Category: evolutionary psychology

The biology of male aggression, and why it’s not all “socialization”

December 19, 2019 • 1:15 pm

While I’ve long been a critic of evolutionary psychology, I’m not stupid or woke enough—unlike some bloggers I won’t name—to dismiss the entire field as worthless. While it’s hard to test whether some behaviors in our species have evolved by natural selection, there are degrees of confidence we can get, and predictions one can make, to judge the likelihood that these behaviors are indeed “darwinian.” While nobody argues that behaviors like preferring your own children over others aren’t products of natural selection, there are those who claim that behavioral differences between men and women are not—and in fact cannot—be based on genes installed in our species by natural selection.

The two sex differences I find most evolutionarily convincing involve human sexual behavior—in particular the observation that males tend to be relatively indiscriminate in choosing someone to mate with, while females are pickier—and the fact that males are more aggressive than females. I feel that these behavioral differences are likely, at least in part, to be the result of sexual selection in our ancestors. I won’t talk about sexual behavior today, as I’ve written about it before, but I do want to highlight an article from last April discussing the evolution of male aggression. It’s by Steve Stewart-Williams, an associate professor of psychology at the University of Nottingham Malaysia Campus, and appeared online in in Nautilus. It’s a short but good summary of why the greater aggressiveness of men than of women almost certainly reflects, at least in part, natural selection in our ancestors. Click on the screenshot to read it, and you should:

I should first emphasize that while Stewart-Williams and I share the view of the evolutionary roots of some male aggression, we both agree that males can also be socialized into being more aggressive by being expected to conform to stereotypes of “masculinity” (remember the car race in Rebel Without a Cause?); and that even if males are more aggressive than females because of natural selection, that doesn’t mean that you can’t make them less aggressive—also by socialization. Any geneticist knows that, for nearly all traits, heredity is not destiny, and the environment can make a big difference.

Nevertheless, the SJW view of differences between men and women’s behavior is that all of those differences are due entirely to socialization, with no moiety due to genetics and evolution. That is an ideological stand that, in view of the substantial morphological differences between men and women, is pretty insupportable.  And that view comes from the fear that if we do find evolution-based differences, it will lead to discrimination—usually against women. My own view is that any genetic differences we see cannot support any moral or legal inequality between the sexes, which is a philosophical position that shouldn’t depend on biology.  (If it did, equality would change as our knowledge of biology changed.)

So I deplore those who try to pretend that differences either don’t exist, or can’t have an evolutionary basis, simply because it’s inconvenient for their ideology. (They always pretend that their criticism is based on science, but they don’t fool anybody with two neurons to rub together.) That’s why the same people who will admit that men are bigger and stronger than women because of genetics and evolution will also assert that there can be no behavioral or psychological differences due to genetics and evolution. 

The caveats duly presented, Stewart-Williams gives several lines of evidence for an evolutionary origin of this behavioral difference. I’ll summarize them briefly; the indented sections are Steve’s writing.

1.) The behavior is consistent across different cultures, when one would expect different degrees and kinds of socialization.

An initial line of evidence is that it’s not only in the West that we find sex differences in aggression. Wherever in the world we look, men are more violent and aggressive than women, especially with other men. The clearest and most persuasive evidence for this comes from homicide statistics: In every country, without fail, men commit the vast majority of homicides (and are more likely to be the victims of homicide as well). If the sex difference in aggression is just an arbitrary product of culture, why does it rear its ugly head in every human group?

Now there are those, says Stewart-Williams, who argue that the difference in aggression is just a non-evolved byproduct of differences in size and strength. If you’re bigger and stronger (presumably for evolutionary reasons), then you can benefit by being more aggressive, and you get pigeonholed into social roles that involve more strength and aggression. But that raises the question of why men are bigger and stronger than women! While you’ll see social-justice warriors trying desperately to explain size and stength differences without invoking sexual selection, a reasonable explanation, based on observations below, including the behavioral differences in sexual behavior as well as parallels from animals like seals and gorillas, is that part of the size/strength differentiation involves men competing for women: to the stronger goes the reproduction.

The avoidance of sexual selection as an explanation is because that implies that there could be behavioral differences between men and women as well (sexual selection involves behavior), and to the Authoritarian Left that idea is to be avoided at all costs.

Here’s how Stewart-Williams rebuts the “byproduct” explanation for differences in aggression:

It’s a clever argument, and one worth taking seriously. On balance, though, I don’t think it flies. To begin with, the Eagly–Wood theory raises some awkward questions. Why wouldn’t natural selection create psychological sex differences as well as physical ones? The mere existence of the physical differences tells us that human males have been subject to stronger selection for aggression and violence than females. Why would this selection pressure shape our muscles, our skeletons, and our overall body size, but draw the line at our brains? And why would natural selection give men the physical equipment needed for violence but not the psychological machinery to operate it? This would make about as much sense as giving us teeth and a digestive system, but not a desire to eat.

That is a strong argument, and one that I haven’t seen rebutted by the haters of evolutionary psychology. Why are our brains the one organ that can’t be differentiated between men and women by selection?

2.) We don’t find, as expected under the socialization theory, larger amounts male aggression in societies that have stricter gender roles and less gender equality.

On top of that, if sex differences in aggression were all down to gender roles, the differences would be larger in cultures with stricter gender roles and greater gender inequality. That’s not what we find, though. On the contrary, it seems to be the other way round. A recent large-scale, multinational study revealed, for instance, that sex differences in adolescent physical aggression are smaller, rather than larger, in less gender-equal nations. Culture clearly matters when it comes to sex differences in aggression—but the effect of culture is apparently very different than the social role theory would lead us to expect.

3.) Males are more aggressive than females from the very beginning of childhood, presumably before they’ve had a chance to be socialized.

