As a college student, Joan Steitz was fascinated by science.

A chemistry major, Steitz stumbled upon molecular biology — then an emerging field — while assisting senior scientists at the Massachusetts Institute of Technology. Through her laboratory stint, Steitz even befriended James Watson, one of the scientists responsible for discovering the DNA double helix. At the time, though, Steitz was something of an anomaly in the science world: she was a woman, the first, in fact, to join Watson’s laboratory. And without many female role models, becoming a top researcher was far from her mind.

But with a supportive mentor and a stroke of luck, Steitz was accepted to Harvard’s biochemistry and molecular biology graduate program — and her plans to become a doctor changed. And in 1963, Joan Steitz — now Sterling Professor of Biophysics and Biochemistry at Yale — became the only female graduate student in Harvard’s biochemistry and molecular biology department.

“It was pretty lonely,” she said, pointing to the lack of females at the time filling positions as faculty members and senior scientists. “I spent most of my life feeling uncomfortable.”

Much has changed since Steitz was a graduate student. And women across the sciences have made the path toward success considerably more accessible, enough so that women’s participation in the sciences — particularly the life sciences — has shot up from 3 percent to over 20 percent over the past four decades, according to the United States Governmental Accountability Office.

But, it seems, women still have a long way to go.

Experts and Yale administrators said, across the country, the proportion of women in the sciences has grown more rapidly at the undergraduate than at the graduate level, and numbers show a leaky pipeline: More women than men still tend to drop off at every academic milestone after the bachelor’s degree on the path to tenure.

Yale’s pipeline

Yale’s own numbers validate the “leaky” gender pipeline. Data from the Office of Institutional Research shows that roughly half of all undergraduate science majors are women and national data shows that, at the undergraduate level, women perform on par with their male counterparts. Yet the percent of Yale’s female untenured ladder faculty in the sciences drops off significantly — last year totalling 29 percent in the biological sciences, and just 18 percent in the physical sciences. At the very end of the pipeline, the numbers are even thinner. Tenured female faculty in the biological sciences numbered 15 percent, compared to 8 percent in the physical sciences.

The leaks along the pipeline to tenure, experts said, tend to occur at transition points: Fewer high school girls than boys intend to major in science and engineering fields, and fewer women than men continue on to study science at the graduate school, and fewer women than men with doctorates in the sciences are recruited into the applicant pools for tenure-track faculty positions.

Even as female faculty move up the ranks after recruitment, studies show that between men and women of the same caliber, differences become apparent in promotions, leadership positions, awards, numbers of published papers and salaries. For instance, this year, only four female faculty members, of which two are in the sciences, held Sterling professorships — the highest academic rank awarded to professors at Yale, out of over 40 Sterling faculty.

In line with national trends, the gender gap among Yale faculty in the so-called ‘harder’ sciences, including physics, chemistry and the engineering fields (as opposed to biology, for example), is larger and, according to analysis by the Women Faculty Forum, slower to change. Since 1982, the annual rate of change in percentage of female faculty averages 0.50 percent in the biological sciences; this figure remains just 0.42 percent in the physical sciences.

Three years after President Levin pledged to increase the number of women by 30 across departments with the most skewed gender ratios, among them the sciences, it may be time to reexamine the contours of the pipeline and the reasons for its leaks.

While it is often difficult to isolate the barriers to promotion for women, science students, professors and experts offer a range of possible explanations.

One one hand, “demand-side” factors — biases in the processes of promotion and hiring, a “chilly climate” for female scientists and less access to female mentors — may be at fault. But the issue may be simultaneously one of “supply,” stemming from factors such as women’s tendency to be dissuaded from fields where they will be in the minority and their greater likelihood of dropping out of the tenure track upon childbirth.

Gender schemas that ‘trap’

While it manifests itself only in its most stark form at the end of the pipeline, the roots of the gender divide begin much earlier, according to professors and researchers.

Meg Urry, chair of Physics and an advocate of women in science, said “at the crux of a very complex issue” lies the idea that people have built-in cognitive structures — called gender schemas — that link notions of masculinity with “the typical scientist.”

As a result, the woman scientist, at the cognitive level, is largely a foreign idea.

“When we think of competence and expertise in science, we think of men,” she said. “At a subconscious level, we think of women scientists differently.”

The result, she explained: “Men start at a high standing, while women start at a deficit.”

Many believe that discrimination involves explicit or outright hostility, but research into current bias against female scientists and engineers finds much more subtle, usually unconscious, forces at play — contributing to the difficult of detecting and correcting such biases, said Virgina Valian, Hunter College psychology professor, who studies gender inequity in academia.

