Brain sex differences: A masterclass in over-interpretation

The eternal quest to prove that men are from Mars and women are from Venus—neurologically speaking, of course. For over a century, scientists (and, let’s be honest, people with opinions) have been poking at brains, measuring corpus callosums, and squinting at amygdalae, all in the noble pursuit of confirming whatever gender stereotypes they already believed.

Take the corpus callosum, that thick bundle of nerves connecting the brain’s hemispheres. Back in 1906, R. B. Bean—a man who clearly never met a bias he didn’t like—declared that its size correlated with intelligence and, naturally, that women (and certain races, because why stop at one bad take?) had inferior versions. His own lab director promptly debunked him, but the myth persisted. By the 1990s, pop science had rebranded the idea: Women have bigger corpus callosums! That’s why they’re so ~intuitive~! Cue a thousand think-pieces about “female intuition.”

Fast-forward to the 21st century, and what do we find? 49 studies saying there’s no meaningful sex difference once you account for brain size. MRI scans? No dice. But hey, why let facts get in the way of a good narrative?

Then there’s the amygdala, the brain’s emotional alarm system. Studies suggest men and women process emotions differently—women may remember emotional events more vividly, while men’s amygdalae light up more for action-oriented responses. Cue the usual tropes: Women are emotional, men are logical! Except—plot twist—it might actually be the reverse. Some research indicates men have more brain real estate devoted to raw emotional reactions (hello, anger) and less to cool-headed logic. Suddenly, the stereotype of the stoic, rational man starts looking like a bad cover story for “I have feelings, and they’re loud.”

And let’s not forget reactive aggression, that charming mammalian trait where threats trigger everything from freezing to full-blown rage. Men, it seems, are hardwired for dominance battles—meaning that “logical” sex might just be the one more likely to flip a table when challenged.

So what’s the takeaway? Brains vary, culture shapes behaviour, and most grand theories about “male vs. female” wiring crumble under scrutiny. But don’t expect the myth-making to stop anytime soon. After all, nothing sells like a good stereotype—even when the science says otherwise.