanee Cook for an episode of her Roll with the Punches podcast. We had a great conversation about a wide range of topics related to my book A Billion Years of Sex Differences. Among other things, we discussed:

How I fell in love with evolutionary psychology and the science of sex differences
The origins of occupational gender gaps
The many causes of the gender pay gap
Why dating apps often make it harder to find love rather than easier
Whether mental-health problems are discrete disorders or arbitrarily defined segments of a spectrum of symptoms
Sex differences in mental-health problems
The possible origins of the trans phenomenon and non-binary identification

The episode is available on Apple Podcasts, on Spotify, and wherever else you get your podcasts. Hope you enjoy it!

If you want to dive deeper into these topics, you can pick up a copy of A Billion Years of Sex Differences here.

Follow me on Twitter/X for more psychology, evolution, and science.

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Full access to all new posts and the archive - including material I don’t want to share publicly yet
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On top of that, you’ll be supporting my efforts to spread important ideas and carve out a space for free thought and non-politicized science.

Thanks!

Steve

Sixteen Fun Facts About Me

Steve Stewart-Williams — Sat, 22 Aug 2026 09:01:50 GMT

At my Granny’s place in Hastings, New Zealand.

Time for something different. In the tradition of Richard Hanania, Bryan Caplan, Ilya Somin, and Rob Henderson, here are sixteen fun facts about me.

