The ‘DNA Testing’ or test to know your ethnic origins, is one of those pieces that the Internet went viral at some point, just at the moment when a whole generation (or perhaps more than one) transferred in the networks that phrase of “we are from a place called the world”: okay, but from what place. Looking to the past has become a lifeline for all those people from an uncertain future. Who I am, where I’m from, why I’m like that.
Our physique is just the beginning of an absolutely sidereal journey… From height to the color of our skin or that of our eyes. Yes, it will be true that the eyes are the mirror of… of our ancestors.
“Originally, we all had brown eyes,” says Professor Hans Eiberg, a member of the Department of Cellular and Molecular Medicine at the University of Copenhagen. Do you have blue eyes? A team of researchers led by Eiberg has tracked down a genetic mutation that took place between 6,000 and 10,000 years ago and is the cause of it.
When the brown went out
All the blue-eyed people living on the planet today, and everyone who lived, share much more than the color of their eyes. Lighter, darker, blue emerged from a genetic mutation that affected the OCA2 gene on the human chromosome. Then came a “switch that literally ‘turned off the ability to produce brown eyes.”
According to Eiberg, the OCA2 gene encodes the so-called P protein, which is involved in the production of melanin, the pigment that gives color to our hair, eyes, and skin. However, the “switch,” which is found in the gene adjacent to OCA2, does not deactivate the gene completely but limits its action to reducing melanin production in the iris, which effectively “dilutes” brown to blue eyes. Here’s the answer: People with brown eyes have considerable individual variation in the area of their DNA that controls melanin production.
To achieve this, Professor Eiberg and his team examined mitochondrial DNA and compared the eye color of blue-eyed individuals in countries as diverse as Jordan, Denmark, and Turkey. His findings are the latest in a decade of genetic research, which began in 1996 when he himself first implicated the OCA2 gene as responsible for eye color.
The constant changes in nature
This mutation from brown to blue eyes is neither positive nor negative. It is, simply, one more of many others: hair color, baldness, freckles and moles… and countless of them that make up human diversity. As Professor Eiberg says, “it simply shows that nature is constantly mixing the human genome, creating a genetic cocktail of human chromosomes and testing different changes as it does so.”
Yet another change is, in fact, the variation in eye color from brown to green. In this case, the explanation would be in the amount of melanin in the iris, while people with blue eyes only have a small degree of variation in the amount of melanin in their eyes. “From this, we can conclude that all blue-eyed individuals are linked to the same ancestor,” Eiberg concludes: “They have all inherited the same switch in exactly the same place in their DNA.”