The Nature-Nurture-Nietzsche Newsletter

The first review of A Billion Years of Sex Differences just appeared in The Times!

I probably wouldn’t have chosen the title - “Why men are promiscuous and women are choosy” - but I’m very happy with the review itself.

Below is a brief excerpt. You can read the whole thing here. And if you’d like a copy of the book, you can order it from the Times Bookshop.

Within every nation, men watch more pornography, use more prostitutes, are more interested in one night stands, masturbate more, cry less, are more likely to murder and die in car crashes than women…
When men have absolute power, they get a harem. When women have power — well, let’s just say that Queen Victoria wasn’t noted for her tendency to fill the court with nubile young men.
And if men can’t get a harem? “Men corner the market on what evolutionary biologists call mate-choice failure, with documented cases involving everything from lampposts to trees to vacuum cleaners.”
Of course, it’s not so much the existence of these differences that is so controversial among his academic colleagues. Rather it is the assertion that these differences are in some way innate. Are women really less likely to fornicate with trees? Or has the patriarchy simply repressed their latent arborophilia?
Stewart-Williams’s position is the former…
Where Stewart-Williams is most persuasive is in laying out the areas of uncertainty, acknowledging the importance of nurture, but arguing forcefully that there is a core of irreducible difference that is so obviously down to nature that — well — it takes a very clever social scientist to claim otherwise.
“No one would argue that female and male raccoons act differently because they’re rewarded for behaviour consistent with arbitrary raccoon gender roles,” he writes. So why do we do that with humans? “Why would natural selection wipe the slate clean of these sex differences in our species alone, only for us to then reinvent the same set of sex differences in every society on record?”

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

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To help support my work, please consider upgrading to a paid subscription. A paid subscription will get you: (1) full access to all new posts and the archive, (2) full access to my “12 Things Everyone Should Know” posts, Linkfests, and other regular features, and (3) the ability to post comments and interact with the N³ Newsletter community.

Thanks!

Steve

Sex Differences in Dream Content

Steve Stewart-Williams — Wed, 20 May 2026 14:59:45 GMT

Photo by Bruce Christianson on Unsplash

Men have more dreams with competition-related themes than women do; women have more dreams with social themes - a pattern consistent with broader sex differences in human motivations. Beyond these domains, however, men’s and women’s dreams are largely similar.

The graph comes from a recent paper by Zachary Grant and colleagues. Here’s an excerpt:

We explore whether sex differences in evolved behavioral and cognitive strategies shaped by distinct evolutionary pressures are expressed in dream content. We hypothesized that biological sex influences dream content; specifically, that females would report more dreams featuring social and emotional themes, while males would more frequently report dreams involving competition-related content (e.g., risk, reward, and threat), reflecting sex-differentiated ancestral challenges. With a sample of 298 participants logging 4641 dreams, we evaluated dream content across six thematic domains: Emotional Valence, Positive Emotional Content, Negative Emotional Content, Social Content, Competition-based Content, and Resource Acquisition-based Content. Using a mixed-effects model, we discovered that males were significantly more likely to report dreams involving competitive content, while females showed a higher propensity for social dream content. No other themes, including the domains of emotional content, yielded significant results. While these patterns are consistent with possible adaptive functions of dreaming, they may also reflect hormonal influences, socio-cultural factors, personality differences, or other non-evolutionary contributors. Our results extend existing literature on sex differences in dream content using text-based scoring methods, offering a nuanced perspective on how dreams may relate to both biological and social influences.

You can access the paper here for free.
For more on the evolution of sex differences, you can preorder my forthcoming book, A Billion Years of Sex Differences, here. Note that paid subscribers to The Nature-Nurture-Nietzsche Newsletter can read exclusive excerpts from the book before the official publication date.

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

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If you’re enjoying The Nature-Nurture-Nietzsche Newsletter and want more of the same only different, consider upgrading to a paid subscription. 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
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The ability to post comments and engage with the growing N³ Newsletter community

Academia's Leftward March

Steve Stewart-Williams — Sat, 16 May 2026 10:02:53 GMT

Photo by Serj Sakharovskiy on Unsplash

Universities have leaned left politically since at least the 1960s. In itself, that’s not a problem. Different professions attract different kinds of people. Artists lean liberal. Soldiers lean conservative. Why should academics be any exception?

But there’s a difference between a lean and a monopoly - and American academia is rapidly approaching the latter. According to a recent paper by Nathan Honeycutt, 74% of US faculty identify as liberal, 15% as moderate, and only 11% as conservative. Remarkably, more faculty identify as “far left” or “very liberal” than with any position right of center.

This matters because intellectual progress depends on disagreement. When dissenting voices vanish, institutions don’t become wiser; they become more vulnerable to groupthink, motivated reasoning, and the comforting illusion that everyone sensible already agrees. If universities lose the capacity to challenge their own assumptions, their claim to be society’s truth-seeking institutions starts to look increasingly shaky.

In this post, I’ll outline five key findings about the political makeup and trajectory of academia, captured in five fascinating graphs.

1. Even the Center is Vanishing

The first graph shows the increasing dominance of the left in academia from the late 1960s to the early 2020s. As you can see, liberals and leftists have always outnumbered the rest, but the skew has grown increasingly strong over time. And not only have conservatives become vanishingly rare, so have centrists. That’s how complete the left’s dominance is: Even moderates are now a fringe group in academia.

2. Representation Matters - But Only the “Right” Representation

An Evolutionary Enigma

Steve Stewart-Williams — Wed, 13 May 2026 10:55:38 GMT

Photo by Alexander Grey on Pexels.

