Daphna Joel is a professor of psychology and neuroscience at Tel Aviv University. In the past decade she has been combining her expertise as a neuroscientist with her interest in gender studies to study the relations between sex, brain and gender. In her research, Joel uses various analytical methods to analyze diverse datasets, from large collections of brain scans to information obtained with self-report questionnaires. She has published over 70 papers in refereed scientific journals and is also the author of Gender Mosaic: Beyond the Myth of the Male and Female Brain (Octopus, London).

The purpose of this discussion was to demonstrate that 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, nor are they aligned along a “male brain–female brain” continuum. Rather, even when considering only the small group of brain features that show the largest sex/gender differences, each brain is a unique mosaic of features, some of which may be more common in females compared with males, others may be more common in males compared with females, and still others may be common in both females and males. The heterogeneity of the human brain and the huge overlap between the forms that brains of males and brains of females can take can be fully appreciated when looking at the entire brain. In accordance with the brain data, our analyses of gender related data revealed extensive overlap between females and males in personality traits, attitudes, interests, and behaviours. Moreover, we found that substantial variability of gender characteristics is highly prevalent, whereas internal consistency is extremely rare, even for highly gender-stereotyped activities. These findings are in line with previous reports that sex/gender differences in abilities and qualities are mostly non-existent or small, that there is extensive overlap between the distribution of males and females also in behaviours, interests, occupation preferences, and attitudes that show larger sex/gender differences  and that there are no or only weak correlations between gender characteristics. Thus, most humans possess a mosaic of personality traits, attitudes, interests, and behaviours, some more common in males compared with females, others more common in females compared with males, and still others common in both females and males.

The lack of internal consistency in human brain and gender characteristics undermines the dimorphic view of human brain and behaviour and calls for a shift in our conceptualization of the relations between sex and the brain. Specifically, we should shift from thinking of brains as falling into two classes, one typical of males and the other typical of females, to appreciating the variability of the human brain mosaic. Scientifically, this paradigm shift entails replacing the currently dominant practice of looking for and listing sex/gender differences with analysis methods that take into account the huge variability in the human brain (rather than treat it as noise), as well as individual differences in the specific composition of the brain mosaic. At the social level, adopting a view that acknowledges human variability and diversity has important implications for social debates on long standing issues such as the desirability of single-sex education and the meaning of sex/gender as a social category.