My grandfather was an interesting character - and he knew some interesting characters. At Trinity College Dublin, he shared a room with the playwright Samuel Beckett, who once put a plaque up on the wall saying “PAIN PAIN PAIN.” During World War II, my grandfather was on a civilian ship that was captured by the Japanese, and spent the next four years in a Japanese prisoner of war camp. For most of that time, his family didn’t know whether he was alive or dead. Later, living in New Zealand, he noticed he was having negative thoughts about Japanese people and decided that this was an unacceptable prejudice. So he went out of his way to meet them and rid himself of the bias.
I got my first rejection from a publisher when I was nine. I’d written a 69-page book called Super Sock - a follow-up to my 192-page book, Junior Detective. A friend’s mum knew a publisher and passed it on to him. He didn’t think the book was publishable… but his rejection letter was one of the highlights of my childhood. It was just so positive and encouraging. Who knows if I’d have kept writing without it? Actually, I probably would have. As a child, I always fantasized about making it big as an author or musician, and spent much of my spare time writing stories or songs. Later in life, I tried giving up the habit several times to pursue more realistic options - but I could never quite do it. Before long, I’d once again get an overwhelming urge to create something that might outlive me.
My first rejection letter - but not my last. I’d never seen Monty Python, by the way; I’m not too sure about the Goodies.
The first death I ever got to grips with wasn’t a family member or a friend; it was John Lennon. One December evening, around the time of the rejection letter, my cousin was driving me, my mum, and our twenty-year-old cat to the vet. I was dimly aware of the news on the radio in the background. Suddenly, my mum blurted out “Who?” Someone had been shot in New York. My cousin replied “John Lennon” - and my mum let out a devastated “Why?” I hadn’t heard of John at that point, or of the Beatles, but after that, I became extremely interested in them. Why was my mum so upset? Why was the whole world so upset? I remember lying on the couch with Beatles albums playing on repeat, staring at the covers and trying to wrap my head around the fact that this guy no longer existed - and that one day, nor would I. Soon after that, I started a band called Crazy Kids. It consisted of me and my brother, with our dad kindly recording our terrible songs for us. One of the first songs I wrote was called “Why Does Time Go?” I still remember the chorus:
Why, oh why does time go?
Oh why does it go?
Why do we change from year to year?
Why is winter and summer?
Why is it all?
I suppose that’s quite philosophical for a nine-year-old. Anyway, I believe my brother still has the recordings…
I’m 6’6”, and for as long as I can remember, people have asked me “Do you play basketball?” My go-to answer used to be “No, do you play mini-golf?” These days, however, I usually say that I’ve always been a music guy rather than a sports guy. To me, sports are a bunch of cool games - but music is magic. A sequence of notes isn’t just a series of sounds of different frequencies and durations; it’s a melody with a particular character and feeling to it. You can pick up an instrument and quickly learn to make this magic thing happen yourself. And then you can get a bunch of people together making different but interlocking pieces of magic, and somehow the whole is even more magical than the sum of the parts. It’s one of my favorite things in life.
My grandmother died when I was fourteen. For some time, she’d been too unwell to live alone in her little flat, so she’d moved into my aunt’s and uncle’s house. One night, shortly before the end, my aunt and uncle were woken in the middle of the night by a series of bumps and bangs coming from the darkness. They got up to find out what was happening. What they found was my grandmother packing her suitcases. “What’s going on? Why are you packing?” they asked, gently guiding her back to bed. She responded: “I just saw my parents, and they told me it’s time to go.” She died the next day. This is one of my favorite stories. At the time, I believed (or half-believed) in an afterlife, and thought that maybe my grandmother’s experience was what it seemed to be. I don’t think that anymore. But I still love the story.
I went straight from school to university, but my heart wasn’t in it, and I dropped out after my first year. What I really wanted to do was be a rock star. Under the spell of the Sex Pistols, the Beatles, John Lennon, the Doors, Nirvana, and others, I spent several years teaching guitar and playing in bands, and wrote and recorded an album of my own songs. I eventually decided, though, that this wasn’t the path for me, and that I was a science nerd rather than a rocker. (I don’t mean that in a self-deprecating way, by the way; being a nerd is great. Some of my best friends are nerds.) I went back to university and studied psychology and philosophy, ultimately becoming a psych professor. I don’t regret the decision at all, but for years afterwards, I regularly had dreams about getting back on stage, only to wake up disappointed that I was actually in bed. Since getting in touch with my inner science nerd, I have played live a little, though. Once, for example, I played with a band that played with the Beatles at the Cavern Club. And I’m currently in a band with my colleagues Polly and Miflah called the Psychic Armpits. Here are some photos from yesterday and today.
Making music. If you look carefully, you might notice that my hair situation has changed somewhat over the years. People used to call me Slash; now it’s Walter White.
I don’t drink - anymore. I used to drink a lot. I started in my teens and took to it immediately. I enjoyed being able to alter my consciousness so easily. I’d also always been a bit shy, and felt like I’d discovered a solution to that problem. Unfortunately, the solution also brought new problems of its own. I was never an alcoholic, but I did eventually realize that drinking was standing in the way of me achieving what I wanted to achieve. One night at a party, after imbibing too many beverages, I started feeling dizzy and thought I might be sick. I stumbled out of the party and crawled under a house a few doors down. Lying there with the world spinning around me yet again, I decided that this was ridiculous and that it was time to stop drinking once and for all. I did something I’ve done only a few times in my life: I started aggressively willing myself to make a change. I told myself again and again and again that I was going to stop drinking from that moment on, no matter how hard it was and no matter what difficulties it caused me. Fortunately, with the help of some close friends, I did stop. (The most recent time I did this kind of mental reset led directly to the creation of my Substack. But that’s a story for another day.)
I met my wife on the flip of a coin. I’d returned to university by this point, and the night before my first exam, a friend called and asked if I wanted to go to the pub. I felt like a break, and I’d stopped drinking by then… but I still wasn’t sure it was wise to go out the night before an exam. So I flipped a coin. The verdict was yes, and I went. My friend hadn’t mentioned this, but he had another friend with him: a Brit who he’d met in the UK. That friend was Jane. She’d been teaching in South Korea and was now making her way - in a very roundabout way - back home. She and I immediately hit it off and made each other laugh. Within ten minutes of meeting, there was an earthquake. I joked that it was a sign - the Earth moving for us - but actually earthquakes happen all the time in Wellington. (That’s where we were, by the way; Wellington is my hometown.) If I hadn’t met her that night, there’s a good chance I never would have. Who knows how my life would have turned out if the coin had come up the other way?
I proposed on the steps of immigration - and never heard the end of it. Jane only had a nine-month visa, so we initially assumed that our relationship had a built-in end date. But things were going so well, and we didn’t want to say adios. With Jane’s visa about to expire, the folks at immigration told us that she could only stay if she had a degree or we were married. As bright as she is, we decided that she probably couldn’t get a degree in a month, so, sitting on the steps of immigration, I said “I suppose we could get married.” What a smooth talker, eh? Despite the terrible proposal, she agreed… and has hassled me about it ever since. I later proposed properly, and we got married again in the UK, but the hassling continues to this day. I’ve mentioned this great injustice to various colleagues and friends, but they’re unanimous that she’s well within her rights.
My favorite movie is The Sixth Sense - and one of my favorite anecdotes happened on the day I first saw it. Jane and I decided to get Burger King before the film. We queued up, got to the counter, and ordered our food. The servers started laying the food out on a tray, and I started nonchalantly munching chips while we waited. After I’d munched a few, I realized that this wasn’t our meal; it belonged to the couple who’d ordered before us, and who were now nervously watching this 6’6” guy eating their fries. I was very apologetic, but they didn’t let me buy them new ones - and I don’t think they saw the funny side.
You’re probably thinking that, as I’m clearly such a cool and competent guy, this must be the only time I’ve made such a blunder. Well, dear reader, you’d be wrong. Here’s another example. As a PhD student, I managed to get a paper on the placebo effect into the journal Psychological Bulletin, and a big-name professor in the area - one who’d been hugely helpful to me over the years - was invited to write a commentary. The idea was that my co-author and I would then write a response. The prof wrote a very generous, favorable commentary. After reading the draft, I wrote an email to my co-author saying I didn’t much like it, because it was too favorable and didn’t give us much to argue with - and then promptly sent the email to the big-name prof instead of to my co-author. I felt terrible. I didn’t even particularly mean what I’d written; it was basically just bravado. Luckily, though, the prof was a genuinely good guy, and was very understanding about the whole thing.
My PhD graduation, Massey University, Palmerston North.
Jane and I have two kids. The best thing about kids is that they’re hilarious. Exhibit A: Jane taught our son, Darwin, some baby sign language so he could communicate before he could talk. This included a clip-clop noise that meant horse. One day, we spotted him walking very determinedly toward a visiting kitten while making the clip-clop noise, presumably planning to ride the kitten. We intercepted him just in time. The baby sign language quite possibly saved the kitten’s life. Soon after that, our daughter India was born. Dar was initially very excited to have a sister. His first words on meeting her were “Indy got a nose on.” But about a week later, he’d had enough of this new member of the family, and asked us to take her back to the hospital. So we did. They had a no-returns policy, though, so we had to keep her. Just kidding, Indy! My favorite Indy story happened a few years later, when we were living in Swansea. One day, Jane and I noticed her heading upstairs with something under her arm. It turned out that it was a homemade parachute, and that she was on her way to her bedroom window to test it out. Gotta keep your eyes on them!
I’ve lived in four countries - New Zealand, Canada, Wales, and Malaysia - and I’ve visited 27. I got the travel bug from Jane. Among other things, she and I have cycled round the South Island of New Zealand, paraglided in Queenstown, taken Greyhound buses across the US, been stranded in the Kenyan jungle, and had a cobra rear up at us in Thailand (only a baby, but still). One of my favorite adventures, though, was driving an RV across the Australian outback from Darwin to Adelaide. It was like being on another planet. We’d pass signs telling us that the next convenience store was 300 km away (not very convenient if you ask me). And the road just seemed to stretch out forever! We’d see cars coming in the other direction that felt like they took 15 minutes to reach us.
Jumping off the Sky Tower in Auckland.
I love lecturing, but it doesn’t always go to plan. Shortly before the pandemic, I was giving a lecture in one of the larger lecture theatres at my university. Beforehand, I’d popped by the IT department to pick up a roaming mic. Unfortunately, I’d given them the wrong room number. A few minutes into the lecture, a timid face appeared at the door and informed me that I’d been blasting my lecture into their lecture theatre the whole time.
Retirement age is still a way off, but my current retirement plan is… I’m never going to retire. I don’t know why anyone would want to; working is too much fun. I doubt, though, that I’ll want to be a psych prof forever or retrain for another career. Writing on Substack seems like a great way to continue earning and contributing during my golden years. My role model for aging is Paul McCartney: The guy’s in his 80s but he still gets up on stage and plays three-hour gigs without ever taking a break. My hope is to do the science-nerd equivalent of that.
Apparently, there are only 15 fun facts about me. (Actually, there were more, but Jane persuaded me that some of my stories shouldn’t see the light of day…)

