The Register reports:
A University of Copenhagen team has identified the gene which around 6-10,000 years ago underwent a genetic mutation in one individual who eventually gave rise to all blue-eyed people.
Professor Eiberg from the Department of Cellular and Molecular Medicine began his research in 1996, when he "first implicated the OCA2 gene as being responsible for eye colour", as ScienceDaily puts it.
Over the next decade, he and his colleagues "examined mitochondrial DNA and compared the eye colour of blue-eyed individuals" in countries including Denmark, Jordan and Turkey.
Eiberg explained: “Originally, we all had brown eyes. But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a 'switch', which literally 'turned off' the ability to produce brown eyes."