May 3, 2021

Debunking the female brain vs. male brain myth (and why it is not as easy as it might seem)


Lise Eliot is out with a new interesting article on the idea that the brain is gendered (i.e. different between men and women). She refers to a new meta-study of research on biological research that, as she sees it, shows that there is no difference between male and female brains beyond size.

I am a big fan of Lise Eliot, who is  a Professor of Neuroscience at the Chicago Medical School at Rosalind Franklin University of Medicine and Science in the US of A. 

Her book Pink Brain, Blue Brain: How Small Differences Grow into Troublesome Gaps and What We Can Do About It taught me a lot about modern neuroscience, and how some scientists takes a too simplistic approach to how our feeling of being gendered is created.

I would argue, though, that the arguments she makes against this part of neuroscience does not prove that there is no biological component to gender identity and that transgender identities therefore must be purely psychological. More about that below.

Mars vs. Venus

In a new article over at Fast Company she writes:

Everyone knows the difference between male and female brains. One is chatty and a little nervous, but never forgets and takes good care of others. The other is calmer, albeit more impulsive, but can tune out gossip to get the job done.

These are stereotypes, of course, but they hold surprising sway over the way actual brain science is designed and interpreted. Since the dawn of MRI [Magnetic resonance imaging, used for brain scans], neuroscientists have worked ceaselessly to find differences between men’s and women’s brains. This research attracts lots of attention because it’s just so easy to try to link any particular brain finding to some gender difference in behavior.

But as a neuroscientist long experienced in the field, I recently completed a painstaking analysis of 30 years of research on human brain sex differences. And what I found, with the help of excellent collaborators, is that virtually none of these claims has proven reliable.

A zombie concept

She argues that the male vs. female brain dichotomy is a zombie concept:

Still, “sexual dimorphism” won’t die. It’s a zombie concept, with the latest revival using artificial intelligence to predict whether a given brain scan comes from a man or woman.

Computers can do this with 80% to 90% accuracy except, once again, this accuracy falls to 60% (or not much better than a coin flip) when you properly control for head size. More troublesome is that these algorithms don’t translate across populations, such as European versus Chinese. Such inconsistency shows there are no universal features that discriminate male and female brains in humans—unlike those deer antlers.

She also put these finding into an LGBTQA context:

The absence of binary brain sex features also resonates with the increasing numbers of people who identify as nonbinary, queer, nonconforming, or transgender. Whatever influence biological sex exerts directly on human brain circuitry is clearly not sufficient to explain the multidimensional behaviors we lump under the complex phenomenon of gender.

Rather than “dimorphic,” the human brain is a sexually monomorphic organ—much more like the heart, kidneys, and lungs. As you may have noticed, these can be transplanted between women and men with great success.

The end to the computer metaphor

There is one thing we have to keep in mind when reading articles like this one, and that is that Eliot is arguing against simplistic understandings of the brain, where scientists think they can pinpoint a physical place in the brain where male and females differ, which is then given the honor of being the seat of gender identity and/or various presumed gender traits.

On the other hand more psychologically oriented researchers have a tendency of downplaying the physical brain part of the equation, discussing the mental part only. This leads to a focus on life experiences, trauma and culture.

I suspect many are trapped in the computer metaphor, where the mind is an app running in "wetware". The biologists want to find a switch on a XX/XY chip that can explain female and male identities, while the psychologists are looking for the relevant code in the program.

The fact is that the brain is not a computer, at least not in the silicon chip meaning of the word. Our mental development –  including learning and personality –  is the result of an interaction between the software and the wetware. When we learn we often grow new brain cells and cell connections.

As Eliot & Co put it in the original science paper (reference below):

Given abundant evidence that experience alters neuronal structure and function, as well as growing knowledge about epigenetic influences on CNS [central nervous system] development, it is impossible to discern the degree to which group-level differences between human males and females are attributable to inborn sex factors versus social-environmental gender learning, acting through lifelong neuroplasticity [i.e. the brains ability to change and grow new cells].

There is more to who we are than our brain

To the extent it makes sense to think of the brain as a computer, we are talking about a kind of "distributed computing". Memories are not saved onto separate chips. Your memory of a particular event is distributed throughout the brain. I wouldn't be surprised if our feeling of being gendered is dispersed in a similar way, in which looking at one particular section of the brain would be of much more limited help.