. . . the sex difference in aggression appears very early in life—usually before children take their first bite of their first birthday cake. From the moment they can move around under their own their steam, boys engage in more rough-and-tumble play than girls. The same sex difference is found in other juvenile primates, and appears to be related to testosterone exposure in the womb. In humans, the sex difference shows up long before kids understand that they’re boys or girls, so it can’t just be that they’re conforming to social expectations about how boys and girls ought to act. In any case, children are terrible at conforming to social expectations, as any parent who’s tried to persuade their progeny to sit nicely and quietly in a restaurant will readily confirm. And not only does the sex difference in aggression emerge early, it remains static until puberty. Absolute levels of aggression trend downward for both sexes; however, the gap between the sexes barely budges. If socialization creates the sex difference, why doesn’t continued socialization before puberty pry the sexes apart?

And here I should add that testosterone has a positive effect on aggression, whether injected or naturally circulating in people with abnormal levels of the hormone for their sex. That, too, points to an evolutionary explanation.

4.) The pattern of male aggression conforms to what we expect if it evolved to promote competition for females.  Stewart-Williams reports that early differences in aggression remain static until puberty, when males suddenly become much more aggressive and much more willing to take risks.  This would be expected because male aggression would be most adaptive when the reproductive benefits are greatest—during early reproductive years (in our relatives, of course, who probably began reproducing much earlier than modern humans). As Stewart-Williams argues:

How would the Nurture Only approach explain the violence gap that opens up between the sexes at puberty? Is there a sudden surge in gender socialization—a surge which, for some unknown reason, happens at exactly the same stage of life in every culture and in many sexually dimorphic species? Is it just a coincidence that this alleged surge in socialization comes at the same time as the massive surge in circulating testosterone that accompanies puberty in males?

He adds that after early adulthood, male aggression goes down steadily for the rest of a man’s life, something that the socialization hypothesis doesn’t explain but the evolutionary hypothesis does: why be aggressive when you get little reproductive payoff but risk being killed or injured by other, younger males?

5.) In many species of animals, including our closest relatives, males are more aggressive than females. If you have a “socialization” theory, you’d have to claim that what everyone accepts in other species as evolved differences in behavior just happen to be the nonevolved products of socialization in humans. What a remarkable coincidence!

A final line of evidence that sex differences in aggression have biological underpinnings is that these differences are not unique to human beings. Indeed, in some cases, the parallels across species are striking. Consider humans and chimpanzees. Among humans, males commit around 95 percent of homicides, and are around 79 percent of homicide victims. Among chimps, on the other hand, males commit around 92 percent of “chimpicides,” and are around 73 percent of chimpicide victims. In short, the sex difference in lethal aggression in the two species is remarkably similar in size.

That’s all I’ll say for now, except to add one more argument that is mine: the aggression difference also goes along with the sexual “choosiness” difference that has been repeatedly observed in psychological studies. Both bespeak a form of sexual selection in which males compete for females and females are choosy about who they select as mates.

I’ll also warn readers that many people who argue against any evolved behavioral difference between men and women are people who likely have an ideological agenda. And they often pretend that they don’t.

At the end, Steve tells us that it’s important to understand the roots of male aggression because it helps us reduce male violence that is harmful in today’s world (my emphasis):

None of this implies, by the way, that we’re necessarily stuck with male aggression, or stuck with aggression in general. As the psychologist Steven Pinker demonstrated in The Better Angels of Our Nature, levels of violence and warfare have fallen steadily over the decades, centuries, and millennia, despite the fact that aggression is part of human nature. In various ways, from policing and government to trade and moral norms, we’ve managed to pull ourselves, to a significant extent, out of the vortex of violence and bloodshed that characterized our species for the bulk of its tenure on Earth.

If we want to continue on this trajectory, however, or ideally to hasten our progress, our best bet is presumably not to delude ourselves about the true causes of our behavior. As policy wonks like to say: Wrong diagnosis; wrong cure. Let’s get the diagnosis right so that we can maximize our chances of curing the scourge of human violence.

I agree with the malleability bit in the first paragraph, but am not so much on board with the idea that we need to understand what causes our behavior because it will help us alter our behavior. After all, whether male aggression be due to socialization, evolution, or a combination of both factors, the treatment is the same: socialize men to be less aggressive!  The reason I want to know what causes our behaviors is pure curiosity.

Evolution denialism from the Left

December 1, 2018 • 1:00 pm

Evolutionary biology gets squeezed from both the Right (many of whose adherents simply deny evolution) and now from the Left as well.  A moiety of the Left, as I’ve written here frequently, has ideological reasons for attacking parts of evolutionary biology, especially those parts that involve genetics and behavior.  So, for example, we see these kinds of views:

1.) Psychological and behavioral differences between men and women are culturally based without evolutionary underpinnings. This view, of course, comes form the mistaken notion that if you admit genetic and evolutionary differences between the sexes, it could buttress sexism. But that needn’t be the case, especially because morality and “rights” shouldn’t rest heavily on biology. The view of equal psychology and behavior in men and women is palpably foolish in view of the physical differences between them that surely reflect evolution in our ancestors. Why would bodies evolve but not brains?

Yet that’s a growing view among the authoritarian Left, some of whom even see all of evolutionary psychology as a worthless enterprise.

2.) There are no meaningful genetic differences between ethnic groups, or “races”, if you will. It’s clear that humanity doesn’t divide neatly into clean-cut groups that can be seen as distinct races into which everyone can be slotted neatly. Still there are meaningful and diagnostic genetic differences between ethnic groups if you analyze a large group of genes together. That in fact is how you can get a good idea of your ancestry from sequencing of a lot of your DNA, as do companies like 23andMe.  While we don’t know whether there are behavioral or psychological differences between ethnic groups that rest on genetic differences, differences that go along with the well known physical differences, it would be both foolish and unscientific to flatly deny that there are differences between groups in psychology and/or behavior.

One would think that Steve Pinker’s book The Blank Slate would have dispelled this kind of blank-slateism, but it hasn’t. In fact, with the rise of the Offense Culture, the Left’s attacks on science have become more intense.  Expect more of them.

3.) In a recent development, there are now common claims that there are not two sexes in humans: that sex is a spectrum, with the implication that it’s continuous. I’ve written quite a bit criticizing this view and the idea that, while everyone admits that there are clearly distinct male and female fruit flies, kangaroos, and robins, humans are the one exception. This is again an ideological viewpoint, not a scientific one, despite the claims of scientific societies and journals that the notions of “male” and “female” are social constructs. The ideological basis for this claim—as misguided as the views that admitting differences between sexes and races will buttress racism and sexism—is the idea that if sex (and gender) were real continuums, this would reduce bigotry against transsexuals and transgender people. Again, we should be fighting for the rights of such people without trying to distort the underlying biology.

