“Thus most humans develop their most important and original ideas between their late twenties and early forties. With the teens and twenties spent gaining the intellectual tools and foundational knowledge needed to take on big problems, the sweet spot for original intellectual work is a person’s 30s: these are the years in which they have already gained the training necessary to make a real contribution to their chosen field but have not lost enough of their fluid intelligence to slow down creative work. By a person’s mid 40s this period is more or less over with. The brain does not shut down creativity altogether once you hit 45, but originality slows down. By then the central ideas and models you use to understand the world are more or less decided. Only rarely will a person who has reached this age add something new to their intellectual toolkit”
https://scholars-stage.org/public-intellectuals-have-short-shelf-lives-but-why/