ED Note: I've often wondered if the long years of post-docs and junior research positions isn't squandering the peak creativity of a generation of scientists in support of their elders' projects.
And I presume a factor like this would not be something the study could adjust for. So if it's true that 35-50 is the peak, that could easily be due to how academia is structured rather than any general factor innate to human beings (like our brain biology).
Perhaps in the future, mathematics & physics advances will dry up, and the response will be a widespread effort to fast-track kids in certain specialisms, so that by the time they're 20 they have the same level of academic & bureaucratic freedom as today's 35-50 year-olds. Wishful thinking?
No, it's probably brain biology.