Tuesday, February 14, 2017
Blue-eyed humans have a single, common ancestor
A genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a switch, which turned off the ability to produce brown eyes. The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives color to our hair, eyes and skin. Variation in the color of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals 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, says Professor Eiberg.
I think mutation of brown eyes to blue represents neither a positive nor a negative mutation. It is one of several mutations such as hair color, freckles and beauty spots. I think this simply shows that nature is constantly mixing the human genome, and creating all sorts of possibilities.