Misconceptions About Eye Pigmentation

New findings have pinpointed the faults in classifying eye color under distinct color descriptors such as blue, green, and brown instead of as certain hues on a continuous gradient.  Use of these broad descriptors in previous studies does not accurately depict eye color or melanin concentration, the pigmented compound found in cells of the eye, skin, and hair that provides protection from ultraviolet light.  A lower concentration gives the appearance of “blue,” with a gradual shift to “brown” as concentration increases.  Species have adapted to certain amounts of melanin in different environments, which is supported by the fact that eye color appears characteristic of certain species.  It is interesting to note that viruses that attack this pigmentation can even be known to change eye color. 

Manfred Kayser of the Erasmus University Medical Center Rotterdam, The Netherlands, quantified the eye colors of 6000 Europeans, demonstrating the immense variations among eye pigmentation, despite the ease of slipping into the basic classifications of blue, green, and brown.  Further research has led to the discovery of different loci associated with eye color, one of which, the LYST gene, was recognized for its pigmentation in other animals.  The other two [unnamed] genes had previously been unlinked with pigmentation.  These three genes compose over 50% of eye color classification, the closest scientists have come.  However, there is still much left to be discovered in terms of predicting eye color.

http://www.sciencedaily.com/releases/2010/05/100506172731.htm