Brain scans prove there is no difference between male and female brains

Neural map of a typical man's brain. Photograph: National Academy of Sciences/PA

Neural map of a typical man’s brain. Photograph: National Academy of Sciences/PA

There is nothing a science journalist likes more than research which seems to prove an unexamined cultural prejudice. Today’s big story  on the ‘proof’ of the difference between observable connexions in male and female brains is a case in point. After studying over 1,000 brains from people covering a range of ages, scientists have discovered, as the Guardian reports it, ‘what many had surely concluded long ago: that stark differences exist in the wiring of male and female brains’.

Two things should immediately give pause here. First, there are no wires in human brains. The centuries-old popular reliance on the metaphor of the machine, now more usually imagined specifically as a computer, is no doubt heuristically useful, but it produces an intellectually sloppy short circuit (to keep the metaphor going): if the brain is wired, then it’s fixed, it has an essential form aligned to its function  – it is, in short, natural. (The wiring metaphor is not the Guardian columnist’s invention, incidentally: one of the study’s authors is quoted talking about the ‘hardwiring’ of women’s brains. And it’s an extremely common metaphor in scientific discourse.)

Second, when science ‘proves’ something that ‘many had surely concluded long ago’, it is fair to ask whether this is because the scientists have proceeded on the basis of an untested assumption, which their badly constructed experiment and fallacious inferences then ‘prove’. That is a central argument of Cordelia Fine’s Delusions of Gender, and it is easy to see how the present study could be open to similar criticisms. In this case, as so often, the prejudice follows this syllogistic pattern:

  1. Men and women are essentially different
  2. Men and women are natural
  3. Therefore the differences between men and women must be natural

The conclusion of the present bit of research – that male and female brains are ‘wired’ differently – circularly establishes (1) above. But it is a contention of a differently motivated body of knowledge, which questions prejudices rather than trying to find proof for them (namely gender studies), that while there are unquestionably differences in the behaviour and patterns of thought, etc., in adult men and women, those differences are not natural but constructed by highly complex and largely invisible social pressures. The gender-studies syllogism is something more like this:

  1. Men and women appear to be different
  2. Men and women are a product of their experience as well as of their genetic inheritance; they are the products of a culture acting on nature
  3. Therefore the apparent difference between men and women must be constructed

The most significant line in the Guardian report is one which is not picked up, in the report, by the authors of the study:

Male and female brains showed few differences in connectivity up to the age of 13, but became more differentiated in 14- to 17-year-olds.

Neural map of a typical woman's brain. Photograph: National Academy of Sciences/PA

Neural map of a typical woman’s brain. Photograph: National Academy of Sciences/PA

That really is very interesting, to anyone willing to pause for thought. Let us allow that the observed differences in adult brains are significant, and that brain science is capable of communicating details of value (though there is considerable scientific scepticism on this point). Those differences are not manifested until the age of 14–17. It follows that the assumption that girls and boys below that age are ‘essentially’ different, ‘because their brains are wired differently’ is unsupported by the evidence. It is wrong to suggest that boys and girls have a ‘natural’ difference, which can be traced to brain design, because the study does not support such a claim. On the contrary, if we think that gendered difference is explicable only by brain design, we ought to conclude from this study that there should be no difference, at least no difference occasioned by brain design, between boys and girls. We should expect boys and girls up to the age of 14–17 to behave the same way as each other, want to wear the same clothes and do the same activities, etc. – i.e. not to exhibit stereotypical gendered behaviours. Those stereotyped behaviours (‘logical thinking’ for boys, ‘intuitive thinking’ for girls, in the words of the study’s authors) simply should not manifest themselves until puberty. So let’s end talk about boys and girls being differently gendered at all.

But it is also necessary to ask why the difference observable in adult brains starts to manifest in the 14–17 age bracket. One answer is that the hormonal changes of puberty ‘must influence it’. That ‘must’ is quite a considerable assumption, and without extensive evidence, it cannot be sustained. The gender-studies assumption would be that it is only by the age of 14–17 that the cultural pressures to conform to certain gendered behaviours can start to have their effect – maybe in profitable interaction with the hormonal changes of puberty. Perhaps the state of puberty enables the brain to refashion itself in order to fix these observable adult differences. But there is no reason to suppose that it is the biological experience of puberty alone which causes those changes to take place. But of course for a scientist desperate to show that gendered differences are ‘natural’, a purely natural explanation of this change will be sought. And yet their own study is fighting against them.