Moreover, the mind is not residing in the brain only. Our emotions – which are an essential part of our sense of self – are anchored in our whole body. When we are happy, our whole body is happy: Our pulse quickens, our cheeks flush, we have butterflies on our stomach.  Gender dysphoria and gender euphoria are not purely mental experiences. They are definitely also bodily experiences, with feedback loops between the brain and the rest of the body.

What the experience of transgender people can tell us is also this: Gender identity cannot be reduced to gender stereotypes. The way some brain researchers are identifying male and female identities in transgender people is by using lists of how well they adhere to female or male stereotypes. That does not work.

We know now that gender identity is not in a one to one relationship with gender expressions, mannerisms, interests or abilities. A lesbian transmasculine woman will see herself herself as a woman, a masculine trans man will not. Indeed, a “femme” trans man (yeah, they exist!) will also "feel like a man”.

You cannot capture this enormous complexity in brain scans and through brain autopsies. Our sense of self is most likely not residing in one particular part of the brain. It might be a systemic property, distributed throughout the whole mind/body system. If that is the case, it would not be less real. 

Heck, it would not be unreal even if it was based in software only. I don't think that is the case, but it would not be less real, for sure.

This leads me to believe that Eliot's biggest contribution to the mind/body debate is not that she had debunked the idea that gender identity has a biological side to it. My own life experience makes it hard to explain my transgender identity without such a component. But she has managed to shoot down the more naive approaches of "gender-in-the-brain research".

See also:

On the statistical difference between men and women
Literature on sex and gender differences
Interesting video sums up research on male and female brains

Crossdream Life discussion.

Illustration: agsandrew

Abstract

Abstract of LiseEliot, AdnanAhmed, Hiba Khan and Julie Patel: "Dump the “dimorphism”: Comprehensive synthesis of human brain studies reveals few male-female differences beyond size" (link to open access science paper)

With the explosion of neuroimaging, differences between male and female brains have been exhaustively analyzed. Here we synthesize three decades of human MRI and postmortem data, emphasizing meta-analyses and other large studies, which collectively reveal few reliable sex/gender differences and a history of unreplicated claims. Males’ brains are larger than females’ from birth, stabilizing around 11 % in adults. This size difference accounts for other reproducible findings: higher white/gray matter ratio, intra- versus interhemispheric connectivity, and regional cortical and subcortical volumes in males. But when structural and lateralization differences are present independent of size, sex/gender explains only about 1% of total variance. Connectome differences and multivariate sex/gender prediction are largely based on brain size, and perform poorly across diverse populations. Task-based fMRI has especially failed to find reproducible activation differences between men and women in verbal, spatial or emotion processing due to high rates of false discovery. Overall, male/female brain differences appear trivial and population-specific. The human brain is not “sexually dimorphic.”

12 comments:

  1. So! Talk 'bout back-peddling! Is it back to Bailey & Triea we go? "The transsexual advocacy website, transsexual.org, puts this theory succinctly: "A transsexual is a person in which the sex-related structures of the brain that define gender identity are exactly opposite the physical sex organs of the body."

    The standard, feminine essence narrative, and the associated brain-sex theory, are incorrect . . "

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  2. Following Eliot's research, the transsexual.org definition is too simplistic, but the underpinning belief – that transgender identities have a biological component – is probably true.

    SO FAR, the scientists have not been able to identify a region of the brain that without doubt is the seat of gender identity. This research field is still in its infancy, so it is far to early to conclude.

    Yet, as I have argued repeatedly on this blog, the "brain gender chip" model has probably always represented a too simplistic approach to an understanding the way gender identity is anchored in our body and mind. I am reminded of the search for a "gay gene", which also turned out to be too reductionistic.

    Eliot & Co's paper is an attack on the "gender is determined by one thing in the brain" paradigm, not an attack on the idea that genes and hormones may play a part in gender identity formation in general.

    It seems to me that you are trying to present this as a debate between "feminine essence" trans activists on the one side and those who think gender is psychological (a social construct???) on the other.

    That would be a misleading presentation of transgender culture and the transgender debate.

    Most of the active trans activists I know of today follow the dominant belief in scientific circles these days, namely that gender identity is formed by an interplay between biological, psychological, social and cultural factors. In other words: They believe this is a complex phenomena, which it obviously is.

    They do not believe in the "feminine essence" approach, and the reason for this is that they – as trans and non-binary – people have experienced first hand how complex these issues are.

    However, some trans activists are drawn to the female brain in a male body paradigm, probably because it so effectively fits their own life experience and because is easier to explain to especially older cis sceptics.

    And then there are those who are more inclined to focus on the social construction of gender and the psychological side of gender, which has caused the "gender ideology" hysteria in right wing extremists circles.

