We are surprised that players like Boris Gelfand and Vishy Anand can/could still play with the best in the world in their 40's and 50's. Are we right to be surprised? On average at what age do strong players reach their peak according to their FIDE ratings?
I wrote some queries against the database I constructed from the FIDE downloadable data, for post 2001, and Olimpbase for pre 2001. I looked at all players with a date of birth year who reached a standard rating of 2200 or above and asked SQL Server to calculate the age at which they achieved their maximum rating and then asked for mean and standard deviation.
This gave me:
Mean age = 33.32 or about 33 years and 4 months
Standard deviation = 12.35 years or about 12 years and 4 months
This kind of makes sense. You don't expect many players to peak in their 60's, although John Pigott reached a peak (so far) in February 2018 when he was 61!. You also see strong juniors give up in their teens and, of course, current strong teenagers will have their maximum rating also in their teens. At least until they reach their twenties :-).