[theorique]

Interesting point. That Rwanda situation is interesting because it enforces a baseline of 30%. I am sure it's easier to get from 30% -> 50+% than it is from a much smaller number to 30%.

Chess, Go, Math Olympiads, and other such pursuits are other examples of situations where female representation is miniscule.

However, we can't assume this is anything biological because that would be sexist, so we need to assume that there is extreme misogyny at play, which increases as the level of competition gets higher and higher.

Philip Greenspun explores this in his article from a few years ago, in the arena of academic science:

http://philip.greenspun.com/careers/women-in-science