Human Brains Have No Gender

A study published last Monday in the Proceedings of the National Academy of Sciences (PNAS) reveals that brains aren’t distinctly “male” or “female.” Scientists from Tel-Aviv University hypothesized that if the brain is truly gendered, MRI scans would reveal consistent structural differences between sexes.  Instead, they discovered that brain features vary across a spectrum like a mosaic. The study concludes that brains are not classifiable as male or female, but instead vary by the features of each individual.

The researchers analyzed MRI scans of 1,400 people and found that finding a set of “male-like” and “female-like” features is more common than finding specifically “male” or “female” features. To determine which features were more “male-like” and “female-like,” they categorized the features based on what sex they appeared in more consistently. The researchers examined differences in volume of gray matter and white matter regions and did find several structural differences between male and female brains. But depending on which area of the brain they looked, between 23 and 53 percent of brains contained characteristics from both “male” and “female” categories while only 8 percent of brains were entirely at either end of the spectrum. In gray and white brain matter, brains were so variable that labeling features as “male” and “female” is practically meaningless.

Although these findings may seem obvious, it is important to recognize that this issue is still questionable to some. Gender expectations have long existed, and oftentimes difference in brain structure is used to justify gender inequality and segregation. The researchers note, “Whereas a categorical difference in the genitals has always been acknowledged, the question of how far these categories extend into human biology is still not resolved.” When faced with cultural expectations, it may be easier to believe that there are stark contrasts between brains in female-sexed bodies and brains in male-sexed bodies, but this new study forces us to challenge notions of gender by highlighting the complexity of pinning down its biological definition.

Daphna Joel, a psychology professor at Tel-Aviv University who led the study, acknowledges these implications in an article in The Guardian co-written with Cordelia Fine:

Our study demonstrates that although there are sex/gender differences in brain structure, brains do not fall into two classes, one typical of males and the other typical of females, nor are they aligned along a “male brain-female brain” continuum…We can see social issues more clearly when we stop viewing them through the distorting lens of sex categories, and start fully appreciating human variability and diversity.

The fact that all of our brains are consistent in their variability only reinforces the idea that we have the potential to transcend gender barriers, racial and ethnic barriers, religious barriers, and national divide, in order to form a society that reflects our status as many parts of one whole. As Joel says, “Is it time to let go of binary thinking and celebrate the fact that there are many different ways to be male, to be female, to be human?”

  • LostLoonie

    I can’t say that I am surprised as I have long believed that a lot of our male/ female traits were more a matter of learning and socialization but I really appreciate having scientific evidence to support my beliefs. Thank you.

    • rg57

      If anything, these results show more than ever the strong biological basis for our behavior.

  • Manuel Berger

    What we do see is that the thickness of the connection between the 2 brain halves is on average thicker in the female brain, allowing for more connections. Testosterone seems to be the determining factor for that. It is even so that girls where the mother has an above average testosterone during pregnancy show the same narrowing of the corpus callosum and show more boy-like behaviour as a child. More connections allows for more intervention of emotion in the thinking process leading to a more caring personality needed for raising a child. Less connections allow for faster decisions in danger or hunting situations. In MBTI terms if causes on average for woman to be more Feeling and for men to be more Thinking. Of course there is a lot of spread on this so if there would be less nurturing influences, 60% of males and 30% of females would have a male-like brain, 60% of females and 30% of males would have a female-like brain. This can go from slightly to extremely outspoken. In the rest of the brain the physical structure seems the same for man and women

    • Anthony Glaser

      After reading your comment I looked at the abstract of the original study. They looked at grey matter, white matter, and connections. This article by Ms. Thompson says that gender could not be identified by a brain’s combination of grey matter and white matter features. I now have to wonder why she left out the results concerning brain connections and gender.

  • Derek

    I am confused. If their are sex/gender differences in brain structure, how are their not differences in male/female brains? Can someone explain?

    • Chris

      What I think it’s saying is that if you had 4 traits (A, B, C, and D), if A & B were male-ish and C & D were female-ish, males exhibiting C wouldn’t necessarily also exhibit D and vice versa for D and for females exhibiting A or B. The point is that there isn’t a spectrum; each trait might skew one way or the other, but they don’t exist on a spectrum of male to female.

    • rg57


    • Anthony Glaser

      When you look at one particular feature of the brain’s grey-matter or white-matter, it is sometimes more prevalent in males or females, but when you look at a combination of such features in any given brain they are typically all over the map (some male, some female) and you can’t tell whether you are looking at a male’s brain or a female’s brain.

      Note that this is only true for grey-matter and white-matter features, in a single study. See the other comments on brain connections.

  • It’s as if gender is more like a big ball of wibby-wobbly gendery-wendery stuff than a strict dichotomy.

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  • rg57

    The headline is wrong. The obvious conclusion to be drawn is that perhaps 8% of humans brains certainly do have a traditional gender (otherwise there would be no “male-like” and “female-like”, i.e. male and female, brain features to be found), and the rest of us are to some degree or another in the middle.

  • John D

    I am so done with the weird prog-liberal transformation of AHA. This study found that there are very different trends in brain function between men and women and yet the headline tries to claim the brains have NO gender difference. The headline is just plain wrong and obvious click-bait bologna.

  • advancedatheist

    Another example where humanists engage in gaslighting to promote an arbitrary progressive ideology. We live in Opposite World now: Syrians are Germans, Islam is a religion of peace, and men are women.

  • TMS71

    When did humanism become a front for cultural marxism?