Answer:

atavism

Answer	Crossword Clue
ATAVISM	Biological reversion
ATAVISM	Throwback
ATAVISM	Reversion to a more primitive type.

ATAVISM	Reversion to more primitive type.
ATAVISM	Reversion to primitive type.
ATAVISM	Reversion to type.
ATAVISM	Reversion to the primitive.
ATAVISM	Reversion to remote ancestry.
ATAVISM	Reversion
ATAVISM	Reversion to an earlier type