Sex Differences in the Human Brain Observed From Birth in Largest Study of Its Kind

Understanding how brain structure relates to behavior is far more complex than simply linking size or tissue type to intelligence or personality.

“It will be important for future studies to directly test whether there are any associations between sex differences in brain structure at birth and cognitive and behavioral outcomes,” Khan said.

Some earlier research suggests that female brains may have more gray matter to balance their smaller overall size, while male brains may require more white matter to connect the different regions of their larger brains.

Still, Khan stressed that future studies must test these ideas directly.

This research may also help scientists better understand neurodevelopmental differences, including why conditions such as autism are diagnosed more often in males than in females.

The search for biological differences between male and female brains has often been controversial, especially when it intersects with social assumptions, stereotypes, or outdated beliefs.

The reality is far more complex and nuanced—and for many scientists, that complexity makes the subject even more fascinating.