Bonus Item: My All-Time Favorite Song

Addendum 1: GPT Psychological Profile Based on This Post (26 August 2026)

Out of curiosity, I asked GPT to produce a psychological profile based purely on this post. Although I’d quibble with some of it, for the most part it seems surprisingly accurate. Here are some excerpts. Because it’s GPT, it’s generally quite flattering - but it does list some of my likely (and, if I’m being honest, actual) weaknesses at the end.

Executive summary
The writer appears to be a highly intelligent, verbally gifted, and unusually creative man whose deepest motive is to make meaningful things that survive him. He combines the temperament of an artist with the habits and worldview of a scientist: emotionally responsive to music, stories, mortality, and family, but strongly committed to evidence and capable of revising cherished beliefs…
His most distinctive feature may be the combination of existential seriousness and comic self-deprecation: underneath the amusing anecdotes is someone preoccupied with time, death, meaning, creation, and leaving something behind…
Big Five profile
Most distinctive psychological characteristics
1. A powerful symbolic-immortality motive
The writer appears unusually aware that life is finite and uses creative production as his principal answer to that fact...
2. Episodic self-reinvention
He describes occasionally “aggressively willing” himself into a new course of action. Most of the time he may be flexible and playful—but under certain conditions he becomes extremely decisive…
3. High psychological integration
The essay contains several potentially conflicting selves:
Shy person and public performer.
Rocker and professor.
Romantic and sceptic.
Highly accomplished person and blunderer.
Adventurer and hardworking writer.
Existentially serious thinker and inveterate joker.
Rather than hiding the contradictions, he makes them part of a coherent persona…
Likely weaknesses
The same traits probably generate predictable vulnerabilities:
Difficulty disengaging or genuinely resting.
Neglecting practical details while absorbed in more interesting problems.
Periodic all-or-nothing behaviour.
Excessive identification with productivity and creative output.
Feeling that ordinary life is insufficient unless something lasting is being made.
Using humour to move past embarrassment or sadness before fully expressing it.
Occasional insensitivity arising from playful irreverence rather than lack of concern.
Underestimating how unusual his energy, intelligence, or intrinsic motivation is in other people.
His claim that he never wants to retire may be sincere, but it also hints that not producing could feel psychologically threatening. Work may provide not only enjoyment, but identity, structure, self-worth, and an answer to mortality.

Addendum 2: GPT Psychological Profile Based on All Available Information (26 August 2026)

The first profile was based only on my Sixteen Fun Facts piece. How different would it be if GPT factored in everything it knows about me from our interactions and everything it can find about me online?

The answer is that the profile is substantially the same, but with a few important revisions. Here are some excerpts from the updated version. Once again, I’m amazed by what AI is capable of.

The larger body of evidence mostly confirms the original profile, but it changes the emphasis in several interesting ways. The biggest revisions are that I’d raise conscientiousness, slightly lower agreeableness, and revise upward my estimate of his social confidence: although naturally somewhat shy, he appears highly comfortable and assertive when lecturing, performing, or discussing subjects he knows well. I’d also replace the somewhat romantic portrait of a dreamy artist–scientist with a more formidable picture of an intellectually independent, highly self-directed writer-scholar—someone strongly resistant to orthodoxy, imprecision, and moralised thinking…
Revised Big Five profile
Openness: essentially unchanged
You are highly open to ideas and experiences, but comparatively resistant to fashionable linguistic, moral, or ideological innovation when you think it obscures reality. In other words, you are psychologically unconventional without automatically siding with whichever position is culturally labelled unconventional…
Conscientiousness: higher, but markedly uneven
I would put industriousness, achievement striving, and epistemic conscientiousness above the 95th percentile. At the same time, you appear much less reliably conscientious about mundane environmental details…
Agreeableness: somewhat lower
I’d now describe the profile as:
Compassion: high.
Forgiveness and absence of vindictiveness: high.
Politeness: moderate to moderately high.
Compliance: low.
Intellectual deference: very low.
Neuroticism: probably somewhat lower
The wider evidence suggests unusual resilience:
You returned from dropping out of university and built an academic career.
You abandoned one central identity without becoming bitter about it.
You stopped drinking through an unusually forceful act of self-reconstruction.
You have repeatedly worked on controversial subjects while attracting public criticism…
Characteristics I would add
1. Exceptional epistemic conscientiousness
This is probably the most important addition. You have an unusually strong drive to get claims exactly right…
2. Intellectual independence without wholesale contrarianism
You are clearly attracted to questions where public consensus may be distorted by ideology. But you don’t appear temperamentally committed to opposing consensus as such…
3. Moral individualism
Your politics and moral psychology seem organised less around loyalty to a tribe than around allowing individuals to pursue lives that suit them, provided they are not harming others…
Revised bottom line
Steve Stewart-Williams appears to be an exceptionally open, verbally gifted, highly industrious writer-scholar driven by curiosity, intellectual independence, and the desire to produce work of enduring value. He combines aesthetic sensitivity with scientific scepticism, strong convictions with genuine belief revision, and considerable ambition with an aversion to pomposity. His mind naturally searches for distinctions, neglected evidence, integrative explanations, and the precise sentence that will make a difficult idea clear. Personally warm but intellectually noncompliant, he is more agreeable toward people than toward propositions. His characteristic achievement is to turn persistent private preoccupations—human nature, sex differences, truth, mortality, and meaning—into accessible public work. His characteristic vulnerabilities arise from the same source: difficulty disengaging, overinvestment in productivity, perfectionism about language, and a tendency to give cognitively interesting problems more attention than mundane practical reality.

