Fifty years after The Feminine Mystique and 40 years after Title IX, the question of why women lag in the workplace dogs researchers and lay people alike. While women are entering the professions at rates equal to men, they rise more slowly, and rarely advance to the top. They’re represented in smaller numbers at the top in fields from science to arts to business.

Some suggest that there is something different about women—women have stalled because of their personal choices, or their cognitive and emotional characteristics, whether innate or socialized. Another possibility is that the obstacles to women’s advancement are located within their environments—that they face barriers unique to their gender.

But while bias has been experimentally demonstrated, it’s hard to study in the real world: Just as it’s hard to isolate a single environmental pollutant’s effect on human health, it’s been near impossible to isolate gender as a variable in the real world and watch how it affects a person’s day-to-day experience.

Until now. Trans people are bringing entirely new ways of approaching the discussion. Because trans people are now staying in the same careers (and sometimes the very same jobs) after they change genders, they are uniquely qualified to discuss the difference between how men and women experience the workplace. Their experience is as close to the scientific method as we can get: By isolating and manipulating gender as a variable and holding all other variables—skill, career, personality, talent—constant, these individuals reveal exactly the way one’s outward appearance of gender affects day-to-day interactions. If we truly want to understand women at work, we should listen carefully to trans men and trans women: They can tell us more about gender in the workplace than just about anyone.

Ben Barres is a biologist at Stanford who lived and worked as Barbara Barres until he was in his forties. For most of his career, he experienced bias, but didn’t give much weight to it—seeing incidents as discrete events. (When he solved a tough math problem, for example, a professor said, “You must have had your boyfriend solve it.”) When he became Ben, however, he immediately noticed a difference in his everyday experience: “People who don't know I am transgendered treat me with much more respect,” he says. He was more carefully listened to and his authority less frequently questioned. He stopped being interrupted in meetings. At one conference, another scientist said, "Ben gave a great seminar today—but then his work is so much better than his sister's." (The scientist didn't know Ben and Barbara were the same person.) “This is why women are not breaking into academic jobs at any appreciable rate,” he wrote in response to Larry Summers’s famous gaffe implying women were less innately capable at the hard sciences. “Not childcare. Not family responsibilities,” he says. “I have had the thought a million times: I am taken more seriously.”