Same-sex sexual orientation is a genuine evolutionary mystery. Traits that reduce reproduction are not supposed to persist - yet homosexuality does.

How?

In this excerpt from my forthcoming book A Billion Years of Sex Differences, I explore the latest scientific answers to this question. Along the way, I dismantle some persistent myths, explain why same-sex orientation is neither a product of socialization nor an evolved adaptation, and argue that the best evidence points to a surprising conclusion: that sexual orientation is biological but largely non-genetic.

You can access the full collection of excerpts here, and preorder the book here (UK) or here (US).

Nature’s Rainbow

Let’s wrap up the discussion of sex differences in sexual psychology by exploring the question I’m most often asked when I give talks on the topic: Why are some people exclusively attracted to members of their own sex?

Heterosexuality is no mystery in evolutionary terms. Its primary function is clearly about making new life, and secondary functions – such as galvanizing the bond between potential parents – are just as clearly linked to the primary function. As soon as we put on our Darwinian goggles, however, homosexuality starts to seem mysterious. The mystery is not that individuals sometimes engage in sexual activity with members of the same sex; the occasional same-sex dalliance is unlikely to have much impact on the number of children one has in one’s lifetime. The mystery is that a non-trivial number of people never want to have sex with members of the other sex. Individuals with such a profile might occasionally have children, especially in societies with strong social pressure to marry and have a family. More than likely, though, they’ll have fewer children than people with a heterosexual (or at least a bisexual) orientation. This is especially true of men, because of men’s higher maximum offspring number.

Source: Felesina and Zietsch (2025).

How, then, does homosexuality persist? To the extent that it’s genetic, why hasn’t selection removed the genes contributing to its development from the gene pool? To the extent that it has non-genetic causes, why hasn’t selection made the development of heterosexuality more robust to perturbations?

Bias in the Criminal Justice System

Steve Stewart-Williams — Sat, 09 May 2026 09:36:10 GMT

Photo from Getty Images.

In Case You Missed It…

We’d all like to believe that the criminal justice system is rational: that punishments are meted out fairly, consistently, and in ways that promote the common good. And contrary to the cynics, they often are. In certain respects, however, the system falls short of this ideal. People’s biases and instinctive taste for vengeance sometimes intrude on legal decision-making, such that offenders are punished in ways that have little to do with fairness or social utility. While racial biases in criminal justice are widely recognized, other biases - including those based on sex - receive far less attention. In this essay, I explore how these biases shape punishment, and what this reveals about the gap between justice as it is and justice as it ought to be.

The Goldilocks Approach to Punishment

When it comes to theories of punishment, one stands head and shoulders above the rest: optimal punishment theory. Most famously associated with the economist Gary Becker, optimal punishment theory treats criminal justice as a matter of balancing costs and benefits. The central idea is that punishments should be set at a level that minimizes both the costs of crime and the costs of punishing it.

This deceptively simple premise yields various concrete proposals about how society ought to punish different crimes and different criminals. One is that crimes that are harder to solve should attract harsher penalties, so the average expected cost of offending remains high despite the lower probability of getting caught. A second is that criminals at greater risk of reoffending should be punished more severely, both to deter them effectively and to incapacitate them for longer. And a third is that punishment should not be shaped by factors that are irrelevant to the goal of minimizing the combined costs of crime and punishment.

In short, punishment should be neither too harsh nor too lenient, but “just right” for minimizing social harm.

Does the System Measure Up?

All of this sounds eminently reasonable - but to what extent does reality approach the ideal? Many studies have addressed this question over the years, but one particularly illuminating contribution is a paper by Edward Glaeser and Bruce Sacerdote titled “Sentencing in Homicide Cases and the Role of Vengeance.” The paper tests some of the central predictions of optimal punishment theory by examining sentencing patterns in US homicide cases.

In some ways, the news is good. Glaeser and Sacerdote report, for example, that offenders tend to be punished more severely when the risk of getting caught is low, consistent with the idea that harsher penalties are needed to deter potential offenders in those circumstances. Thus, arson-related homicides receive longer sentences than homicides during robberies, which in turn receive longer sentences than homicides during drunken brawls.

Sentence length and apprehension rates across homicide types. Apprehension rate is measured as fraction of homicides in which police have a charged suspect (that is, report offender data) in the Uniform Crime Reports Supplementary Homicide Reports. Source: Glaeser and Sacerdote (2003).

Also consistent with optimal punishment theory, offenders at higher risk of reoffending tend to be punished more severely. People who kill during a robbery, for instance, receive longer sentences than those who kill during a fight or lovers’ quarrel.

Sentence length and recidivism rates across homicide types. Recidivism rates are fitted values based on offender characteristics. The coefficients for the fitted values are estimated using the BJS data set “Recidivism of Felons on Probation, 1986–1989” (Bureau of Justice Statistics 1992). Source: Glaeser and Sacerdote (2003).

So far, so good. In these respects, the system behaves roughly as optimal punishment theory would predict and recommend.

But then things start going off the rails.

Bias in the Machine

One of the central premises of optimal punishment theory is that factors unrelated to crime risk should play no role in determining punishment. But Glaeser and Sacerdote found compelling evidence that they do.

The researchers looked at two broad categories of influence: demographic characteristics of the offender and demographic characteristics of the victim.

