Behind Blue Eyes

Somewhere between 6,000 and 10,000 years ago the first milkman was questioned by a suspicious husband.

A team of scientists believe they have tracked the genetic mutation that leads to blue eyes, pointing to that period of as thier first appearance.

The mutation affected the so-called OCA2 gene, which is involved in the production of melanin, the pigment that gives color to our hair, eyes and skin. The genetic switch that gets flipped is located in the gene adjacent to OCA2, but 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.

Before then, the scientist say everybody had brown eyes.

For more scientific discourse, Crystal Gayle weighs in on the topic: