Sex Differences in Science, Tech, Engineering, and Math

In a previous post [Men’s Struggle for Status and Relevance], I discussed male-male competition from an evolutionary perspective and described how this manifests in the here and now as men’s focus on achieving cultural success. The latter involves gaining some level of control of culturally-important resources, such as money, and being successful in a valued niche, such as having a job in a prestigious field. In the modern world, occupational success means cultural success and cultural success means reproductive success for men (e.g., they are more likely to marry). In traditional societies, men are much more focused than women on attaining social and cultural status, because success often means the difference between reproducing or not. To be sure, high social status is important to women and their children, but the consequences of not achieving it are not as severe as they are for men.

It follows that more men than women will have an inherent motivational bias to devote time and effort into achieving success in their cultural niche, and this is the case in the modern workplace. Across occupations “evidence consistently suggests that despite comparable educational qualifications, tenure, and occupational attitudes, women have not achieved occupational status comparable to that of men” (S. D. Phillips & Imhoff, 1997, p. 46). I am not arguing that bias does not sometimes contribute to these differences, but rather it is not a sufficient explanation for all of them. In addition to motivation, there are sex differences in cognition and interests that contribute to the sex differences in occupational choices and attainment. I illustrate these for science, technology, engineering, and mathematics (STEM) fields, as these are often a source of social and political contention.

Sex differences in STEM are largely in fields that focus on inorganic topics, such as physics, engineering, and computer science, and not the life sciences and related fields, where women sometimes outnumber men. In addition to sex differences in cognition and interests, men and women who enter these fields make different work-life trade-offs. More men than women work long hours and are relatively more career-focused and thus achieve more on average, whereas more women than men prioritize relationships with family and friends over occupational accomplishment. The sex differences in these trade-offs are not restricted to STEM fields, as they are broadly evident across occupations.

Success in STEM careers, such as engineering, is made easier by a number of cognitive factors, including above-average intelligence and above-average spatial, mathematical, and mechanical competencies. On average, boys and men and girls and women are about the same in intelligence and mathematical competencies, but there are more men on the high (and low) end. Boys and men also have advantages in spatial abilities and mechanical reasoning that will contribute to success or at least ease of learning in some but not all STEM fields.

These types of sex differences are not the whole story and maybe not even the most important part of the story. This is because it is not simply the absolute level of performance in mathematics or other areas that influences college course taking and career choices. Each individual’s best academic area is also important. People who are relatively better in language-based (e.g., reading comprehension) than mathematics-based areas are more likely to obtain college degrees (e.g., in the humanities) and pursue careers that capitalize on this comparative advantage, even if they have exceptionally high mathematical abilities. Throughout the world, adolescent girls are on average relatively better in language-based than mathematics- or science-based areas, whereas adolescent boys show the opposite pattern, and this in turn at least partially contributes to the sex difference in STEM career choices.

Nevertheless, I suspect that sex differences in interests are relatively more important than the cognitive and academic ones for understanding why more men than women enter and stay in inorganic STEM fields. When women and men are free to choose their own careers, their occupational interests and choices consistently differ. On interest tests, “young women [score] higher than young men on domestic, artistic, writing, social service, and office service vocational interests and young men [score] higher than young women on business, law, politics, mathematics, science, agriculture, athletics, and mechanical interests” (Willingham & Cole, 1997, p. 178). The sex difference in vocational interests is especially striking among the mathematically gifted. When they are in their 20s, for every mathematically-gifted woman who is working toward or who aspires to earn an advanced degree in a mathematics-intensive STEM field, there are eight equally-talented men. These differences are related, in part, to the sex difference in interest in people (or living things more broadly, favoring women) and things (favoring men), whereby talented women are more likely to pursue science-related fields (e.g., medicine) that involve working with people.

Whatever the mix of factors influencing the sex differences in inorganic STEM fields, they appear to be more fully expressed in wealthy, equalitarian societies. These are societies in which women and men are freer to pursue their interests which in turn often increases the magnitude of many sex differences, including pursuit of college degrees in STEM fields. One reason is that most of these nations have social safety nets that make the pursuit of high-paying occupations less critical than in other nations. The safety net in turn frees women and men to pursue occupations that are consistent with their interests and their comparative academic advantages.