Let’s begin with the offender. A large body of research suggests that various demographic traits influence sentence length even after controlling for potential confounds such as crime severity and criminal history. Perhaps the least surprising example is that Black offenders tend to receive longer sentences than White offenders for the same crime. More surprising to many is that men tend to receive longer sentences than women. Indeed, women from every ethnic group - even the least favored - tend to receive shorter sentences than even the whitest of White men.

Mindreading Mishaps

Steve Stewart-Williams — Wed, 06 May 2026 11:51:06 GMT

Photo by cottonbro studio on Pexels.

People aren’t always great at figuring out what’s going on in others’ heads. Nowhere is this truer than in the realm of sex and love. Here are three findings from recent research by Paola Baca and colleagues, cataloguing common mindreading errors in the sexual sphere.

Both sexes overestimate the average person’s desired number of sexual partners. Men overestimate the average man’s desired number more than women do. Men and women overestimate the average woman’s desired number to the same degree.
Both sexes overestimate how willing men and women would be to have sex with someone they’ve known for a given length of time: an hour, an evening, a day, a week, an month, etc. They especially overestimate men’s willingness.
Both sexes overestimate how comfortable the average man is with sex without love. Men slightly overestimate how comfortable the average woman is; women get it about right.

Notice that, in all these cases, men and women do in fact differ on the relevant traits, but that the differences aren’t as large as people think. This has an interesting implication. It suggests that the main lesson of research on sex differences isn’t that the sexes differ when people thought they were the same, but rather that they don’t differ as much as people tend to assume!

You can access the published paper here or request a free copy from the authors here.
For more on this topic, you can preorder my forthcoming book, A Billion Years of Sex Differences, here. Note that paid subscribers to The Nature-Nurture-Nietzsche Newsletter can read exclusive excerpts from the book before the official publication date.

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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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If you could do any of the above, I’d be hugely grateful. The support of readers like you helps keep this newsletter going and growing.

Thanks!

Steve

Keeping It Casual, Part 3

Steve Stewart-Williams — Sat, 02 May 2026 12:03:15 GMT

Image: GPT

Why are men more interested than women in casual sex and sexual variety?

The standard answer is simple: Men can father more children, so they evolved to want more partners.

It’s a nice, tidy story - and it’s partly true.

But it also fails to explain a lot of what we actually see in the world. In many species, females are far more promiscuous than the standard story predicts. And in our own species, sex differences in sexual psychology, though real, are smaller than you might expect.

In this excerpt from my forthcoming book A Billion Years of Sex Differences, I lay out a new way of thinking about the evolution of sex differences in sexual psychology - one that goes beyond the usual focus on maximum offspring number and brings a wider range of evolutionary forces into view.

You can access the full collection of excerpts here, and preorder the book here (UK) or here (US).

The Evolution of Sex Differences in Sexual Psychology: It’s Not (Just) What You Think

We saw in the last excerpt that sex differences in sexual psychology aren’t just a product of culture; there’s also an innate contribution. Importantly, though, to say that there’s an innate contribution is to say nothing about how it came about. Why did natural selection ‘decide’ to give men and women somewhat different, somewhat incompatible desires? If a god were behind it, we might suspect that he was playing a cruel joke on us or trying to make the soap opera of human life more entertaining for himself. With natural selection as the architect, however, no such explanation is available. Somehow, male-typical sexual leanings must have been adaptive for our male ancestors, whereas female-typical sexual leanings must have been adaptive for our female ones. The only real question is why.

Now, you might think you know the answer already. I touched on it in Chapter 4, and in any case, the basics are quite well understood these days. But not so fast. As with sexual selection, the evolutionary explanation for sex differences in sexual inclinations is long overdue for an overhaul. The aim of this section is to sketch out a new and improved version of the explanation. We’ll start with the standard story, then gradually thicken the plot.

The standard story goes like this. As a result of sex differences in reproductive physiology, men can potentially have many more offspring than women. A man who has, say, five sexual partners in a year could end up with five new offspring; in contrast, a woman who has five sexual partners in a year would probably end up with no more offspring than she would if she’d just had one.

This created very different selection pressures for our male vs our female ancestors. Men who sought multiple partners typically had more offspring than men with less wide-ranging interests, and the genes underpinning that tendency became increasingly common in the human gene pool. Men evolved a higher sex drive, a greater hunger for casual sex, a stronger desire for sexual variety, and a capacity to be quickly aroused by sexual stimuli (which for most of our evolution meant flesh-and-blood women rather than porn).

An Innate Sense of Beauty?

Steve Stewart-Williams — Thu, 30 Apr 2026 12:46:52 GMT

Photo by Ana Klipper on Unsplash

Long before they can walk, talk, or tie their shoelaces, infants have a rudimentary sense of beauty. By four months of age, babies look longer at patterns that adults judge to be beautiful. This suggests that, like our love of faces, the aesthetic sense may be built into the human mind from the start.

Relation between preference judgement and looking time in the visual preference task for a randomly chosen participant in each age group. Each dot represents the looking time to one pattern with PJ value x within a pair (two dots per trial). Dashed lines give the 99% confidence interval for the slope and intercept parameter of the predicted values (plain line). Source: Mottier et al. (2026).

