According to a story on Physorg.com, researchers at the University of Copenhagen have concluded that all blue-eyed people on the planet are descended from a single ancestor who lived six to ten thousand years ago. The ancestor was the first to have a genetic mutation that reduces the amount of melanin in the iris of the eye:
“Originally, we all had brown eyes”, said Professor Eiberg from the Department of Cellular and Molecular Biology. “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”.
Brown- and green-eyed people have a large variation in the amount of melanin in the iris, which is caused by the OCA2 gene, but all blue-eyed people have only a small variation. This lead the researchers to conclude that all blue-eyed people are linked to the same ancestor. Blue-eyed people “have all inherited the same switch at exactly the same spot in their DNA,” from this single ancestor. By studying the mitochondrial DNA in blue-eyed people in many countries over the last ten-plus years, the researchers were able to estimate the date the mutation causing blue eyes arose.
It is surprising that something so common as blue eyes is such a relatively recent genetic occurrence. More and more studies are concluding, however, that genetic changes in humans are not only still going on, but may actually be accelerating. Indeed, a U.C. Davis economic historian, Gregory Clarke, has speculated that behavioral changes, which may have partially arisen from the process of evolution, could be responsible for the Industrial Revolution. His thesis, in a book entitled A Farewell to Alms, is that “middle class” behaviors like thrift, prudence, literacy, and hard work became more widespread because those behaviors made people wealthier, and wealthier people had more offspring than poor people. According to an article in the New York Times:
As the progeny of the rich pervaded all levels of society, Dr. Clark considered, the behaviors that made for wealth could have spread with them. He has documented that several aspects of what might now be called middle-class values changed significantly from the days of hunter gatherer societies to 1800. Work hours increased, literacy and numeracy rose, and the level of interpersonal violence dropped.
Another significant change in behavior, Dr. Clark argues, was an increase in people’s preference for saving over instant consumption, which he sees reflected in the steady decline in interest rates from 1200 to 1800.
“Thrift, prudence, negotiation and hard work were becoming values for communities that previously had been spendthrift, impulsive, violent and leisure loving,” Dr. Clark writes.
The possibility that our modern industrial society results from relatively recent genetic changes that affected behavior leads me to wonder — what’s next?
(Photo from Flickr.com by BigBlonde, used under a Creative Commons License.)
Categories: Science