When Debbie Sterling arrived at Stanford University to study mechanical engineering, she was in for a surprise.

She was only one of two women in the Stanford 2005 class of mechanical engineering students. In fact, women constitute only 14 percent of engineers in the workplace today.

When facing a situation like this, many people would conclude that women just aren't smart enough or interested enough in math to be engineers. Instead, Sterling concluded that girls and women were being steered away from STEM (science, technology, engineering and math) by social stereotypes. So she decided to make it her life's mission to erase the gender gap in STEM by creating GoldieBlox, a book series and toy construction set that lets kids imitate Goldie, a girl inventor who solves problems by building simple machines.

As admirable as Sterling's mission appears to be, I have a different explanation of why there are more male engineers than female engineers. My view is backed up by a good deal of scientific evidence, but, despite this, I guarantee one thing: My explanation will both gratify and enrage people on both sides of this debate.

Women Are Smart Enough to Be Engineers

Despite herculean efforts to prove otherwise, men and women tend to score equivalently on tests of raw IQ. When it comes to mathematics—a core requirement for engineering—women score on average only 32 points lower than men on SAT mathematics—a mere 3% difference. While men outnumber women in the "genius" SAT math score range (700-800), the ratio is not that large (1.6 to 1). Even with that difference, it is not the case that more undergraduate men than women are selected by top engineering programs. Of the top STEM programs in the country, most have male-to-female undergraduate student ratios close to 1:1.

Men show only an insignificant 5-point advantage over women on the quantitative section of the Graduate Record Examination, and they score one point lower than women on the analytic section.  Again, of the top STEM graduate programs in the country, most have male-to-female student ratios close to 1:1.

The percentage of women (45%) employed as beginning assistant professors in STEM fields is about the same as men (55%). But their career trajectories diverge substantially after that. Only 38% of women make tenure, and only 22% are promoted to full professor.

Does this mean women can't handle the job? The bulk of the evidence on this "leaky pipeline" points to one simple fact: Establishing a science career is incompatible with having a family.

The demands of caring for young children are incompatible with the demands of establishing a research lab in preparation for tenure review, yet the tenure push coincides exactly with a young scientist's prime reproductive years—and that is true for both men and women. But women are less willing to sacrifice having and caring for children than are men, and so they drop out of academic research at twice the rate of men.

One option women scientists have chosen in recent years is to step out of (or never enter) the tenure track in favor of taking positions that are annually renewed, such as adjunct professorships. The difficulty with this option is that once one is off the tenure track, it is virtually impossible to get back on it. Those who manage to make it through to tenure often reduce their research productivity for a few years while their children are young, thereby making their dossiers seem less impressive than their male counterparts who refuse to slow down to accommodate the demands of childrearing.

Claudia Goldin, Henry Lee Professor of Economics at Harvard University, argues that the solution to this problem (and the salary gender gap in general in the workforce) is for the workplace to embrace flexibility. Outdated notions of traditional career trajectories should be discarded, and emphasis should instead be placed on results regardless of where or when the work was done.

Men Do Not Outnumber Women in All STEM Fields

Is it the case that men vastly outnumber women in STEM careers? Well, it depends on the STEM career. Look at the percentage of STEM bachelors degrees awarded to female students for the last two decades.

Percent STEM Bachelors Degrees Awarded to Women

Notice that there is no gender difference in the biosciences, the social sciences, or mathematics, and not much of a difference in the physical sciences. But women are "underrepresented" in engineering and computer science, and they are "overrepresented" in psychology (NSF breaks psychology out into a separate category due the very large number of students who major in this field.) Here is the breakdown for PhD degrees:

Percent of PhD STEM degrees awarded to women

So it isn't the case that women are not interested in STEM. They are just as interested in the biosciences and social sciences, a little less interested in math and physics, and not much interested in computer science and engineering.

We see the same disconnect when we look at the percent of women working in STEM fields outside of academia, as shown in this table from http://www.catalyst.org/knowledge/women-sciences:

Women gravitate toward specific STEM fields

Notice that women are as likely as men to be biological scientists, medical scientists, and chemists. They are much less likely than men to be computer scientists or physical scientists. Even when we look within a field we find similar differences in male and female interests. Here is where women and men tend to congregate in medical subspecialties. Notice that women are more likely to prefer pediatrics general medicine, and general medicine to surgery. In other words, women prefer to spend their work time interacting with patients rather than tinkering with the organs inside their patients.


