Are male and female brains absolutely identical?

January 20, 2017 • 12:30 pm

The Guardian has a review out of Cordelia Fine’s new book, Testosterone Rex: Myths of Sex, Science, and Societywhich continues her critique of innate differences between male and female brains and behaviors. The Amazon summary includes this:

In Testosterone Rex, psychologist Cordelia Fine wittily explains why past and present sex roles are only serving suggestions for the future, revealing a much more dynamic situation through an entertaining and well-documented exploration of the latest research that draws on evolutionary science, psychology, neuroscience, endocrinology, and philosophy. She uses stories from daily life, scientific research, and common sense to break through the din of cultural assumptions. Testosterone, for instance, is not the potent hormonal essence of masculinity; the presumed, built-in preferences of each sex, from toys to financial risk taking, are turned on their heads.

Moving beyond the old “nature versus nurture” debates, Testosterone Rex disproves ingrained myths and calls for a more equal society based on both sexes’ full, human potential.

Now I can’t quibble with the last sentence, though I can say that we simply don’t know very much about evolutionarily-based differences in behavior between the sexes. I guess I’m an equity feminist, feeling strongly that members of both sexes (or of a spectrum of genders) must be offered equal opportunities and educations from the very outset: from birth.  But if there are innate differences between genders or sexes, that won’t necessarily guarantee equality of outcomes. All we can do is ensure that nobody is discriminated against based on their genitalia, their chromosomes, or their own perception of gender.

I read Fine’s previous book, Delusions of Gender, and thought it was pretty good in taking apart some poorly designed experiments that themselves seemed to reflect the researchers’ ideologically driven agenda of hard-wired sex differences. But I also thought that Fine herself was at least partly motivated by ideology (the view that there are absolutely no behavioral differences between the sexes that don’t arise from social conditioning), and so my opinion of the book was mixed. In the end, I agreed with Diane Halpern’s take in Science on that book (Halpern also reviewed Brain Storm by Rebecca M. Jordan-Young, a book I did not read):

Cleverly written with engaging prose, Delusions of Gender and Brain Storm contain enough citations and end notes to signal that they are also serious academic books. Fine and Jordan-Young ferret out exaggerated, unreplicated claims and other silliness regarding research on sex differences. The books are strongest in exposing research conclusions that are closer to fiction than science. They are weakest in failing to also point out differences that are supported by a body of carefully conducted and well-replicated research.

I haven’t read Fine’s latest book, and so will address only the Guardian‘s take on it, which I find bizarre. One caveat is that it may be misrepresenting Fine’s views. But the quoted part below, which I’ve put in bold, suggests that the whole paradigm of sexual selection, and attendant behavioral differences between males and females, should be thrown out because of one flawed experiment:

Here’s one example Fine offers of Testosterone Rex mangling the way we think about sex. In the 1940s, biologist Angus Bateman conducted a series of experiments on fruit flies that appeared to show conclusively that competition between males for “fertile female vessels” was the driving force of evolution. The hypothesis goes something like this: laying eggs is a more substantial physical investment than producing sperm. Therefore, to maximise reproductive success, females should be selective and cautious while males should be promiscuous and competitive; therefore, women are domestic and monogamous, while men are thrusting away both in the public sphere and in as many beds as possible.

It’s elegant, it’s intuitive, and it’s wrong. Bateman’s experiments were biased by design and by his unexplained exclusion of data that, when included in a recent reanalysis, actually showed that males and females both produced more offspring when they had more mates. But there are limits to promiscuity as a strategy: taking into account female fertility, a man has more chance of being hit by a meteor than fathering 100 children with 100 different women in a year. The player who says it’s in his genes is missing a vital part of the story.

It’s true that Bateman’s experiment, purportedly showing that males had a much higher variance in mating success than did females—a crucial assumption of sexual selection theory—was flawed. This was pointed out in a PNAS paper by Patricia Gowaty et al., who noted that the use of certain mutations as genetic markers biased the outcome towards the sexual-selection hypothesis: that males are more promiscuous in mating, and females pickier, because females make a greater reproductive investment than males. But they didn’t say Bateman was flat wrong in seeing males more promiscuous than females; they said his results were “inconclusive.”

