I quite liked this article by Emily Willingham on the male/female brain: she points out something that is obviously true, that individual brains are a complicated mosaic of traits, and that you simply can’t reduce all of the variety to a simple binary.

Humans want tidy patterns, to have things link up neatly and make sense. Our brains strain to make these connections whether they are genuine or not. What’s more difficult is looking past illusory patterns and thinking more deeply about what we’re really seeing. As tempting as it is to collapse a human’s entire being, including the brain, into a single term – male, female – an honest look at how we really behave makes such reductionism look shallow, at best. The most observant among us manage this in-depth examination. These acute observers are not the scientists, who can be remarkably myopic and rigid within their corners of research, but the storytellers. You can’t tell a good story about people if you’re not a keen observer of human behaviour, and it’s in our storytelling traditions that we find example after example of an inherent if unconscious understanding of the mosaic brain.

It was good, but the article didn’t go in the direction I expected it to go — I guess I’m more reductionist than I thought. When I started reading about brains being a mosaic of different properties, I first leapt to the idea of epigenetic variability in the regulation of of “male” and “female” genes. (Isn’t that where you go, too?)

Here’s the deal. You know that there is this beautifully intricate process called X-chromosome inactivation, or dosage compensation, in which individuals with more than one X chromosome epigenetically shut down most of the genes on all the additional X chromosomes. It’s a really cool process — think about it, the molecules involved have to count chromosomes, and I don’t understand how they do that — but it’s also leaky. About 15% of the genes on the X chromosome escape inactivation, by unclear mechanisms. And further, some of those genes are variable in how frequently they escape inactivation.

For a given gene, escape from X inactivation is not necessarily consistent between individuals or between tissues and/or cells within an individual. A comprehensive survey in human confirms the original observation that some genes only escape X inactivation in subsets of cells. Interestingly, many genes (∼10% of X-linked genes) behave in this manner, resulting in potentially variable expression levels between female tissues and individuals. Whether, in turn, this generates female phenotypic variation is an interesting possibility that remains to be explored. Partial or variable escape from X inactivation is in agreement with progressive incorporation of genes into the X up-regulation/X inactivation systems once the Y paralog degenerated.

Female brains are literally mosaic in their patterns of gene expression — some cells will have one X chromosome active, others will have the other X chromosome switched on, and further, there is a random pattern of genes on the X chromosome that are variably silenced, and different patches of the brain will use different alleles.

And guys, don’t think you can escape this phenomenon: epigenetic regulation is simply a little bit sloppy, and so your brains have random inactivation of some undetermined set of regulated alleles. It’s not as simple as having a boy set of genes and a girl set of genes that are uniformly and universally working in a predictable way in every brain.

But that’s only adding to Willingham’s points. Male and female are clearly insufficient labels to pigeonhole the complexity of the human brain.

By the way, if you want to see the inverse of this argument, take a look at this inane tweet.

Starting to suspect that non-binary, feminism, and transphobia discussions in my family became disconnected from MSM’s version a few years ago. From my sister-in-law, exiled Prof. Heather Heying: https://t.co/mGtZVOSn9t — Eric Weinstein (@EricRWeinstein) December 26, 2017

Among sexually-reproducing multicellular organisms, nearly every species has two distinct gamete types (“anisogamy”). Female: big, cytoplasmically rich, sessile.

Male: small and mobile.

That is true. If only we could reduce human beings to single reproductive cells, the gender binary would be valid. Unfortunately for their perspective, it isn’t. Our brains are not single-celled gametes, and I would hope don’t even contain any gametes, which would be creepy and icky.