Sex and the Brain

I just noticed an new article in PNAS – research by Daphna Joel a behavioral neuroscientist at Tel Aviv University. Using MRI, she concludes that the brains of men and women aren’t really different. She suggests that the notion that men and women behave differently may be a myth.

She is, of course, utterly full of shit. It’s fountaining out of every pore: her hair will never go gray. We know of many sex differences in the brain – not just volume, not just the fraction of gray matter vs white matter, not just big differences in the incidences of neuropsychiatric disorders like autism and anorexia nervosa. In a few cases (like CAH, or androgen sensitivity, or maybe Turner’s syndrome) we know something about the developmental mechanisms involved. We see analogous differences in animal models: and no, it’s not culture.

If you want to determine a brain’s sex from MRI data (without cheating by looking at the Y chromosome) you build a statistical discriminator – you don’t create a continuum of “femaleness” to “maleness,” for the entire brain and score every individual region-by-region to find out where they fall on that male-to-female continuum.

Moreover, similarity in gross anatomy does not ensure similar behavioral tendencies. If I compared the brain of a pit bull with that of a similar-sized border collie, I doubt if I could see the behavioral differences in the size of the amygdala or whatever. Those behavioral differences exist, they’re innate, they have a physical/genetic basis – but at the moment I couldn’t tell you what brain differences to look for. Could be differences in the distribution of neurotransmitter receptors, or differences in axon length, or dendrite connectivity – lots of things, including many that wouldn’t show up on MRI. Many couldn’t be seen by Ramón y Cajal.

As for her expertise on behavioral differences between men and women – she’s a maroon. Reminds me of John Money, and his crap about how you have to learn to be a boy or a girl. Which he knew was false (David Reimer). She probably thinks Mattel has brainwashed male rhesus monkeys into liking toy trucks.

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103 Responses to Sex and the Brain

  1. Jay1 says:

    2014 sex differences in brain structure meta-analysis looking at 126 studies:

    2015 study says no difference in hippocampus, and:

    “Many people believe there is such a thing as a ‘male brain’ and a ‘female brain,'” Dr. Eliot said. “But when you look beyond the popularized studies — at collections of all the data — you often find that the differences are minimal.”

    Meta-analyses by other investigators have also disproved other purported sex differences in the brain, Dr. Eliot noted. There is no difference in the size of the corpus callosum, white matter that allows the two sides of the brain to communicate, nor do men and women differ in the way their left and right hemispheres process language.

    • Toddy Cat says:

      “you often find that the differences are minimal.”

      I’m sure that if you’re interested in minimizing them, the differences are minimal. Of course, taken as a whole, the differences between male and female bodies are also “minimal” in the grand scheme of things, yet most of us find these minimal differences pretty important.

    • anon2 says:

      Interpreting her remark with a heap of charity, it might be addressed at the “Men are from Mars, Women are from Venus” crowd, who believe that our brains are so different even our attempts at communicating with each other are all but doomed to failure.

  2. Jim says:

    This thing about no significant behavioral differences between men and women is so unintuitive that I think even most leftists have given it up if they ever really believed it. For some of the other types of PC nonsense it is hard to tell whether some people may actually believe them but I think very few have ever swallowed the no sex difference in behavior garbage.

    • gcochran9 says:

      In practice, one probably needs to operationally define different forms and levels of “belief”. If I count ” willing to argue for it in public” as a level of belief, things are worse than you suggest. It’s not hard to find people who will argue that men are not really stronger than women, even though the difference in upper body strength is three standard deviations.

      • James Miller says:

        I was sitting at a table with a lot of college students and a female Exercise and Sports Studies professor. I asked this professor if men’s advantage in most sports was because of genetics and she said yes. As I recall, a few students expressed genuine surprise at this answer.

        • Jim says:

          Certainly in any sport emphasizing upper body strength men in general would have a big advantage. Billiards might be a sport in which women could often outdo men. Better fine motor control.

          • gcochran9 says:

            Except that they don’t.

          • Yudi says:

            Men’s superior visuospatial abilities surely come into play there.

          • Josh says:

            Men are also probably psychologically more driven to excel at sports even where they don’t have physical advantages.

          • Jacob says:

            I’ve been wondering if differences in 3D versus 2D visual perception/processing are part of why boys (in most populations) have so much harder a time learning to read than girls.

          • namae nanka says:

            ” why boys (in most populations) have so much harder a time learning to read than girls.”

            While there is evidence for delayed verbal abilities for boys relative to girls, the biggest problem is that boys don’t like to read(unlike the maths gap where girls get better grades even in maths and put in more effort) what is allowed in the school according to feminist sensibilities.