One example of such research comes from social psychology, where researchers have developed the “Implicit Association Test” to reveal unconscious biases, she said. In a variation of the test, results show that respondents, men and women alike, are quicker to pair words linked to concepts of science with masculine words over feminine words — suggesting that masculinity is more closely cognitively linked with science than is femininity.

Part of the fight, Urry said, is therefore simply getting people to admit to these biases.

“How do we tell our colleagues these things are happening?” she said. “As a scientist, one of our core value beliefs is objectivity. If someone tells us we’re biased, we just don’t believe it.”

Urry added that the IUT catches bias in individuals who are conscious of the phenomenon. Despite her own “desperation to appear unbiased,” she said the test proclaimed her to more quickly pair male words than female words with scientific ones.

Under prevailing gender schemas, women are also seen “as either nice or competent, but much less frequently both,” Valian said. In other words, competent women may be often viewed as “overaggressive,” whereas traditionally subservient women may be seen as “incompetent.” As a result, women who perform well in their fields may be attributed negative personality stereotypes, she explained.

Valian pointed to a 2004 experiment by Madeline Heilman to prove the point. In the experiment, she said participants were asked to rate both male and female vice presidents in one of two situations: one where the person was presented as a stellar performer, and other, where no information about the person’s job performance was provided. In the latter condition, men and women were rated as equally likable, and the male was rated as more competent. But in the former condition, women were rated as less likable than men.

A by-product of gender schemas and the low numbers of women in science is that women are more often identified by their gender than men, in place of their professional or personal qualities, said Hannah Brueckner, director of undergraduate studies in sociology professor and women’s faculty forum steering committee co-chair. This makes the “gender role trap” more immediate in the sciences than it would be in more gender-diverse fields, she explained.

“If you’re in the minority, like women are in the sciences, you get talked about like a woman,” she said. “Your successes or slight mistakes are identified with your gender rather than with you as an individual.”

Urry agreed, saying that having less than a “critical mass” of female scientists means that their “gender” is much more conspicuous. She recalled that she recently came across a very positive letter about a talented female scientist. The letter noted that the scientist had managed to succeed despite having a family — bringing her status as a woman into sharp focus.

“That would have never gotten mentioned if she were a guy,” Urry said.

Brueckner said the inadvertent identification of women with their gender may cause them to experience “stereotype threat” — a concept from social psychology that describes an individual’s tendency to underperform when brought to be made aware of their membership to a traditionally discriminated group. This may mean they may come into science fields with diminished expectations about their own abilities or simply aim lower than they would otherwise, she said.

Steitz, who said her department of MB&B is comprised of about 20 percent female faculty, said the challenge lies in equal representation. She added that, while the number of women in her department is an improvement upon previous years, the issues that women face when they are part of the minority will persist unless the environment has a 50:50 gender ratio.

Since implicit gender biases exist in hiring and promotion — similarly qualified women are hired and promoted less frequently than their male counterparts — chairs of departments at Yale need to be cognizant of such forces, Steitz said.

Addressing unconscious bias in hires

At Yale, numerical representation has been a key part of the initiative to improve gender distribution in the sciences, said Judy Chevalier, associate provost for faculty development. The University’s 2005 commitment to increasing the number of full-term female faculty in underrepresented areas by 30 follows a longer history of work on diversity, she said.

In 1984, Yale set the goal of doubling the number of tenured women in the Faculty of Arts and Sciences — and achieved the goal within six years. As a result, between 1999 and 2005, the number of female faculty members increased by 43 percent overall, and by 113 percent in the sciences.

If the University succeeds on its newest goals of securing 30 new female hires, the addition would represent a 20 percent increase in female faculty overall and an 83 percent increase in female faculty in underrepresented departments, according to the Provost’s Office. The program promises extra resources to departments that identify qualified female or minority candidates as an incentive to diversify their searches, Chevalier said.

She said the University’s new diversity policies — which were enacted under the office of Provost Kimberly Bottomly — are much more comprehensive in nature, coupling the strategy of increasing female hires with the newer strategy of training current faculty about unconscious bias.

“You have to think about the ways in which well-intentioned searches might not always produce diverse results,” she said. “and how to make people aware of their biases.”

In addition to holding regular information sessions and conferences for chairs and faculty about diversity and unconscious bias, Chevalier said Yale now requires all faculty search committees to appoint a “diversity representative” who is responsible for ensuring a broad and effective ladder faculty search.

Because a disproportionate portion of female faculty at Yale are junior faculty, recent efforts to strengthen mentoring programs for junior faculty have also given more female scientists access to institutional support, Chevalier said.