The graph comes from a recent paper by Hélène Mottier and colleagues. Here’s the abstract:

The present study investigated the emergence of a visual preference for beautiful kinetic dot displays during development. The displays were previously judged for relative beauty by an independent group of adults. Preferential looking was measured with an eye tracker in 4- to 24-month-old infants and adults. Analysis of the overall preferential looking response over the 5 s of stimulus display indicated that adults’ judgement predicted preferential looking at all ages tested. Analysis of the time course of this attentional response indicated two different mechanisms: (i) a fast-orienting response towards motion patterns that were not judged as beautiful by adults, and (ii) a slower but longer-duration response towards motion patterns that were judged as beautiful by adults. The contribution of these two mechanisms to the overall preferential looking response changed with age in a consistent manner. Because the beauty ratings of adults were associated with a later but longer-duration visual attention response in infants, and most preferred patterns differed in many aspects from non-preferred patterns, we propose that a sense of beauty, defined in adults as a pleasurable mental state leading to sustained visual attention, may influence behaviour by four months of age when looking at kinetic dot displays.

You can access the paper here for free.

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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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If you could do any of the above, I’d be hugely grateful. The support of readers like you helps keep this newsletter going.

All the best!

Steve

Echolocation in Humans, Altruism in Dogs, and Mental-Health Outcomes of Gender Reassignment

Steve Stewart-Williams — Tue, 28 Apr 2026 11:52:15 GMT

Photo by mali desha on Unsplash

In Case You Missed It…

Welcome to the April 2026 edition of the N³ Newsletter Linkfest: a collection of links to papers and articles that grabbed my attention over the last month. On the menu today…

An innate sense of kindness in humans and dogs
Why greater gender equality means fewer babies
Three new findings on personality, three new findings on sex differences, and three new findings on gender issues
The lengths females go to to avoid unwanted male attention
The downside of reclaiming slurs
And we’ll ask: Which is more common, misogyny or misandry? Does gender reassignment help or harm the mental health of youth with gender dysphoria? And does DEI foster inclusion and mutual understanding or division and hostility?

The first half of the Linkfest is free to read for everyone; the rest is for paid subscribers. I tend to put my spicier content behind a paywall, so if you want a taste of that, consider becoming a paid subscriber.

You can read about the benefits of a paid subscription here, and you can access the complete collection of Linkfests here.

But First, Some News…

I’ll be appearing at the How the Light Gets In festival in Hay-on-Wye this May 22-25, doing a debate about the merits and demerits of spirituality, a podcast with , and an event for my forthcoming book A Billion Years of Sex Differences.

Wanna come? You should come; it’ll be fun!

Explore tickets

Echolocation in Humans

Some blind people don’t just learn to live without vision; they replace it with something arguably just as impressive: echolocation. Specifically, they make click sounds with their mouths, then use the returning echoes to detect objects and navigate through the world. In a clever EEG study, blind echolocators outperformed sighted participants at locating objects in the dark, progressively refining their spatial judgments by integrating echoes across multiple clicks. [Link.]

Born to Give

Toddlers, it turns out, are tiny altruists: They’re happier giving treats away than receiving them. Not only that, but they’re happier when they personally give the treats than when someone else does, and happier when they give them spontaneously than because they were told to. This is suggestive evidence that human altruism is driven by the inbuilt emotional rewards of lending a helping hand. [Link.]

Toddlers were first introduced to a puppet (“meet Monkey”) and then received eight treats (“receive treats”). They then participated in four counterbalanced phases: costly giving (giving one of their own treats to Monkey), non-costly giving (giving a treat provided by the experimenter to Monkey), observe giving (watching the experimenter give a treat to Monkey), and give to self (giving a treat provided by the experimenter to themselves). Source: Tan et al. (2026).

Happiness ratings during different phases of the treat giving game. Black dots indicate average scores and red dots indicate median scores. *p < 0.05, ***p < 0.001. Source: Tan et al. (2026).

Dogs Help, Cats Watch

Dogs are about as helpful as toddlers, but cats look out for number one. In a fascinating recent experiment, a human parent pretended to be looking for a lost object. Around three-quarters of toddlers and dogs tried to help. Most cats, in contrast, sat back unless there was something in it for them. Helpfulness, it seems, comes more naturally to some species than others. [Link.]

Dark green represents subjects displaying prosocial behaviors (showing, giving the object to caregiver). Light green indicates subjects showing behaviors that could be attributed to either stimulus enhancement or prosociality (approaching the object, manipulating it without giving it to caregiver). Source: Csepregi et al. (2026).

More Equality, Fewer Babies

Fact: Across countries, greater gender equality is associated with lower fertility. Theory: With greater freedom and material wealth, women become less dependent on men, and thus less likely to form pair bonds. Combine this with reliable contraception, and the fertility rate comes crashing down. [Link.]

There is a strong association between the freedoms a nation grants its women and how high its fertility rate is. The Pearson correlation is r ≈ 0.81, while the rank order correlation is r ≈ 0.86, N = 172. Note: Data from United Nations (2024) and UNDP (2025). Source: Larsen et al. (2026).

The Missing 5’11” Men

Something strange is happening with self-reported height among men: There aren’t enough 5’11” men, and there are too many 6’0” men. Hmmm... [Link.]

The Paradox of Upward Mobility

We tend to assume that people who are born poor and get rich will be more sympathetic to the plight of the poor than those who are born rich and stay rich. But it’s the other way around: Those who start out poor are less sympathetic. [Link.]

A Billion Years of Plate Tectonics

This incredible animation compresses a billion years of plate tectonics into just 40 seconds. We tend to think of land masses as stable - but they’re in constant motion. They just move a lot more slowly than us. [Link.]

Three New Findings on Personality

Top 10 Most Replicable Findings from Behavior Genetics, Part 2: Findings #6-10

Steve Stewart-Williams — Sat, 25 Apr 2026 09:36:52 GMT

Photo by Pixabay on Pexels.

