Do distinct 'female' and 'male' brains exist?
New study suggests that most people's brains have a mix of gender traits.
Many men and women have long bought into the idea that there are "male" and "female" brains, believing that explains just about every difference between the sexes. A new study challenges that belief, questioning whether brains really can be distinguished by gender.
In the study, Tel Aviv University researchers searched for sex differences throughout the entire human brain. They analyzed the brains of 112 men and 169 women, aged 18 to 79. Altogether, they looked at over 1,400 MRI scans and 116 brain regions, searching for both connections and anatomical differences.
And what did they find? Not much. Rather than categorizing brains as "male or "female," research suggests that brains fall into a wide spectrum, with most people falling right in the middle.
“The theory goes that once a fetus develops testicles, they secrete testosterone, which masculinizes the brain,” says Daphna Joel, who led the study. “If that were true, there would be two types of brain.”
But there aren't two types, she said. Instead, her research found many different types that can't always be distinguished by gender.
But there are some gender-based similarities, she said. Twenty-nine brain regions seem to be different sizes in men and women, including the hippocampus, which plays a role in memory, and the inferior frontal gyrus, which is involved in risk aversion.
While the "average" male and "average" female brains were slightly different, you couldn't tell it by looking at individual brain scans. Only a small percentage of people had "all-male" or "all-female" characteristics.
Larry Cahill, a neuroscientist at the University of California, Irvine, said the Tel Aviv University study is an important addition to a growing body of research challenging traditional beliefs about gender and brain function. But he cautioned against concluding from this study that all brains are the same, regardless of gender.
There’s “a mountain of evidence proving the importance of sex influences at all levels of mammalian brain function,” he told The Seattle Times.
If anything, he said, the study suggests that gender plays a very important role in the brain – "even when we are not clear exactly how."
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