But Steitz said Yale has not been “setting an example” on the issue of gender diversity, falling behind some peer institutions like the University of Wisconsin, which she said requires its department chairs to undergo a comprehensive training program that addresses gender bias.

While the University has been taking some steps towards the issue, she said, “it hasn’t really taken the situation seriously enough to do everything it can.”

The Women’s Faculty Forum’s analysis of the leaky pipeline at Yale places the University roughly on par with Princeton and Harvard in terms of its achievements on the gender equity front.

For instance, Yale still faces “dual-career” problems with accommodating its faculty members’ spouses, Brueckner said. Because the Universities like Yale have not been aggressive enough in facilitating the job search for spouses of prospective professors, research shows that more women than men in academia, potentially even more so in scientific fields, end up teaching in second- or third-tier colleges, sometimes even quitting work altogether, she said. While not a reason to promote complacency, there may be reason to believe that some of the gender imbalance at the end of the pipeline may sort itself out in time.

The fact that women’s participation is much thinner at higher ranks in the sciences may partially just be residual of an older era, Graduate School Dean Jon Butler said. As such, gender equity at the faculty level may increase as younger, more gender-equal, groups move through the pipeline, he explained.

“You have to realize you’re working with 10- to 15-year-old pools,” he said. “It takes time for people to get promotions.”

Still a male world?

But some experts say that correcting gender-biased hires solves only part of the problem. Science fields have a long way to go before they can successfully support the dual identities of female scientists who are both professionals and mothers.

Science may be at an even greater risk for fostering a “hostile” environment than some other fields, because, as a field largely pioneered by males, it still often presupposes a now-outmoded male model, according to Sophie Huyer, Executive Director of the Gender Advisory Board of the UN Commission on Science and Technology for Development.

Historically, that career model depended on a faculty member having a wife to take care of the household and the family, she said. The model still fits some men but is increasingly unsuitable, as women enter the sciences in larger numbers and dual-income households begin to uphold more gender egalitarian dynamics.

“Science is still built on the model of the male researcher who can work all hours because he has a wife at home,” she said. “Women scientists don’t have wives at home.”

As a result, Huyer explained, the female scientist seeking to balance her work and personal life is often unable to put in the same numbers of hours at her day job as a man of similar skill — and may end up publishing fewer papers for reasons out of her direct control, she said.

Some women leave science altogether because of domestic responsibilities. Indeed, as Brueckner notes, women in the sciences still suffer from “a black mark” associated with taking time off from work for pregnancy or childcare.

“Returning back to work after childbirth is difficult in a field where the biological clock can be incompatible with the tenure clock,” she said. “So sometimes women don’t come back.”

Hannah Chaplin, a graduate student in molecular biology, said that the decision of when to have children “is still very much an issue” among her female friends who are graduate students in the sciences.

Even in fields such as medicine where woman scientists have made considerable inroads in recent years — in 2006, 61 percent of graduates from medical schools nationwide are women and Alpern said YSM’s own composition fluctuates between 50 to 60 percent women — structural barriers for women with domestic responsibilities remain, said Yale Medical School Dean Alpern.

Last year, 19 percent of tenured faculty at the medical school were women, according to the OIR.

While women may be represented equally in the clinical tracks of medicine, they remain sparse among the ranks of physician-researchers — reflected in the much lower numbers of associate and full-term female than male faculty at YSM, he said.

Alpern explained this trend by comparing the flexibility afforded in clinical settings to that afforded in research settings.

“Academic medicine is a very unforgiving field,” he said. “If someone has a child and takes leave to deliver the child, we [Yale] will extend the tenure clock, but that doesn’t mean the granting agencies will.”

At the graduate level, Butler said Yale has a childcare policy that is much more family-friendly than some peer institutions. Under the policy, both new mothers and fathers receive a semester of support from the graduate school directly after a childbirth event. Most graduate schools restricted child support polities to female graduate students, he added. The McGonagal Center also coordinates family activities for graduate students with children, Butler said.

But at the University-wide level, Yale-related day-care facility – including programs like the Yale Babysitting Service — leave “much to be desired,” according to Brueckner. She said many Yale-affiliated childcare arrangements have long wait lists and are often very expensive, leaving many faculty members to work out daycare arrangement on their own.

The “male” culture of traditional science goes beyond just the expectation of long hours at the expense of time at home. Urry said that, within the research world, science has a necessary culture of “self-aggrandizement” that may be foreign to some women who have been socially conditioned to value modesty and thereby put them at a disadvantage in relation to their male peers.

“I was taught, like many other women of my vintage, not to brag,” she said. “But in science, often the value of your work depends on how much you talk about it.”