In Case You Missed It…

What if upbringing matters far less than we think, and the environment is shaped in part by our genes? What if many familiar “environmental” effects aren’t really environmental at all?

These ideas might strike you as counterintuitive or even obviously wrong. But they’re not just random hypotheticals. They’re among the most robust and consistently replicated findings in behavior genetics - a field that’s produced some of the strongest results in all of psychology.

In this post, I finish outlining the Top 10 most replicable findings from behavior genetics, first identified in a classic paper by Robert Plomin and colleagues.

And I ask: Why have these findings proved so unusually robust when so much of psychology has failed to replicate? What’s the secret sauce?

If you’re interested in what bedrock looks like in psychological science - and in ideas that might quietly reshape how you think about human nature - this post is for you.

6. Psychological Stability Is Largely Genetic

Why do people remain recognizably themselves over the years? Why do smart people tend to stay smart, shy people tend to stay shy, and depression-prone people tend to stay depression-prone?

Behavior genetics provides a clear answer: Psychological stability is largely due to genes. The same genetic influences tend to operate across the lifespan, helping anchor individual differences over time.

Psychological change, in contrast, is more often environmental in origin. New experiences, new life events, and shifting contexts nudge around our psychological dispositions in ways not directly predictable from our genes.

The fact that genes explain psychological stability rather than change might sound obvious, but it’s not. Genes don’t just switch on at conception, then remain active till the last days of life. Many remain dormant until needed at puberty or other key life junctures. In principle, then, genes could help explain psychological change as well as stability. As it happens, though, they generally don’t. For the most part, stability is genetic, whereas change is a function of the environment.

7. The Environment is Partially Heritable

Now things get really interesting.

Not only are all psychological traits heritable, but the environment is heritable too. Even variables we think of as entirely environmental - parental treatment, social support, major life events - are shaped in part by our genes.

How can this be?

Keeping It Casual, Part 2

Steve Stewart-Williams — Thu, 23 Apr 2026 11:28:30 GMT

Image: GPT

Across cultures and centuries, men have shown a stronger interest in casual sex and sexual variety than women. Or so says common wisdom. But is common wisdom right?

In the first post in this series, I argued that it is. In this post, I’ll tackle the harder question: Where do the differences come from? Are they purely products of social pressure, double standards, and patriarchy - or do they run deeper than that?

Long story short, the evidence points strongly toward the latter. Among other things, sex differences in sexual psychology are stubbornly persistent over time, consistent across cultures, and - most tellingly - mirrored in other species, from baboons to hedgehogs to fruit flies. That’s hard to blame on the patriarchy.

If you want to understand what really drives one of the largest and most debated differences in human psychology, read on.

This post is an excerpt from my forthcoming book A Billion Years of Sex Differences. You can access the full collection of excerpts here, and preorder the book here (UK) or here (US).

People Prone to Corporate Bullshit Tend to Make Worse Leaders

Steve Stewart-Williams — Tue, 21 Apr 2026 11:08:06 GMT

Photo by Charles Forerunner on Unsplash

People who fall for buzzword-laden corporate waffle tend to be worse leaders and poorer decision-makers. Receptivity to “corporate bullshit” is linked to lower analytic thinking (first graph below) and worse judgment in workplace contexts (second graph).

Corporate Bullshit and Analytical Thinking

Bivariate correlations between Corporate Bullshit Receptivity and analytic thinking style variables. A heat plot displaying Pearson’s correlation coefficients (larger, top number) and p-values (smaller, bottom number) for the associations between Corporate Bullshit Receptivity and analytic thinking style variables. Source: Littrell (2026).

Corporate Bullshit and Workplace Judgement

Bivariate correlations between Corporate Bullshit Receptivity and job-related variables. A heat plot displaying Pearson’s correlation coefficients (larger, top number) and p-values (smaller, bottom number) for the associations between Corporate Bullshit Receptivity and each job-related variable. Source: Littrell (2026).

The graphs come from a fascinating recent paper by Shane Littrell. Here’s the abstract:

From boardrooms and brown bags to emails and earnings calls, business culture often seems overrun by “corporate bullshit,” a semantically empty and often confusing style of communication in organizational contexts that leverages abstruse corporate buzzwords and jargon in a functionally misleading way. At best, corporate bullshit can sometimes seem harmless. At worst, it can disrupt organizational and employee effectiveness in numerous ways including obstructing clear communication, increasing employee disengagement, tarnishing a company’s reputation, and exposing businesses to potential financial and legal risks. Here, results from four studies (total N = 1018) report the construction and validation of the Corporate Bullshit Receptivity Scale (CBSR), a novel measure of individual differences in susceptibility to corporate bullshit. Results show that corporate bullshit receptivity is distinct from a general affinity for corporate speech, negatively associated with measures of analytic thinking, and positively related with other bullshit-related constructs in theoretically-consistent ways. Importantly, corporate bullshit receptivity is positively associated with several workplace perception variables and is a robust negative predictor of work-related decision-making. Overall, the findings establish the CBSR as a valid and reliable tool to aid researchers and practitioners in examining the causes, correlates, and consequences of receptivity to bullshit in organizations.

You can access the paper here or download a free version here.

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

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.

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 excerpts from my forthcoming book 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 the growing N³ Newsletter community

If you could do any of the above, I’d be hugely grateful. The support of readers like you helps keep this newsletter going and growing.

Thanks!

Steve

Top 10 Most Replicable Findings from Behavior Genetics, Part 1: Findings #1-5

Steve Stewart-Williams — Sat, 18 Apr 2026 10:35:22 GMT

Photo by Tiến Anh Hoàng on Pexels.

