Actually, an evolutionary reason for acne has been proposed: if we stipulate that it is an advantage to be fully grown and independent before you have kids yourself, it makes evolutionary sense for dist of young breeding age (but to young that they *should* be breeding) to look gross to each other.
Let 'em grow up, become strong and independent, and THEN have clean skin and be attractive.
(Now why anybody would still get them after 40 is a riddle to me...)
Since when have zits ever stopped teenagers from making zug-zug (movie "Caveman" reference)? They're like bunnies if given the chance. Zits seem to signal; "The time for making zug-zug has commenced"
Dogs occasionally get zits as well. Dunno about monkeys and apes.