First the good news: More women are getting Ph.D.s than men, capping a decades-long march toward parity. And it’s not just in the humanities and social sciences. They also outnumber their male colleagues in the biological and health sciences. But the bad news is that they’re less likely to enter and remain in scientific careers. Beyond the doctoral level, the ratio of women to men starts to dip below one.

A new report tries to explain why that’s happening.