Old Blue Eyes and the Mutant Gene

Blue-eyed humans have a single, common ancestor – University of Copenhagen

Some 6-10,000 years ago, probably in the agricultural lands to the north east of the Black Sea, a person was born with strange, blue eyes. He or she was the common ancestor of all blue-eyed people alive today.

This is the conclusion of Professor Hans Eiberg and his colleagues from the Department of Cellular and Molecular Medicine, University of Copenhagen. They arrived at this conclusion after analysing the genes of a large Danish family to pinpoint the area of DNA responsible for regulating the OCA2 gene known to be the major contributor to human eye colour. This gene, HERC2 exists in a number of alleles, one of which is the mutation that causes blue eyes.

These mutations in regulator areas often act like switches, turn a gene on or off. However in the case of the blue-eye allele, it acts to reduce the activity of of the OCA2 gene, not abolish it altogether. If it had turned off the OCA2 gene altogether, carriers would have been born with no eye pigmentation, a condition known as albinism.

This mutation was found in 155 blue-eyed individuals from Denmark, 5 from Turkey and 2 from Jordan.

This mutation probably came into Northwest Europe with a migration of agriculturalists, the Yamanaya, from the Black Sea area. These people may have been responsible for introducing pale skin acquired from Neanderthals into Europe. Other studies have shown blue eyes may be subject to positive sex selection otherwise there is no biological advantage to blue, brown or intermediate eye colour. Because if this sex selection, however, it is not possible from genetic drift calculations to estimate the exact time when the mutation arose, however, its highly conserved nature suggests it was relatively recent.

Now, that's all very interesting as an analysis of how and when we got blue eyes, especially in Northwest Europe, but what does it tell us about the creationists dogmas about mutations always being detrimental? Manifestly, this is untrue. Without sex selection, blue eyes don't become detrimental. They become just another variant of human eye colour, none of which has any advantage over any other.

But what about that sex selection? Why on earth would an intelligent designer create a preference for blue eyes in a mate when blue eyes don't carry any benefits? And why would it wait until 6-10,000 years ago, then make the carriers migrate into one small corner of Eurasia?

Once again, the refutation of creationism comes purely incidentally by a simple exposition of the facts. Evolution explains it perfectly. Creationism, not at all. Tweet

Reference:

Eiberg, H., Troelsen, J., Nielsen, M., Mikkelsen, A., Mengel-From, J., Kjaer, K. W., & Hansen, L. (2008).
Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression.
Human Genetics, 123(2), 177–187. doi: 10.1007/s00439-007-0460-x

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