Originally, all humans had brown eyes, said Professor Hans Eiberg from the Department of Cellular and Molecular Medicine but new research shows that people with blue eyes have a single, common ancestor. The professor said a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a "switch," and "turned off" the ability to produce brown eyes. A team at the University of Copenhagen tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of all blue-eyed humans alive on the planet today.