The Guardian‘s canard about the unlikelihood of a male fathering 100 children with 100 different women is simply misdirection: the question is whether some males get a lot of offspring compared to others (higher variance in reproductive success) while the variance among females is smaller. If that is the case, then there will be male-male competition—either direct or through display, ornaments, and so on—to woo discriminatory females.

In fact, Bateman’s experiment has been repeated properly in other species, with exactly the predicted finding of higher male variance and of males competing to fertilize scarce uninseminated females. To throw out the whole edifice of sexual selection (and I’m not using it to claim that “women are domestic and monogamous, while men are thrusting away both in the public sphere and in as many beds as possible”) because of one flawed experiment is to neglect the pervasive evidence from many areas that males are indeed evolutionarily adapted to try to mate as often as possible, while females are adapted to be more choosy. We don’t jettison an entire body of consilient evidence because one guy did a bad experiment.

Data supporting sexual selection, and a greater promiscuity of males rather than females, include the following:

  • In human, primate, and many other animal species, males do indeed have a higher variance in reproductive success than do females (it’s been measured). It would be extraordinary if that was just a coincidence based on “social conditioning” in humans but evolution in all the other species that don’t have social conditioning.
  • The theory of sexual selection is well worked out, and precisely explains this difference in sex-specific behavior.
  • In species in which males make a greater reproductive investment than females, like seahorses and pipefishes (the males get “pregnant,” holding the eggs and young in pouches), we see the exact opposite of what we normally see. The males are choosy, while females, who produce eggs faster than males can accept them, are promiscuous. In fact, in those groups it is the females who are brightly colored and ornamented while males are drabber: the opposite of the normal situation, but exactly as sexual selection theory predicts.
  • The difference in body size and strength between human males and females implies an evolutionary basis, almost certainly having something to do with male-male competition, as it does in many mammals, insects, and other groups (see my posts here and here). Holly Dunsworth, whose theories I’ve criticized, has never responded to my comments.
  • Replicated experiments in both humans and other animals show a strong difference in promiscuity (in humans it’s done using experiments in which attractive strangers proposition people of the opposite sex). Again, it would be extraordinary if the parallel between human and animal behavior were purely coincidental.
  • There is no convincing way to explain the pervasive existence of bright coloration, elaborate plumage (maladaptive for survival), calling and displays, and other “look-at-me” features of males versus females other than sexual selection.  How that selection works may be enigmatic (do the male traits show good genes? good phenotypes? appeal to some innate preferences of females?)—but all of it supports the action of sexual selection.
  • Bonobos (“pygmy chimps”), which may behaviorally more similar to humans than are “regular chimps”, have a fairly matriarchal society with more promiscuous mating of females than do other chimps, but still show a 25% greater body weight in males than females. Is that a holdover from an ancestor, or a byproduct of males competing for females? (After all, bonobo females are still saddled with pregnancy and child-rearing, and thus have far fewer potential offspring over their lives than do males.)
  • Finally, insofar as the morphological traits are connected with differences in sexual behavior and proclivities of males versus females, it shows some genetic differences affecting behavior between the sexes—and differences that may rest largely in brain wiring. Now that needn’t reflect a difference in male versus female brain structure, as it could simply represent how brains that are identical produce different responses when affected by different hormones produced outside the brain. (Testosterone, for example, may trigger “promiscuous mating” genes that reside in both male and female brains but are activated only by male hormones.)

As I said, I haven’t read Fine’s latest book; what I’m reacting to here are the two bolded paragraphs in the Guardian summary—paragraphs implying (based on the flawed study of Bateman) that sexual selection simply doesn’t exist: it’s all social conditioning and the Patriarchy. But there are simply too many biological facts (first adduced by Darwin) to support that conclusion, not least the number of animals lacking a “patriarchy” who show strong evidence for sexual selection and sexual behavior resembling those of humans.