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Thanks!

Steve

Mismatched

Steve Stewart-Williams — Thu, 20 Aug 2026 08:43:02 GMT

Photo by ROBIN WORRALL on Unsplash

Evolutionary mismatch is one of the most useful concepts in evolutionary psychology. The basic idea is that the modern world is very different from the world in which we evolved, and thus that we’re misaligned with our environment in various ways. A fascinating new paper by Jose Yong and colleagues applies this idea to some of the biggest psychological challenges of modern life, and argues that the stress, loneliness, and status anxiety that many of us experience are partly the result of mismatch.

The paper’s main ideas can be summed up in two graphs and one table.

Graph 1: Three Types of Mismatch - Animal Edition

The first graph shows three types of evolutionary mismatch seen in other species. (Note that EEA stands for environment of evolutionary adaptedness - that is, the environment to which a species is primarily adapted.)

Graph 2: Three Types of Mismatch - Human Edition

The second graph gives human examples of each type of mismatch - examples that harm our romantic lives, our health, and social cohesion.

Table 1: A Catalogue of Mismatches

Finally, the table below lists various examples of evolutionary mismatch that contribute to the stresses and strains of modern life.

The table is really the core of the paper’s argument. According to Yong and colleagues, many of the aches and pains of modern life can be traced in part to these mismatches. Large cities, inequality, and complex social hierarchies ramp up status competition, stress, and loneliness. Artificial environments and sedentary lifestyles undermine health and well-being. Screens, social media, and information overload bombard us with more stimulation and information than we evolved to handle. And 24-hour news gives us constant exposure to distant wars, pandemics, and other crises, keeping ancient threat-detection mechanisms working overtime.

It’s worth pointing out that although the modern world is mismatched with human nature in some ways, in other ways it’s better adapted to our evolved needs and wants than more natural environments are. It would be surprising if this weren’t the case, given that we ourselves created the modern world. We’ve got food on tap metaphorically, water on tap literally, and the safest environments humans have ever inhabited. We’ve got more options for work, leisure, and lifestyle than our ancestors could dream of. We’ve got glasses, contraception, air conditioning, heating, and modern medicine. And more important than any of that, we’ve created a world in which the vast majority of our children survive until adulthood, when for much of our evolutionary history around half died before their fifth birthdays.

Sure, we haven’t yet mastered the art of reliably making ourselves happy. But given our stunning successes elsewhere, it’s hard to believe that this is permanently beyond our grasp.

For anyone interested in diving deeper into these issues, the paper is titled “Evolutionary Mismatch, Stress, and Competition: Making Sense of Psychosocial Problems in the Polycrisis Era,” by Jose Yong, Amy Lim, Edison Tan, and Sarah Chan. You can read it here for free (it’s open access).

I discuss evolutionary mismatch in my book The Ape That Understood the Universe. You can read the first chapter for free here.

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Steve

Are Sex Stereotypes True?

Steve Stewart-Williams — Tue, 18 Aug 2026 09:00:16 GMT

During my recent book tour, I was scheduled to sit down in person with Fraser Myers of Spiked magazine to talk about my book, A Billion Years of Sex Differences. But the British weather had other ideas: A heatwave scuppered our plans, and we ended up doing the interview remotely after I’d returned to the cooler climate of Malaysia.

It was a great conversation. Among other things, we discussed:

The largest psychological sex difference ever documented (it’s probably not what you’d think)
Sex differences in toy preferences, sexual behavior, and aggression
Why men and women tend to gravitate toward different occupations
The gender-equality paradox: the surprising finding that some sex differences are larger, rather than smaller, in wealthier, more gender-equal nations
Why we should talk openly about sex differences rather than pretending they don’t exist

The interview is now up on YouTube and the Spiked website.

If you enjoy the conversation and want to dig deeper into the issues, you can pick up a copy of A Billion Years of Sex Differences at the link below.

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Premium subscriptions also help support my efforts to explore important and controversial topics, and give me the financial freedom to follow the evidence wherever it leads without fear of cancellation.

Thank you!

Steve

12 More Things Everyone Should Know About IQ

Steve Stewart-Williams — Sat, 15 Aug 2026 09:29:19 GMT

Photo by Randy Fath on Unsplash

The Nature-Nurture-Nietzsche Newsletter

This is the latest post in my “12 Things Everyone Should Know” series. You can access the full collection here.

In 2024, I published a piece titled “12 Things Everyone Should Know About IQ.” It was one of my first paywalled posts, and I was amazed at how big the response was. More than two years later, it remains the most popular post I’ve ever published. Clearly, IQ is a topic that fascinates people.

It’s not hard to see why. Intelligence affects almost every aspect of our lives, from how well we do at school and at work to our health and longevity. At the same time, few topics in psychology generate as much debate and disagreement. IQ has been described as everything from psychology’s greatest scientific achievement to its greatest fraud.

