31

I need to bring up something that's been bugging me.

We talk all the time about how sex isn't just genitals, it's every piece of our being. If you look into it, even our non-sexual organs are genetically dimorphic between men and women.

The inconsistency to me though is when we say there's no such thing as a female brain. All of a sudden, all of the femaleness that is intrinsic to every other part of who we are becomes invisible. I understand that we don't want to lend credibility to the idea that TIMs can have a "female brain," but even the research that exhibits sexual dimorphism in brains doesn't show that--in fact, while "trans brains" are mildly shifted towards their "preferred gender," they are still well-within normal ranges for their sex, and still outside the average range for their "identity." It's not a gotcha, and I don't think we need to be afraid of it.

The graphic on this study (under Results) is especially good to look at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8955456/

If anything, I think admitting that female brains do exist (with some variance within the sex, of course) and that TIMs do not have them is perfectly good evidence for being gender critical. (And for those who criticize lesbians for not sleeping with TIMs because we're genital fetishists, well, no, the brain plays a part too. Suck on that, "hearts, not parts.")

Some might call it sexist to say there are differences between male and female brains, but I think the it's more that the sexist conclusions that people come to as a result of the difference existing are problematic--ie: because "female brains" exist, women must be more predisposed to doing housework, or some other nonsense.

Also, when we talk about puberty blockers being harmful because of the importance of sex hormones in adolescent brain development, I think it's a bit willfully ignorant to not assume that estrogen and testosterone might have different effects on the brain.

Prove me wrong, please, or give me another way to think about it! I just think it's something worth tackling head on, rather than brushing aside.

I need to bring up something that's been bugging me. We talk all the time about how sex isn't just genitals, it's every piece of our being. If you look into it, even our non-sexual organs are genetically dimorphic between men and women. The inconsistency to me though is when we say there's no such thing as a female brain. All of a sudden, all of the femaleness that is intrinsic to every other part of who we are becomes invisible. I understand that we don't want to lend credibility to the idea that TIMs can have a "female brain," but even the research that exhibits sexual dimorphism in brains *doesn't show that*--in fact, while "trans brains" are mildly shifted towards their "preferred gender," they are still well-within normal ranges for their sex, and still outside the average range for their "identity." It's not a gotcha, and I don't think we need to be afraid of it. The graphic on this study (under Results) is especially good to look at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8955456/ If anything, I think admitting that female brains do exist (with some variance within the sex, of course) and that TIMs do not have them is perfectly good evidence *for* being gender critical. (And for those who criticize lesbians for not sleeping with TIMs because we're genital fetishists, well, no, the brain plays a part too. Suck on that, "hearts, not parts.") Some might call it sexist to say there are differences between male and female brains, but I think the it's more that the sexist conclusions that people come to as a result of the difference existing are problematic--ie: because "female brains" exist, women must be more predisposed to doing housework, or some other nonsense. Also, when we talk about puberty blockers being harmful because of the importance of sex hormones in adolescent brain development, I think it's a bit willfully ignorant to not assume that estrogen and testosterone might have different effects on the brain. Prove me wrong, please, or give me another way to think about it! I just think it's something worth tackling head on, rather than brushing aside.

43 comments

[–] SecondSkin 29 points Edited

There are female brains: the brains in female bodies are female brains. They have female chromosomes in all their cells and female hormones in them.

Vice versa for male brains.

At birth female and male brains are not functionally different.

Brain development is use dependent. Tell girls they are good at listening and caring then they practice these skills and their brains develop the neurological connections in these areas.

Tell boys they are good at being adventurous and math and they practice these skills and develop neurological connections in these areas.

The variation in older male and female brains are the result of this socialisation that conditions our brains.

That doesn’t change the fact that at birth female and male brains have no functional differences.