While some of those whom Fine has criticized may have distorted their science in the name of ideology, I worry that Fine is doing the same thing. I will find out when I read her book. But certainly the Guardian has engaged in scientific distortion in its article about Testosterone Rex. 

69 thoughts on “Are male and female brains absolutely identical?

  1. Whatever differences we have due to our biology can be overridden by humans by simply choosing to behave however we want, unlike other animals who are indeed “controlled” by their genes.

      1. Although I don’t agree that we can override our biology (I think there are differences between men and women that have nothing to do with social conditioning) technically, we can choose not to menstruate.

        There are contraceptive methods that stop ovulation. Women can choose to have their ovaries removed surgically. Losing too much weight also stops ovulation.

        Of course, those are all actions we would have to take after the inevitable has already happened.

      2. I do not understand Jiten’s comment this way; rather, I think (s)he is referring to human societal norms, written and unwritten – laws, customs, ethics, the male “code of honor”, things that we women appreciate truly only when we meet an aggressive male who, for one or another reason, is free from these inhibitions.

          1. Women, like men, tend to behave as is best for their genes when they can get away with it. The best for a woman’s genes is to be in a monogamous relationship with an alpha male. The next best thing is to be in monogamous relationship with some man, to have as a lover a man with good-looking genes, and to trick the former into supporting children of the latter.
            Men from the elite are generally wanted as lovers, but so were gladiators.

            “Faustina Junior inherited her mother’s playful disposition and more. Rumors of her adulterous affairs were rampant, with it being generally known that she had a penchant for sailors and gladiators. Another widely accepted rumor was that Commodus (her only son to survive childhood) was sired by one of her gladiator lovers rather than her husband.” (D.L. Vagi, Coinage and History of the Roman Empire)

            I have seen two fictionalized accounts of Spartacus’ life in which he himself has a child with a high-ranking Roman woman.

      3. Yes but only if you take your birth control pill without stopping for your period and when you do that there are consequences.

        Starving also helps too. 🙂

    1. Unless, of course, we are not aware of how our biology, experiences, and societies shape our individual world views.

      In any event I could have been a stay-at-home-dad (we discussed it) but I couldn’t have been a child-bearer.

    2. Except that biology often drives what we want. Our desires naturally arise from our individual biological differences. What we want is usually a mere extension of who we are biologically.

    3. I think that response is the most naive simplistic erroneous statement I have heard in a long time.
      We cannot ‘simply’ choose to behave however we want.
      And, more so, we cannot ‘choose’ our wants.

      Or our potential abilities.

  2. Does Fine have some kind of agenda in mind? Or is it just because a forceful, contentious argument stands to sell more books? Great post. Informative. Fine does have a lot of work cut out for her.

  3. The claim that sexual selection does not exist is absurdly false, and belies a stark lack of knowledge of non-human species. I’ve always found Jerry’s third point above to be one of the most conclusive: sexual selection is not about male vs. female, it’s about which sex happens to make a greater reproductive investment. The fact that we see sexual selection in action in those species where the males make the greater investment is striking evidence of the evolutionary phenomenon, and proves that it is not simply a “social construction” or perception that we have based on gender.

    There is also the loss of sexually dimorphic features and behaviours in species where reproductive investment is essentially equal between the sexes, as in the gulls that I study, the oystercatchers on the coasts, or plenty of other bird species. I would guess that such “reproductive equality” is only possible in species where most of the biological development of the offspring from inception to birth occurs outside the body of one of the parents. If one parent has to carry the offspring for any extended period of time (like the male seahorses, or any female mammals), then that is a massive reproductive investment that the other sex is just not going to be able to make up for. But with many bird species, most of that development occurs in the nest, outside of the parent’s body. That allows the chance for evolution to balance sexual differences, as both parents can balance their reproductive energies.

    1. It’s another outside the body example, but as I recall male rattlebox moths make a substantial investment in offspring through a nuptial gift. The result is choosy males, who need time and energy to produce the gift, as well as choosy females, who not only prefer bigger males who can offer bigger gifts but will have pheromone choruses to increase the chances of attracting the large, fluffy mothman of their dreams. Both genders are brightly colored. There are probably gift giving and fertilization shenanigans I don’t remember mixed in as well.

