atavist
/ˈætəvɪst/
noun
- An organism or individual that shows atavism; a person or thing that is a throwback to an earlier ancestral type.
- The botanist called the plant an atavist because its flowers resembled those of a species extinct for millions of years.
- The rare white tiger was an atavist, carrying a gene from its ancient ancestors.
- In the novel, the character was an atavist who behaved like a caveman in modern society.