    (Right wing religious fanatics and TERFs seem to be the dominant "feminine essence" believers these days, not trans activists.)

    In other word: There are a lot of different beliefs among trans people, which is to be expected. This reflects the fact that our understanding of sex and gender is continuously developing.

    Bailey and Blanchard also believe that their transsexual types have a basis in brain biology. They are strongly influenced by the part of scientific research that want to reduce the complexity of gender formation to identifiable parts of the brain.

    They love to speak about "the feminine essence" narrative, however, because it is a way for them to create a false enemy image of trans activists, a trans narrative that can be easily dismissed and that should, as they see it, support their position.

    The irony is that their desire to reduced female identities to "femininity" and male identities to "masculinity" are as old fashioned and misleading as the "feminine essence" theory they are arguing against.

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  3. Actually, the more I think about this, the clearer it becomes that this is a generational divide, more than a factual one.

    The "feminine essence" approach (that femininity and masculinity are somehow completely hardwired) represents a 19th and 20th century paradigm, shared by nearly everyone at the time. This fit with the idea that gender roles and gender stereotypes were natural and unavoidable and that a social order based on these differences therefore was the best one.

    The trans activists of the time where as much children of their culture as everyone else, so it made sense to find meaning in the same narrative.

    However, in the late 20th and early 21st century, both research, philosophy and politics have moved beyond this narrative, mainly because the increasing gender equality has shown us that women, if they are allowed the freedom to thrive, do not live up to the stereotypes, and the roles and abilities assigned to them.

    The increasing tolerance of queer, trans and non-binary people has also made gender variance more visible. We now know that gender identity does not automatically lead to specific gender expressions or gender roles.

    (A side note: This was always a middle and upper class phenomenon. Working class people and farmers knew a different reality, where women had a more pro-active role in their daily lives)

    Blanchard & Bailey are actually stuck in "the feminine essence" narrative, as they see femininity and expression of sexual orientation. Only androphilic trans women are feminine, as they see it, as they are wired for femininity. They are conflating gender identity with sexual orientation and gender expression, which is a 19th century logic (inversion theory), not a 21st century one.

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  4. To conclude: Transgender identities are not about femininity or masculinity. They are about being male, female or non-binary. Gender expression (as in femininity and masculinity) is not the same as experienced gender identity, which means that research based on the idea that gender identity is followed by specific interests, mannerism, abilities or emotional responses are bound to fail.

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  5. has no one read felix conrad!? we've been down this road. they won't find it in scans because the answer is in the software layer. that layer/ circuitry is laid in utero and is influenced by in utero testosterone levels. felix empirical proof lay in observing the animal kingdom - not us humans. male and female cormorants have complex patterns and behaviors universally specific to one sex over the other. but really just about any sexually dimorphic animal exhibits such bifurcation of actions ie stereotypical sex behavior. how does a male beetle "know" to mount a female beetle and not vice versa? how do make birds know to build nests to impress and woo a prospective female bird. felix chose the commerants because of their complex mating process but specifically because if a cormorants baby dies she wanders the beach looking for an abandoned baby to adopt. the males never do that and cormorants are well studied birds scientifically. so if gender X, and A occur perform J, but if Gender Y and A occurs do not perform J. it's ironclad.

    their is a gender core emitting an electrical/software signal i am/feel male or i am/feel female. you won't see it on a fmri scan because it's software and we still don't understand how any of that is run in the brain. if such a gender core on the software layer didn't exist then sex specific tasks in the animal kingdom breakdown entirely. like a black hole things can be known without being seen.

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  6. I have tried to read one of Felix Conrad's books. I was unimpressed by his expression of his layperson's opinions and rationalizations instead of supporting his arguments with hard facts.

    re: Comparing human gender to animals. There are plenty of examples (rare, certainly) of animals exhibiting gender/sex characteristics that are not in alignment with their physical sex.

    re: "gender core emitting an electrical/software signal." Picturing our brains as some sort of highly complex computer/processor is handy especially for people like me. I am an electrical engineer and computer scientist. It's none, though, by brain scientists that this analogy quickly breaks down.

    I agree that black holes demonstrate things that can be known without being seen.

    Jack: thanks for this excellent post. I used to think that gender and sex were binary, one or the other. But we know this isn't true. Another black hole that can be known but in this case is seen/demonstrated by those whose sexuality, gender, and other feelings exist on a continuum.