    2. I recently had some FB “friends” claim that, “race has no biological meaning.”

      Similar nonsense.

      When I insisted that racial differences are controlled by genes, and therefore, of necessity, they have biologicla “meaning”, they then claimed it happened due to genetic drift (only). (I said it was most likely sexual selection.)

      Racial differences seem, to me, likely to be sexually selection in action. It has the hallmarks:

      1) There is noting we pay more attention to in our fellow humans as the face: The window into the intentions of our neighbors.

      2) Most racial differences (and all the ones people really focus on) are on the face/head.

      3) This divergence happened really fast in evolutionary terms.

      This all says sexual selection to me.

      1. The below link will interest you jb: “Why Do Europeans Have So Many Hair and Eye Colors?” by Peter Frost from 2006 [, but with updates]:

        Frost favours sexual selection as the main drive. I haven’t yet had time to look at other views on the matter so if anyone has links to material critiquing Frost I’d love to know about it.

        1. I suppose that in high latitude, light hair colors could be selected not only because of eventual correlation with light skin, but also because of penetration of UV through it into the skin for vitamin D synthesis in people walking outdoors barehead. But I am too lazy to check for research.
          Eventual advantage of light eye color is more difficult. I’ve found research that in older people, it results in more damage to the retina, i.e. disadvantage. However, I guess that in the bleak northern habitats, letting more light to the retina could adjust the circadian clock. Again, too lazy to check.

      2. I recently had some FB “friends” claim that, “race has no biological meaning.”

        I was going to launch off on a discussion of alcohol dehydrogenase and the ability to digest dairy….however, in starting to look stuff up, I came across something more relevant to Jerry’s original post. From Wikipedia on alcohol dehydrogenase:

        Alcohol dehydrogenase activity varies between men and women, between young and old, and among populations from different areas of the world. For example, young women are unable to process alcohol at the same rate as young men because they do not express the alcohol dehydrogenase as highly, although the inverse is true among the middle-aged.[23] The level of activity may not be dependent only on level of expression but also on allelic diversity among the population.

        And here is reference 23: Parlesak A, Billinger MH, Bode C, Bode JC (2002). “Gastric alcohol dehydrogenase activity in man: influence of gender, age, alcohol consumption and smoking in a caucasian population”. Alcohol and Alcoholism. 37 (4): 388–93. doi:10.1093/alcalc/37.4.388. PMID 12107043.


        Now, that’s not a brain or behavioral difference. However, a sex-related difference in the ability of young humans to metabolize alcohol certainly affects their behavior, and, from what I remember of my teenage years, greatly affects sexual selection. 🙂

        1. However, a sex-related difference in the ability of young humans to metabolize alcohol certainly affects their behavior, and, from what I remember of my teenage years, greatly affects sexual selection.

          Is than an argument supporting implantation of a 10-year contraceptive in all children at about age 13~14, regardless of physical gender. Let them get the stupidities of youth out of the way before needing to consider whether or with whom they reproduce?
          After all, it is (TTBOMK) well established now that the adolescent brain continues to develop on fairly predictable lines though the end of teenage years and into the early 20s. The natural corollary of that would be to increase the age of majority (voting, going to die for one’s politicians, taking out loans or other contracts) to somewhere in the early 20s.

        2. There are tons of differences between the sexes in how various compounds are metabolized. Doctors, for example, often have to adjust the dosage of various medications based on the patient’s sex, as men and women metabolize most medications at different rates.

      3. I think that other selection factors were even more important: under high UV, dark skin protects from skin cancer and preserves folate, and under low UV, light skin allows vitamin D synthesis.

            1. I’ve not heard of any convincing argument why either. An important question – since I have heard unconvincing arguments about hundreds of generations living with East Siberian winters – would be how epicanthic folds are distributed in Sami and the various groups of “Inuit”.

      4. Sometimes, some people use the term “race” to indicate different types of human beings, rather than different evolutionary modifications in the same species. It is possible that your FB “friends” were trying
        to indicate that, in general, all humans modified in whatever way by evolution are able to produce offspring together. In that sense, they are all one “race”.