In Case You Missed It…

Psychology has been having something of an identity crisis lately.

Over the past few decades, a growing number of classic findings have failed to replicate. Indeed, one of the most replicable findings in psychology, ironically enough, is that only around 50% of psychology findings are replicable.

Psychology isn’t unique in this respect; similar concerns have been raised in many other fields. But psychology is a particularly popular field, and one with clear implications for policy, so its potential to mislead is great.

That being the case, it’s important to ask: Which findings in psychology do replicate?

One area with a particularly good track record is behavior genetics, which studies the nature and nurture of individual differences in mind and behavior. In a classic paper drawing on decades of twin, adoption, and genomic research, Robert Plomin and colleagues highlighted ten findings from the field that have proven remarkably robust. These aren’t trivial or esoteric findings. They’re large and often surprising, and have far‑reaching implications for our understanding of psychology.

In this post, I’ll outline the first five of Plomin and co.’s Top 10 most replicable findings from behavior genetics, covering everything from selectively breeding the minds of other animals to the increasing importance of genes with age. I’ll tackle findings #6-10 next weekend.

1. All Psychological Traits Show Genetic Influence

The first finding is sometimes known as the First Law of Behavior Genetics: Individual differences in all psychological traits are shaped in part by individual differences in genes.

This is true of intelligence, personality, mental illness, substance use, political attitudes, religiosity - even food preferences and social media habits. Across thousands of studies, identical twins are consistently more similar than fraternal twins on these traits, and adopted children are more similar to their biological parents than their adoptive ones. Twin and adoption studies have very different underlying logics, yet they converge on the same conclusion: Genes matter.

And often they matter a lot. For intelligence, heritability averages around 50% across diverse countries and cultures. For personality, it usually falls between 30% and 50%. For mental-health problems such as schizophrenia and autism, it clocks in at 80% or more: on a par with the heritability of height.

To be clear, heritability isn’t static; it varies from place to place and time to time. But we’ve yet to find a place or time where it’s negligible for any major psychological trait.

The First Law of Behavior Genetics wasn’t always widely accepted. Indeed, in some fields, such as education, it’s still not. However, within psychology and allied disciplines, it’s now recognized as one of the best-established findings we have.

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2. No Psychological Traits Are 100% Heritable

The first finding emphasizes genes; the second restores balance to the force. Genes matter a lot, but so do non-genetic influences. No psychological trait is 100% heritable, and most are nowhere near it.

This isn’t due to limitations in the methods of behavior genetics. Some physical traits have extremely high heritability levels - up to 90% for height, for example. Thus, the methods could give higher heritability estimates if heritability were actually higher.

Admittedly, psychological measures are usually noisier than physical ones, which depresses heritability estimates to some degree. Even so, the estimates are far enough away from 100% that improved measurement is unlikely to bring them anywhere close to that ceiling.

This finding matters more than it might first appear. It’s natural to assume that behavior genetics tells us about genes rather than the environment. In fact, though, it tells us about both. More than that, behavior genetics provides the strongest evidence we have that the environment plays a crucial role in shaping individual differences. That’s because the methods of behavior genetics control for the effects of genes, whereas other methods don’t. Given how substantial genetic effects are, the failure of most socialization research to do this is a profound oversight. Ironically, then, the clearest demonstration of the importance of the environment comes from a field often assumed to downplay it.

Recent Human Evolution in West Eurasia

Steve Stewart-Williams — Fri, 17 Apr 2026 23:46:20 GMT

Photo by Alexander David on Unsplash

A new Nature paper by Ali Akbari, David Reich, and colleagues explores recent evolution - that is, evolution in the last 14,000 years - in West Eurasians.

Comparing the genomes of ancient West Eurasians to those of modern ones, they found strong evidence that gene variants associated with intelligence were under positive selection, whereas gene variants associated with body fat, darker skin, and disorders like schizophrenia and bipolar were under negative selection.

The body-fat finding is particularly interesting; it fits with the idea that farming reduced the need to stockpile fat on the body, and thus that farming populations evolved to do less of it.

We show 12 instances where tests of polygenic selection—γ, γ_sign and r_s—are all significant, with the relevant statistics at the top of each panel. The mean PGS of West Eurasian individuals over 10,000 years is denoted by a solid black line, with the 95% CI in grey. The red line represents the linear mixed model regression, adjusted for population structure, with slope γ. The circles represent mean PGS in Western hunter–gatherers (green; n = 131), early European farmers (orange; n = 452) and steppe pastoralists (pink; n = 293); the error bars indicate 95% CIs. All P values are two-sided and evaluated against a Bonferroni-corrected threshold for multiple testing (P < 8.9 × 10⁻⁵). Source: Akbari et al. (2026).

Here’s the abstract:

Ancient DNA has transformed our understanding of population history, but its potential to reveal as much about human evolutionary biology has not been realized because of limited sample sizes and the difficulty of distinguishing sustained rises in allele frequency increasing fitness—directional selection—from shifts due to migrations, population structure, or non-adaptive purifying or stabilizing selection. Here we present a method for detecting directional selection in ancient DNA time-series data that tests for consistent trends in allele frequency change over time, and apply it to 15,836 West Eurasians (10,016 with new data). Previous work has shown that classic hard sweeps driving advantageous mutations to fixation have been rare over the broad span of human evolution. By contrast, in the past ten millennia, we find that many hundreds of alleles have been affected by strong directional selection. We also document one-standard-deviation changes on the scale of modern variation in combinations of alleles that today predict complex traits. This includes decreases in predicted body fat and schizophrenia, and increases in measures of cognitive performance. These effects were measured in industrialized societies, and it remains unclear how these relate to phenotypes that were adaptive in the past. We estimate selection coefficients at 9.7 million variants, enabling study of how Darwinian forces couple to allelic effects and shape the genetic architecture of complex traits.

