We’ve all heard the stereotypes: men are better at maths and logic, women are better at emotions and communication. But what if we told you that these differences have nothing to do with our brains?
A new study has revealed that men and women have almost identical brains – and that the only difference is size.
The study, led by neuroscientist Lise Eliot from Rosalind Franklin University of Medicine and Science in the US, analysed hundreds of brain scans from two large databases and found that men and women’s brains are hardly different at all.
The researchers used a data-driven approach to measure individual differences along a male-female dimension for brain and behaviour based on average sex differences in brain structure and behaviour, respectively.
They found that women tend to have slightly thicker cortices than men, which have been linked to higher intelligence scores. However, men had higher brain volumes than women in every subcortical region they looked at, including the hippocampus, amygdala, striatum and thalamus.
But these differences were largely due to brain size, not sex or gender. The researchers explained that brain size varies among individuals, and larger brains tend to have more volume in certain regions. They also found that the variability of brain structure within each sex was much greater than the average difference between the sexes.
“This means that the brain differences between large- and small-headed men are as great as the brain differences between the average man and woman,” Dr Eliot said. “And importantly, none of these size-related differences can account for familiar behavioural differences between men and women, such as empathy or spatial skills.”
The study also compared the brain scans with maps of gene expression in the brain based on postmortem tissue samples. They found that regions with relatively high expression of sex-chromosome genes tended to have greater volume in males than females. However, this did not explain the behavioural differences between the sexes.
The researchers concluded that sex differences in the brain are tiny and inconsistent, and do not reflect any innate abilities or traits. They suggested that behavioural sex differences are more likely to be influenced by social and cultural factors.
“Our findings suggest that behavioural sex differences are, to some extent, related to sex differences in brain structure but that this is mainly driven by differences in brain size, and causality should be interpreted cautiously,” Dr Eliot said.
The study was published in the journal Psychological Science and involved data from more than 2,000 healthy adults from the Queensland Twin IMaging study and the Human Connectome Project.
The study challenges the common perception that men and women have different brains that make them good at different things. For example, some studies have suggested that women are better at recognizing faces and emotions, while men are better at spatial tasks and mathematics.
However, these studies have been criticized for being based on small samples, using unreliable measures, or ignoring environmental influences. The new study is the first to combine a large amount of data from different sources and use a sophisticated statistical method to examine sex differences in the brain.
The researchers hope that their findings will help to reduce stereotypes and biases about men and women’s abilities and preferences. They also hope that their study will inspire more research on how social and cultural factors shape human behaviour.
So next time you hear someone say that men are from Mars and women are from Venus, you can tell them that they’re wrong – we’re all from Earth!