Perhaps you’ve heard about a precocious study making the rounds about the differences between male and female brains. Perhaps you’ve noticed it reported under headlines like, “Stereotypically ‘male and female brains’ aren’t real, say scientists” or “Brains aren’t actually ‘male’ or ‘female,’ new study suggests” or “Scans prove there’s no such thing as a ‘male’ or ‘female’ brain” or “Male brain vs. female brain? Research says they’re unisex” or “There Is No Difference Between Male and Female Brains, Study Finds” or “There’s no such thing as a ‘male brain’ or ‘female brain,’ and scientists have the scans to prove it” or “Men are from Mars….and so are women! Scans reveal there is NO overall difference between the brains of the sexes” or “A welcome blow to the myth of distinct male and female brains.”

I could go on, but I won’t. Given all these headlines, it might surprise you that the study all these journalists are reporting on actually finds strong evidence of differences between male and female brains. The study is “Sex beyond the genitalia: The human brain mosaic” by Daphna Joel et al. (and that’s a big et al!). It’s sadly behind a paywall, but here’s its abstract in full:

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. Documented sex/gender differences in the brain are often taken as support of a sexually dimorphic view of human brains (“female brain” or “male brain”). However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females) and internally consistent (i.e., a brain has only “male” or only “female” features). Here, analysis of MRIs of more than 1,400 human brains from four datasets reveals extensive overlap between the distributions of females and males for all gray matter, white matter, and connections assessed. Moreover, analyses of internal consistency reveal that brains with features that are consistently at one end of the “maleness-femaleness” continuum are rare. Rather, most brains are comprised of unique “mosaics” of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our findings are robust across sample, age, type of MRI, and method of analysis. These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare. Our study demonstrates that, although there are sex/gender differences in the brain, human brains do not belong to one of two distinct categories: male brain/female brain.

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