        Yes. We pay close attention to faces. However,
        the younger we are and more interested in sexual interactions, the more attention is paid to sexually attractive characteristics.
        Human females have tendencies to be attracted more to certain male physical characteristics
        than others (height, muscles, body hair or lack thereof). And, we know how males are thought to observe closely and react to female T&A.

  4. The bit about arguing to discard a whole theory because of one flawed experiment reminded me of the creationist argument to do likewise, just because the Kettlewell experiment on peppered moths had a flaw (and not a fatal one).
    Thine agenda is but plain for all to see.

  5. Even when the satanic specter of the patriarchy is at its nadir, men and women still behave in a way where men prefer promiscuity and women don’t.

    Norway is one country that has the highest levels of gender equality and still women regret casual sex more than men do.

    Indeed, men regret *turning down* a one night stand more than women do in Norway.

  6. How does Fine explain the behaviour of bowerbirds? That’s clearly an example of sexually dimorphic behaviour accountable only by differences in male and female brains. It’s not like girl bowerbirds are discouraged from taking bower lessons at bower school.

  7. Vive la différence in the boudoir, I always say, but la mort aux différences in the workplace, and the classroom, and every other place, nook, or cranny wherein societal opportunity lies.

    I think that makes me an “equity feminist,” too.

  8. “But the quoted part below, which I’ve put in bold, suggests that the whole paradigm of sexual selection, and attendant behavioral differences between males and females, should be thrown out because of one flawed experiment…”

    If we had to throw out entire paradigms and theories because of one, or even multiple, flawed studies, views like those espoused by the author of this book would be the first to go.

  9. Biology is a much component of our behavior than ideology. You can push, you can stick your fingers in your ears and deny all you want, but we are primates, we are mammals.

    Just because some people don’t like it doesn’t chang a thing.

  10. Thinking about it, these people are in a way like the creationists…. thinking of humans as a ‘special creation’ completely different from the animals.

    1. +1

      We have discussed here science denial on the Left. This is a clear example.

      Thanks as ever to our host for a science post!

  11. PCC, you wrote, “Bonobos (“pygmy chimps”), which may be more closely related to humans than are “regular chimps”.” You know that bonobos and chimps are equally closely related to us. Probably you meant, “Bonobos (“pygmy chimps”), which may be more SIMILAR to humans than are “regular chimps”.

    1. I was going to ask Jerry to elaborate on this matter as well, though it is not central to the topic of his post.

      Also, the spelling of “distortion” is distorted by a typo in the last sentence of the post.

      Otherwise, great post. I wouldn’t be surprised to hear any day now that biology denialists have started claiming that development of vaginas and penises are the result of the way parents raise their children.

    2. I even wonder if we can say humans are more similar to bonobos than to chimps.
      Eg. Bonobo ‘society’ is rooted in female to female sexual bonding. Chimps are promiscuous during oestrus.
      I think the sexual behaviour of both is quite dissimilar to most human sexual behaviour.

  12. Here’s another thought.

    Assume for the moment that ALL differences in gender behavior are societal. The question becomes: where are the matriarchal societies (funny that any proposed ones seem to be isolated tribes in New Guinea). Why don’t we see societies where women are generally the more aggressive, the more dominant in politics and war? Did they never start? Did they fail to develope?

    If those societies don’t exist there needs to be a complling reason… typically the feminist argument might be along the lines of ‘women aren’t like that’, which could well be true, but then that contradicts the original premise that there is no difference men and women.

    1. Its just plain wrong. A peacock’s tail (vs. a peahen’s) is not a pea-bird ‘societal’ development.

      Which is one reason I’m withholding judgment. If that’s what the Guardian thinks she’s saying, then I expect the fault is in the Guardian, not in Dr. Fine’s hypothesis.

