Thursday, January 31, 2008
One Common Ancestor Behind Blue Eyes
By Jeanna Bryner, LiveScience Staff Writer
posted: 31 January 2008 08:34 am ET
People with blue eyes have a single, common ancestor, according to new research.
A team of scientists has tracked down a genetic mutation that leads to blue eyes.
The mutation occurred between 6,000 and 10,000 years ago. Before then, there were no blue eyes.
"Originally, we all had brown eyes," said Hans Eiberg from the Department of Cellular and Molecular Medicine at the University of Copenhagen.
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.
"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.
If the OCA2 gene had been completely shut down, our hair, eyes and skin would be melanin-less, a condition known as albinism.
A little bit of commentary seems appropriate here.
There are those among us, actually probably a majority,
for whom this article will be no surprise.
They will say: "Yes we know, between 6 and 10 thousand
years ago, her name was Eve..."