I think that perhaps the most important trend of the past thirty years is the
increased importance of cognitive skills relative to physical labor. Obviously,
this has been going on for more than just the past thirty years, but during the
past thirty years we saw an acceleration. This has had a number of
1. It changed the role of women. Their comparative advantage went from
housework to market work.
2. This in turn, as Wolfers and Stevenson have pointed out, changed the
nature of marriage. Men and women look for complementarity in consumption rather
than in production.
3. This in turn leads to more assortive mating, with achievement-oriented men
looking for interesting mates rather than for good maids.
4. This in turn leads to greater inequality across households. It also
fosters greater inequality among children. The children of two affluent parents
are likely to have much better genetic and environmental endowments than the
children of two (likely unmarried) low-income parents.
5. Inequality is exacerbated by globalization and technological change. If
your comparative advantage is basic physical labor, you have to compete with
machines as well is with workers from the Third World.
The net result is an economy that has improved considerably for people with
high cognitive skills, but which has improved only somewhat for people with
relatively low cognitive skills.