The Treatise tries to analyze not only modern Western families, but also those in other cultures and the changes in family structure during the past several centuries.

Why in almost all societies have married women specialized in bearing and rearing children and in certain agricultural activities, whereas married men have done most of the fighting and market work?

My work on human capital began with an effort to calculate both private and social rates of return to men, women, blacks, and other groups from investments in different levels of education.