    I'm currently reading "Histories of the Transgender Child" by Julian Gill-Peterson. Julian successfully shows us how transgender awareness and treatments have evolved so much in the last 100 years.

    Imagine, for example, experiments where doctors transplanted testicles from one man to another (who was trans and/or gay) to see if that might cure the patient. Needless to say, no, it didn't.

    I think the gray areas between male/female gender, sexualities, and other such things underscore how difficult it is to locate and determine how such rare existences are brought about.

    It's fair, I think, to consider sexuality. Look at the LGB acronym. Sexuality was originally thought to be a binary hetero/homo characteristic, leading to the first letters of the LGB acronym being L and G (G and L for some). It was only later that the existence of bisexuality was asserted sufficiently to add the B.

    It would certainly be nice to be able to point at something that determines things like gender and sexuality. I spent about a year reviewing research to determine for myself that gender awareness is a real/valid phenomenon. And then about a year considering whether I am transgender. Another year determining where I am on the transgender continuum. Three years with more than fifty before that knowing that something wasn't quite right with me. I'd argue that it's the forces of socialization that caused me to take such a long time to find my authenticity.

    Compare that with today's trans children who "just know" that they're one or the other. They don't get bogged down in the gray area. Although I wish I could have been one of them, while reading "Histories of Transgender Children" I appreciate how fortunate I am to be living now instead of 100 years ago.

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  7. Felix actually calls himself an agnostic when it comes to what causes transgender identities, which is a fair position to take. I am far too curious and impatient to be happy with that.

    As for exclusive, gendered behavioural patterns in animals: Yes, you will find strong behavioral patterns of that kind among many animals, but we are also facing a strong selection bias here. Scientist have a tendency of seeing what they want to see, so that the enormous variation you find in the animal kingdom is lost.

    This apply to same-sex sex (which we now know is quite common in a lot of species), various morphs of individuals from the same sex, and overlap in gendered behavior between males and females. There are also species with more than two sexes, and species where individuals may change sex.

    I know of a female dog who would love to hump your leg if you let her (!). Females mount males among a lot of mammals, probably because males and females share the same programming and because it is part of the general infant play repertoire.

    The huge differences we find among animals should also make us cautious as to generalize on the basis of one species. I always refer to chimpanzees and bonobos in such discussions. They are our closest relatives in the animal kingdom, so you should think we were pretty similar when it comes to basic sex behavior. Not so. Chimp tribes are run by males, bonobo tribes by females. Chimps often use physical violence to solve conflicts, while bonobos use sex.

    One of the clearest signs of gender differences is found in song birds, where the brains of the males are very different from the brains of females. The ability to sing requires a the large song section of the brain found among males. The ability to sing is not software based only in those species, for sure, but I am sure you will find a large overlap in sexual behavior elsewhere.

    So yeah, it is complicated.

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    1. i wasn't disputing that their are shared traits among the sexes in many species. what i'm pointing out is there is an evolutionary biological component to having an intrinsic knowledge of what you are (male or female) otherwise things get complicated. nature gets it right 99.5% of the time for a reason. there must be a gender core empirically. while I'm mostly agnostic like felix, the argument stands on its own merit. we have enough biological data from the animal kingdom to confirm that male animals know they're male and female animals know they're female. not in reflective sense but in the instinctual sense. the statement "i feel like a women" when you're biological a man is likely being driven out of an instinct. what im suggesting is that felix is right that there is a unit of the brain's software that is emitting its gender as an electrical impulse into other areas of the brain. this likely is triggering the brain to kick on software generally reserved for one gender over the other, but not always exclusive. no doubt hormones play into this in a big way as well, as they promote or suppress certain behaviors. so there is an interplay in the brain where certain softwares are triggered by gender instinct and throttled heavily by the ratio of T vs E in the brain. just like T vs E causes all sorts of physical changes in tissues throughout the body, it has its most pronounced effect on brain tissue. but to summarize, i don't believe that male and female humans are interchangeable and that it is only a "social construct". to me gender is innate. gender core theory as espoused by felix conrad, models how such a system might behave, and will handle virtually all notions of gender including non binary, and bi-gender. i view it as a black hole since we still don't yet understand the software layer of the brain computing stack (and probably never will). i can't see it, but i know it to be empirically too.

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    2. If I had not been transgender myself, I would probably found it easy to embrace the "gender *identity* is a social construct" concept. As it is now, I find it hard to explain my gender dysphoria without a biological component, so yes, I – like you – believe that we have an inborn drive towards identifying as one gender.