The attacks on evolutionary biology on the Left are summarized in the Quillette piece below (click on screenshot) by Colin Wright, identified as having “a PhD in evolutionary biology from UC Santa Barbara [and currently studying] the social behavior of ant, wasp, and spider societies at Penn State.”

I have to say that if you’ve read here regularly, you’ll already know much of what Wright says. But not everyone reads here regularly, or reads all the biology-themed articles, so Wright’s is a good piece to get up to speed, even if the heavy breathing about social justice is a bit gusty. Here are two excerpts, the first emphasizing the religious-like human exceptionalism of biology ideologues:

Given that humans are sexually dimorphic and exhibit many of the typical sex-linked behavioral traits that any objective observer would predict, based on the mammalian trends, the claim that our behavioral differences have arisen purely via socialization is dubious at best. For that to be true, we would have to posit that the selective forces for these traits inexplicably and uniquely vanished in just our lineage, leading to the elimination of these traits without any vestiges of their past, only to have these traits fully recapitulated in the present due to socialization. Of course, the more evidenced and straightforward explanation is that we exhibit these classic sex-linked behavioral traits because we inherited them from our closest primate ancestors.

Counterintuitively, the social justice stance on human evolution closely resembles that of the Catholic Church. The Catholic view of evolution generally accepts biological evolution for all organisms, yet holds that the human soul (however defined) had been specially created and thus has no evolutionary precursor. Similarly, the social justice view has no problem with evolutionary explanations for shaping the bodies and minds of all organisms both between and within a species regarding sex, yet insists that humans are special in that evolution has played no role in shaping observed sex-linked behavioral differences. Why the biological forces that shape all of life should be uniquely suspended for humans is unclear. What is clear is that both the Catholic Church and well-intentioned social justice activists are guilty of gerrymandering evolutionary biology to make humans special, and keep the universal acid at bay.

Wright notes that he and others are afraid to go against the prevailing Leftist Biology Dogma (LBD) for fear of social opprobrium and even career damage. This is when I’m most happy that I’m retired, for I have nothing to fear or lose from saying what I feel. Here’s Wright on the chilling effect of LBD and the vacuous idea of a “sex spectrum”:

Despite there being zero evidence in favor of Blank Slate psychology, and a mountain of evidence to the contrary, this belief has entrenched itself within the walls of many university humanities departments where it is often taught as fact. Now, armed with what they perceive to be an indisputable truth questioned only by sexist bigots, they respond with well-practiced outrage to alternative views. This has resulted in a chilling effect that causes scientists to self-censor, lest these activists accuse them of bigotry and petition their departments for their dismissal. I’ve been privately contacted by close, like-minded colleagues warning me that my public feuds with social justice activists on social media could be occupational suicide, and that I should disengage and delete my comments immediately. My experience is anything but unique, and the problem is intensifying. Having successfully cultivated power over administrations and silenced faculty by inflicting reputational terrorism on their critics and weaponizing their own fragility and outrage, one fears whether there was no belief or claim too dubious that administrations wouldn’t cater to. Recently, this fear has been realized as social justice activists attempt to jump the epistemological shark by claiming that the very notion of biological sex, too, is a social construct.

As a biologist, it is hard to understand how anyone could believe something so outlandish. It’s a belief on a par with the belief in a flat Earth. I first saw this claim being made this year by anthropology graduate students on Facebook. At first I thought they mistyped and were simply referring to gender. But as I began to pay closer attention, it was clear that they were indeed talking about biological sex. Over the next several months it became apparent that this view was not isolated to this small friend circle, as it began cropping up all over the Internet. In support of this view, recent editorials from Scientific American—an ostensibly trustworthy, scientific, and apolitical online magazine—are often referenced. The titles read, “Sex Redefined: The Idea of 2 Sexes Is Overly Simplistic,” and “Visualizing Sex as a Spectrum.”

This politicizing of science can lead to no good, but I’m already seeing those who object to unfounded blank-slateism branded as racists and sexists. That’s not a scientific discussion, but truth-shaming, and it bodes ill for evolutionary biology.

h/t: Matt

Andrew Sullivan on evolutionary psychology

January 21, 2018 • 11:00 am

Since Andrew Sullivan has moved to New York Magazine, I find him more liberal, more tempered, more rational, and more readable. His three-part essay this week is notable for what he says in the first part: “#MeToo and the Taboo Topic of Nature” Don’t be put off by the title: it’s really a discussion of evolutionary psychology infused with Sullivan’s experiences as a gay man.

One thing that makes the Left less appealing than it used to be is its overt resistance to scientific findings that supposedly go against the liberal narrative. For example, any suggestion that there might be evolutionary differences between human ethnic groups, or between men and women, is not only denied, but has become so taboo that merely to bring up these subjects risks opprobrium from the Left. Evolutionary psychology and studies of “race” have been demonized by many to the extent that these endeavors are sometimes deemed worthless.

Likewise, the Left obdurately resists any notion that there are evolved differences between the behavior, abilities, or preferences of men and women. Cordelia Fine, for example, has made this her goal, and while her two books on the subject are good in parts, they’re also deeply flawed in some of their critiques. For instance, males are larger and stronger than females, and it’s hard to explain this without invoking sexual selection. And if sexual selection on the human body caused dimorphism in morphology, isn’t it reasonable to expect it to have caused differences in behavior and brains— just the kind of differences that produce behaviors we see in human society? (Males are generally promiscuous and willing to mate with many females, looking for signs of reproductive capacity, while women are pickier, and more attuned to signs of males being good providers. Males are also more competitive and take more risks when they’re of reproductive age.) Another example: P. Z. Myers is on a constant tirade against evolutionary psychology, and has made the ludicrous statement that “the fundamental premises of evo psych are false.” But those “fundamental premises” are only that the human mind, like the human body, bears traces of our evolutionary ancestry and the selective pressures that molded it. (See my longer response here and here.)

