For the last 20 years, the most male dominated field studied is math, then operations research, then philosophy, and economics. In philosophy, the most masculine subfields include space and time and set theory, and the most feminine moral philosophy.
In general, women researchers find living things more interesting, especially young living things.
The single most masculine subfield in the study is the mathematics of Riemannian manifolds.
The usual way to think about this is that this represents a crisis. Steps Must Be Taken to smash the glass ceiling holding women down in Riemannian manifolds so that they can bring their valuably diverse insights to solving Riemannian manifolds, whatever those are.
On the other hand, my view (being a Larry Summers-like thought criminal) is that children and other living things are important, and I'm glad that smart women are working enthusiastically on subjects that they find fascinating.
[Eine weibliche Eigenart auf den Punkt gebracht... Ich empfehle es, den Artikel auf der Originalseite ohne Auslassungen zu lesen. Überhaupt sind mehrere Artikel von Steve Sailer lesenswert.]