New Brain Study Indicates Great Gender Diversity

I would like to draw your attention to a recent article in the Guardian, which covers the research of a Israeli research team who have found that there is a huge overlap between male and female brains.

A complex mix of the "feminine" and the "masculine"

The volumes (green = large, yellow = small) of brain regions in 42 adults, showing
the overlap between the forms that brains of females and brains of males can take.
Image by Zohar Berman and Daphna Joel

The main point for me is not whether these researcher are "right" or not. Neuroscience is in constant flux, and there will probably never be a final theory that explains everything about this extremely complex organ.

What is interesting for me is how similar research data can lead to very different conclusions all depending on the point of view of the researchers.

The Guardian writes:

'Scientists analysed brain scans of more than 1400 men and women and found that while some features are more common in one sex than the other, each person’s brain has a unique “mosaic” of these features, as well as others seen commonly in both.

“What we show is that there are multiple ways to be male and female, there is not one way, and most of these ways are completely overlapping,” said Daphna Joel, a psychology professor who led the study at Tel-Aviv University.'

Scientists inclined towards gender stereotypes will focus on the macro level

This is nothing new. Even the neuroscientists who believes strongly in the dichotomy between "male" and "female" brains know that there is a lot of variation between individual brains, both male and female, but they interpret patterns they see on an aggregated level as proof of there being unique "male" and "female" brains. 

These aggregated findings are then used to confirm the gender stereotypes of the -- let's say -- sexually driven aggressive man and the passive and nurturing woman.

Overlap is the norm, stereotypical brains the exception

What is interesting with this study is that the researchers focused on the areas where there is least overlap between men and women on an aggregated level.

The Guardian again:

'Across the four different sources of brain scans they studied, the scientists found the percentage of “internally consistent brains”, in which all regions were at the male end or all at the female end, varied from zero to 8%, while those with both male-end and female-end features ranged from 23% to 53%.'

So even if you look at those regions who are supposed to prove that men and women are different, you find that most men have "female" traits and most women have "male" traits. At this point, of course, you have to ask yourself whether it makes any sense at all to call these traits "male" and "female."

The Slider Model

This is actually where I can say "I told you so!" 

I presented a similar "mix" model of gender traits, abilities, sexualities and interests back in 2010, in the blog post "The cause of crossdreaming - an alternative model". I did so, not because I was way ahead of contemporary neuroscientists, but because this is a way of thinking that goes all the way back to the 19th century. 

This "new" way of looking at the brain biology of sex and gender is very similar to the one of -- for example -- Magnus Hirschfeld, the great pioneer of transgender research, as presented in his book on transgender people in 1910.

This research does not solve the nature/nurture riddle

Does all of this mean that there cannot be a biological component to transgender conditions, and that the social constructivists were right all along? This is all about nurture and not about nature?

No, this research cannot be used to prove either of these standpoints. Brains are flexible; they change with the way we use them. Whatever it is these scans measure, it can be inborn, the result of a brain adapting to social training and external stimuli or (most likely) a combination of  both.

There may still be parts of the brain that triggers people to orient themselves in the world as men, women or something else entirely. We simply do not know.

What the research does indicate, however, is that there are no fixed gender traits unique to each gender, and that having interests, abilities or desires normally allotted to "the opposite sex" is the norm, not the exception.

Daphna Joel explains why the idea of male and female brains are much more complex than many believe in this popular TEDx talk. Note that she actually dismisses the terminology of "male" versus "female"parts of the brain, even if she uses the terms to make her point. "It is meaningless to talk of the sex of the brain," she says.

Daphna Joel, Zohar Bermanb, Ido Tavorc, Nadav Wexlerd, Olga Gabera, Yaniv Steind, Nisan Shefia, Jared Poole, Sebastian Urchse, Daniel S. Marguliese, Franziskus Lieme, Jürgen Hänggif, Lutz Jänckef, and Yaniv Assaf: "Sex beyond the genitalia: The human brain mosaic." Proceedings of the National Academy of Sciences 2015.

Magnus Hirschfeld: Transvestites: The Erotic Drive To Cross Dress 1910/1991, Translated by M. A. Lombardi-Nash

See also:
On the statistical difference between men and women

Joan Roughgarden on social evolution

What brain science says about M2F transsexuals