With all the fuss about the low percentage of women faculty in science and engineering, people have started asking, "Why aren't more women going into these fields?"

Maybe the real question is, "Why are so many men going into them?"

Science and engineering demand big investments for uncertain rewards. Students must endure four years of difficult undergraduate courses, perhaps a few years of master's study and around seven years of graduate study to earn a Ph.D. Their reward for a decade of minimum wage apprenticeship? More of the same.

Most Ph.D.s go through several postdoctoral positions before getting on the tenure track, which itself is not job security but only a chance to compete for it. Compare this with law and business, where talented students can start making high salaries while their science friends are still teaching freshman physics labs.

Getting a faculty position is especially hard for scientists, because outside of the biosciences, there's a bigger supply of science Ph.D.s than the market can employ. The Bureau of Labor Statistics predicts that employment of physicists and astronomers will grow more slowly than the average profession, and that employment of mathematicians will actually contract. Even for biological scientists, the bureau predicts "considerable competition for independent research positions."

John Katz, a physics professor at Washington University, St. Louis, published a letter on his Web site advising students not to go into science. "Why am I (a tenured professor of physics) trying to discourage you from following a career path which was successful for me?" he wrote. "Because times have changed (I received my Ph.D. in 1973, and tenure in 1976). American science no longer offers a reasonable career path. If you go to graduate school in science it is in the expectation of spending your working life doing scientific research, using your ingenuity and curiosity to solve important and interesting problems. You will almost certainly be disappointed, probably when it is too late to choose another career."

So maybe not going into science isn't a sign that women aren't as capable as men: maybe it's a sign that they're a bit smarter.

And there's reason to believe that the smartest students are turning away from science. A recent study -- published by Issues in Science and Technology, the quarterly policy publication from the National Academies of Science -- found that the top scorers on the Graduate Record Exam, or GRE, are increasingly choosing other fields. Eight percent fewer of the top scorers went into science and engineering in 2000 than in 1992. The drop for mathematics was 19 percent; for engineering, 25 percent. In contrast, 88 percent more top GRE scorers enrolled in graduate programs for health professions like physical therapy, speech and language pathology and public health. Business administration enrollment was up by nearly one-third.

But the stereotype of scientists as society's smartest people persists. In their book "Know Your Child's IQ," Glen Wilson and Diana Grylls write that people with IQs of 140 are often professors and research scientists, whereas nurses and schoolteachers should have IQs around 120.

Are scientists really smarter? And is science really a more intellectually challenging job than other jobs?

Having researched in six labs and won three national science scholarships, I'd say no to the second question. In my experience, lab technicians' work is no more mentally stimulating than working on an assembly line, and most senior scientists' work writing grant applications is uncannily similar to public relations.

The emotional benefits of science are also exaggerated. Rather than discovering things no one has known before, scientists usually study a single topic ad nauseam, with no clear connection between their work and any benefit to humanity. If people want to feel like they are helping others, they I might consider going into social work, nursing or teaching.

Funny, those are the fields in which women are overrepresented. Women make up 80.6 percent of elementary and middle school teachers, 90.2 percent of registered nurses and 89 percent of nursing, psychiatric and home health aides. These are fulfilling careers with good job-growth outlooks. Maybe we need to start asking not, "Why aren't there more women in science and engineering?" but, "Why aren't there more men in nursing and teaching?"

Andrea Runyan likes science. Really. E-mail her at arunyan@stanford.edu.