A report by the National Academies of Science released Monday concluded that the underrepresentation of women in science is caused by institutional barriers and discrimination, not a lower “intrinsic aptitude” for science.

The studies laid out a number of recommendations for universities to level the playing field for men and women seeking faculty jobs — including reviewing the process by which faculty are evaluated and publicizing the percentage of women in science departments. At Yale, which launched an initiative last fall to improve the representation of women in the sciences, 12.7 percent of the current faculty in science departments is female, compared to 29.8 percent of the entire faculty.

Donna Shalala, the chair of the National Academies committee that wrote the report, said in a press release that U.S. science and engineering research is hampered by the absence of women in the field.

“Fundamental changes in the culture and opportunities at America’s research universities are urgently needed,” said Shalala, who served as secretary of health and human services under former President Bill Clinton LAW ’73. “The United States should enhance its talent pool by making the most of its entire population.”

Deputy Provost Charles Long said hiring female faculty is a top concern for Yale.

“It’s a very big priority, particularly in the sciences,” Long said. “I’ve always been a believer that you should hire women wherever you can, but we need to make a special effort there.”

Data reviewed by the committee shows that women drop out of career paths in science and engineering at all stages in the academic ladder, from high school through full professorships. Among undergraduates at Yale, women are significantly less likely than their male peers to major in the physical sciences, where they comprise 31 percent of majors, although they are more evenly represented in the biological sciences.

Yale molecular biophysics and biochemistry professor Joan Steitz — who also served on the committee that produced the report — said women are not necessarily discouraged by overt discrimination, but rather the accumulation of cultural and social pressures against continuing in science.

“What the report is really about is all the very subtle things that happen that disadvantage women just very, very slightly,” she said. “But when you add up lots of little things, then people get discouraged, and they don’t want to continue.”

One social psychologist who spoke to the committee studied letters of recommendation written for male and female candidates and found that the letters written for women tended to be shorter than those written for men and used different language, Steitz said. Women tended to be praised for their teaching and training, she said, while men were praised for their research and collegiality.

Steitz said Yale has made progress by improving family leave and child care policies and by bringing women into top administrative positions, but the University still faces many of the same cultural issues that the committee identified nationwide.

“I think Yale has been a lot better than some places, but I don’t think it’s at the very top in being aggressive about these things,” she said.

The ongoing faculty diversity program is designed to increase the proportion of female professors in science departments and minorities throughout the faculty. The program required departments to consider a diverse pool of candidates for each position and promises extra resources to departments who identify qualified female or minority candidates.

But Yale still faces problems hiring academics who are married, Steitz said, in part because New Haven is essentially a “one-university town.” The University has not been aggressive in facilitating the job search for spouses of prospective professors, she said, which may discourage top candidates from coming to Yale.

The study was prompted by comments by former Harvard President Lawrence Summers, who suggested in January 2005 that women tend to have a lower “intrinsic aptitude” for science than men, and Steitz said several chapters of the report are directed specifically at Summers’ comments.