Some would like to see novel approaches to treating systemic problems that often work against women’s scientific ambitions. Mary Ann Mason and Marc Goulden of the University of California, Berkeley, have gathered extensive data showing stark male-female differences in the family structure and personal lives of academic researchers at the top tiers of the profession.

Surveying outcomes for 160,000 Ph.D. recipients across the United States, the researchers determined that 70 percent of male tenured professors were married with children, compared with only 44 percent of their tenured female colleagues. Twelve years or more after receiving their doctorates, tenured women were more than twice as likely as tenured men to be single and significantly more likely to be divorced. And lest all of this look like “personal choice,” when the researchers asked 8,700 faculty members in the University of California system about family and work issues, nearly 40 percent of the women agreed with the statement, “I had fewer children than I wanted,” compared with less than 20 percent of the men. The take-home message, Dr. Mason said in a telephone interview, is, “Men can have it all, but women can’t.”

From a purely Darwinian point of view, expecting a young woman to sacrifice her reproductive fitness for the sake of career advancement is simply too much, and yet the structure of academic research, in which one must spend one’s 20s and early 30s as a poorly compensated and minimally empowered graduate student and postdoctoral fellow, and the remainder of one’s 30s and into the low 40s working madly to earn tenure, can demand exactly that.

Nor do all young men in science accept the notion that their lab bench must double as a sleeping cot while their wives take care of the kids. In a new survey of 19,000 doctoral students at the University of California, Dr. Mason and her colleagues found that while two-thirds of the respondents either had or planned to have children, 84 percent of the women and 74 percent of the men expressed worry about the family-unfriendliness of their intended profession, and many had changed their plans accordingly. While 40 percent of the male science graduate students and 31 percent of the women said they had begun their Ph.D. programs intent on pursuing an academic career — still considered the premier path to science glory — a year or more into their studies, only 28 percent of the men and 20 percent of the women still hoped to become research scientists at a university.

Dr. Mason and other legal experts suggest that President Obama might be able to change things significantly for young women in science — and young men — by signing an executive order that would provide added family leave and parental benefits to the recipients of federal grants, a huge pool of people that includes many research scientists.