You can access the paper here for free.

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Keeping It Casual, Part 1

Steve Stewart-Williams — Thu, 16 Apr 2026 11:09:14 GMT

Image: GPT

Men and women are similar in many ways - but if there’s one area where we might expect them to differ markedly, it’s sexual behaviour.

In this excerpt from my forthcoming book, A Billion Years of Sex Differences, I kick off a three-part exploration of female-male differences in sexual psychology, focusing in particular on attitudes to casual, no-strings-attached sex.

In the first instalment, I examine the evidence for these sex differences: Are they real, or just old-fashioned stereotypes?
In the second, I look at the origins of the differences: Are they purely a product of culture, or is there also an innate contribution?
And in the third, I consider the evolution of the differences: Why might natural selection have favoured somewhat different sexual inclinations in men than in women?

You can access the full collection of excerpts here, and preorder A Billion Years of Sex Differences here (UK) or here (US).

But First, an Announcement…

I’ll be promoting A Billion Years at the How the Light Gets In festival in Hay-on-Wye this May. If you want to join me for champagne, cake, and a discussion of the evolution of sex differences, click here to book your place!

Keeping It Casual, Part 1

Perhaps you’ve heard the rumours, but men and women aren’t always on the same page when it comes to sex and love. This is nicely illustrated by the story of a young woman who, tired of receiving unsolicited dick pics from every Tom, Richard, and Harry, decided to return fire with her own ‘crotch shot’. To her surprise, the recipients didn’t react the way she had. Rather than being shocked or chastened, they were over the moon.

The behaviour of the woman in this scenario, and that of the men who sent the dick pics to begin with, exemplifies what psychologists call failures of cross-sex mindreading. Why are such mindreading mishaps so common?

After many years of studying and seeking an answer, I’ve hit upon a radical new theory that, in my view, lays this age-old mystery to rest: Men and women are different.

Wait a minute, you might protest; didn’t you just finish arguing that men and women aren’t particularly different? Well, I did. Sex differences in humans are generally modest. However, when it comes to sexual psychology, the gaps are notably larger. In fact, it’s in the realm of sexuality that we find the single largest psychological sex difference ever documented in our species. (See if you can guess what it is; I’ll come back to it later.)

Certainly, most sex differences in sexuality aren’t like night and day. But they are big enough to matter. That’s why the shelves of most bookstores are groaning under the weight of books about navigating sex and relationships. Let’s explore some of the sex differences that turn these tomes into bestsellers.

Who Counts as a Victim?

Steve Stewart-Williams — Tue, 14 Apr 2026 09:04:58 GMT

Photo by engin akyurt on Unsplash

In Case You Missed It…

Liberals and conservatives both want to reduce harm and help victims. Where they differ is in who they see as the victims.

The disagreement isn’t that liberals think Black people are the victims whereas conservatives think White people are, or that liberals think poor people are the victims whereas conservatives think rich people are.

Instead, each side conceptualizes victimhood in a fundamentally different way.

Liberals tend to see victimhood as group-based, dividing the social world into vulnerable oppressed groups and invulnerable oppressors. Conservatives, in contrast, tend to see victimhood as individual-based and more evenly distributed across groups.

This pattern is shown in the graph below.

Relationship between political orientation and assumptions of vulnerability. Source: Womick et al. (2026).

The graph comes from a recent paper by Jake Womick and colleagues. Here’s the abstract:

Moral disagreement across politics revolves around the key question, “Who is a victim?” Twelve studies explain moral conflict with assumptions of vulnerability (AoVs): liberals and conservatives disagree about who is especially vulnerable to victimization, harm, and mistreatment. AoVs predict moral judgments, implicit attitudes, and charitable behavior—and explain the link between ideology and moral judgment (usually better than moral foundations). Four clusters of targets—the Environment, the Othered, the Powerful, and the Divine—explain many political debates, from immigration and policing to religion and racism. In general, liberals see vulnerability as group-based, dividing the moral world into groups of vulnerable victims and invulnerable oppressors. Conservatives downplay group-based differences, seeing vulnerability as more individual and evenly distributed. AoVs can be experimentally manipulated and causally impact moral evaluations. These results support a universal harm-based moral mind (Theory of Dyadic Morality): moral disagreement reflects different understandings of harm, not different foundations.

You can access the paper here or download a free version here.

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Steve

Warning: Politics May Be Bad for Your Mental Health

Steve Stewart-Williams — Sat, 11 Apr 2026 09:46:22 GMT

Photo by diana kereselidze on Unsplash

In Case You Missed It…

This is my 300th post on Substack, and the second installment of my new “Warnings” series. You can access the full collection here. Hope you enjoy it!

For many of us, politics isn’t just something that happens “out there.” It’s woven into everyday life - and not always to our benefit. Sometimes, in fact, it can be deeply upsetting. Could the constant drumbeat of negative political news be undermining our mental health?

A recent paper in the Journal of Personality and Social Psychology tackles this important question, and concludes that the answer is yes. Day-to-day political exposure reliably evokes negative emotions - anger, sadness, disgust, and the like - which in turn erode both psychological and physical well-being.