The reason that some Leftists oppose this kind of science, of course, is because they think it enables racism and sexism, with the premise being that any observed differences will be grounds for discrimination. But that need not be true: for example, groups will differ on many axes: better on some, worse on others. More important, and as I’ve emphasized endlessly, the moral and political equality of groups should not be grounded on empirical research. For if you do that, and then, like Fine, slant your analyses to match your ideology, asserting that women and men are absolutely equal in all respects, then your argument for equality becomes vulnerable to future empirical observation of differences. Further, as Pinker emphasized in his Spiked remarks at Harvard, if the Left tries to deny scientific findings, it simply drives people toward the right. Our best strategy, and one that comports with centuries of moral philosophy, is to be open to scientific research but absolutely committed to equality of opportunity for all.

Sullivan’s piece is about the denial of evolutionary psychology by the Left; he too thinks that it’s maladaptive to pretend that all groups are, on average, exactly the same. His perspective as a gay man is quite interesting. An excerpt (my emphasis):

. . . in our increasingly heated debate about gender relations and the #MeToo movement, this natural reality [the effects of testosterone on behavior, based on Sullivan’s own experience with hormone therapy]— reflected in chromosomes and hormones no scientist disputes — is rarely discussed. It’s almost become taboo. You can spend a lifetime in gender studies and the subject will never come up. All differences between the sexes, we are now informed, are a function of the age-old oppression of women by men, of the “patriarchy” that enforces this subjugation, and of the power structures that mandate misogyny. All differences between the genders, we are told, are a function not of nature but of sexism. In fact, we are now informed by the latest generation of feminists, following the theories of Michel Foucault, that nature itself is a “social construction” designed by men to oppress women. It doesn’t actually exist. It’s merely another tool of male power and must be resisted.

This is, however, untrue. Even the newest generation of feminists concede this on the quiet. Although they will organize to shut down an entire magazine to prevent an airing of an alternative view of gender, they are not currently campaigning to shut down the Planet Earth series because it reveals that in almost every species, males and females behave differently — very differently — and there appears to be no “patriarchy” in place to bring this about at all. They know enough not to push their argument into places where it will seem to be, quite obviously, ridiculous. But it is strikingly obvious that for today’s progressives, humans are the sole species on this planet where gender differentiation has no clear basis in nature, science, evolution, or biology. This is where they are as hostile to Darwin as any creationist.

And this is stupid. The alternative explanation — that these core natural differences between men and women have been supplemented by centuries of conscious oppression — is staring us in the face. The fascinating conundrum is where one ends and the other begins. How much of this difference is natural and how much is social? That is the question. And the answer is a tricky one. Is the fact that the vast majority of construction workers are male and the huge majority of nurses are female a function of sexism or nature? Is male sexual aggression and horniness a function of patriarchy or testosterone? Is the fact that women now outnumber men among college graduates a function of reverse sexism or nature?

My suspicion is that it’s more about nature than about society, and one reason I believe this (apart from all the data) is I because I’m gay. I live in a sexual and romantic world without women, where no patriarchy could definitionally exist, a subculture with hookups and relationships and marriages and every conceivable form of sexual desire that straight men and women experience as well. And you know what you find? That men behave no differently in sexual matters when there are no women involved at all. In fact, remove women, and you see male sexuality unleashed more fully, as men would naturally express it, if they could get away with it. It’s full of handsiness and groping and objectification and lust and aggression and passion and the ruthless pursuit of yet another conquest. And yes, I mean conquest. That’s what testosterone does. It’s also full of love, tenderness, compassion, jealousy, respect, dignity, and a need for security and a home. It’s men’s revenge on men. The old joke applies: What does a lesbian bring on a second date? A U-Haul. What does a gay man bring on a second date? What second date?

I know this must be a pain in the neck for most women. But it’s who we are. It’s a blessing and a curse. It’s called being male, this strange creature, covered in hair, pinioned between morality and hormones, governed by two brains, one above and one below. We can and should be restrained, tamed, kept under control. But nature will not be eradicated. And when left-feminism denies nature’s power, ignores testosterone, and sees all this behavior as a function entirely of structural patriarchal oppression, it is going to overreach.

. . . Trump understands this dynamic intuitively. Bannon believed it was integral to the Trump project, and wants the slanted elite discourse on men to continue and intensify. I think this issue was an under-acknowledged cause for Clinton’s failure. At some point, Democrats and liberals are going to have to decide if they want to “problematize” half the voting population. They are going to have to figure out who they really side with: Brooklyn or much of America? Reality or an ideology? Both genders or one?

Sullivan goes on to describe how gay men, in their own relationships, show the same dynamics that that straight men do with women, while lesbians in relationships show behavior similar to straight women. (Read the piece to see Sullivan’s joke about this.) To Sullivan, this is evidence that the important differences of sexual behaviors between men and women are based on hormones and genetics, not pure social conditioning. (I suppose one could counterargue that even gay men and women were socialized when young, but a counter-counter argument would note, as Sullivan did above, that there are striking parallels between sexual dimorphism in human sexual behavior and animal sexual behavior. Is there a patriarchy in wild chimpanzees?)

Sullivan is not, of course, defending the sexual predators singled out by #MeToo. He’s merely pointing out that in our future discussions of the fraught sexual dynamics between men and women (or men with men, or women with women), we must take into account that there are biological differences between the sexes that will affect their behavior.  It’s always better to know what’s true when trying to deal with a problematic issue.

Read the whole piece (the other two pieces, not as thought-provoking, are about Trump’s wall—Sullivan is for it, but not for the reason you think—and about how underrated Washington, D.C. is).

 h/t: Gregory

When ideology trumps biology

March 9, 2017 • 11:00 am

If I was the late Andy Rooney, I’d say “You know what really bothers me? When science shows some facts about nature, and then someone rejects those facts because they’re inconvenient or uncomfortable for their ideology.”

