Masters of Evolution is a 1959 science fiction novel by Damon Knight. It first appeared in 1954 in Galaxy Science Fiction as the novella "Natural State". Knight subsequently expanded the text by about 5000 words, and the longer version was published by Ace Books in 1959 as Masters of Evolution, in a dos-a-dos paperback that included George O. Smith's Fire in the Heavens (Ace Double D-375).