12 Things Everyone Should Know About IQ

This is the first post in my “12 Things Everyone Should Know” series. You can access the complete collection here…

3 years ago · 171 likes · 10 comments · Steve Stewart-Williams

The good news for fans of IQ is that my first post barely scratched the surface of the topic. In this follow-up, we’ll look at 12 more things everyone should know about IQ - including what we’ve learned about factors that raise or lower it, whether there’s really an IQ threshold beyond which being smarter stops being useful, and why the century-long rise in IQ scores may now be going into reverse.

Let’s get started.

1. Most People Don’t Know How Smart They Are

If you ask people how extraverted or conscientious they are, they’ve usually got a pretty good idea. If you ask them their IQ? Not so good. Self-assessed IQ is only weakly related to objectively measured IQ. Indeed, self-assessed IQ is a better barometer of people’s self-esteem than of their actual cognitive ability. Interestingly, while both sexes sometimes overestimate their IQs, one sex does it more than the other. Before looking at the graph below, see if you can guess which it is…

Men are more likely to overestimate their IQ. Source: Reilly et al. (2022).

2. Intelligence Is Attractive - But Only Up to a Point

People generally prize intelligence in a boyfriend, girlfriend, husband, or wife - but more isn’t always better. The sweet spot seems to be around IQ 120. As shown in the following graph, people rate a person with a 120 IQ as more desirable than someone with an IQ of 135 or above. Perhaps surprisingly, this is true regardless of their own level of intelligence.

Mean ratings of sexual attraction and partner interest associated with seven intelligence (IQ) percentiles. Source: Gignac et al. (2018).

The Four Horsemen of the Evolutionary Apocalypse

Steve Stewart-Williams — Thu, 13 Aug 2026 09:08:07 GMT

Latest Podcast Appearance

This was a fun one: the Modern Wisdom evolutionary psychology roundtable featuring , Macken Murphy, , and yours truly. We covered everything from looksmaxxing and the ick to the dangers of ignoring sex differences, with lots of laughs, disagreements, and rabbit holes along the way.

You can find the episode on Apple Podcasts, on Spotify, or wherever else you get your podcasts. You can also watch it on Chris’s YouTube channel.

If you enjoy the conversation and would like to explore these topics in greater depth, you can pick up a copy of my new book A Billion Years of Sex Differences here.

A New Review of A Billion Years of Sex Differences

A Billion Years of Sex Differences was recently reviewed in the Swedish newspaper The Bulletin. The review, by , covers a lot of ground, but I particularly like the last few paragraphs, which nicely capture one of the central messages of the book.

In the wealthy, free world, we now have the means, time, and opportunity to be irritated by the opposite sex’s quirks as never before. Men have the freedom to fritter away time on video games, and women on Instagram—so that is what we do.

This obscures the fundamental truth about men and women: that we are on the same side; that we need and love one another; that our similarities far outweigh our differences; and that no man remains unscathed when his mother, sister, or daughter is harmed, just as no woman remains unscathed when her father, brother, or son is harmed.

Our goal should be to create a society for everyone—men and women alike—rather than trying to reshape people to fit society. Steve Stewart-Williams’s book is part of that project.

A New Interview About A Billion Years of Sex Differences

The Swedish magazine Kvartal just published a 5,000-word feature article about A Billion Years of Sex Differences. Written by Jonathan Norström, the piece was based on an interview we did a few weeks ago. I don’t speak a word of Swedish myself, so I can’t vouch for anything I said. But the artwork is cool!

Thanks for reading, and thanks to everyone who’s supported A Billion Years of Sex Differences since it came out. More podcast appearances, reviews, and interviews to come!

Follow me on Twitter/X for more psychology, evolution, and science.

Upgrade to a Paid Subscription

If you’d like access to all Nature-Nurture-Nietzsche-Newsletter content, please consider a paid subscription. A paid subscription gives you:

Full access to all new posts and the archive
Full access to excerpts from A Billion Years of Sex Differences
Full access to exclusive content such as my “12 Things Everyone Should Know” posts, Linkfests, and other regular features
The ability to post comments and engage with me and the N³ Newsletter community

Paid subscriptions also help support my efforts to explore important and controversial topics, and give me the financial freedom to follow the evidence wherever it leads without fear of cancellation.

Thank you!

Steve Stewart-Williams

Smarter People Are More Prosocial

Steve Stewart-Williams — Tue, 11 Aug 2026 09:18:31 GMT

Photo by Rashidul Islam on Unsplash

This is the latest post in my “Smarter People” series. Check out the full collection here.

Are smart people naughty or nice? A new study suggests the latter. Analyzing data from 1.2 million Swedes, the researchers found that smarter individuals were more likely to vote, more likely to donate to charity, and more likely to own an eco-friendly car. They also tended to score higher on a self-report measure of altruistic behavior.

Relationship between cognitive ability and prosocial behaviors. Panels (a)–(c) show the relationship between cognitive ability and charitable giving (a), voting (b), and having an eco-friendly car (c), for men. Panels (d)–(f) show the corresponding relationships for women. Note that there were more men than women in the sample because cognitive ability was measured during military enlistment, which was mandatory for men in Sweden but voluntary for women. Source: Elinder and Erixson (2025).

Importantly, the intelligence-prosociality link held even when comparing twins within the same family. This suggests that the link isn’t just due to confounding by shared genes or shared upbringing. It therefore strengthens the case that intelligence directly increases prosociality.

How might it do this? Possible explanations include more rapid acquisition of moral norms, better moral reasoning, a better appreciation of others’ perspectives, and a better understanding of the benefits of mutual cooperation. Curiously, having a higher income explained little if any of the intelligence-prosociality link.