*edit to say: hormones influence at puberty is complex. We know that going through the normal puberty for the sex of the body is advantageous for brain development. Female versus male hormones are more complex than oestrogen versus testosterone. There’s no way of having a control to show that female hormones have a very different impact than male hormones on brain development. The huge wealth of research of adult brains show that there’s more difference within male brains and more differences within female brain development than there is between them, and a large overlap between them. If o versus t had some drastic different impact then we would see male brains be very different from female ones. And that’s not what’s seen in the research. Our bodies being prevented from going though the normal human development that they are designed to go through limits brain development. That might be fully reversible, it might not. Using pbs followed by wrong sex synthetic hormones might cause same brain development. It might not. There’s no way of establishing either without experimenting on children. And collecting data on children who are being groomed by predators and then have adults pander to their threats of suicide and demands for medicalisation, won’t give valid results either, because brain development is use dependent and so their brains will develop the neural pathways to threaten and manipulate and believe lies, not to think critically and develop negotiation skills and inter personal relationships skills.

You said going through puberty is advantageous to brain development, something I never thought about but it seems obvious now that you said it, so I have a question. Does that mean kids put on puberty blockers will be less intelligent than kids who just go through normal puberty?

The more I read about this, the more I think these kids are so effed

Yes, there are studies done on girls who went on lupron for precocious puberty and their IQ dropped an average of 8 points if I remember correctly. Hormones aren't just cosmetic, people! We need them for many things.

Oh man. These poor kids. I was diagnosed with depression and anxiety as a kid and it makes me cringe to think of what would happen to me if I was born 10 years ago instead of 40 years ago

I completely agree--I wouldn't think there would be any difference at birth. I'm more referring to when people say that it's ridiculous for TIMs to claim to have a female brain because there is no such thing as a female brain... I've seen it again and again on here. It just strikes me as an odd claim from the GC folk.

It's not an odd claim because we do literally mean that no neurologist on the planet could look at a brain scan and know whether the brain belonged to a woman or a man.

The only way to reliably identify a brain as female is to check the biological sex of the person whose body it's in.

[–] ProxyMusic 12 points Edited

We all have female brains. But your female brain is different to my female brain, and both our female brains our different to Second Skin's female brain. Because brains are plastic, meaning throughout our lives they are shaped by our life experience, nutrition, hormones, metabolism, how much we use our brains, what we use them for - and by experiences like trauma, abuse, shock, happiness, bereavement, clinical depression, pregnancy, childbirth and maternity, aging, menopause, diseases of aging etc.

The human brain begins developing physically during gestation in utero and continues developing through childhood, adolescence and the first half of our 20s. The human brain doesn't reach physical maturity until we are 25/26.

TIMs think all girls and women have brains that make us pretty much the same - and that our brains are pink, small, delicate and not up to the rigors of logical, rational thought.

When TIMs say they have a female brain, they mean they what they believe is to be a female psyche - which is a psyche that likes the color pink, glitter and "girly" things. If they are tweens, teens or adults, it means that certain aspects of stereotypical sex bomb "femininity" gives them boners. TIMs think that a female brain/psyche = a male AGP brain/psyche.

BTW, I believe there probably are quite a few physical differences in male and female brain cells and some brain functioning - and that the more sophisticated research is done on cells and genetics, the clearer this will become. The sex hormone receptors in the brains of males and females, for example, appear to be different in nature, location, number and function. But as of yet, we don't know what the physical brain differences are, or how large and significant they are. Nor do we really know what, if any, real and lasting consequences they have in terms of brain functioning, processes, psychology and behavior.

So far, most of the physical brain differences found in the sexes have been small and subtle ones. Male and female brains are much more alike than they are different, and there is considerable overlap between the two sexes. Doctors and scientists can't tell the difference between a male brain from a female brain just by looking at its gross morphology.

I suspect that if and when more cell research finds physical sex differences in the brains of humans, those differences are gonna turn out to be very different than to the kinds of differences that have long been assumed to exist. I also think there will continue to be enormous variations in the brains from one woman to the next, and from one man to the next. I also think the human brain is so incredibly complex that it'll never be figured out fully.

[–] SecondSkin 6 points Edited

The female brain in an adult means either biologically female; so female chromosomes and hormones. Which a TiM can’t have (synthetic hormones are not hormones).

Or it means socially conditioned brain development, where there’s a difference. Which TiMs can’t have because they aren’t socialised as a woman. 🤷🏼‍♀️

So they can’t have a female brain.

