There is a big literature on the ages at which intellectuals peak in life. The rate of publishing papers peaks about tenure time. Physical sciences peak earlier than social sciences. And per paper, each one has an equal chance to be a person’s best paper, regardless of at what age it was written.
Being a polymath, I’ve posted lots on the topic of polymaths over the years. Seen as a production rather than a consumption strategy, polymathing is mainly looking for and building on connections one finds between distant intellectual areas. And while I haven’t seen data to confirm it, my personal experience suggests a hypothesis: polymaths peak later in life.
Why? Because our key intellectual strategy of looking for connections between areas should work better as we learn more areas. And I feel like I see this in my own life. While my stamina and raw speed or intensity of thought is probably declining with age, knowing more things makes it easier for me to learn the basics of each new area. When I seek concrete examples of things, I have a far larger library to draw on, and I find closer better examples more easily. And when I ponder a puzzle, I can find many more analogies and kinds of explanations to consider. Furthermore, I better know roughly want to expect re what sorts of connections won’t yet have been found, which are how valuable, and what it would take to test them or get folks to listen about them.