Which at least would explain the saying ‘Well, I’ll be a monkey’s uncle.’

The split between the human and chimpanzee lineages, a pivotal event in human evolution, may have occurred millions of years later than fossil bones suggest, and the break may not have been as clean as humans might like.

A new comparison of the human and chimp genomes suggests that after the two lineages separated, they may have begun interbreeding.

The New York Times