[–] Dee 3 points

Men can't have "female brains" for the simple reason that they're not female. Being female, and having a brain, doesn't cause us to automatically want to conform to gender norms imposed on us by society. That's the gist of it, I guess.

Would it make a little more sense to think of how we might say 'there's no such thing as a female heart' (ie hearts pump blood, all hearts do this, to a greater or lesser degree depending on the health and fitness of the person it is in, the function and operation of the heart isn't appreciably different depending on the sex of the person, we can pretty much extrapolate how hearts work in humans from observing both male and female hearts, etc) and also, at the same time, any heart inside a female person is a female heart?

there's no such thing as a female heart' (ie hearts pump blood, all hearts do this, to a greater or lesser degree depending on the health and fitness of the person it is in, the function and operation of the heart isn't appreciably different depending on the sex of the person,

Actually, male and female human hearts are very different to one another in terms of structure and function. Male and female hearts do the same job overall, but the way they go about it is different.

While it is widely recognized that the female heart is smaller than the male heart, it has long been ignored that it also has a different microstructural architecture. This has severe implications on a multitude of cardiac parameters.

Here, we systematically review and compare geometric, functional, and structural parameters of female and male hearts, both in the healthy population and in athletes. Our study finds that, compared to the male heart, the female heart has a larger ejection fraction and beats at a faster rate but generates a smaller cardiac output. It has a lower blood pressure but produces universally larger contractile strains. Critically, allometric scaling, e.g., by lean body mass, reduces but does not completely eliminate the sex differences between female and male hearts.

Our results suggest that the sex differences in cardiac form and function are too complex to be ignored: the female heart is not just a small version of the male heart.

When using similar diagnostic criteria for female and male hearts, cardiac disease in women is frequently overlooked by routine exams, and it is diagnosed later and with more severe symptoms than in men. Clearly, there is an urgent need to better understand the female heart and design sex-specific diagnostic criteria that will allow us to diagnose cardiac disease in women equally as early, robustly, and reliably as in men.

https://www.frontiersin.org/articles/10.3389/fphys.2022.831179/full

Pretty much every organ and system of the human body that has been looked at to see if there are sex differences has turned out to have extensive and significant differences that aren't visible to the naked eye or just by looking at the gross morphology. Heart, liver, pancreas, kidneys, digestive tract, skeletal muscles, lungs, airway cells, respiratory system, immune function and response... and so on - they all are different in male and female humans

I think I hear what you're saying, but hearts actually do exhibit sexual dimorphism as well... True that functionally they are the same, but the differences might matter more when considering, for example, heart diseases I would think? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8189176/

[–] ProxyMusic 2 points Edited

At birth female and male brains are not functionally different.

But my understanding is that we don't really know for certain if the brains of male and female babies are indeed not functionally different at birth. How exactly would you test brain function in newborns to see if there are any sex differences?

Dr Lise Eliot is the expert in this field. She had the largest studies of sexed brain functionality. Iirc these use neural imaging and so on. It’s a long time since I’ve studied her original work (or feels like it anyways) but it was generally accepted as sound when we evaluated it in class and her work is widely accepted, published in peer review journals, evidence based.

[–] ProxyMusic 1 points Edited

She had the largest studies of sexed brain functionality. Iirc these use neural imaging and so on.

But did she do really do her research on newborns? I am taking issue with the claim that we know for certain that "at birth female and male brains are not functionally different."

I'm willing to believe this, but I still don't see how that would be possible to come up with practical, accurate ways to test newborns for differences in brain function so that we know for sure. Newborns cry, sleep, eat, poop, wee, cuddle/snuggle and suckle. They can startle and feel pain, but they can't even see or make out colors yet. They can't hold their heads up yet, or turn their heads in the direct of a sound. How exactly did/would anyone measure neonates' brain functionality?

I see such research as having ethical roadblocks too. I also can't imagine mothers/parents volunteering their healthy newborns to get brain imaging.

I just looked up Eliot's work, and see she published a paper in 2021 which is a review of all the research in this area. She says:

studies of infants and children are rarer and generally much smaller than studies of adults.