            ” In one of the earliest cross-cultural studies, Preston (1962) found that although girls outperformed boys in the American sample he tested, the reverse was true for the German students. German boys outperformed girls on every measure of reading achievement except speed. Subsequent investigations supported the contention that female superiority is not universal. When Johnson (1973-1974) investigated sex differences in reading among pupils of four Englishspeaking countries, he reported that in Canada and the United States girls outperformed boys, but that was not the case in either England or Nigeria. Other countries where girls were not found to be superior in reading were Denmark, Japan, India, and Finland (Downing et al., 1979; Downing, May, & Ollila, 1982).”

            Now you don’t even find such exceptions and the difference keeps increasing.

            “Between 1992 and 2002, among high school seniors, girls lost two points in reading scores and boys six points, leaving a 16-point differential … Although one might expect the schools to be trying hard to make reading appealing to boys, the K-12 literature curriculum may in fact be contributing to the problem. … Unfortunately, the textbooks and literature assigned in the elementary grades do not reflect the dispositions of male students. Few strong and active male role models can be found as lead characters. Gone are the inspiring biographies of the most important American presidents, inventors, scientists and entrepreneurs. No military valor, no high adventure. On the other hand, stories about adventurous and brave women abound. Publishers seem to be more interested in avoiding “masculine” perspectives or “stereotypes” than in getting boys to like what they are assigned to read. … the evidence is accumulating that by the time they go on to high school, boys have lost their interest in reading about the fictional lives, thoughts and feelings of mature individuals in works written in high-quality prose, and they are no longer motivated by an exciting plot to persist in the struggle they will have with the vocabulary that goes with it.”


          • Jacob says:

            The reading gap is almost certainly not the result of short-term cultural factors.

            Eight assessments generate valid estimates of U.S. national reading performance elementary through high school. Females outscore males on the most recent administration of all eight tests. On the 2012 PISA, 15-year-old females outperformed males in reading in all sixty-five participating countries.

            Moreover, this is about boys learning to read more slowly, not men being less interested in books. Tests of adult reading ability show no U.S. gender gap in reading by 25 years of age.

            Some of it may be the result of differences in the timing of verbal development, but my guess is that visual perception is more important.

          • namae nanka says:

            “The reading gap is almost certainly not the result of short-term cultural factors.”

            Even when it’s grown in the past decades?

            “On the 2012 PISA, 15-year-old females outperformed males in reading in all sixty-five participating countries.”

            And? PISA themselves pointed out that the gap has grown since 2000’s PISA and they had some pdf subject to the issue.

            “Moreover, this is about boys learning to read more slowly”

            Ok, but what does 3D/2D perception difference have to do with this? It’s not like there’s much of a difference in advantage that boys have on either.

      • TWS says:

        There was a writer at Unz who was shocked, shocked I tell you to discover male female strength differences. He wrote a whole article about it. An HBD guy who was stunned to discover the differences. He must have never had a girlfriend or played sports.

        I’ve seen boy high school basketball teams with more people who could dunk the ball than the entire WNBA. Some people are too brainwashed to see what is in front of their eyes their whole life.

    • Jay1 says:

      I think you could only get that idea if you spend too much time reading the comment sections on websites like this. Go argue that sex differences exist on some popular websites like Reddit, feminist websites like Jezebel, or any popular science blogs, and see what happens.

      • Anonymous says:

        The people who come out of the woodwork when you do something like that aren’t representative either. Most people just pay lip service to this idea to keep up appearances; they believe all sorts of things that contradict it and don’t think twice about it. But they’ll still go around repeating the same fashionable nonsense at dinner parties because they have it compartmentalized so thoroughly.

      • Toddy Cat says:

        Well, yeah, but that tells you more about the denizens of those sites than it does what most people believe. If you took a poll of Americans asking if biological sex differences exist, I’d be willing to bet 75-80% would say yes.

      • namae nanka says:

        On reddit you have the SJW police and lot of drama.

  3. JayMan says:

    “I just noticed an new article in PNAS – research by Daphna Joel a behavioral neuroscientist at Tel Aviv University. Using MRI, she concludes that the brains of men and women aren’t really different. She suggests that the notion that men and women behave differently may be a myth.

    She is, of course, utterly full of shit. It’s fountaining out of every pore: her hair will never go gray.”

    You’re a national treasure. I literally LOL!

  4. pyrrhus says:

    This cutting edge science of equality hasn’t yet reached the NYFD…

  5. New Scientist called this “A welcome blow to the myth of distinct male and female brains”. Does that imply that scientific findings of distinct male/female differences would be unwelcome news for the outlet? I thought science was supposed to indiscriminately welcome any evidence as long as it’s credible.

