In the publication, Joel and the team determined that the study "undermines any attempts to distinguish between a 'male' or 'female' form for specific brain features."
Analysis of over 100 studies showed that the volume of a male brain is typically 8 to 13 percent larger than that of a female brain, on average. In an effort to determine if this equaled a significant cognitive difference, scientists studied brain scans of over 1,400 men and women.
The Los Angeles Times reports that scientists were unable to identify patterns separating male and female brains. No scan, group examined, or section of the brain consistently showed any features distinguishing between the two sexes.
In a study, published Monday in the Proceedings of the National Academy of Sciences, the team wrote, “Although there are sex/gender differences in brain structure, brains do not fall into two classes, one typical of males and the other typical of females,”
The team was led by Daphna Joel, a psychobiologist at Tel Aviv University in Israel, who went to work looking for brain features that were explicitly male or female. Measurements were taken in hopes of finding data that skewed one way for one sex, and not for another, with very little overlap.
The researchers began with MRIs that measured the amount of grey matter in 112 male brains and 169 female brains, with ages ranging from 18 to 79. From there, the scientists identified 116 separate regions of the brain, focusing on the 10 that displayed the greatest difference between male and female. The 281 brain scans were then divided into three categories: most male, most female, and neutral.
Six percent of the brains ranked “most male” or “most female ” with 35 percent showing “substantial variability,” displaying both male and female traits.
In the publication, Joel and the team determined that the study “undermines any attempts to distinguish between a ‘male’ or ‘female’ form for specific brain features,” Joel added that the findings of the study have, “important implications for social debates on long-standing issues.”