Also, all the studies she references on infants and children - and in her work and the work of others she looks at - is solely focused on gross morphology such as total brain size/volume or structure, structure, segmentation, and the relative size of different parts of the brain. AFAICT, the research doesn't look at brain function at. Nor does it look at brain structures, tissues or cells at the microscopic level.

https://www.sciencedirect.com/science/article/pii/S0149763421000804

Brain imaging strikes me as a pretty blunt instrument. It can detect brain structures and some kinds of imaging done in certain ways can detect brain activity. But brain imaging can't detect microscopic tissue and cell differences - and my hunch is that the differences in male and female brains will turn out be microscopic ones at cellular and genetic level.

I see Eliot has a couple book out about brain differences in children, which I have just ordered. Thanks for mentioning her. I've been meaning to read these books for years.

When people are making the argument that "female brains" don't exist, it is because it is a response to the idea of a "female brain" as demonstrated by this graphic. The idea that gender, sex role stereotypes and roles, are innate and result from different brain structures between men and women is what this idea of a "female brain" comes from. Female brains, brains developed as a part of a female body, exist, but "female brains", a sexist idea, does not.

Absolutely this. Female brains definitely exist but the assumption that they can't do everything male brains can do, just as well (or better), is the problem.

OH! That makes sense... I can see how I misunderstood then, I thought they were trying to say that sexual dimorphism just doesn't exist when it comes to the brain. Thank you for clearing that up~

When they say 'female brain" they mean a stereotypically "feminine" mind/psyche/personality - which they assume, mistakenly, is innate and physical in origin.

I've seen it abused by TIMs who say "the brain scans of some males show patterns more similar to those of females, not other males, therefore this proves they are women in mens' bodies."

Men are, on average, taller than women. Yet many individual women are taller than many individual men. So this is the rhetorical equivalent of saying "this man if 5'4, and the average height of a woman is 5'6, while for a man is 5'9. Therefore, this man is actually a woman because SHE is 5'4."

Yes, sexual dimorphism is real - and one facet of this is that, since most health benchmarks and therapies are normed for men, we are under/misdiagnosed and not as well treated. The problem is when it's turned into a scientistic factoid by TIMs to 'prove' their point.

I increasingly think the lesson is just not to argue with people incapable of good faith, rather than try and either explain or oversimplify reality, which is complicated but still doesn't prove you can be "born in the wrong body."

Theoretically even if there were blue and pink brains, and the pink brain was born in a male body, it doesn’t mean born in wrong body. If this hypothetical situation was real it could just mean that human species has developed to the extent female brains can be in male bodies and vice versa. Like x men shit. Even if it were real it doesn’t mean they need to mutilate their bodies or use spaces for the opposite sexed body. We don’t pee from our brains, a female brain in a male body doesn’t need the female toilets.

If it were hypothetically even possible.

Also, when we talk about puberty blockers being harmful because of the importance of sex hormones in adolescent brain development, I think it's a bit willfully ignorant to not assume that estrogen and testosterone might have different effects on the brain.

Yes, I am sure the different hormones have an effect. But's important to keep in mind that estrogen is only one of several sex hormones we make and that affect us females.

Moreover, research on humans and other animals considered similar show that males not only make estrogen directly in their testes and other parts of the male reproductive tract, just as females make testosterone in our ovaries - but that males also convert some of the testosterone and other androgens they make into estrogens - estradiol and estrone - in some of their body parts/tissues through the process of aromatization due to the enzyme aromatase. Aromatization is a process that only occurs one way, turning androgens into estrogens. Aromatization does not convert estrogen into androgens.

Interestingly, one of the main sites where males appear to convert quite a lof of their T into E through aromatization is the male brain.