    From a progressive perspective it’s going to be tough to argue that men and women don’t have significant differences in brain function while maintaining that women can be trapped in the body of a men, and vice versa.

    • gcochran9 says:

      A – sex differences in brain function and anatomy – incontrovertible. B -There’s no evidence for claims of a female brain in a male body, or vice versa. Just crazy talk. I mean, people with Cotard’s syndrome think that they’re dead, but they’re not really, and there’s no reason to take them seriously.

      • Fourth doorman of the apocalypse says:

        Click to access Swaab_07.pdf

        Transsexuality is characterized by a conviction of having been born in the wrong body. The prevalence of transsexuality is 1:10,000 for male-to-female transsexuals and 1:30,000 for female-to-male transsexuals. Gender problems often crop up even early in development. Mothers report that, from the moment their sons learned to talk, they insisted on wearing their mother’s clothes and shoes, only showed an interest in girls’ toys, and mostly played with girls. On the other hand, not all children with gender issues eventually become transsexual. Only in 23% of the cases does a childhood gender problem lead to transsexuality in adulthood.2

        To the extent that those numbers are correct, 1:10,000, is an interesting number, ISTM.

      • JediWonk says:

        My first wife (the major-company ballerina) summed me up to her co-workers as being “a woman in a man’s body, but the woman is gay.” Just about everyone I knew was shocked when I announced my upcoming marriage. A typical comment was, “But you’re gay!”

        Except the actual gays. They never came near me, even in the ballet studio dressing rooms.

        There would have to be some fitness disadvantage in being as sexually passive as I am, and what is the offsetting advantage of being a software geek type even in just the last 10,000 years?

  6. AppSocRes says:

    Usually I eschew ad hominem argument but in my opinion the institutional name, “Rosalind Franklin University of Medicine and Science”, suggests that the inmates may have axes to grind. I’d be leery of potential bias in studies of sex differences coming from this outfit, particularly when they run counter to other recent studies of a similar nature, e.g., that referenced by Jay1, above. The logo of the school is hardly reassuring — check it out on Wikipedia — since it suggests a bit of a chip on the institutional shoulder.

    • Jay1 says:

      The one Greg mentioned came from Tel Aviv University, the one I mentioned came from Rosalind Franklin University.

      • AppSocRes says:

        I apologize to both of you for getting confused here. It seems like these “studies” have been popping up all over the place. One thing I just realized is that two meta-analyses of the type being done in these studies could incorporate identical sets of research and still reach exact opposite conclusions based on how they weight the reliability of each individual piece of research. My guess is that for some analysts this crosses the boundary between subjectivity and advocacy.

  7. Space Ghost says:

    Even if you choose, for political reasons, to completely ignore all available data about behavioral differences between males and females, there is still a part of the brain called the sexually dimorphic nucleus that is larger in males than in females, in every species of mammal that has ever been investigated. So we could additionally posit, for no reason whatsoever, that every other brain structure is statistically the same between males and females, and there would still be that pesky SDN making it easy to distinguish male brains from female ones.

  8. melendwyr says:

    Well, obviously people learn which symbolic behaviors represent maleness and femaleness, and adopt those their societies proclaim as appropriate. (Which always made me wonder about the supposed male homosexual lisp.) But it’s not quite the same thing as learning to be male or female.

    And of course the differences are small. Humans are less sexually dimorphic than most primates, maybe all of them. That doesn’t mean that we can’t tell apart men’s physiologies from women’s pretty reliably, even excluding genitalia. There’s inevitably going to be lots of overlap, but that’s not the same as identical or equivalent.

    • gcochran9 says:

      I found a nice reference on this. Humans are more sexually dimorphic than you think, particularly if you consider lean body mass. Human females have larger fat stores than other primates. So.. Stature dimorphism is about 8%, body mass 15-20%. But in fat-free body mass, men are 40% heavier and have 60% more muscles mass than women. Men have 80% greater arm muscle mass, 50% more lower body muscle mass. Men have 90% greater upper-body strength, a difference of about 3 standard deviations [the average man is stronger than 99.9% of women.] Men have 65% greater lower-body strength, 45% higher vertical leap, 22% faster sprint times.

      In the past, using muscle-powered weapons, women made piss-poor warriors.

      One thing that I didn’t appreciate until recently was the degree to which women are more physically fragile, at least in certain respects. When I was growing up, I never even heard of an ACL tear, but now I know several young ladies with tendons borrowed from a corpse.

      • TWS says:

        That’s right folks keep pushing your girls to play sports with the boys. It’ll be fine. Encourage them to play lots of rugby.

        Or maybe they just need 10000 hours of practice to beat the men? People are idiots.

        • Jim says:

          Maybe tiddlywinks?

