There’s No Such Thing As A “Man’s Brain” Or A “Woman’s Brain”

In almost every episode of Bones, a show that followed a fictional forensic anthropologist on her adventures analysing skeletons for the FBI, Dr. Temperance Brennan glanced at a pelvis or a skull and determined whether the skeleton was male or female. She could tell someone's sex assigned at birth even without the presence of their genitalia because there are differences in bone structure that delineate sex.

When it comes to the brain, however, there's no such tell. A scientist couldn't see a disembodied brain and know whether the person it belonged to was a man or a woman, says Gina Rippon, PhD, a professor of cognitive neuroimaging at Aston University.

So, why do we have so many stereotypes about men's brains versus women's brains? As common myth goes, men's brains are better suited to math and science, they're better at navigating and driving, and they're more logical (while women are ruled by their emotions). None of these stereotypes are inherently true, but they have the power to influence both our scientific understanding of men's and women's brains and the choices we make for our lives.

When these stereotypes interfere with a scientific study, researchers call it neurosexism. It's a term coined by psychologist Cordelia Fine to explain how pre-existing stereotypes about men and women shape neuroscience research. Past studies have claimed that "different wiring" in men's versus women's brains can explain why men have better motor skills and women are more analytical, or that a difference in how the brain "fires" explains women's connection to emotional memories. Dr. Fine and other neuroscientists argue that studies like these are biased, because they assume that men's brains are different from women's brains.

Thinking that because someone was born with a female brain, they're going to be more empathetic and nurturing than someone born with a male brain might lead a neuroscientist to search for that answer when it might make more sense to compare those traits based on educational experience, age, or the way someone was raised. In those cases, a researcher's unconscious bias influences the design of their study and the results, which means they could miss other explanations for the behaviour they're studying.

But, it's not just neuroscientists who fall prey to neurosexism. Perhaps an even greater concern is people who take a neuroscientist's findings and use them to reinforce gendered stereotypes, says Indre Viskontas, PhD, a neuroscientist and science communicator. Remember that infamous Google memo? Google employee James Damore wrote a 10-page anti-diversity rant claiming that biological differences between men and women make women less suited for jobs in technology. He claimed women "have a stronger interest in people rather than things," which makes them better suited for "jobs in social or artistic areas."

"He was taking data from neuroscience studies and using it to justify gender discrimination," Dr. Viskontas says. "It happens too often for my comfort."

It's stereotypes like those that can actually direct how people live their lives, Dr. Rippon says. Our culture encourages girls and boys to go down different paths, and neurosexism can powerfully reinforce those stereotypes. "If you believe something is 'caused' by the brain, you are equally likely to believe that it is fixed, natural, and can’t or shouldn’t be changed," Dr. Rippon says.

Yet, it's still important to look for differences in male versus female brains. "We shouldn’t ignore that there are differences," Dr. Viskontas says. "In Alzheimer's disease, there’s an allele of a particular gene that can determine someone's risk. In women, you can have only one of the bad alleles and that increases your risk, while men need both of the alleles. If we pretended that there are no differences, we wouldn’t understand why females are at greater risk."

So, yes, there are some differences between genetically-male and genetically-female brains. In fact, if you look at a large enough sample of male and female brains, the averages of certain features (like the size of a certain brain region, or even total brain size) will be different, but there will also be a lot of overlap. All of these differences exist on a continuum, Dr. Viskontas says. And, it's not totally accurate to call them "male" or "female," because almost no one has a fully male or fully female brain. "There’s so much variability, it becomes meaningless when you’re talking about empathy or abilities in math," she says. So, unless you're a neuroscientist trying to create a drug that will affect men or women differently, thinking of brains as male or female isn't helpful. All it does is falsely bolster gendered stereotypes.