Aromatase is the enzyme responsible for converting testosterone to estradiol. In mammals, aromatase is expressed in the testes, ovaries, brain, and other tissues. While estrogen is traditionally associated with reproduction and sexual behavior in females, our current understanding broadens this perspective to include such biological functions as metabolism and cognition. It is now well-recognized that aromatase plays a vital lifetime role in brain development and neurobehavioral function in both sexes.

https://www.frontiersin.org/articles/10.3389/fnmol.2018.00374/full

Estrogen masculinizes neural pathways and sex-specific behaviors:

Male behaviors require both testosterone and estrogen. Circulating testosterone activates the androgen receptor (AR) and is also converted into estrogen in the brain via aromatase. This conversion is the primary source of estrogen to the male brain. It is unclear whether testosterone and estrogen signaling interact to masculinize neural circuits. Using a genetic approach, we show extensive sexual dimorphism in the number and projections of aromatase expressing neurons. The masculinization of these cells is independent of AR but can be induced by either testosterone or estrogen, indicating a role for aromatase in sexual differentiation of these neurons. We provide evidence suggesting that aromatase is also important in activating male aggression and urine marking as these behaviors can be elicited by testosterone in males mutant for AR. Taken together with additional findings, our results suggest that aromatization of testosterone into estrogen is important for the development and activation of neural circuits that control male territorial behaviors.

Estrogen is also essential for male behaviors. The requirement for estrogen to masculinize behavior seems counter-intuitive as this ovarian hormone is essentially undetectable in the male circulation. All estrogenic steroids are synthesized in vivo from testosterone or related androgens in a reaction catalyzed by aromatase. Aromatase expressing cells in the brain convert circulating testosterone into estrogen, and it is this local estrogen that is thought to control dimorphic behaviors in males (Figure 1A) (MacLusky and Naftolin, 1981; Naftolin and Ryan, 1975). Consistent with a requirement for estrogen in male behaviors, aromatase activity is essential for male behaviors.

Estrogen mediates many of its effects by signaling through the estrogen receptors ERα and ERβ, which exhibit overlapping expression patterns, and regulate masculinization of the brain and behavior in a complex, redundant manner (Bodo et al., 2006; Ogawa et al., 1999; Ogawa et al., 2000; Ogawa et al., 2004; Perez et al., 2003; Rissman et al., 1997).

The role of a third estrogen receptor, GPR30, in male behaviors is presently unknown (Revankar et al., 2005).

The dual requirement for testosterone and estrogen signaling in male behaviors suggests that these two pathways may interact genetically to control these dimorphic displays. One potential site of interaction is the control of aromatase expression.

We find extensive, previously uncharacterized sexual dimorphisms in both the number and projections of neurons expressing aromatase. The masculinization of these neural pathways is independent of AR but can be induced in neonatal females by testosterone or estrogen, indicating that aromatase plays an important role in the sexual differentiation of these neurons. Moreover, testosterone activates male typical fighting and urine marking independent of AR, demonstrating that the differentiation and function of the neural circuits underlying these behaviors are governed by testosterone, at least in part, after its conversion into estrogen. Finally, our results show that adult gonadal hormones of either sex can support male territorial marking and fighting provided estrogen has neonatally masculinized the underlying neural circuitry.

Circulating testosterone and locally derived estrogen in the brain are critical for the expression of male behaviors. It has been difficult to determine the individual contributions of these two hormones to masculinization of the brain and behavior. Our gene targeting strategy has allowed us to identify at cellular resolution the small population of aromatase expressing neurons that can synthesize estrogen from testosterone. Testosterone appears to serve, at least in part, as a pro-hormone for estrogen for the male typical differentiation of aromatase positive neurons and for masculinization of territorial behaviors.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851224/#:~:text=Male%20behaviors%20require%20both%20testosterone,estrogen%20to%20the%20male%20brain.

IIRC trans brains aren’t “shifted” at all because that study didn’t control for homosexuality.

that was a point i forgot to add! i wonder how studies will look with more AGPs than HSTSs...

