Marriage age gap and education

So far as I can tell it is really quite unusual that in our society we are forced to spend a great deal of time with people the exact same age as us. All the time I spent in high school, and most of the time in undergrad and grad school everyone was pretty much the same age as me. This is such a usual situation for modern Americans that it probably does not seem as unusual as it is. Think about how the typical American lived two hundred years ago. Perhaps they spent a couple years in school but that was likely a large school house with students of many ages together. At home children probably spent most of their time playing with siblings or whoever the neighbor kids happened to be then went to work with their parents at a fairly young age.

This huge change in the people we interact with must have fairly large social consequences, but I have trouble coming up with what they are. The only one I can think of that really seems to fit the mold is the age gap in marriage. For many decades now the average gap in age between a husband and his wife has been decreasing. This has typically been attributed to women having increasing incomes, and perhaps this is part of it, but I suspect it is not all of it. Probably six out of ten people I met at Cornell or Fresno State were within three years of my age. There were a few professors, post docs, and undergraduates/high school students I spent time with but for the most part I did not spend much time with these people. So, if I am being forced into social settings with people the same age as me wouldn't I be expected to date within this age range?

Picking out the correlation and causation here would be a nightmare, but I suspect you could look at income gaps between men and women and number of years of formal education in some group in society and determine whether number of years of education is a better predictor of marriage age gap than income inequality between the sexes.