She added that “all women science faculty” have had the experience of voicing an idea at a group meeting that receives little attention — only to find when that same idea is voiced by a male peer, more people respond to it in a positive way.

Shirley McCarthy, professor of Diagnostic Radiology and Obstetrics and Gynecology at the medical school, said that, while medicine has the critical mass of women to be less hostile than some other science fields, subtle discrepancies still emerge. For instance, fields, such as ob/gyn or pediatrics, which have higher proportions of women, often have fewer resources than highly male-dominated fields like surgery, and female faculty often have fewer mentoring opportunities available to them.

“There used to be overt wisecracks when I was young,” she said. “Now its subtle, not in-your-face kind of stuff … little things that you wouldn’t stop to notice.”

Seemingly “little” disadvantages, while perhaps inconsequential in themselves, Valian said, accumulate to create much larger disadvantages like lower salaries and less frequent promotions.

“All of these little things are like little molehills, but mountains are molehills piled one on top of the other,” she said. “If you don’t get your share of the small gains, you can’t parlay them into larger gains.”

‘Hard’ vs. ‘soft’

The sciences across the board show different levels of permeability to such demand and supply forces — at least judging from the numbers. These differences are apparent as early as the undergraduate level.

Data provided to the News by the OIR shows that many more women choose to major in the biological sciences at the undergraduate level than in chemistry, physics and engineering.

This year, women made up 42 percent of all science majors, but only 29 percent of science majors other than biology and molecular biophysics and biochemistry. Fifty-one female seniors declared majors in MCDB or EEB, compared to 35 male seniors. But collectively, across the Chemistry, Physics, Astronomy and Engineering departments, female senior majors total 39, compared to 75 male senior majors.

As such, the overall 50:50 undergraduate gender ratio among the natural and physical sciences may belie the true extent of gender disparities — and the extent to which certain fields are gender unequal from the very beginning of the pipeline.

Some professors note that, unlike biology, which reached its critical mass of students some years ago, the harder sciences remain much slower to change.

Dean of undergraduate studies in Physics Peter Parker said the number of female majors in physics — currently at about 30 percent — is “taking a while to build up.”

“I don’t know why it’s not 50 percent,” he said. “We shouldn’t be satisfied with less than 50 percent.”

Predictably, this trend continues at the graduate level. According to data provided to the News by the Graduate School of Arts & Sciences, in 2008 the number of female graduate students in the biological sciences outstripped the number of men by a large margin: 395 compared to 276. But this trend was reversed for the physical sciences. Female graduate students in the physical sciences totaled 110 in 2008, while male students in the same field numbered 260; in the engineering and applied sciences, 57 female students and 105 male students enrolled.

Butler said the numbers of female chemistry graduate students has seen some recent “hopeful increases” but is still not up to the levels of women in biological sciences.

Urry said another way of looking at the differences across sciences is to realize they vary not on whether, but where, the “big leaks” in the pipeline occur. For biological sciences, the leak is right after graduate school. But for the hard sciences, the biggest one occurs much earlier, before women begin college, she said.

Professors search for an explanation for the persistent discrepancy between the so-called hard and soft sciences, but step carefully around the argument of “innate difference.”

Most studies of brain structure and function and human cognitive development have revealed little biological differences between men and women that can account for the lower representation of women in these fields — but some experts say that women may be socially conditioned to think more holistically than men. Huyer said that, while data and evidence is still controversial, some studies find women tend to be turned off from harder sciences more often than men because they perceive them to lack a “context or larger value.”

In surveys, more college-age women than men say that helping others or contributing to society is an important factor in selecting their desired careers, she said.

Urry agreed, saying that some research shows that more women than men tend to be high-context learners — “learners who need to know what the point is before the commit to a new fact.”

She explained that fields like biology that have recently seen influxes of women are inherently high-context, while some of the physical sciences — at least at face value — are perceived as more abstract.

“Women want a theory that is tied into a context,” she said. “They don’t want to learn about micrometers and calipers — they want to learn about why and how measurement fits in as a concept to physics.”

Urry said that, at Yale, the physical sciences and engineering have traditionally emphasized abstract theory and concepts, often at the expense of their real-world applicability.

Students differ in their experiences with the physical sciences and engineering at Yale, but many agreed that the departments have a theory-heavy focus.

Physics major Chris Pollard ’09 said that his experience has varied from class to class; while classes such as “Classical Mechanics” have been accompanied by demonstrations with oscillators, others like “Quantum Mechanics” have been necessarily theoretical because of the nature of their subject matter.

