The Amazon molly, a small freshwater fish that can clone itself without male DNA, has been discovered to solve a major evolutionary problem that could kill off a species long-term. The fish originated around 100,000 years ago after a hybrid pairing between two other fish: the Atlantic molly and the Sailfin molly. They still mate with males from related species, but their male DNA does not end up in the offspring. Instead of mixing genes between two parents, they copied DNA segments from one chromosome to repair or replace damaged sequences on another, creating genetic variation and eliminating harmful mutations. The discovery could help scientists better understand crop genetics or diseases like cancer.