If – as I am sure is the case – the scientists believe that boys and girls exhibit different gender behaviours, they can find no explanation for this in the brain science in their study. That is to say that the brain science of this study does not explain the difference they observe, and that anyone can observe, in the gendered behaviours of boys and girls. Let us generalize that statement just a little bit: the brain science of this study does not explain the observable difference between gendered behaviours at all. Boys and girls do exhibit differences in gendered behaviour, after a while (certainly by the age of 13 it is pronounced), but the brain science does not have an explanation for that. And yet the scientists assume that their brain science does explain the difference between the gendered behaviours of adult men and women. Reports on this study therefore hold, unwittingly, to two irreconcilable claims, which can only be explained by a refusal to acknowledge the prejudice that is absolutely driving the inferences from the study: first, that the brain science doesn’t prove gendered difference, and second that the brain science does prove gendered difference.

The majority of reports on scientific studies of human behaviour and culture suggest that science has ‘proven’ an orthodox cultural assumption. This provides good copy because it’s nice for the layperson, who shares these orthodox cultural assumptions, to feel that someone clever has spent a few million quid investigating the matter with expensive machines and a research team of other very clever people. It allows people to say ‘Well I could have told you that!’ in the pub, and feel very contented. Good public ‘impact’, no doubt. But when the assumptions underlying the study in general, the specifics of its design, and the science’s blindness to its own internal contradictions are so patently dubious, there is no reason at all to be persuaded by its claims. Yet again, I’m left feeling that, brushing aside the collegial pieties about humanities scholars respecting scientific research (when there is no expectation that this respect should be returned), the old ‘two cultures’ argument has some legs left. A major part of humanities research and teaching continues to depend on a thoughtful critique of the cultural assumptions, hugely invidious, which science of this sort unquestioningly bolsters.

10 thoughts on “Brain scans prove there is no difference between male and female brains

  1. Thanks for a great post. It’s really good that someone’s taken the time to articulate what many people have been thinking.

    Here are my two pennies which may help to offer a cultural explanation of the ‘puberty phenomenon’.

    Between the ages of 14 and 17 years old many young people in the UK get their first jobs, or at least gain some kind of financial/spending freedom through pocket money or babysitting fees. This could help explain why it is in this stage of life that cultural pressures to conform really set in. With even a limited amount of financial freedom young people can begin their lifelong quest of ‘buying’ an identity. That is, they can form and then continually mould ‘who they really are’ through choices of what to wear/listen to/and where to go. For this reason a huge amount of advertising and cheap products are aimed at this age bracket, enticing young people into an identity market from which it is very difficult to escape. In a culture where ‘is it a boy or a girl?’ is asked before even the baby’s health is investigated, it is unsurprising that asserting gender is a primary concern to one who suddenly has the ability to begin self-construct.

    1. Thanks for this. I entirely agree that with the onset of a requirement, however qualified (since there’s presumably still parental support at this stage), to enter into the capitalist sphere of circulation by getting a job, pressure to adopt a specifically gendered identity suddenly enters a new stage. The place of men and women in the world of work is of course highly regulated (so that women earn less than men for the same work) and highly gendered. The interaction of these economic pressures with the awakening of sexual awareness, with its attendant demands to adopt a rigidly gendered identity, is also, surely very strong. As I said in my original post, I’m entirely relaxed about the idea that biological changes at this time might make the brain particularly open to the possibility of changing certain kinds of connexions. However, as someone pointed out to me on Twitter earlier, it’s also been suggested by neuroscientists that brain plasticity can be observed in, for instance, the enlarging of the hippocampus of taxi drivers in response to their extensive navigation experience (see this old news article on that story: http://news.bbc.co.uk/1/hi/sci/tech/677048.stm). So there might not even be anything special about puberty, in terms of brain plasticity – though there certainly is something very special about puberty in terms of new forms of cultural pressure.

  2. I am not sure that this is not so much a good example of what gender studies has to say about science, so much as science reporting. However I think it is good to point out that this study does not definitively explain all ages gender differences in terms of brain differences, nor do the authors claim it does.

    The results for under 14s are not necessarily contradictory though, as you claim. It could be that some differences do exist in under 14s but the signals were too subtle to detect by this method, or that the sample of under 14s in the study was too small to demonstrate a statistically valid difference. Which begs another question – as a statistical study I am also equally interested in the variation, as well as the average, so how many men had “female” connected brains and visa versa, (please pardon the reductionism)?

