Half of all recent M.D.s are women and nearly half of all recent Ph.Ds in biology are women. So are the majority of new psychologists (67%), veterinarians (75%) and dentists (70%). But why are so few women joining the ranks of mathematicians, engineers, chemists, computer scientists, and physicists?
In the top 100 U.S. universities, only between 9% - 15% of tenure-track academic positions in mathematically-intensive fields are held by women. Among full professors in these math-intensive fields, women number below 10%. In contrast, women are much better represented in the social sciences and humanities, often comprising nearly a third or more of professorial posts, with the exception of economics in which they constitute only 16% of positions.
In our book, “The Mathematics of Sex: How Biology and Society Conspire to Limit Talented Women and Girls” (Oxford University Press), we examine evidence from around the world in endocrinology, economics, sociology, education, genetics, and psychology about why the math-intensive fields of mathematics, computer science, physics, engineering, and chemistry are so lopsidedly male. We examine three classes of explanations that have been offered to explain the dearth of women in these fields: ability differences that favor males in mathematics and spatial ability, biases and barriers that impede women’s progress in these fields, and career/lifestyle preferences that propel women into other fields.
Our general conclusion: The imbalance in math-intensive careers can not be accounted for by sex differences in mathematical and spatial ability that have been reported between male and females (to the extent that this is a factor, it is a minor one), nor can they be attributed to current biases, though past cohort discrepancies may be explained in such terms, because women are hired for tenure-track positions at rates roughly comparable to their proportions in the scientific Ph.D. pools--and often at rates slightly above their proportions. The single biggest factor in women’s underrepresentation in these fields is that women opt out of such careers at a fairly young age: In surveys of adolescent girls, very few say they desire to be an engineer or physicist, preferring instead to be medical doctors, veterinarians, and lawyers. Although females earn a large portion of baccalaureate degrees in all fields of science, including math-intensive fields (e.g., 46% of mathematics majors are females), disproportionately fewer women enter graduate school in these fields, and fewer of the women who go on to earn Ph.D.s apply for academic jobs even though among those who do apply, they are more likely to get interviewed and hired. There is no consensus yet as to why fewer women earning PhDs in math-intensive fields apply for tenure track positions, but one reason that women in all fields opt out of academia has to do with a desire for flexibility: Women want some job flexibility to raise children, and the timing of childrearing coincides with the most demanding period of an academic career, such as trying to get tenure, or working exorbitant hours to get promoted.
For the same reasons, women drop out of scientific fields even after entering them -- especially math and physical sciences -- at significantly higher rates than do men, particularly as they advance. Even in fields such as medicine where women now comprise half of the graduating classes, those entering academic medicine drop out at higher rates than do their male counterparts. The tenure structure in academe demands that women who have children make their greatest intellectual achievements contemporaneously with their greatest physical and emotional achievements, a feat fathers are rarely expected to accomplish. When women opt out of careers (or segue to part-time work in them) to have children, this is a choice men are rarely required to make. Of course, this affects al women, not only those who are in math-intensive fields. And it also can be seen among women scientists who work outside the academe, such as pharmaceuticals, sales, research. They leave these careers disproportionately in their mid-thirties, presumably to start families. But when you couple this with the fact that so many fewer women enter the PhD pipelines in the math-intensive fields, this is a major reason for the shortage of women professors in these fields today.