Xiaochen Su ’10, a double major in economics and electrical engineering, said the theoretical nature of many of his engineering courses “does not really matter” in the context of many student’s future goals. He said that like himself, few students plan to go into engineering after college. Pollard does not feel that a theoretical focus is a limitation of his classes either.

“I think it’s very important to understand the theory, because when it comes down to it, who understands what an atom ‘looks’ or ‘feels’ like?” he said. “We just know how they act and interact, and the easiest way to convey that is through mathematical equations.”

Axel Schmidt ‘09, another Physics major, said that the major tends to dichotomize theory and its experimental branches — with core requirements for the majors that include classes in both areas, with some crossover. This makes classes such as “Electricity and Magnetism” “full of grueling exercises in mathematics” but retain its focus on practical devices, such as waveguides and transformers, he said.

But T. Kyle Vanderlick, dean of engineering, said that while the physical sciences and engineering program at Yale would benefit from stressing application, ultimately both sexes — not only women — seek context.

“We [Yale] need to make the links between what student are learning in class and what’s going on in the world,” she said. “It’s a priority for our new school of engineering to make those connections.”

‘Diversifying the pipeline’

While the leaky pipeline helps elucidate the phenomenon of women’s lower participation in science on many levels, it can often be over-cited as a cause, Chevalier said.

“People use the pipeline as an excuse,” she said, adding that faculty may simply point to lower numbers of women in the applicant pool as a reason for a lack of diversity among department.

But Yale’s responsibility, she said, lies not only at the final step — recruiting and hiring more female faculty — but equally, and perhaps more importantly, in “diversifying the pipeline.”

Yale’s initiatives going forward have stressed that a true effort towards gender equity in science requires close collaboration with the undergraduate program, the graduate program and the post-doctoral office to improve its numbers, she said.

At Yale College, programs like the Science, Technology and Research Scholars attempt to expose women and underrepresented minorities to science research early in their college careers in the hopes of getting them hooked onto science. STARS, which gives its participants a stipend to pursue summer research, also offers additional mentoring to its participants that may encourage them to major in natural-science and engineering fields.

At the graduate school, faculty have regular meetings with the Office of Diversity to devise new recruiting strategies for women and minorities in fields, like science, where they are still under-represented, Butler said.

And University-wide, opportunities for female mentors in science are growing. The Graduate School offers ‘Women Mentoring Women,’ a program through which graduate students organize workshops and programs to encourage cross-disciplinary mentoring between female students and faculty. Women in Science at Yale — a group that brings together over undergraduates, graduate students and postdoctoral fellows over interested in women in science — matches undergraduates interested in science to female graduate student mentors.

Vanderlick said she thinks mentoring is the most effective way for older women to attract younger women to science.

During her time at Princeton, where she served as chair of the chemical engineering department before taking helm as Engineering Dean at Yale, Vanderlick said that she really learned the importance of role models when the department hired a female dean of engineering.

“It was the first time I was in an environment where I actually had a woman in a position higher than me — I’ve always been someone else’s role model,” she said, “I can’t tell you how much of a difference it made to seeing the possibilities open to me.”

Parker added that, for the first time, the Physics department has four female faculty members — a development he hopes will attract more women to the major.

Chevalier said that women in top science positions at the University — like Urry and Vanderlick — will go a long way inspiring burgeoning female scientists. Monica Cowan ’09, a Mechanical Engineering major, said that while her own decision to pursue a largely male-dominated field of study was not influenced by female mentors, Vanderlick’s appointment to the post of dean of engineering “definitely won’t hurt the numbers.”

Indeed, OIR data shows that the representation of undergraduate women in a given field appears to increase with the presence of female faculty in the relevant department — accounting for about a quarter of the sex-ratio differences between majors.

Chapin, director of the WISAY mentoring program WISAY, said the program was started with the intent of offering younger women the chance to interact with those who have “done it successfully” in order to provide them guidance and bolster their feelings of confidence going forward.

She compared programs like WISAY to the process of adding small weights to the other end of a currently still unbalanced scale.

“Its the case that discrimination happens in small chips,” she said. “So the idea is to stack many little small pebbles on the other end of the balance to compensate.”

Eventually, with such institutional policies and measures in place, professors said leaks in the pipeline can be plugged. Huyer said that once women can accumulate “a critical mass” in a science, they can ensure a “tipping point” — a period of very quick growth. Biology’s tipping point came several year’s ago, she explained, and trends show that — given continued and aggressive action — some of the physical sciences may soon reach their own tipping points.

Butler added that, while much more remains to be done, more has been done in the past 20 years about gender equity than collectively ever before.

“Twenty years ago, no graduate schools even talked about the issue of gender diversity either women and minorities,” he said. “Now everyone talks about it.”