Is systemizing a feature of the extreme male brain from an evolutionary perspective?

• Systemizing has been proposed as essential difference between men and women.
• We tested the hypothesis that systemizing captures interest in novel niches.
• Occupational interests capture some variance in sex differences in systemizing.
• Systemizing is unlikely to reflect an essential sex difference.

Sex differences in empathizing with others and systemizing the abstract rules that govern the operation of things and the natural world have been proposed as the core, essential differences between men and women. We evaluate this assertion in the context of Darwin’s (1871) sexual selection and specifically test the hypothesis that the systemizing measure captures interest in evolutionarily novel occupational niches associated with interests in science, technology, engineering, and mathematics (STEM). Young adults (n = 233, 149 male) completed the Empathizing Quotient (EQ), the Systemizing Quotient (SQ) and the RIASEC Personality Type Inventory to assess six career interest groups. Sex differences were found on the EQ, SQ, Investigative interests and interest in things, a subset of items from the Realistic scale. Mediation analyses revealed that occupational interests partially mediated the relation between sex and SQ scores, whereas controlling for Investigative interests increased the sex difference in EQ scores. These results provide partial support for the hypothesis and suggest SQ captures, in part, occupational interests in evolutionarily recent STEM fields.