      That being said, the existence of the continuum and the reality of non-binary people tell me that this is a fuzzy phenomenon, and not one set in stone.

      But having an inborn gender identity does not mean that Eliot is wrong in critiquing the idea that this identity is anchored in one part of the brain only, or that differences in brain structures reflect some kind of gender destiny.

      First of all: All of these studies talk about averages. There are a lot of cis women with "male brains" and vice versa. Baron Cohen, one of the strongest supporters of the male vs. female brain dichotomy found that less than half of the women he studied had "female brains". So if a cis woman has a "male like brain", but nevertheless feels deeply that she is a woman, the concept of "female brains" cannot explain experienced gender identity.

      (Note also that these studies rarely correct for the fact that our brains are plastic and change as we learn. The average differences some see in brain structures may have been caused by social learning.)

      Furthermore, given that homo sapiens is one of those species where the differences between men and women, even as regards size and looks, are small (compared to, for instance, the gorilla), it makes sense to conclude that yes, the differences between men and women as far as inborn abilities, behaviours, and interests go, are small or non-existent.

      From an evolutionary perspective we may imagine that the evolutionary trajectories of homo sapiens and the bonobos, as opposed to the gorilla, have moved towards gender equality.

      But we might also imagine that our common ancestor, whatever ape that was, presented differences more like the one found in gorillas. We may have inherited our strong feeling of gender identity from that species, but not is inborn gender roles.

      It seems to me that one of the big problems here is that the term "gender", although being more nuanced than "sex", is still too broad to capture the complexity of what we see.

      Gender roles and gender stereotypes may indeed be socially constructed. That does not necessarily mean that our gender identity is.

      So, it seems to me our positions are pretty close as far as gender identity goes. The main difference is that I do not believe that strong gender dichotomies found in some species mean that we will find such divides in all species.

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    3. i believe much of the gender roles are societal reinforcements of what are the generalized stereotypical traits exhibited by makes our females a innate behaviors. its irrefutable that women are the ones who give birth and nurse. therfore nurturing behaviors predispose them to take on certain societal behaviors as an expectation. that's not to say a woman can't be butch and join the army and fight on the front lines, but that's the exception. same goes for men. its irrefutable that men are superior in body size and are primed for being hunters. we are also known to be suystemizers over being socializers. that's not to say a man can't be a socializer and a nurturer. rather there is a societal expectation of how a man is to behave. tribes depended on these traits of men and women for survival for millions of years. 100 years of a social experiment doesn't erase millions of years of evolutionary instinct. that all being said, i like you can't square away gender as a social construct movement. its all bullshit in the face of persistent consistent insistant gender dysphoria. there is a biological component. gender core theory can handle the notion of gender as a spectrum. for example bi gender people might have two cores. non binary people have a particular electrical threshold for the core to emit male otherwise female. some days that signal comes out make some days it comes out female. there's many ways to look at it from an engineering standpoint. from my perch with GD, i will always view it as a black hole. i know it exists but i can't see it. i sure as hell can feel it being on E/spiro for 4 years. for me that's the hardest evidence of the biological component. the sheer effect of E on my GD brain.

      by the way, we should have video zoom for people who might want to interact in a more human way and aren't afraid to do so.

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  8. "I think the gray areas between male/female gender, sexualities, and other such things underscore how difficult it is to locate and determine how such rare existences are brought about."

    I agree. Nature is messy. Evolution is messy. It is not a journey towards perfection, but a continuous experimentation where traits mix and morph across sexes and genders.

    And yes, the concepts and models we use to understand all of this is also changing, which this post i a clear illustration of. We are trying to hit a moving target while moving.

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  9. This morning I'm listening to "Hidden Brain," a delightful and informative NPR podcast that explores fascinating issues and questions, some existential.

    The episode is titled: "One Head, Two Brains", and I think it adds to this discussion about female vs. male brains in that it underscores the challenges in determining and identifying how we're aware of our authentic gender, sexuality, etc. I suggest listening to it:
    https://podcasts.apple.com/us/podcast/one-head-two-brains/id1028908750?i=1000519944167

    On another note: have you heard of or studied "fuzzy logic"? Fuzzy logic provides a way for computer control systems to be programmed to accommodate natural variations in real-world conditions. An example is how the Shinkansen trains in Japan are able to consistently and smoothly leave and arrive at stations, and to repeatedly stop at the same location.

    From that Hidden Brain podcast, fuzzy logic provides a metaphor (however inaccurate) for me to consider how human brains understand and comprehend their characteristics.

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