    2. There used to be matriarchal societies in prehistory and early history (some into more recent history). Some clans were ruled by women and their consorts were selected for a limited period of time (a set number of years) and then changed out for a new consort. To some degree this was because women were thought to be related to earth, agriculture, fertility and life. In some matriarchal societies, only women owned property and inheritance to children came from the mother.
      Children usually can be certain of who their mother is/was. In some cultures, males responsible for training male children were brothers of the female, not the husband. It has been said that monogamy came about in patriarchal societies so property could be inherited by the male’s children as, supposedly, children from a monogamous marriage were certain to have been generated by the husband.

      There also were societies in which men and women were relatively equal in clan leadership and warfare. There are numerous examples of this having happened throughout the world. The Celts and Gaels were particularly noted for this. Women fought alongside the men. And remember the British queen, Boedicea (sp?)who successfully fought the Romans. Also,
      the Mongols were equal opportunity horse riders and warriors.

      We’ve been taught that history is written by winners. History also was selectively written in patriarchal societies to minimize matriarchies, female leadership, ownership and warrior capabilities.

      1. The Polynesian society in which I taught through the Peace Corps was then relatively patriarchal, but historically had been in some ways very matriarchal. Kind of a mix. Men waged war, yes, but inheritance was through mothers, not fathers. Women had married but historically (but not then) also had sex with whoever they wanted. A man’s first responsibility was to care for the children of his sisters and of his female cousins on his mother’s side, not to the children of his wife. The highest rank in society was not the king, but the king’s oldest daughter — or her daughter. Traditionally (but no longer) the king’s daughter had such a high rank that nobody could marry her, but she could have children.

  13. I’m an equity feminist, feeling strongly that members of both sexes (or of a spectrum of genders) must be offered equal opportunities and educations from the very outset: from birth. But if there are innate differences between genders or sexes, that won’t necessarily guarantee equality of outcomes. All we can do is ensure that nobody is discriminated against based on their genitalia, their chromosomes, or their own perception of gender.

    Right on sir!

  14. Given the two competing explanations are “crazy scientist” or “idiot reporter misrepresenting scientist”, I’ll withhold judgment on Dr. Fine. At least for now. I know which one I think is more likely…

  15. It’s in The Guardian, so what did you expect. This sort of stuff is in the papers (dare I say it?) DNA.

  16. Though not disagreeing with points laid out in the OP including that Fine might have been misunderstood by The Guardian, for me focusing on life history strategies is a way more fruitful way in interpreting mating by embedding the behaviour within a larger matrix than just sexual selection and genetics. For example, females in harsher environments will be less choosy in selecting mates.

    “Compared with other mammals, humans show more of a mix of life history strategies. While humans show an unusually high degree of parental investment in their offspring compared to other mammals, humans also display more r-selected patterns of development such as high fertility and shorter inter-birth intervals compared to close primate relatives.”

  17. The Guardian has just ejaculated and missed. No insemination was possible from such a weak unhealthy sperm of an idea.
    Sexual selection is ubiquitous and a truly amazing fact of nature, i think the Guardian have backed a sterile offspring with no chance of propagation.
    As a humanist i don’t get this trying to divide the world by gender. While recognizing the differences it brings it should have no bearing on behaviour, once fully understood in humans via nature (how it works, we see the pitfalls) by nurture, it would be clearing the obstacles not creating more.

  18. I saw one youtube discussion where someone pointed out that we are a sexually dimorphic species, eg. that’s why we segregate sports at the Olympics – all the 100 m records are held by men (on average men are more muscular). The point being made was that if you agree we are sexually dimorphic physically, then it isn’t unreasonable to assume that there are some mental and behavioural differences too. This complies with Jerry’s comment that we should all have equal opportunities, but that doesn’t mean we will have similar outcomes.

    1. I think the far left is so scared of potential discrimination (i.e., limiting opportunity or creating biases in hiring, etc… based on sex) that they want to erase any possible basis for it, even if the basis happens to be true.

      It’s a legitimate fear. After all, women have been discriminated against for hundreds if not thousands of years, even without any understanding of genetic differences. And I think bioethicists are concerned about discrimination based on genetic information regardless of whether it’s sex-based or not. Its easy to see historic discriminatory tendencies against women lining up with new gene-based discriminatory tendencies to cause some men to discriminate even more against women because of genetic differences.