          • TWS says:

            Since girls are more delicate (suffer more and more serious injuries) playing rough sports than boys perhaps non-contact sports? Perhaps sports that don’t allow tackling with the legs? Perhaps sports where you don’t have to get tendons fixed on a 13 year old? I love my sister but she allowed her daughters to play rough contact sports sometimes trying out on boys teams. Both required surgery and both cannot play any level of contact sport now.

            Recognize there are differences or suffer the consequences. I prefer to see what is in front of my eyes.

      • Little spoon says:

        Some time ago, razib expressed surprise at the degree of grip strength difference between men and women. It seems a lot of people are surprised when they see the empirical difference between male and female muscle mass and stregnth in data tables. I dont find any of it surprising at all though. It’s all about what I would estimate based on intuition. Perhaps because I am small the difference is more obvious.

        • TWS says:

          We live in such a feminized society that he had been that thoroughly brainwashed. It’s like his generation has been told they can fly if they just wish happy thoughts and are stunned when it doesn’t happen.

          I couldn’t believe he had never noticed what was once common knowledge and is still common sense. I figured only children believed the fantasies of tv and movies where 90# pixies beat up on 250# men. I think I was a little harsh with him in his comment section. He never posted my comments.

      • melendwyr says:

        “Humans are more sexually dimorphic than than you think”
        No, they’re about as dimorphic as I think they are.

    • ursiform says:

      Gibbons, for example, are less sexually dimorphic than humans. Gorillas and orangs much more so. Chimps and bonobos not so different. Monkeys all over the place …

      • Jacob says:

        Gibbons sure have a lot of behavioral differences by sex, though, and the coloration makes them easy to tell apart. We used to go watch them at the Bronx Zoo, and the contrast between the screaming and wildly playful males (they used to go slap the back of the tapir in the same enclosure with them and then jump back up on the tree when he turned around, repeat ad infinitum) and sedately nursing females was never lost on the 7th grade classes I brought with me.

  9. Expansion of “statistical discriminator” reference:

    Interesting response to PC “sex similarity” hypothesis of Hyde. Worth a read.

  10. Larry, San Francisco says:

    They mentioned this article in the Economist (which is really on a downward spiral these days). Utter BS. I am a statistician/data scientist, The proper method to test a claim like this you would use a machine learning technique (like neural nets) to train data on male and female brains, You would then predict sex on a holdout sample on which you perform a chi-square test on whether the predictions from the hold out sample were random or not. My guess is that any machine learning technique would predict better than random.

    • gcochran9 says:

      Is this equivalent, in the limit, to linear discriminant analysis? Do you people talk about Mahalanobis distance?

      • Scott Locklin says:

        I bet you could do this with Fisher LDA. The data isn’t available in any obvious way, but the “supporting information” appendix to her paper doesn’t actually support what the headline and her TED talk suggests. All it says is, more or less, “no single feature we looked at is a perfect discriminator.” Which is a lot like saying height doesn’t perfectly predict sex. Or, “I hope to confuse the rubes with bad statistics.”
        Also, she has a man chin. I couldn’t help but notice. This probably makes me a bad person.

        • gcochran9 says:

          Right: moderate predictive power on a bunch of features can add up to near-perfect prediction when you consider them all. Like with gene frequencies: How often will another Finn have the same allele as a Zulu? Fairly often, although not as often as with another Finn. How often is a Finn more genetically similar overall to a Zulu than a Finn, considering all genes? Never!

          Be fair: why would you think that this liar knows anything about statistics?

          You know, they should have me give a TED talk: I’d talk about Mary Jo.

        • AnonymousCoward says:

          Also, this Israeli lady is fake blonde. Somehow, it’s less evil to notice this, than to notice her man-jaw. I think part of why it’s less evil is that women notice other women bleaching more than men notice it, and often talk about it with other women. So, it must be ok.

          You can google backwards and see that Daphne has been harping this intersex stuff for as long as she’s been doing anything, and that she’s done essentially nothing else.

        • Some data are available, I have already tried. Use e.g.

          The William W. Howells Craniometric Data Set consists of craniometric measurements taken from 2524 human crania from 28 populations. Up to 82 measurements were obtained from these crania. In addition, Dr. Howells obtained data from 524 “test” crania (crania not included in the main data set). Sex was estimated from crania by Dr. Howells and is also provided in both data sets, and additional notes are provided about the provenance of the “test’ crania. The links to the data may be found at the bottom of this page.

          I seem to recall that non-CV logistic regression gets about 80% accuracy in this dataset. CV will lower this value. Probably random forest or something could perform much better.

          • Scott Locklin says:

            The problem with that is, I’d just be doing logistic regression on Howells model of sexing crania. If you should turn up measurements of this kind though, I’d love to have it and have a public laugh at ole man chin’s bad stats.