Trans brains aren't skewed towards their preferred gender, the paper got it wrong, the correlation was with sexual orientation, not "gender identity". So far there have been no trans brain markers observed. Basically on average, but not always, certain structures are enlarged in gay men and women (who are mainly straight), and that first trans study was done with all HSTS TIMs, aka gay men, so obviously some of their brains looked like that. Straight TIMs don't have anything like it. Obviously hormones impact the brain, I think people saying there is no female brain were railing against the idea that men and women are diametrically opposed with no overlap, which makes sexism easier to defend (for example, "all women are incapable of math", or "all men are incapable of communicating their feelings in a calm manner"). Also the brain isn't just formed through genetics and hormones, life experience wires the brain. The trauma from growing up female in this dangerous world certainly impacted how our brains function. In any case, even if they do find a trains brain marker some day, it still wouldn't justify the erosion of women's rights.

Re: "hearts not parts", the straight TIMs fail on that front too. I've had the misfortune of interacting with a ton of them since I'm a lesbian in a big city with "queer" friends who bring them around (also have read my friend's dating app messages from many of them). Not a single one of them acts like a woman! Not even slightly! They are selfish and feel entitled to women's time, attention, and bodies in a way that is fully male. They corner women and go into graphic detail about disturbing sex topics, either unaware of her discomfort or enjoying it. They threaten stalking and rape when someone politely turns them down. Not only that, but the libfem women don't treat TIMs like women either, they defer to them like they defer to men. If a lesbian acted how they act no one would think twice about kicking her out of a friend group.

I have been saying for years that while man's and women intellectual habilities are not the same, it doesn't mean that woman are less intelligent. There are different strength ON AVERAGE like for height and such and those strength are all valid: we just need to judge differently. However, lots of people found it was sexist of me to say brains were different 🤯

And the trans's lady brain are just ridiculous... That's something else, and THAT is sexist.

I think you're right. As I commented elsewhere (and others have brought up more eloquently), the issue is when the female brain is shorthand for women not being as intelligent or capable as men.

But there likely are differences, if only in the chromosomal makeup of brain cells. Apparently pregnancy also changes the brain quite seriously (they compare it to the changes brought about during adolescence) and permanently, though I don't know the full extent or indeed if the full ramifications are fully understood yet by researchers (I listen to a lot of podcasts, so have no sources to hand, and tend to be multitasking while listening so foggy on the details - an ironic case of mum brain!). So maybe in addition to male and female brains, we should be thinking in terms of child, adolescent and adult brains, and nulliparous and mother brains (and possibly post-menopausal brains?). I hasten to add that given how plastic and adaptable the brain is, I would be surprised to see major differences in function between adult brains (neurodiverse aside). Just because I had a baby doesn't mean I have forgotten how to read, eg. In fact now I can read and respond while making sure my toddler doesn't set the house on fire.

[–] BlackCirce 🔮🐖🐖🐖 2 points

It was recently established that human brains are monomorphic. There are no significant sex differences in brain structures that hold up across diverse populations.

GCs have become obsessed with demonstrating sexual dimorphism in humans (which is moderate at best), to the point where it almost comes across as a belief in female as a separate species. Humans are not extremely, severely, dramatically dimorphic, but we aren’t monomorphic either, and that’s that.

There are over 6500+ genetic differences between men and women. Sex codes over a 3rd of our genes differently.

So our bodies are drastically dimorphic. Our brains aren’t, outside of chromosomes and other biological differences that don’t relate to functionality.

What you're suggesting makes sense to me, OP. I am not an expert in the area, but I know evolutionary biologists Heather Heying and Bret Weinstein have discussed sex difference in the brain--I think they've discussed how males start out relatively more focused on objects and females are more interested in faces.

I mean, there is such a thing as a female brain: it's a brain in which all the neurons have XX chromosomes, and which has been bathing in female levels of estrogen from the time it was in utero.

What there is NOT is a brain structure or organization that is found in all non-trans women, and in trans-identified men.

Yes, of course there is a female brain. It is a brain that belongs to a female. Every cell is XX. Strogen induces more neuroplasticity and vasodilation. That's what we know.

There isn't however a statistical significance in morphological and structural analysis between female and male brains. There is no gender center in our brains.

Thus there is no material reality to the claim "born in the wrong body". It is purely a belief on "female essence", same old misogyny you can find criticized extensely by Simone B, with the addition of the idea that this essence can exist on poor men's bodies, as well, so we better let them pee into our bathrooms. It's in their essence.

Load more (1 comment)