      But obviously I think the “solution” of rejecting what science discovers is wrong. In this case, the right way may be the hard way. Meaning the morally and scientifically acceptable solution we might get stuck with is to teach a truth that causes some men (or women!) to become irrationally biased against women (or men!), and then have to do the hard work of fixing the irrational biases they leap to. But hopefully this is a case of two steps forward, one step back is still progress…which is still one step ahead of where we were.

      1. One key aspect of this whole discussion concerns the claim/paradigm that humans are ‘blank slates’.
        The sub-title of Steven Pinker’s book ‘The Blank Slate’ (2002) ‘The Modern Denial of Human Nature’ sums things up nicely, particularly with regard to differences in the sexes and across race.
        Pinker stresses the point you make Eric, about fear of discrimination: “To acknowledge human nature, many think, it so to endorse racism, sexism, war, greed, genocide, nihilism, reactionary politics, and neglect of children and the disadvantaged.”
        Denying what’s true about our nature and our reality causes more problems than it solves,
        Chris G.

  19. Thank you for highlighting the role of differential variance in reproductive success in the evolution of mating systems. The examples of species showing the “Bateman effect” are favorites in my Animal Behavior course. Of course I also call my students’ attention to Dr. Gowaty’s paper and the commentary by Dr. Tang-Martinez.

  20. Is it time for the good PCC(E) to write “Why Human Sexual Dimorphism is True”? Maybe Dawkins can write “The Gonad Delusion”.

  21. Sexuality may have evolved for reproductive purposes, but human beings and their cousins seem to pay a lot more attention to the entertainment value. Creative beings that we are, we’ve come up with an enormous number of ways to enjoy sex without reproduction.

    1. And not only men and cousins (bonobos), but also hypho, whales and others. Because seems that sex is also used to wide social relations, maintain family group to defend children etc. Exactly that is the huge mistake of christian churches: to build a “reproduction only” related moral for sex, avoiding then extramarital relations, LGTB behavior and even anti-conception methods. All based in a biology of the IV BC. Imagine that we even now dont know animal behavior deeply and they took teachings from Aristotelian biology to as God revelation about sex…

  22. I saw one science experiment at regionals yesterday that was about how women can not react to things as quickly as a man could. I have no idea how his project was even approved to be in regional competition based on his sample size of thirty with no demographics at all.
    I was happy my girl made it to city this year. Thank you for what you did for us years ago Jerry. I will never forget how you reached out to me to help her to be more involved in science. Thank you.

  23. Dear Dr. Coyne.
    Only to show how far we are from knowing brain structure and differences among men and women, here a recent study about how pregnancy modifies the structure of women (less grey substance) to help her to pay more atention to baby. And no, no women will change this even willing:

    “Pregnancy leads to long-lasting changes in human brain structure.”

    Brain structure certanly is different between both, and no will will controle your behavior, at least not doing an anti-natural effort with measures probably difficult to maintain along time.
    But, of course, rights, opportunities, roles in society must be equal, althow problably the election of miss world probably will be monopoliced by womans and had woodcutter probably by man…

  24. And if there are genuine differences in any sort of ability, the conclusion is not: “we can’t let sex S do them”, but rather “we have to help sex S do them”. To some extent – the hard part is figuring out how much help is needed.

  25. It is well known among neuroanatomists that, at least among mammals, male and female brains are NOT absolutely identical.

    The anterior hyphothalamus/preoptic area is visibly different in males vs. females; more so in some species than in others. Given a section through the right level, a specialist can sex the brain at a glance. This brain region is likely involved in the regulation of sex hormones, and of sexual behaviors such as lordosis. Whether it is involved in broader aspects of behavior, such as aggressiveness or asking directions, requires further grant money.

    At one time it was thought that human females had, on average, a larger corpus callosum than males, especially in the genu (the front end). This finding led to some silly hand-waving explanations of why women are more intuitive and holistic. I don’t know if the corpus callosum observations have held up.

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