How do people deal with the ever-present drip, drip, drip of negative news? How does it affect their motivation to engage in political action? And are these effects stronger on one side of the political aisle than the other?

All will be revealed in this post!

From Big Shocks to Daily Drips

We sometimes think of politics as something distant, played out in parliaments, ministries, and presidential palaces a million miles away. But politics often seeps into day-to-day life. Turn on the news, scroll through social media, sit down at dinner, or chat with colleagues, and there it is. For many of us, politics has become a central feature of our lives and identities. In a very real sense, the political is personal.

How, then, does politics affect people’s well-being? Much of the existing research on this topic has focused on major events such as elections, referenda, and political upheavals. And the findings are, in a way, reassuring. Even when people are deeply invested, the emotional impact of these events tends to fade quickly. For example, the 2016 US presidential election - despite its intensity - didn’t lead to lasting declines in well-being among those disappointed by the result. Most people quickly adjusted to the new normal.

However, politics isn’t just a series of isolated shocks. It’s a continuous stream of events: scandals, conflicts, policy announcements, controversies. Each on its own might be minor. Together, however, they form a background hum of tension. Politics, in other words, may be a chronic stressor - and chronic stressors can undermine psychological and even physical well-being.

The People Most Confident in Their Political Views Know the Least About Politics

Steve Stewart-Williams — Thu, 09 Apr 2026 10:07:45 GMT

Photo by Blake Weyland on Unsplash

In Case You Missed It…

When it comes to politics, confidence and competence don’t always go hand in hand. In fact, often they go in opposite directions: The people with the least political knowledge are the most confident that they’ve got everything figured out - as shown in the figure below. (FOK = feeling of knowing; CJ = confidence judgments.)

Relationship Between Political Knowledge and FOK and CJ Bias. Panel A: Scatterplot showing FOK bias as political knowledge increases. Panel B: Scatterplot showing CJ bias as political knowledge increases. Source: Fulton et al. (2026).

The figure comes from a paper by Erika Fulton and colleagues. Here’s the abstract:

Accurate metacognition is essential to informed political decisions and preventing the spread of misinformation, but research on metacognitive monitoring of political facts, outside of misinformation studies, has not met metacognitive research measurement standards. We addressed this limitation and assessed potential factors (political knowledge, political orientation, and cognitive style) related to this type of metacognitive monitoring accuracy. A sample of 216 Amazon Mechanical Turk participants completed measures of political orientation, political knowledge, and cognitive style, along with a test of political metacognitive monitoring accuracy, between February 2021 and March 2022. Participants were generally overconfident in their political knowledge, especially those with less political knowledge and who were more conservative, with conservatives also showing worse relative metacognitive accuracy. Cognitive style partially explained differences due to political orientation. Our participants were U.S. residents and disproportionately White, male, and lower-to-middle income, so studies of other samples and political contexts are needed for generalizability. Results also build on cue theory, showing that political knowledge and political orientation can act as metacognitive judgment cues. The study highlights the need to improve political metacognitive monitoring accuracy and reveals three targets for intervention: political knowledge, political orientation, and cognitive style.

You can access the paper here or request a free copy here.

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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.

Like and Restack: Click the buttons at the top or bottom of the page to boost the post’s visibility on Substack.
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Upgrade to Paid: A paid subscription gets you:
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If you could do any of the above, I’d be hugely grateful. The support of readers like you helps keep this newsletter going and growing.

Thanks!

Steve

Should We Trust Social Science Research?

Steve Stewart-Williams — Tue, 07 Apr 2026 10:07:11 GMT

Photo by Markus Spiske on Unsplash

The Nature-Nurture-Nietzsche Newsletter

In Case You Missed It…

As a reader of The Nature-Nurture-Nietzsche Newsletter, you’ve no doubt heard of the replication crisis: the finding that only around half of studies in the social sciences replicate. Well, here’s a question for you: Is that finding itself replicable?

A massive new study by Andrew Tyner and colleagues, published in the journal Nature, addresses that thorny question, and comes to a strong conclusion: Yes.

The researchers attempted to replicate 274 findings drawn from 164 papers published between 2009 and 2018, spanning 54 journals across the social and behavioral sciences. The replication studies were well-powered, with a greater than 99% chance of detecting the original effect if the effect were real. The team used the original materials wherever possible, and the replication plans were peer-reviewed in advance. In short, this was about as careful and systematic a replication effort as you could hope for.

What did they find? The headline result is that only around 55% of the original results held up. Not only that, but among those that did replicate, the effect sizes were notably smaller in the replications - roughly half the size of the originals.

Different fields showed somewhat different replication rates. As the graph below shows, education was in first place, with economics bringing up the rear. My own field of psychology fell somewhere in the middle of the pack. That’s not much of a boast, though, given that there’s only about a 50% chance that any given psychological finding will replicate.

Source: Sánchez-Tójar et al. (2026).

On the one hand, this is somewhat depressing news. On the other, we shouldn’t forget that some findings in psychology are as solid as anything else in science. As I argue in the essay linked below, not everything you were taught in intro psych was false!

10 Highly Replicable Findings from Psychology

Psychology’s Reputation Problem…

a year ago · 86 likes · 15 comments · Steve Stewart-Williams

You can access the Tyner paper here.
You can request a free copy here.
In a few weeks, I’ll be publishing a piece on the Top 10 most replicable findings from behavior genetics. Stay tuned!

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

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.

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 excerpts from my forthcoming book, 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 the N³ Newsletter community