Indeed, when people ignore such inconvenient truths, it not only makes their cause look bad, but can produce palpable harm. Case in point: the damage that the Russian charlatan-agronomist Lysenko did to Soviet agriculture under Stalin. Rejecting both natural selection and modern genetics, Lysenko made all sorts of wild promises about improving Soviet agriculture based on bogus treatment of plants that would supposedly change their genetics. It not only didn’t work, failing to relieve Russia of its chronic famines, but Lyesnko’s Stalin-supported resistance to modern (“Western”) genetics led to the imprisonment and even the execution of really good geneticists and agronomists like Niklolia Vavilov. The ideological embrace of an unevidenced but politically amenable view of science set back Russian genetics for decades.

Other cases in point: the denial of evolution by creationists, and of anthropogenic global warming by conservatives. I needn’t belabor these.

We see this in other areas, too—especially with issues like differences between the sexes, ethnic groups, and evolutionary psychology. The assumption here is that any research on these areas could only serve to reinforce sexism and bigotry, so not only is that research denigrated, but there is an a priori ideological assumption that all groups are genetically equal for areas like behavior, mentation, and so on.  The error of this viewpoint is that whatever the truth is, it shouldn’t—and largely doesn’t—matter in the modern world. Society has advanced to the point where we recognize that equality of treatment and opportunity is the proper way to treat men, women, those of different ethnicities, the transgendered, and so on. There’s no need to assume that a biological “is” translates into a societal “ought”. As Steve Pinker has emphasized many times, we’re well past that view.

But the opposition to research on group and sex differences continues. One of its big exponents is the author Cordelia Fine, who has written two books with the explicit aim of showing that there are no reliably accepted evolved and biological differences in behavior between men and women. I read her first book, Delusions of Gender, and found it a mixed bag: some of her targets did indeed do bad science, and she properly called them out; but the book was also tendentious, and wasn’t objective about other studies. I’m now about to read her second book, Testosterone Rex: Myths of Sex, Science, and Society.  Judging from the reviews, which have been positive, it’s just as much a polemic as the first book, and has an ideological aim.

Because I haven’t finished it, I won’t judge it as a whole, but I do want to concentrate on one argument Fine makes that reviewers have found congenial.  That is her supposed debunking of the claim that men have often evolved to be promiscuous, and women to be more choosy, because of the potentially greater reproductive payoff for multiply-mating males compared to multiply-mating females. Lots of psychological studies have supported this difference in human sexual behavior, and of course it holds widely across the animal kingdom as well (there are exceptions exactly where we expect: when the reproductive payoff for multiple matings is greater for females than for males, as in seahorses). This difference between the sexes is in fact the evolutionary basis for sexual selection, and for the consequent observation of males courting females with behavior, ornaments, calls, and the like, with females choosing among displaying males. This is so common in animals as to constitute almost a biological “law”, with the exceptions proving the rule.

Fine denies this evolutionary basis, leaving her unable, of course, to explain sexual dimorphism in humans or any species. Her denial appears to be based on an early flawed experiment of Angus Bateman in fruit flies, which indeed turned out upon reanalysis to be inconclusive.  I’ve discussed this whole issue before, and you can read about it here, and how Sarah Ditum, the Guardian’s reviewer of Fine’s new book, was taken in by Fine’s bogus arguments. (Ditum is not a scientist.)

In my earlier post I pointed out the pervasive biological evidence that in both humans and other species,  the conditions for sexual selection  hold—a greater variance in male than in female reproductive output—probably explaining why men are bigger and stronger than women, and have beards and other secondary sexual differences. It also explains why male peacocks have showy tails, why male sage grouse do “jumping displays” to attract females, why male insects have weapons and ornaments, and so on. (See my bullet-point list of biological facts in that post.) Further, though Bateman’s experiments were flawed, they have been repeated properly in other species and have shown that, yes, males in general have the potential to have many more offspring than females: a higher variance in offspring number).

On February 23 the New York Times also reviewed Testosterone Rex, and the reviewer, the journalist Annie Murphy Paul, also fell for the bogus no-difference-in-reproductive-variance argument (she’s not a scientist). As she said:

Well, then, what about the even more entrenched idea that evolution has primed men to desire many and varied sex partners? Here Fine quotes the Bradley University psychologist David Schmitt: “Consider that one man can produce as many as 100 offspring by indiscriminately mating with 100 women in a given year, whereas a man who is monogamous will tend to have only one child with his partner during that same time period.” Fine expertly fillets this familiar premise, noting, among other inconvenient facts, that “the probability of a woman becoming pregnant from a single randomly timed act of intercourse is about 3 percent,” and that in historical and traditional societies, as many as 80 to 90 percent of women of reproductive age at any one time might already be pregnant, or infertile while they were breast-feeding. “The theoretical possibility that a male could produce dozens of offspring if he mated with dozens of females is of little consequence if, in reality, there are few females available to fertilize,” Fine comments. Think about it: For every man on the prowl, there simply aren’t a hundred women available to bear his child. For all men not named Genghis Khan, monogamy must have started to look like a pretty smart bet.

This is someone who doesn’t know what she’s talking about. Humans in Western society are now socially monogamous, but in effect many are polygamous, committing adultery. Men have been shown, time after time, to be less discriminating and more promiscuous than females. And many of those women who were pregnant were not pregnant by their social mate—if indeed our early ancestors had social mates—but by “alpha” males who got more than their share of offspring, or by those who mate with other males’ mates on the sly—what John Maynard Smith called “sneaky fuckers”. Most species of birds that look socially monogamous, for instance, pairing up in the nest and cooperating in brood care, have been found by DNA analysis to actually be committing adultery all over the place, so that the appearance of pairing gives a false idea of who’s really producing the chicks.

Such is the invidious result of having a non-scientist judge a scientific argument; and yes, the Times screwed up big time.  But someone who should know better is the evolutionary biologist and blogger P. Z. Myers, who bought into Fine’s bogus argument and fallacious mathematics in a post called “Cordelia Fine is doing the math.” Myers accepts Fine’s contention that promiscuous males don’t really have more offspring than do choosy human females—females who are prevented from getting fertilized when they’re pregnant.  Her arguments are wrong—for one thing, she sets unrealistic error limits for promiscuous males to outdo monogamous ones—but Myers has always rejected biology that is ideologically unpalatable to him.

