Messrs Becker and Posner (neither of which are spring chickens) consider the question of age and academia.
Things are a bit different this side of the pond (generally politicians and economists complain that people retire too early) but what seems to be a common problem is the gap between taking your PhD and getting some kind of long-term employment. I will side with B+P in the observation that academic careers are front-heavy, i.e. people are generally more creative in their 20s and early 30s. Add generational effects from the big expansion between 1965 and 1975 and things get funny.
Another observation could be that the prime age in politics has been decreasing. Whereas a politician’s career used to reach its peak between the age of 50 and 60, the decade between 40 and 50 now seems to be the peak, at least in Scandinavia.
So, we are living longer but have no clue what to do about people who have passed 50.