Perhaps it is because they actually married them when they were young, but at any given time your average "trophy wife" will by in her 30's?
This is a complex problem. I'm not sure the answer can be found without some in-depth statistical analysis.
Also, Rubix seems to be looking at things from the wrong perspective. It's not that women don't get with older men, it is likely the case that all the older men, and the men of status are taken. The younger men are not. Looking at it from the older men's point of view: what is the likelihood of an older, successful, single man getting together with women of a given age? I would guess it is much higher for younger women.
Why don’t men go for younger women? That’s not quite accurate, because they do, but we seem to have a cultural norm against girls who have recently exited puberty, even though they are highly fertile. Some time in the last few hundred years, we reached a cultural norm that as a man gets older, it’s increasingly less appropriate for him to be with a sixteen year old. That’s not long enough to override thousands of years of evolution, so what could have contributed to it?
The best solution I’ve heard started by looking at who benefits from this norm [older women] and wondering whether they could have contributed to it. After all, the strength of this norm has been increased in the last sixty years or so, which coincides with the period in which women’s power has increased.
One alternative I heard recently is that it doesn’t make sense biologically to go for women who are recently post-pubescent, as they don’t make the best mothers. Instead, a slightly older woman [mid-twenties] makes sense to be the best mother. This is perfectly plausible.
Another, less plausible, suggestion I’ve heard is that it’s to do with mental capacity. I find this unconvincing because we have few objections to a high-status man dating a beautiful but low-intellect woman.
Thoughts?