In a rare occurrence at his site, the commenters, usually a choir of osculatory praise, gave him pushback. In fact one,  “Charly”, did the math correctly and showed that males in relationships with multiple females (bigamous or polygamous) have the potential to have more offspring than do monogamous males, supporting the ideas that men are selected to compete for women. (Duh!) Charly ended his calculations with this statement: “But maybe my reasoning and math is wrong, I am sure someone will point flaws out.”

In the next comment, Myers admitted that Charly’s math was actually right—math that invalidates Fine’s argument—but then he said this:

And there we have it, ladies and gentlemen, brothers and sisters: an admission that the biology is right, at least in theory, but the person who did the calculations is immoral.  What better example can we find of someone who opposes the truth because it’s ideologically repugnant? Even Myers’s regular commenters couldn’t live with that pronouncement, with one even asking if he was all right. I won’t speculate on his state of mind, but I will say that he’s on the wrong side in this argument.

Well, be that as it may, we have two lessons from this kerfuffle.

a). Magazines and newspapers should get scientists, or at least journalists who are scientifically educated, to review books about science. Science journalists without training in math and evolution are unqualified to review Fine’s book.

b). It’s always better to accept a scientific fact than to reject it on ideological grounds. For people will know the truth, and when they see it rejected because of confirmation bias, they can see what’s going on.

It always hurts your cause to behave that way. If science finds that men and women behave differently for evolutionary and genetic reasons, or that humans have behaviors that are holdovers from selection in our ancestors, we can deal with that. Such findings do not inexorably lead to racism, sexism, or bigotry, and there’s no reason why they should. Sure, there may be a few misguided individuals who mistake an “is” for an “ought,” but society no longer works that way.  Rejecting the facts because you don’t like them, or because they go counter to your political leanings, is a sure recipe for sinking your cause. First apprehend the facts, and then just deal with them.


I get pushback on the sexual-selection theory for sexual dimorphism

December 18, 2016 • 12:33 pm

Last week I published a post intended to show that the profound sexual dimorphism for human size (and musculature) reflected sexual selection in our ancestors, a form of selection that can be explained only by an evolved difference in behavior: in humans, as in many other species in which females invest more in reproduction than do males, males (who often make little reproductive investment, sometimes only sperm) must compete with each other for access to females. The behavioral difference is a marked tendency to be promiscuous, compared to the greater choosiness of females. That behavioral difference is in turn a direct result of an evolved difference in gamete size and reproductive investment between males and females.

Competition among males for females can involve either direct male-male “battles” (as in elephant seals, gorillas, and chimps, as well as stag beetles and deer), or female choice of males based on of their ornamentation (as in African widowbirds, peacocks, and lions). I think the size dimorphism of humans is more likely a result of male “battling” for dominance and access to females than simply female preference for large males, though of course both factors can be involved. But regardless of whether the sexual selection involves inter-male competition—what Darwin called “the law of battle”—or female preference, it implies a behavioral difference between the sexes, and one involving the traits most crucial for evolution: those directly involved in sexual reproduction.

I also adduced four other bits of evidence predicted by the sexual selection hypothesis, which you can see at my earlier post. Those predictions were made before the data were collected, and they were confirmed. There are many other data supporting the sexual selection theory, and I’ll discuss them tomorrow. One I’ll mention now is that the measured variance in reproductive success among human males is higher than among human females, particularly in hunter-gatherer tribes. That is, in such groups some males leave a lot of kids (and thus their genes) and many others leave none, while, in contrast, the variation in offspring number among females is much lower. The difference in variance between males and females, by the way, is directly correlated with the degree of sexual dimorphism in those groups: the greater the difference in variance among males than among females—and thus the more polygynous the society—the greater the sexual dimorphism for body size. That relationship is a prediction made by the sexual selection theory.

Now, however, Holly Dunsworth, a biocultural anthropologist at The University of Rhode Island, has taken issue with the long-accepted theory of dimorphism (it’s not mine; Darwin was the first to suggest it!), and goes after me in a blog post called “In man’s evolution, woman [sic?] evolve too.” (That post was also picked up and supported by Jesse Singal in a column in New York Magazine, which makes the same errors as Dunsworth).

Dunsworth offers her own thesis, which, she says, puts more emphasis on female evolution.  I suspect her own hypothesis is in fact ideologically driven, and also neglects the possibility, which I did indeed raise, that female preference has evolved.  Apparently anthropologists bridle when what evolves in females during sexual selection is psychology rather than morphology! I also see that Dunsworth has emitted a very long string of tweets about my piece, which suggests some obsessiveness about the sexual-selection hypothesis and male-male competition. I don’t engage in Twitter battles, which are unproductive, but will make my positions clear on this site.

At any rate, here is Dunsworth’s own theory of why human males are bigger than females (I’ve put her theory in bold).

It’s not that Jerry Coyne’s facts aren’t necessarily facts, or whatever. It’s that this point of view is too simple and is obviously biased toward some stories, ignoring others. And this particular one he shares in this post has been the same old story for a long long time. [JAC: Yes, because it’s supported by lots of diverse evidence and makes predictions that have been met!]

What about the other side of the body size sexual dimorphism story?

What about the women?

Selection could well be the reason they stop growing before men and why they end up having smaller bodies than men, on average.

Perhaps men can make babies while growing, but perhaps women can’t. Energetically, metabolically. So reproduction wins over growth. We reach sexual maturity and stop growing. Is that just a coincidence?

Why doesn’t this (and other tales) fit alongside the big-aggressive-males-take-all explanation for sexual dimorphism? #evolution

Not only is it absent, but selection on women’s bodies be the driving force (if such a thing could be identified) and, yet, it’s as if women don’t exist at all in these tales except as objects for males to fight over or to fuck (but *thankfully* there’s that female choice!).

Knowledgeable people aren’t objecting to facts, as Coyne suggests. They’re objecting to biased story-telling and its annoying and harmful consequences, which Coyne doesn’t acknowledge or grapple with in his piece. [JAC: I do indeed acknowledge that we must be mindful of the misuse of biological facts, and not use what we deem “natural” to make social policy. Did Dunsworth even read what I wrote?]