        • “No single feature we looked at is a perfect discriminator.” Well, sure. Perhaps even vaguely interesting.

          At carnivals they used to have guys who would guess your weight within a few pounds, which they presumably couldn’t make money at if they didn’t notice more than one thing about you. Yet there was enough vagueness in a clothed presentation that they didn’t win all the time, which is what made it a fun bet.

          You will notice that there was no “guess your sex” booth across the midway. The exceptions, even with people trying really hard, would be too few to be interesting. I work in mental health and have known lots of trans people over the decades. You can usually tell, even when people devote their lives to disguising it. Not always, but enormously.

          BTW, the trans statistics usually try and include people with Kleinfelter or Turner’s Syndrome people to pad their own numbers, which is often deeply insulting and distressing to them. I guess they don’t count.

      • Larry, San Francisco says:

        Although I haven’t thought about it that way, it is basically non-linear discriminant analysis (you have non-linear multi-dimensional surfaces instead of planes cutting through the data). The chi-square test is basically non-parametric unlike the Mahalanobis distance. The idea is that you can think of each realization as a Bernoulli trial (i.e. coin flip). With large enough N the frequency of make a wrong prediction (i.e predict the wrong sex) will be normally distributed. Under the null hypothesis that there is no difference between men’s and women’s brains you should expect half your forecasts to be wrong. If the frequency of making the wrong prediction is much lower than you can reject the hypothesis that the 2 groups are the same, I hope that is reasonably clear.

      • RCB says:

        Linear discriminant analysis is a particular kind of classification model, which assumes that each class (here, men vs. women) has associated with it a multivariate Gaussian distribution of predictor variables (brain measurements). The decision boundaries are linear under the assumption that each class has the same covariance matrix (if not, it’s called quadratic discriminant analysis, I believe). It’s clearly not the only model for classification: there’s logistic regression, for example. I don’t know if it has any asymptotic relationship to neutral networks – probably not. More generally, “machine learning” just refers to the process of fitting fancy models to data and trying to estimate how well they can predict new data; it doesn’t refer to any model in particular.

    • DdR says:

      God, I thought it was just me who thought that the Economist has become a shill for the Establishment. I can barely read it anymore with a straight face when, for instance, they applaud Angela Merkel for her strength and courage to allow in millions of refugees. Or that Japan would avert economic disaster if only more women were allowed to enter the workforce. Or that global warming is proven based on consensus and that every should just tow the line.

      And naturally, they hate Donald Trump.

      • Tarl says:

        A while back an issue had Merkel on the cover and called her “the indispensable European”. I thought the proper caption for her should have been, “dispensing with Europeans”.

  11. ES3 says:

    How can the writer reference a mix of “male and female brain features” if there are no brain differences between between genders? Sloppy stuff.

  12. Fourth doorman of the apocalyse says:

    But, but …

    花木蘭 proves that there is no difference between men and women!

    • Sandgroper says:

      Actually, 婦好 does, if her grave goods are anything to go by, and if the occasional exceptional woman proved anything.

      • Fourth doorman of the apocalyse says:

        Or perhaps it just proves that the Emperor got tricked into marrying a lady boy.

        But seriously, let us take the stories depicted by the grave goods as true, all it proves is that the occasional female overlaps the low end of the male range.

        Remember, that statement the average man is stronger than 99.9% of women.

        On the other hand, perhaps she had Androgen Insensitivity Syndrome … I wonder if there are enough such individuals to get good stats on muscle mass and strength?

        And, being serious again, women have it easy! They are the only ones who can have babies, and they are optimized for it. Why do they need to compete with men in an area where they are not equipped to compete?

        • Sandgroper says:

          She gave birth to children, including Prince Jie, the next in line to the throne. In addition to the evidence of the grave goods in what has been proven to be her tomb, quite a lot was written about her at the time, in relative terms, including that she presided over the human sacrifices, and that she led numerous military campaigns. None of that needed to require a lot of muscle, particularly. What might be interesting is that she died young, about 30. The Shang were prodigious rice wine drinkers, and they drank the wine from bronze drinking cups that had a very high lead content. Research has shown that rice wine kept in bronze vessels with that much lead content rapidly achieves a high enough lead content to be fatal – so it looks like either she might have died from lead poisoning, or have been so weakened by lead poisoning that she was overcome in the final battle she took part in. There is some writing to suggest the latter – that she attempted the battle despite being “exhausted” and that she was killed by an enemy officer. All credible enough.

          The people who study these things are pretty convinced that she was the most powerful military figure for her time. That doesn’t need to mean she was physically strong – she was a general, and a priestess; a powerful figure by virtue of who she had control over.