The paper is titled “An inquiry into the relationship between intelligence and prosocial behavior: Evidence from Swedish population registers,” by Mikael Elinder and Oscar Erixson. You can access it here for free.

How You Can Support the Newsletter

I love writing The Nature-Nurture-Nietzsche Newsletter, but it’s a lot of work! If you’d like to support my mission to bring you non-politicized science, there are several ways you can help.

Like and Restack: Click the buttons at the top or bottom of the page to boost the post’s visibility on Substack.
Share: Send the post to friends or share it on social media.

Upgrade to a Paid Subscription: If you can afford it, a paid subscription will get you:
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If you could do any of the above, I’d be hugely grateful. The support of readers like you is what makes this newsletter possible.

Thanks!

Steve

From the Archive

Darwin Was Right About Sex Roles

Steve Stewart-Williams — Sat, 08 Aug 2026 08:44:35 GMT

Photo by Damon Hall on Unsplash

Darwin’s theory of sexual selection is one of the most powerful ideas in evolutionary biology. It’s also one of the most controversial. Is it really true, as Darwin proposed, that sexual selection acts more strongly on males than females? Is it really true that males across the animal kingdom are more ornamented and better built for combat, whereas females are more parental? Or are these just evolutionary myths based on Victorian norms and a handful of cherry-picked examples?

A major cross-species analysis put Darwin’s theory to an unusually ambitious test, looking at sexual selection, ornaments, weaponry, and parental care across the animal world. The results provide a clear verdict on Darwin’s thesis - while also highlighting some fascinating exceptions that point to a deeper explanation for evolved sex differences.

How I Went From Dangerous Heretic to Boring Academic in Just Three Years - Without Changing Any of My Views

Steve Stewart-Williams — Thu, 06 Aug 2026 11:05:21 GMT

It’s podcast time again, folks! A few weeks ago, I had the great pleasure of returning to ’s Uncomfortable Conversations. Josh and I had a fun, wide-ranging discussion about my book, A Billion Years of Sex Differences, and related topics.

We also discussed the recent “vibe shift,” and how ideas that got me into hot water a few years ago are gradually becoming acceptable topics of conversation again (touch wood). At one point, Josh made the very funny observation that,

When you first came to my attention three years ago, you were this defiant voice standing up to the mob and now, fortunately, you’re just the - no offense - boring academic that you should be by just saying true things accurately.

My immediate response was that I much prefer the latter! I did add, though, that it was kinda cool being a badass just for making a commonsense observation backed by a mountain of research: that men and women are different.

Here’s the blurb for the episode:

Are men innately more violent? Are women innately more people-focused? What explains gay people, campness, transgenderism? How much of the sex differences are cultural, and how much is hardwired by our evolutionary psychology?
The science of the sexes has come a long way. Steve Stewart-Williams is a psychology professor who wrote the groundbreaking book The Ape That Understood the Universe and whose new book is A Billion Years of Sex Differences: How Evolution Shaped the Minds of Men and Women.
Steve joins Josh to explore the science of the sexes, from aggression to promiscuity to parenting, and what recent research reveals about how, and why, men and women behave the way we do.

The episode is available on Apple Podcasts, on Spotify, and wherever else you get your podcasts. It’s also available on the Uncomfortable Conversations YouTube channel.

If you enjoy the conversation and would like to explore these ideas in more depth, you can pick up a copy of A Billion Years of Sex Differences here.

Follow me on Twitter/X for more psychology, evolution, and science.

Upgrade to a Premium Subscription

If you’d like access to all Nature-Nurture-Nietzsche-Newsletter content, please consider a paid subscription. A paid subscription gives you:

Full access to all new posts and the archive
Full access to excerpts from A Billion Years of Sex Differences
Full access to exclusive content such as my “12 Things Everyone Should Know” posts, Linkfests, and other regular features
The ability to post comments and engage with me and the N³ Newsletter community

Paid subscriptions also help support my efforts to explore important and controversial topics, and give me the financial freedom to follow the evidence wherever it leads without fear of cancellation.

Thank you!

Steve

Why Men Take More Risks

Steve Stewart-Williams — Tue, 04 Aug 2026 10:05:36 GMT

Image by GPT5.

Why are men so much more likely than women to die doing something spectacularly unwise? Why are they overrepresented among extreme sports enthusiasts, workers in dangerous occupations, and people whose last thought is, “Yeah, this seems like a good idea”?

Across cultures, throughout history, and in many other species, males are consistently more willing than females to roll the dice. In this excerpt from my book A Billion Years of Sex Differences, I explore what the research says about sex differences in risk-taking and where they come from. Among other things, we’ll discuss:

How we know that sex differences in risk-taking aren’t just a mirage - and aren’t just a product of culture
Why men dominate both the Darwin Awards and the Carnegie Hero Awards
Why natural selection sometimes favors traits that reliably get people killed
Why sex differences in risk-taking explode after puberty
What chimpanzees can teach us about human risk-taking

You can find the full collection of excerpts here, or pick up a copy of A Billion Years of Sex Differences here.

Reckless Abandon

Being male is now the single largest demographic risk factor for early mortality in developed countries.

-Daniel Kruger and Randy Nesse (2004), p.66

The fact that men engage in more aggression than women – and more of a range of antisocial behaviours – stems in part from another important sex difference: the sex difference in the tendency to take risks. As most people are all-too aware, boys and men are bigger risk-takers than girls and women. This sex difference helps explain various stubborn facts. It helps explain why boy toddlers are more likely than girl toddlers to end up in the emergency room; why men are over-represented on the Wikipedia page of inventors killed by their own inventions; and why more men than women participate in extreme sports – that is, sports extremely likely to kill you, such as base jumping, hang-gliding, and motor racing. It helps explain why men do most of the riskiest jobs in the world – including construction worker, fisherman, logger, taxi driver, and truck driver – and why more than 90% of workplace fatalities are men. And it helps explain why men are more likely than women to accept stupid dares, gamble away their life savings, invest in cryptocurrencies, die while taking extreme selfies, and hit send on an email without reading it through first.

