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

In contrast, males were found to have more white matter on average. White matter is made up of long nerve fibers called axons, which act like communication cables, allowing distant parts of the brain to connect and share information.

“The brains of males and females are more similar than they are different,” Khan said.

There were also differences in specific brain regions, but the overall message was that many of the structural differences seen in older children and adults are already present from birth.

However, researchers caution against overinterpreting these findings.

Questions about differences between male and female brains often lead to assumptions about thinking, behavior, or intelligence. But Khan emphasized that this study should not be understood that way.

“The brain is not ‘sexually dimorphic’ the way reproductive organs are,” she explained. “The brains of males and females are more similar than they are different, and it is important not to overstate or exaggerate these differences.”

She also noted that these findings reflect group averages and may not apply to every individual.