          And she was one data point. She is not unique, though, there have been other Chinese female generals, but not many. One is recorded as having had her gut cut open in combat, so she wrapped a scarf around her to stop her intestines from spilling out, declared that it was the day she would die, mounted her horse and charged into battle, being brought down and killed by enemy archers.

          The point I was making was that Mulan was probably fiction, and if not was likely not Chinese. Fu Hao was real, and her accomplishments are quite well attested to.

  13. Fourth doorman of the apocalyse says:

    Razib weighs in on sex differences in strength:

    • namae nanka says:

      The calculation of d combines the SDs of both population groups, so the difference appears smaller(if you’d like to calculate the overlap) since the female SD is lower.

  14. Hey now wait a minute you old crudgemudgeon, I have on high authority, Cosmopolitan Magazine no less, that “this is the reason you don’t always feel girly!” and they go to say “and maybe it’s the coolest reason ever!”

    It refers to this study and finishes with this “High five people who don’t always feel like one specific gender. Science has your back.”

    Every time I get a haircut I have no choice but to read old Cosmopolitan magazines which I leaf through confirming once again the quote “I love humanity, it’s people I can’t stand.”

  15. Tarl says:

    Reminds me of John Money, and his crap about how you have to learn to be a boy or a girl.

    It is not an accident that he was childless. Anyone who has children – especially if you have one of each kind – can easily see that boys act like boys and girls act like girls without any instruction at all.

    • gcochran9 says:

      I think it’s fair to say that it wasn’t an accident.

      • IC says:


        Without sex education (or porn education, or peer education, natural animal porn), do human instinctively know what to do when they grow up? There are incidences that married couple remained virgin due to their ignorance about sexual reproduction.

        However animals seems never having this kind of problem even though they grew up without any adult animal showing them what to do. If you grew up on a farm, you knew it is true that animals do not need to learn about sex. They just know by instinct.

        • Bert says:

          I remember an anecdote by Desmond Morris. Two apes of some kind, one male and one female, had grown up isolated from other apes. They had both taught themselves to masturbate, but when put in the same cage they didn’t have sex; instead, they furiously masturbated, each in it’s own corner.

          • IC says:

            The anecdote sounds almost like a joke which has a lot of entertaining value. I laughed out loud when I was reading it. Seriously I believe it and this actually give me some ideas to form hypothesis (speculation).

            It is very likely that neocortex development is inversely correlating with instinct behaviors based on the your information and my own observation. Apes are at top end of neocortex development. At other end, birds and reptile have very small/zero neocortex. As we know neocortex is inhibitory to lower brain structure (or primitive brain structure). Primitive brains carry out most instint behaviors (no learning needed). Neocortex carry out most complicated behavior based on learning.

            So reptilians need no learning for most their behaviors including sex (genes carried most behavior infor). Birds need no learning. Apes including human, on the other hand, have to learn to do sex which is natural to primitive animals. Chicken can function almost normal when neocortex is cutted out. Without neocortex, human is pretty much brain dead.

            Follow Rushton style of analysis to apply species difference onto human difference. Based on this hypothesis, smarter you are, less instinctive behavior, more learning needed to function. Since learning is malleable process, human behavior is more likely product of immediate environment for smarter people. Thus more nurture and education are needed for smarter people. Less intelligent people have more behavior based on primitive part of brain and have more impulsive behavior, have less educational effect, are stubborn. Open mind attitude is correlated with more developed neocortex.

          • JayMan says:


            “So reptilians need no learning for most their behaviors including sex (genes carried most behavior infor). Birds need no learning. Apes including human, on the other hand, have to learn to do sex which is natural to primitive animals. Chicken can function almost normal when neocortex is cutted out. Without neocortex, human is pretty much brain dead.

            Follow Rushton style of analysis to apply species difference onto human difference. Based on this hypothesis, smarter you are, less instinctive behavior, more learning needed to function. Since learning is malleable process, human behavior is more likely product of immediate environment for smarter people. Thus more nurture and education are needed for smarter people. Less intelligent people have more behavior based on primitive part of brain and have more impulsive behavior, have less educational effect, are stubborn. Open mind attitude is correlated with more developed neocortex.”

            It’s a nice and oft-repeated story, but somehow I doubt that’s how it actually works.

          • IC says:

            As a typical scientist, social approval (or social validation) has little impact on my thinking process. I am more interested in objective evidences (both pro or con) as provided by other comments.

            But thanks for reading my comment. Still appreciate your contribution.

