Posted by: tiffanyakraus | November 1, 2015

Brown Eyed Girl Turned Blue

He had these eyes. They were blue and they looked bluer because he had a dark head of hair. They were soulful, in some way; they seemed to say things that I knew he’s probably never say out loud.     — Audrey Bell

I have always been captivated by eye color. My mother and I both have stormy blue eyes, my brother dark, light absorbing brown eyes, and my grandmother’s eyes are sea foam green. As a young child I wondered how three generations could have such a variation in shade and color. It wasn’t until I was 10, and the family got its first computer and internet access, that I was able to research this question.

There are several genes that regulate pigment particles in the eye. Currently, 8% of the world’s population is estimated to have blue eyes. Ireland has the most with 57% of their population sporting the color. The blue color variation goes back at least 6,000 if not 10,000 years. Before that, all eyes were some variant of brown. A single mutation in a solitary individual introduced blue eyes to the world’s population.

Professor Hans Eiberg and his team at the University of Copenhagen found the mutation in the OCA2 gene codes for the P protein that is involved in the production of melanin (the pigmentation that controls eye, skin, and hair color). While not completely turned off, the mutated gene causes less melanin to be produced in the eye. Other than changing the eye color, this can also cause lighter eyed people to have a higher risk for many UV related eye diseases.

Melanoma of the uvea is one of the more common possibilities. This form of cancer causes melanocyte cells to become cancerous in the choroid, ciliary body, and iris. Several treatments are available including surgery and plaque therapy (a type of radiation treatment). One of the best ways to stop this or other eye conditions is to protect your eyes from UV damage by wearing proper sun protection.

Pigmentation is also linked to other parts of the body. Separate studies have shown people with lighter colored eyes have higher tolerances for alcohol but are also more likely to abuse it. These people are able to imbibe more libations than their darker eyed companions. There are a few theories on why this is.

One explanation is that the darkness of the eye is connected to neural transmissions in the central nervous system (sheaths of melanin cover neuronal axons that may act as an insulator). This connection would give blue and other light eyed people slower neural transmissions because of the lack of melanin. In laymen’s terms, the brain isn’t getting the response it needs to know if a person is drunk. So, as they say on Tumblr, you might want to slow your roll if you have blue eyes and like to party.

The human eye and its history are amazing. From mutations to libations, there is much to learn. Join me next time when I cover the wonders of brown eyes.

Sources:

http://www.edinburghnews.scotsman.com/news/health/why-edinburgh-residents-are-likely-to-be-blue-eyed-1-3577755

http://www.sciencedaily.com/releases/2008/01/080130170343.htm

http://www.kellogg.umich.edu/patientcare/conditions/uveal.melanoma.html

http://www.unt.edu/rss/class/mike/5700/eyecoloralcohol.pdf

Title Credit:

http://www.roxette.se/

About the author: Tiffany Kraus is a territory sales manager for Amcon Labs who writes in her spare time.  She will do anything to slip in her favourite comic book, movie, or TV show characters into her writing especially if they are a pirate. For medical advice please ask a medical professional.

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