All blue-eyed people have a single, shared ancestor, scientists say. And all those baby blues are the result of a genetic mutation that occurred between 6,000 and 10,000 years ago, LiveScience reports. Before that, everyone had brown eyes. The mutation limits the effects of the gene that produces melanin, which colors our eyes and hair, thus diluting browns to blues.
"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," said one researcher at the University of Copenhagen. Today, up to 40% percent of Europeans have blue eyes. "This gene does something good for people," said another researcher. "It makes them have more kids." (Read more science stories.)