This reminded me of the argument about Pokemon and their ages, since evolution is actually not tied to it.

Granted that this based on the anime. Maybe Pokemon evolutions truly are tied to their "mental" age somehow, which would be a curious thing if so. You could have a 20-something-year-old baby Pokemon that never evolves past the infant stage due to still being too unhappy evolve, to which my first impression would be "that's kind of fascinating", and my second impression would be "I'm in this photo and I don't like it".

"Daddy~"