Percent of female physicians by specialty

If we look inside the Ivory Tower of academia, we find the same distribution


Women in academic STEM fields

If we look at the entire workforce (not just STEM fields), we find this:


Women in the workforce

The data clearly show that women are more likely than men to be employed in "people oriented professions", such as nurses, therapists, and teachers than they are to be employed in "object oriented professions" such as computer scientists or engineers.

Women and Men are Interested in Different STEM Fields

One interpretation of the gender difference in STEM careers (and the workforce in general) is that women are not making these choices in order to study what is intrinsically interesting to them but because they are herded into areas that are more "gender appropriate".

For example, Dr. Andress St. Rose, one of the authors of Why So Few? Women in Science, Technology, Engineering, and Mathematics, puts it this way:

Another common but somewhat misguided explanation for female underrepresentation in STEM is that while girls and young women may be just as able as young men, they are not as interested in science and engineering. From early adolescence, girls report less interest in math and science careers than boys do (Turner et al. 2008), and among children identified as mathematically precocious, girls were less likely than boys to pursue STEM careers as adults (Lubinski and Benbow 2006). Girls’ lower reported interest in STEM may be partially explained by social attitudes and beliefs about whether it is appropriate for girls to pursue these subjects and careers.

It is this assumption that drove Debbie Sterling to found GoldiBlox. The problem with this "blank slate" interpretation of gender differences is that it is at odds with the results of most developmental and comparative studies. Newborn girls prefer to look at faces while newborn boys prefer to look at mechanical stimuli (such as mobiles). Girls and juvenile female monkeys show a greater interest in young infants than do boys and juvenile male monkeys. But when it comes to toys, a consistent finding is that boys and juvenile male monkeys strongly prefer mechanical toys over plush toys or dolls, while girls and female juvenile monkeys are more eclectic in their tastes, showing no significant preference between the two. (See this for summary of this research.)  It is not difficult to see how such early emerging preferences can end up shaping career choices later on: Women tend to gravitate toward science fields that focus on living things and agents, men to science fields that focus on objects.

In fact, it is difficult to avoid seeing irony in the fact that Sterling is not employed as an engineer. Instead, she is CEO of a company that makes science and engineering toys for children.

Why Close the Engineering Gap?

To those who insist that large amounts of money must be channeled into "closing the gap" in all STEM fields, I ask this simple question: Why?

If women simply are not as interested in being engineers as they are in being biologists, why should they be cajoled and tempted (and sometimes shamed) into being engineers?

Some have argued that women keep themselves poor by pursuing careers in low-paying fields (such as nursing or teaching) rather than careers in high-paying fields (such as engineering computer science). So I would ask another question: Is the work traditionally done by women really of intrinsically less value to society and the GDP than is the work done traditionally by men?

Actually, we have some data on this. The percentage of male nurses increased from 3% in 1970 to 10% in 2011. And with this increase has come a nurse gender wage gap: In 2011, the average female nurse earned $51,100, 16% less than the $60,700 earned by the average man in the same job.

It is difficult to avoid the conclusion that male-dominated professions are high-status professions precisely because they are male-dominated, and female-dominated professions are low status precisely because they are female-dominated. When men move into traditionally female-dominated professions, the salaries and status levels of those professions rise.

Rather than rushing to traditionally male professions to shore up our status and our income levels, perhaps we need to reject the implicit belief that whatever men are doing must be more important and valuable and whatever women are doing must be the career dregs that men fobbed off on us.

In other words, we should not be ashamed if our interests differ from men's, and we should place greater intrinsic and monetary value on the work we like and want to do.

Copyright Dr. Denise Cummins March 20, 2014

Dr. Cummins is a research psychologist, a Fellow of the Association for Psychological Science, and the author of Good Thinking: Seven Powerful Ideas That Influence the Way We Think.

More information about me can be found on my homepage.

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