It turns out that maybe women aren’t from Venus and men aren’t from Mars. In fact, according to a new study, an individual brain very rarely has all “male” traits or all “female” traits. The new research suggests that the male and female brain are much more likely to be a mixed bag of some features that are more common in women and some that are more common in men.
Overall, the data from the new study makes it clear that human brains cannot be easily divided into two sex-based categories, according to lead author Daphna Joel of Tel-Aviv University and her colleagues on the project.
The new study was published Monday in the Proceedings of the National Academy of Sciences.The researchers examined MRI scans of more than 1,400 brains, studying the brain anatomy instead of how the brains work.
More on new male and female brain comparison study
The researchers examining the brain MRIs scored traits such as tissue thickness or volume in different parts of the brain. The method involved scoring the traits that showed the greatest sex differences, then dividing the scores into a mainly male zone, a primarily female zone, and a middle zone.
The key finding in the study was that less than 6% of the total 1400 brains were “all female” or “all male”, and this result was confirmed across analyses of multiple data sets.
In an interesting confirmatory study, Joel et al. used a similar approach to assign psychological and behavioral scores from two prior studies with more than 5,000 participants, and the results were quite close.
Taken as a whole, the results demonstrate that “human brains do not belong to one of two distinct [male and female] categories.”
Larry Cahill, a neuroscientist at the University of California who was not involved in the study, said he agreed that most brains contain various male and female anatomical traits. That, however, doesn’t rule out significant differences in how the brains of the two sexes function.
Cahill went on to note that there’s “a mountain of evidence proving the importance of sex influences at all levels of mammalian brain function.”
He concluded by noting that this earlier research shows that sex must impact brain function, “even when we are not clear exactly how.”