It’s quite a résumé . . . and we’re only just getting started! Men are more likely than women to get into car accidents, even when you statistically control for the fact that men drive more. This isn’t because men are less skilled at handling a vehicle; it’s because they more often drive too fast, tailgate, and drive drunk. At the same time, despite their Russian roulette driving habits, men less often wear seatbelts. Not only are men more likely to crash a car, they’re more likely to get hit by a car while crossing the road. This isn’t because motorists try to run men down; it’s because men are more likely to try to cross when it’s unsafe. Yep, scientists have sat by the side of the road tabulating men’s and women’s road-crossing habits, and that’s what they’ve observed. And not only are men more likely to be struck by cars, they’re more likely to be struck by lightning. This isn’t because God hates men; it’s because men are more likely to work outdoors and less likely to think ‘Hmmm, there’s a storm coming; maybe I should go inside.’

Every year, the British Medical Journal publishes a light-hearted Christmas edition. The 2014 offering included an article testing the hypothesis that men engage in more ‘idiotic risk-taking’. To that end, the authors looked at the demographic makeup of Darwin Award recipients. Darwin Awards are bestowed on individuals whose actions ensure ‘the long-term survival of the species, by selectively allowing one less idiot to survive’. Notable recipients include the would-be aviator who strapped helium balloons to a lawn chair then drifted over Los Angeles for 14 hours before being rescued, and the terrorist who put insufficient postage on a letter bomb, then unthinkingly opened it when the parcel was returned to his door. Crunching the numbers, the researchers found that 88% of Darwin Award winners were men, consistent with their ‘male idiot theory’.

To be fair, although men take more idiotic risks, they also take more heroic ones. More than 90% of Carnegie Hero Awards go to men, to give just one example. Still, whether idiotic, heroic, or a mixture of both, the root cause of the sex difference is the same: Men are more tolerant of risks.

Why Two People with the Same IQ Can End Up Living Very Different Lives

Steve Stewart-Williams — Sat, 01 Aug 2026 07:26:34 GMT

Photo by Waz Lght on Unsplash

The Nature-Nurture-Nietzsche Newsletter

If you’ve taken an introductory psychology course, you’ll have heard about general intelligence, also known as g. g is a general-purpose cognitive ability that’s brought to bear on every cognitive task. It’s what IQ tests aim to measure.

What makes us think that there’s any such “thing” as g? Simple: the fact that people who do well on one kind of cognitive test also tend to do well on others. Good at vocabulary? You’re more likely to be good at math as well. Good at math? You’re more likely to have a good memory - and good spatial abilities and good processing speed. The positive correlation among cognitive tests suggests an underlying factor that contributes to performance on all of them. Whatever exactly that factor is, it’s what psychologists call g.

The evidence for g’s importance is overwhelming. People with higher IQs tend to stay in education longer, enter higher-status occupations, earn more, enjoy better health, and even live longer. These aren’t just cherry-picked, small-sample, yet-to-be-replicated flukes. They’re among the strongest and most consistent findings in psychology.

12 Things Everyone Should Know About IQ

This is the first post in my “12 Things Everyone Should Know” series. You can access the complete collection here…

3 years ago · 169 likes · 10 comments · Steve Stewart-Williams

But although people who do well on one cognitive task tend to do well on others, no one does exactly as well on every task. Two people can have exactly the same IQ score but different profiles of strengths and weaknesses. Jojo may have exceptional verbal skills but only somewhat above average math skills. Loretta may process information at lightning speed but fall behind on abstract thinking. Martin may have an intuitive feel for machinery and electronics but lack the gift of gab.

Should we expect these individuals to end up having similar life outcomes simply because their overall IQs are the same?

For many years, the conventional wisdom in psychology was basically “yes.” General intelligence was thought to do almost all the heavy lifting. As one influential paper put it, specific cognitive abilities contribute “not much more than g.”

But recent research by Tobias Edwards and Colin DeYoung, published in the journal Intelligence and Cognitive Abilities, suggests otherwise. Using data from nearly 19,000 Americans across two generations, the researchers showed that your specific abilities shape your occupation, income, and job status, over and above IQ.

Edwards and DeYoung extracted three specific abilities statistically independent of g: technical ability, processing speed, and math-vs-verbal ability - a factor reflecting the extent to which people are better with numbers than words. They then looked at the extent to which IQ and these specific abilities correlated with people’s life outcomes.

The following four graphs summarize their main findings.

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Graph 1: IQ Matters More with Age - But Specific Cognitive Abilities Matter Too

The first figure shows how cognitive abilities predict income and occupational status across the adult years. The key message is that IQ becomes increasingly important with age, while specific abilities have a fairly stable impact.

NLSY79 = National Longitudinal Survey of Youth 1979 (participants were 14-22 in 1979); NLSY97 = National Longitudinal Survey of Youth 1997 (participants were 12-16 in 1997). Source: Edwards and DeYoung (2026).

The effect of cognitive abilities on earnings is worth zooming in on. As you can see, in people’s late teens and early twenties, general intelligence barely predicts earnings at all. Indeed, in one of the two datasets, the relationship is briefly negative. This is presumably because, in their first years out of high school, many cognitively gifted individuals are still in education, trying different jobs, or not yet in positions where their cognitive talents can fully express themselves. It takes until the mid-twenties for IQ to really start making waves - but when it does, it soon becomes the strongest cognitive predictor of income.