          • IC says:

            Both pumpkin person and Anatoly Karlin had made claimed that intelligent people are more vulnerable to brain wash than stupid people since stupid people have no brain to be washed. I was uncertain about this claim. Obviously stupid animals (like reptile) certainly are not trainable. Smarter the animals, more trainable. There is certain logic for the claim. But in human, the issue become more complicated. Very stupid is certainly hard to learn any thing. Moderate intelligence is open to learn new thing but often lack of independent critical analytic ability to differentiate truth vs fiction, plus pressure of social approval. These are the people who are intelligent enough to be brain-washed. Very intelligent people are more like scientists who can both learn and do independent critical analysis based on evidences. These people are actually not easily brain washed since they form their view about thing quite independently like those self-actualizers.

            (Autonomy. Self-actualizers are free from reliance on external authorities or other people. They tend to be resourceful and independent.)

          • IC says:

            There is a very entertaining post yet serious research about bullshit (BS) detection . Kind of related to brain wash, clever silly stuff from Greg prior post. Glad some people do serious research about people’s silly belief.

            this study seems to confirm much that is instinctively known (or at least has been assumed): analytic thinking probably decreases susceptibility to BS; paranormal beliefs go hand-in-hand with such susceptibility. It also tells us that susceptibility to nonsense is quite widespread in the population, who tend to be far more easily persuaded by emotional, vague, seemingly “profound” appeals than they are by data, science, and evidence.


          • IC says:

            If people have no experience with animals on the farm, you all can observe insects who almost never their parents around in most temperate region. They mostly emerge from eggs in spring survived from last winter. Without any adult teaching and showing, these new generation insects all know what to do instinctively almost anything in their life. All their behavior is based on instinct which is carried by genes.

            Anecdote by Desmond Morris is behavior of animals more similar to us.

          • georgesdelatour says:

            Replying to IC:

            Orwell said there are some ideas that are so obviously stupid, only really clever people are capable of the mental gymnastics needed to believe in them. I suspect that their apparent difficulty/absurdity gives a kind of in-group snob appeal to those who supposedly understand them.

            Three examples come to mind:

            The Holy Spirit. Pneumatology is abstruse. The ordinary member of a Christian congregation has no idea what it’s all about, and probably doesn’t feel any need to know more.
            Marxism. Even though it’s supposed to be about helping the masses, Marxism has a whole superstructure of Hegelian bullshit. Marx put it there specifically so that vanguard intellectuals like hime could feel superior to the ignorant hoi polloi. Theodor Adorno is probably the best example of an intellectual who seems to have been drawn to Marxism specifically in order to weaponise his distain for petit-bourgeois philistines and hicks.
            Deconstruction. Nuff said.

          • IC says:

            Example of instinct brain is strong in primitive animals.

  16. Earlier comments seem to express uncertainty about accuracy of discrimination. Two references:
    Larry Cahill:
    And confused response by the usual suspects:

    Cahill cites Jahanshad: 93 per cent sex classification accuracy on connectivity alone. A few more variables? 99 per cent, I’d guess.

  17. John Money lives in infamy. He was responsible for ruining the life of David Reimer, recorded in “As Nature Made Him: The Boy Who Was Raised as a Girl.” Sad story. Check Wikipedia if you like.

    • Abelard Lindsey says:

      I read about David Reimer. I also remember having heard about his suicide in the early 00’s. My only thought is that John Money should be in prison.

  18. Nuclear Lab Rat says:

    Greatly enjoyed that post. Thanks for writing it.

  19. namae nanka says:

    There’s the Gender Similarities Hypothesis arguing something similar, where the ‘veteran (gender) gap buster’ Janet Hyde shows that gender differences are small on various behavioral traits. Quite a few citations too.

    Except when you combine them,

    “Multigroup latent variable modeling was used to estimate sex differences on individual personality dimensions, which were then aggregated to yield a multivariate effect size (Mahalanobis D). We found a global effect size D = 2.71, corresponding to an overlap of only 10% between the male and female distributions. Even excluding the factor showing the largest univariate ES, the global effect size was D = 1.71 (24% overlap). These are extremely large differences by psychological standards.”

    Also, there was a recent study where one of the researcher admitted to having a huge bias towards not seeing gender differences for like twenty years but she couldn’t ignore them any longer.

    So there’s hope for the Lise Eliots(mentioned in the first reply) and Cordelia Fines of the world.

    • Fourth doorman of the apocalypse says:

      Anyone with any experience with men and women and boys and girls must surely have known that the Gender Similarities Hypothesis was a crock of shit.

  20. TangoMan says:

    I fondly remember dropping this bomb on creationists during the Larry Summers’ persecution. I suppose that the present-day feminist response would be “mouse brains are completely different from human brains.”

    Sexually dimorphic gene expression in mouse brain precedes gonadal differentiation.

