Those of us with brown eyes might be jealous of our friends with pretty blue peepers, but it turns out that everyone in the world with the striking feature can be traced back to one single person.
Researchers from The University of Copenhagen discovered a genetic mutation that happened somewhere between 6,000 to 10,000 years ago in one person, likely in Europe. That person passed along the mutation to their descendants who then passed it on to their children.
Thousands of years later, the current 200 million people in the world that have blue eyes are all bound together by this common ancestor.
So how did this all happen?
“Originally, we all had brown eyes,” said Professor Hans Eiber, one of the authors on the study from the Department of Cellular and Molecular Medicine. “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.”
OCA2 is also the gene that affects whether people are born with albinism. If OCA2 is destroyed or turned off, people will be born without the ability to produce melanin.
Although it’s classified as a “mutation,” there’s nothing negative about it – or even positive. According to the study, it neither increases or decreases a human’s chance at survival. It’s similar to other mutations, such as having freckles or detached earlobes, in the sense that there’s no real advantage or disadvantage to having it.
“it simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so,” says Eiber.
It’s pretty cool when you think about it – if you have blue eyes, you’re somehow distantly related to Queen Elizabeth!