    1. The question about how many people have the ‘wrong’ sex’s brain, or have some kind of half-way house, is of course one of the most important ones, and one that gets lost in the ideological insistence on the gender binary. There are only two positions, according to that ideology: men and women. The kind of complex variation of that picture that you’re implying has to be radically simplified into just those two polar opposites. An ‘average’ expression of each option will be given, but the variation within each group and the overlap between them will be ignored or declared statistically insignificant. This is the only way that the binary can be perpetuated. If we focused too much on the many cases which show the model as too reductive, it would undermine the premise. So complexity is ignored and oversimplification becomes ‘hard fact’. If scientists were so unreflective about complexities in chemistry and physics as they are often about human behaviour, we’d be in trouble.

  3. “Abstract:

    Sex differences in human behavior show adaptive complementarity: Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills. Studies also show sex differences in human brains but do not explain this complementarity. In this work, we modeled the structural connectome using diffusion tensor imaging in a sample of 949 youths (aged 8–22 y, 428 males and 521 females) and discovered unique sex differences in brain connectivity during the course of development. Connection-wise statistical analysis, as well as analysis of regional and global network measures, presented a comprehensive description of network characteristics. In all supratentorial regions, males had greater within-hemispheric connectivity, as well as enhanced modularity and transitivity, whereas between-hemispheric connectivity and cross-module participation predominated in females. However, this effect was reversed in the cerebellar connections. Analysis of these changes developmentally demonstrated differences in trajectory between males and females mainly in adolescence and in adulthood. Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.”

    While I don’t think that the original article’s title/tone is especially good, that article seems to have based its information on the actual study, the abstract of which i have posted above.

    1. Yes, I’m sure they wrote it on the basis of the abstract or a press release. That would be normal for journalists, who want to waste no time assembling their information. That’s one reason why journalism is often so distorting. But look at the first sentence of that abstract. The rigid separation of male and female behaviours, essentially fixed to the sex of individuals, is the stated assumption of the study. *All* men and women exhibit these characters, do they? There’s no variation within the sexes? No continuum that these two polar points are crudely simplifying? No, the two positions are presumed to be a full and sufficient explanation of variations in human character, and then an extremely local material explanation is sought for this in the brains, hormones, genes, etc. of individuals. But there are wider material contexts to consider: the materiality of the other humans with whom we all interact, the materiality of our natural environment, and so on. The first of those, the interaction with other humans, is enormously complex, and in order to keep the matter simple and so as not to question the initial assumption, it is disregarded. The study can proceed on the basis of examining an individual’s brain alone. A shabby way to proceed.

      1. “Sex differences in human behavior show adaptive complementarity: Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills. Studies also show sex differences in human brains but do not explain this complementarity.” If you added “on average” then I don’t think it is particularly controversial. Including proper statistical language around “averages” and “standard deviations” is always bound to appear clumsy and so is often left out. They seem to be making the point that there are (a) physical differences in male and female brains, and (b) social differences in male and female behaviour. On average. But, until now there has been no study directly connecting the two.

        It would be odd if there wasn’t a reason for the difference in male and female brain size. It could be as simple as body size – most disparity in average brain size between species is explicable due to the size of the body organs of the animal which the brain indirectly controls.

        It used to be thought that that the average difference in brain size explained why women weren’t as “intelligent” as men. As a mathematician in a maths department run by a female professor of diminutive stature I can’t believe that. I’d also include my own maths hero, the diminutive Emmy Noether, probably the (after Einstein) greatest mathematical physicist of the 20th century.

        On the other hand I wouldn’t be surprised to discover that embryonic development lead to (on average) different levels of brain function. It doesn’t seem odd to me that female brains might develop to better at nurturing while male brains are better at tasks that reward good hunting skills. But we also know that the Y chromosome that men possess has a very small number of genes so if it is true then they must control the activity on genes both men and women to get these disparate outcomes. Personally I agree that later (post embryonic) influences make more of a difference. Same, same genes, different behaviour.

        I agree though that the language used by the researchers was inadvisable. I imagine they are seeking further funding for their studies and believe this a good way to achieve that aim.

  4. It’s funny that the author of this article essentially parodies science, then attacks the parody while uncritically stating the claimed gender studies syllogism without mention of the fact that number three is essentially purely an assumption and in fact contradicts the last part of number two.

    Furthermore even the quote in the article states there were few differences between boys and girls, not no differences. It would be perfectly biologically reasonable that we diverge dramatically in the brain just as we do in the rest of our bodies.

    Additionally scientists do not ignore the influence of nurture. Would the author of this article contend that my two children do not have some intrinsic fundamental differences in personality? Nor do these researchers contend that everyone of either sex is identical.

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