    The classic view of brain sexual differentiation and behavior is that gonadal steroid hormones act directly to promote sex differences in neural and behavioral development. In particular, the actions of testosterone and its metabolites induce a masculine pattern of brain development, while inhibiting feminine neural and behavioral patterns of differentiation. However, recent evidence indicates that gonadal hormones may not solely be responsible for sex differences in brain development and behavior between males and females. Here we examine an alternative hypothesis that genes, by directly inducing sexually dimorphic patterns of neural development, can influence the sexual differences between male and female brains. Using microarrays and RT-PCR, we have detected over 50 candidate genes for differential sex expression, and confirmed at least seven murine genes which show differential expression between the developing brains of male and female mice at stage 10.5 days post coitum (dpc), before any gonadal hormone influence. The identification of genes differentially expressed between male and female brains prior to gonadal formation suggests that genetic factors may have roles in influencing brain sexual differentiation.

  21. Jay1 says:

    If you want to determine a brain’s sex from MRI data (without cheating by looking at the Y chromosome) you build a statistical discriminator – you don’t create a continuum of “femaleness” to “maleness,” for the entire brain and score every individual region-by-region to find out where they fall on that male-to-female continuum.

    What are some examples of such a statistical discriminator in use?

    It reminds me of the “Genetic Structure, Self-Identified Race/Ethnicity, and Confounding in Case-Control Association Studies” study by Tang et. al which looked at 326 locations on the genome in individuals from the self-identified races White, African American, East Asian, and Hispanic. Their computer program put individuals into different groups of individuals of the same self-identified race with 99.86% accuracy.

    Or A.W.F Edwards’ “Lewontin’s Fallacy” paper where “Edwards argued that while Lewontin’s statements on variability are correct when examining the frequency of different alleles (variants of a particular gene) at an individual locus (the location of a particular gene) between individuals, it is nonetheless possible to classify individuals into different racial groups with an accuracy that approaches 100 percent when one takes into account the frequency of the alleles at several loci at the same time” (Wiki)

    If you did something similar with multiple “markers” of the brain to put individuals into two different groups, would male and female still look like a continuum or would it look like two separated or nearly separated groups?

  22. Jay1 says:

    The PNAS article by Joel is here if anyone wants to read:
    Sex beyond the genitalia: The human brain mosaic

    Click to access joel2015.pdf

  23. Matt says:

    Reading the reporting on this in the press last week, I remember them being pretty clear that there wasn’t a lot of overlap between sets of male and female brains overall, primarily due to allometry (large male brain size, absolutely and proportionately), plus other statistical tendencies for regional volumes.

    What this seems to make clear is that there isn’t any region of the brain where even a large plurality of men has a relatively larger volume than a large plurality of women (over large volumes, having read Space Ghost’s comment on the SDN)?.

    That’s seems kind of…. as expected? It adds information that rejects a naive model of brain sex differences (men usually have region X larger than women, etc.), without rejecting a model of differences (these emerge through a few different correlated factors, not a single region).

    I don’t see male-female brain differences as anything that has any degree of opprobrium in the mainline press. They’re pretty much in British newspapers any given month, and tend to appear in the popsci press like New Scientist, etc. with regularity. (IRC New Scientist had a headline article earlier in the year or last year about how male and female brains apparently achieve similar results through entirely distinct processes – they pretty much run with anything).

  24. Jedi says:

    I can always have fun with the “sex-difference deniers” by mentioning that I once dated a woman who worked for a company where some jobs were only given to men and others only to women. Indeed, even though I was (and still am) a software geek, I had filled in for the man she usually worked with and, indeed, was better at one might call the “heavy lifting” that his job required.

    I have been able to keep some of them going for up to 15 minutes about how the DOJ should crack down on that company before I had to deliver the punchline that it was one of America’s “Big Six” ballet companies. And yes, not even all the guys could do the one-arm overhead lifts in “Don Quixote” grand pas-de-deux reliably. I could never dance a single step, but they worked the first time, every time for me.

    People at my health club found it a little unusual that a racquetball court was being used by a woman wearing pointe shoes, but they got over it.

    Ballerinas are heavy. They look stick-thin but they are solid muscle. Their bodies give the term “firm young flesh” a whole new meaning, and, of course, they are as flexible physically as I am morally. The lady in question was your standard-issue 5′-6″ tall and 110 pounds. Suzanne Farrell’s career was ended when Peter Martins retired because NYCB did not have another man tall enough/strong enough to partner her.

  25. Julian says:

    Doreen Kimura wrote about this stuff years ago, documenting average male/female differences.

  26. Fourth doorman of the apocalypse says:

    Some people should consider that their name is not suitable for the field they have chosen:

    Click to access Swaab_07.pdf

  27. Pingback: Sex and the Brain | Vanaland

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