I’ll respond to her hypothesis tomorrow (she calls mine a “story,” a snarky way of denigrating it since there’s ample evidence supporting the sexual selection hypothesis), but right now I want to make three points:

  • Dunsworth, who says that I am a sucker for unsupported just-so stories in evolutionary psychology, doesn’t seem to realize that I have a long history of criticizing adaptive evolutionary-psychology stories unsupported by evidence (go here, for instance).  In fact, evolutionary psychologists used to be mad at me, considering me overly critical. But there are some aspects of evolutionary psychology, like that of human sexual behavior mirrored by sexual dimorphism in body size, that are more scientific, for they make testable predictions that have been met. It would be churlish and intellectually blinkered to ignore both this hypothesis and the evidence that supports it, equating this to more speculative adaptive hypotheses that I’m warier of.
  • Dunsworth’s own “story” really is closer to a story, as it’s contradicted by the known facts about human reproduction. I’ll let the readers figure out what those facts are.
  • Finally data on the nature and traits that are sexually dimorphic in humans have, as noted above, been predicted by the sexual-selection hypothesis but not by Dunsworth’s “growth and reproduction tradeoff hypothesis.” So not only is her hypothesis contradicted by data already known, but is countered by many facts about sexual dimorphism in body size, not only in humans, but also in our primate relatives and other animals. Comparing the sexual selection theory with the tradeoff story, it’s clear that the former is the best explanation for the facts.

I conclude that Dunsworth knows nothing of my history of writing on evolutionary psychology and, further, is remiss in her own scientific approach, offering a story that’s amenable to her ideology because it allows females to evolve (mine does too!), and also a story that not only fails the empirical tests, but can’t predict the observations that sexual-selection theory can. Too, there seems to be more than a touch of intellectual mendacity in the way both she and Singal blithely ignore the supported predictions of the sexual-selection theory. Believe me, it’s more than “just a story.”

I’ll have more to say on this tomorrow, but am throwing it out here now for the readers to chew on.

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Male and female gorilla. Guess which one’s the male?

The ideological opposition to biological truth

December 14, 2016 • 10:00 am

One distressing characteristic of the Left, at least as far as science is concerned, is to let our ideology trump scientific data; that is, some of us ignore biological data when it’s inimical to our political preferences. This plays out in several ways: the insistence that race doesn’t exist (and before you accuse me of saying that races do exist, read about what I’ve written here before: the issue is complex), that there are no evolutionarily-based innate (e.g., genetically based) behavioral or psychological differences between ethnic groups, and that there are no such differences, either, between males and females within humans.

These claims are based not on biological data, but on ideological fears of the Left: if we admit of such differences, it could foster racism and sexism.  Thus. any group differences we do observe, whether they reside in psychology, physiology, or morphology, are to be explained on first principle as resulting from culture rather than genes. (I do of course recognize that culture can interact with genes to produce behaviors.) This ideological blinkering leads to the conclusion that when we see a difference in performance between groups and genders, the obvious explanation is culture and oppression, and the remedy is equal outcomes rather than equal opportunities. Yet in areas like most sports, where everyone agrees that males are on average larger and stronger than females, it’s clear that the behavioral differences (i.e., performance) result from biological differences that are surely based on evolution (see below). In sports like track and field or judo, nobody would think of making males compete with females.

But that’s not a good way to act. The Left has historically been characterized by respect for the facts, and the refusal to even consider that such differences could be based in part on genes is an unwelcome and unhealthy departure from our traditional embrace of rationality. Yes, phony biological data has been used to support racism and sexism, but remember that that is the fault of human prejudice, cooked data, and an inability to do proper experiments that have all resulted in terrible data being used to support human prejudices. Finally, of course, culture can influence behavior, including reinforcing biologically-innate behaviors if they are seen as “normal.”

To claim that there are no evolutionary differences in behavior and psychology between men and women is fatuous.  The data show otherwise, though of course for most traits we don’t know if it’s genetic. But the default hypothesis, based on observation of other species (especially primates) is that at least some psychological and behavioral differences will be based on genes that evolved via selection in our ancestors. Why is the brain immune to evolved, sex-specific differences but the body is not?

Thus, to claim, as does P.Z. Myers in a new post, that higher testosterone levels in males have minimal influence on their aggressiveness compared to the effects of culture, is a claim based not on data—which show that he’s wrong—but on ideology. And so he and his commenters try to refute the testosterone-effect notion using anecdotes: some males aren’t aggressive, Myers himself is not aggressive (!), aggression is due “mostly” to cultural difference (the “patriarchy”) rather than to biological differences, and so on. To read the comment thread is to see a bunch of progressives desperately squirming to avoid the obvious.

Well, I’m not an expert on testosterone, but what I do know is that levels of that hormone are not only correlated with aggression within and among the sexes, but that injecting it into both men and women also makes their behavior and psychology more aggressive. Thus the correlation at least partly reflects causation.

But let’s look at some data showing prima facie that there are biological differences in behavior between males and females, and that those differences reflect the working of natural selection—in the form of sexual selection—in our ancestors. To do this, we’ll use body size as an index of behavior. I’ll try to be brief.

It’s well known that in virtually all species of primates (there are a few exceptions in lemurs), and in other groups such as pinnipeds, males are larger than females. That is not cultural, but genetic; if you rear gorillas in any habitat, the males are going to grow up larger than females. You can see the data among species yourself in a 2006 paper by Adam D. Gordon (reference and free link below), showing an almost universal trend for the male/female body mass to be larger than 1 in primate species (in every species there are of course some small males and large females, but we’re talking about averages).

Why is this? It reflects evolved male behavior: the tendency of males to compete for females, and the advantage of large body size in that competition. Whether the advantage be in direct competition, so that the larger you are the more you can fight off other males (gorillas, elephant seals), or in female choice, so that females choosing large males can gain protection for her young from marauding males (also gorillas), the difference in size reflects something almost universal among animals: males, who have cheap gametes, must compete for females who have expensive gametes and invest more in reproduction.  And that is why, in study after study in humans, male sexual behavior shows promiscuous mating, while females are more selective. That’s not necessarily all biological, but some of it surely is given that our closest relatives show the same behaviors and that there is no such thing as The Gorilla and Chimpanzee Patriarchy.

