Why are blue eyes blue?
The sappy 70's song "Don't it make my brown eyes blue" inevitibly leads us to think about whether brown eyes can be turned blue. Maybe the song was inspired by colored contact lenses! But why are there variations in eye color? Why are there so few blue-eyed people?
An article in the journal Human Genetics from 2008, indicates that blue eyes are the result of a single gene mutation that occurred between 6000 and 10000 years ago. The article was written by a cellular molecular biologist, Hans Eiberg.
"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," Eiberg said.
The genetic switch is located in the gene adjacent to OCA2 and rather than completely turning off the gene, the switch limits its action, which reduces the production of melanin in the iris. In effect, the turned-down switch diluted brown eyes to blue.
In some patients, this switch