[einhverfr]

And also see this: http://www.massey.ac.nz/~rmclachl/overthehill.html

However, I wonder if there is something else going on here. What I noticed in the list (and in the article I am linking to) is that the early peak seems less obvious from a historiography perspective than it does from a contemporary perspective. So I can't help but wonder if there is a qualitative difference in the sorts of contributions that younger and older mathematicians make.

Thinking more in terms of fluid vs crystalized intelligence here, but wondering if there is something else. I know my fluid intelligence is not where it was ten years ago, but part of that is a greater understanding of the problem domain. I can see more possibilities, and I see different ones than I would have before.

So I don't think it is as simple as we might want to think but I do think that thinking patterns (and abilities) change qualitatively as we age in ways which are favorable for important contributions when viewed through the light of history. Whether a thesis review board would agree is a different matter.