Here’s further evidence that the larger size and strength of males is reflected in their behavior—and was almost certainly promoted by sexual selection:

  • In human societies studied by Richard Alexander, those societies that are more polygynous (in which males compete more intensively for females) show greater sexual size dimorphism than societies that are more monogamous. This was a prediction made before the data were acquired—a prediction derived from sexual selection theory. And it was fulfilled.
  • Among species of primates, there’s a good correlation between the polygyny of a species and sexual dimorphism: those species in which males have a higher variance in offspring number, and in which males thus compete more intensely for females, also show a greater ratio of male/female body size, even when corrected for phylogeny. (Too, in primate species in which males fight each other over females, the relative size of the canine teeth, used in battle, is larger than in species showing less direct male-male competition.)
  • In humans, as in many other species in which males compete for females, the sex ratio at birth favors males. They then die off at a higher rate due to higher risk-taking and exploratory behavior, until at reproductive age (about 25), the sex ratio is equal. Then, as males continue to die off, the sex ratio reverses, becoming female-biased at greater ages. This is exactly what evolutionary theory predicts: if there are biological differences in mortality rates, then evolution will adjust the sex ratio so it’s equal at the time of reproduction.
  • In line with the above, in humans and other primates, males show from the outset great exploratory and risk-taking behaviors, and as adults show many other behaviors that differ from those of females, such as greater dispersal. Is this due to the Primate Patriarchy? Probably not, given that these differences in behavior are shown in many species besides ours and make evolutionary sense.

As I said, some of this is in our own species may be due to culture, for culture can reinforce pre-existing biological differences that have come to be seen as “natural.” (I don’t need to emphasize here that I don’t think that what is “natural” in other primates, or what has evolved in our own species, should be accepted as the right way to behave!). Further, some have suggested that the size differences between men and women reflect ecological rather than reproductive differences—say in foraging behavior. But the data don’t support that, and they do support predictions made from the sexual-selection hypothesis. And even if ecology does play a role, that still reflects evolutionarily produced changes in some aspects of behavior.

All this is to say that body size is a proxy for behavior in our own group—primates—and that body size correlates with behavior: sexual behavior. To deny that the differences between human males and females in size and strength are evolved is to deny at the same time that differences in behavior between males and females is evolved. Only the blinkered ideologue would do that. Sadly, these ideologues continue to promote antiscientific ideas on the Internet.

I am not making claims here about other behaviors differing among the sexes, since there are no morphological correlates with other behaviors as clear as that between body size and sexual behavior. But the male/female difference in body size does reflect differences in psychology—psychology of mate acquisition. This alone shows an evolutionarily-based difference between men and women, one that is almost certainly does not rest entirely on culture, for we see the same differences in species lacking our culture. There is no Primate Patriarchy outside our own species.

And if all this be true, then it would be foolish to deny prima facie that there are other evolved differences in psychology between men and women, some reflected in morphology (why are men hairier than women?).  The conventional wisdom should never be that men and women are biologically identical in their psychology and behavior, amiable as that may be to Leftist ideology. The primacy rests not with ideology, but with data; and while we can act against what the evolutionary data tell us (as we do when we use contraception), we should not deny that the data exist, or exercise confirmation bias so we try to dismiss data that contravene our ideology while welcoming data that support it. What we need to do is accept the data, but then adjust our society so that we realize the outcomes we want from our (partly evolved) morality. And that doesn’t mean structuring our society so that morality parallels biology.

And you can bet your tuchas that the ideologues will do their best to undercut (or ignore) the data adduced above. And for similar arguments but a lot more data, see Steve Pinker’s book The Blank Slate, which has a new Afterword with a detailed update on gender.

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Gorilla female and male. Females weigh about half as much as males.

h/t: Steve Pruett-Jones

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Gordon, A. D.  2006. Scaling of size and dimorphism in primates II: Macroevolution.  Int. J. Primatol. 27:63-105.

Michael Moore, misandrist, and a note on sex differences in behavior

October 31, 2016 • 11:30 am

Michael Moore has taken out after men on his Twi**er feed; here’s a sample of three in order of posting:

I don’t know what to make of this. Certainly men have been dominant over history, denying women the opportunity to melt the ice caps, build smokestacks or start the Holocaust (though there were plenty of women guards who abused women in the women’s camps). And the reason men have been dominant is largely sexual selection, which happened to make women the childbearers and the men larger and stronger. This is NOT to say that socialization and sexism have played no role in the oppression of women, for a group with higher status and dominance will culturally try to maintain that privilege. But the inequality between the sexes had to start somewhere, and that start is sexual selection. (Again, I’m not justifying the inequality, just explaining its inception.)

But I have a feeling that Moore means something more here: that women are by nature less aggressive and competitive, and more conciliatory.  That is, some part of these differences are inborn—genetic. And I suspect he’s right. But evolutionary biology also helps explain that, since men must compete for women and status, and the hormones that promote that behavior can have all sorts of bad side effects. I have little doubt, in fact, that a world in which women had power equal to that of men would be a world we’d like better. But to say that is to admit that the differences in behavior between men and women are not purely cultural. They must be at least partly based on evolved genetic differences. (Of course men and women have almost the same sets of genes, except for those on the Y chromosome, but evolution has caused them to be expressed differently in the sexes.) If there were no genetic differences, and women gained full equality of power and opportunity (i.e., experienced the same cultural environment), then culturally-based differences would disappear, and women and men would behave the same. (What that behavior would be is of course unpredictable.)

Moore’s tweets, then, while expressing a social reality, are also a tacit admission of biological differences in behavior between the sexes, something that to most evolutionary biologists is palpably true, but is anathema to many liberals and feminists—especially gender feminists. If you maintain that women are by nature the kinder, gentler, sex, and will always be so, then you’re usually admitting that the behavioral differences between men and women are based on part on genes.

I have to add a sardonic tw**t by one of my hosts here in Singapore, Melissa Chen:

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