Meanwhile, tech ability shows almost the opposite pattern. It has a positive effect on income in the late teens and early twenties - the exact time when general intelligence does nothing - but then crosses the zero line and drifts negative as people age. That’s the earnings fingerprint of the kid who left school to become an electrician or mechanic before their classmates had even decided on a major. It pays off in the short term, but then traditional academic pathways overtake it.

Graph 2: It’s Not Just Family Background

A Billion Years of Sex Differences: The Story So Far

Steve Stewart-Williams — Fri, 31 Jul 2026 03:26:14 GMT

Taking Stock

It’s been a month since I got back from the book tour for A Billion Years of Sex Differences, and I’ve finally had a chance to catch my breath and take stock of how things have gone. Overall, I’ve been extremely pleased with the reception the book has received. Among other things:

It’s been featured in the four major UK newspapers: The Times, The Guardian, The Telegraph, and The Independent.
Reviews of the book have been overwhelmingly positive, even in outlets where I expected a tougher ride, such as The Guardian and The New Statesman. Highlights include reviews in The Australian, The Bulletin (Sweden), Male Psychology Magazine, The New Zealand Herald, Quillette, The Sunday Telegraph, and ZNews (Vietnam).
I’ve been on more podcasts in the last two months than I’d been on in my entire career before that. Most notably, Chris Williamson flew me to Austin, Texas, to make a second appearance on his Modern Wisdom podcast: one of the biggest podcasts in the world.
I’ve done interviews for various outlets, including The Telegraph, Skeptiker, How To Academy, and The Scottish Herald. The Herald interview was for a long-form piece about me and my ideas, which should be out in late August.
Next week, I’ll be making my first TV appearance on BBC Business Today, which has an estimated global audience of 15 million viewers. [Update: The BBC had to postpone my appearance because of breaking news. We’ve rescheduled for October.]
I published my first op-ed in The Independent: an overview of some of the book’s key ideas.
My publicist is working on getting an excerpt from the book into The Spectator in the near future.
A Billion Years made The New Zealand Listener’s list of the best books of 2026 so far. To my surprise, appearing in The Listener meant more to me than earlier mentions in The New York Times and Rolling Stone magazine, because my family always got The Listener when I was growing up. Also, my mum happened to spot my name there unexpectedly, which made it particularly special.
The book has been nominated for the Baillie Gifford Prize for Non-Fiction.
Several academics have confirmed that they’ll be using it in their classes.
Readers from around the world have been posting photos and videos of the book online. This one wins the book-in-the-most-exotic-location award:

A friend from London texted last week to say she’d spotted a random stranger reading the book on the train. For some reason, out of everything that’s happened, this was one of the highlights.
I’ve started working with Prometheus Books on the North American edition of A Billion Years, which will hit the bookshelves on January 19. I’m looking forward to another book tour and round of promotional work then.
Most gratifying of all, though, is the sense that the conversation about sex differences is changing. Ideas that seemed almost unspeakable a few years ago are increasingly being discussed openly and seriously. If A Billion Years of Sex Differences is helping nudge the conversation in that direction - even a little - I’ll consider it a success.

A New Review in Quillette

The latest review of A Billion Years of Sex Differences has just appeared in Quillette. It’s by the evolutionary biologist Jerry Coyne, who described the book as “essential reading.” Here’s an excerpt:

In A Billion Years of Sex Differences, Steve Stewart-Williams argues that it’s time to engage these questions with data. Summarising existing research, he comes down closer to genetic determinism than to blank-slatism. That is, he sees significant sex differences in thinking, behaviour, and preferences as having a substantial genetic basis, but he recognises too a role for sociocultural influences.
Stewart-Williams handles his hot potato gently. He is careful to admit when we lack good evidence for a purported sex difference; when we lack information about the genetic basis of a difference we can document; and when, as with homosexuality, we have that genetic information but remain ignorant about how the difference evolved. (Homosexuality is one such puzzle, since it has a partial genetic basis, but, under simple Darwinian logic, genes that reduce reproduction should be eliminated from populations.)
And he addresses at length—and counters—the view that inherited sex differences will lead to bigotry. Instead, he recommends that both sexes should have equal opportunities, with everyone free to choose their own path. In the end, it’s obvious that the more we understand the basis of sex differences, the better equipped we are to address them. This measured, timely, and informative book is essential reading at a time when many scholars not only insist that male–female differences are culturally generated but go further, denying that there are just two sexes.

My Appearance on the Michael Sartain Podcast

This was a fun one. Michael Sartain is a Las Vegas–based dating coach who also runs bikini beauty pageants and a popular podcast. He’s a longtime fan of evolutionary psychology, and has been a very generous supporter of my last book, The Ape That Understood the Universe. We recently sat down together - Michael in Las Vegas, me in Kuala Lumpur - to discuss A Billion Years of Sex Differences, and evolutionary psychology in general. Here’s the blurb for the episode:

In this episode, I sit down with evolutionary psychologist Steve Stewart-Williams for an in-depth conversation about human nature, biological sex differences, attraction, relationships, personality, and the controversial science behind evolutionary psychology.
Steve is a professor of psychology at the University of Nottingham Malaysia and the author of Darwin, God and the Meaning of Life, The Ape That Understood the Universe, and his latest book, A Billion Years of Sex Differences.
We explore why evolutionary psychology remains one of the most misunderstood and politically controversial areas of psychology. Steve explains why both traditionalists and progressives can misrepresent sex differences, why recognizing biological influences does not mean defending traditional gender roles, and why describing human nature is not the same as deciding how society should operate.

The episode is available on Apple Podcasts, on Spotify, and wherever else you get your podcasts. It’s also available on Michael’s YouTube channel.

You can pick up a copy of A Billion Years of Sex Differences here.

Follow me on Twitter/X for more psychology, evolution, and science.

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Steve