According to a new study by the University of Copenhagen, people with blue eyes most likely share a common ancestor who lived 6,000 to 10,000 years ago:
“Originally, we all had brown eyes,” Professor Hans Eiberg of the University of Copenhagen said in a press release. “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.”
I can’t say I understand all the DNA explanations for how this switch happened — you can read all about it here — but the article says the genetic mutation didn’t completely deactivate the gene that determines eyes, hair, and skin — if it had, all blue-eyed people would be albinos.
The research team believes the mutation happened in the northern area of the Black Sea, meaning that they assume “the first blue-eyed humans were among the proto-Indo-Europeans who subsequently spread agriculture into western Europe and later rode horses into Iran and India.”
Since blue eyes are a recessive trait, the gene must be inherited from both parents. It wouldn’t have been until the original mutant’s grandchildren or great-grandchildren got together that the very first blue-eyed person was born. Imagine how weird that must have been.
The mutation also increases the likelihood of blond hair and fair skin, which stimulates greater production of vitamin D — a requirement for health and survival in sun-deprived northern places.