Pinker's comment about spatial and quantitative skills varying *within a gender* based on sex hormone levels sparked my interest and made me recall reading the research showing sex hormones have profound effects on the development of the brain in a fetus.

There is much similiar research being done. Here's an interesting one:

http://www.bio.psy.ruhr-uni-bochum.d...CycleMRTmh.pdf

This finds signigicant variation in womens' spatial skills over the menstrual cycle as sex hormones fluctuate. Testosterone improves spatial skils and estrogens reduce it.

Another older found estrogens improve verbal skills as well as fine motor skills.

-Richard