Today lets talk all about blue eyes! Shall we??
Blue eyes contain low amounts of melanin within the iris stroma; longer wavelengths of light tend to be absorbed by the underlying iris pigment epithelium, and shorter wavelengths are reflected and undergo Rayleigh scattering. The type of melanin present is eumelanin.
The outer surface of the iris of a blue-eyed person is clear, lacking the outer layer of pigmentation that is found in brown eyes. Their color is caused by the inner layer of pigmentation and the semi-opaque fibrous tissues that lie between the two layers.
Blue eyes are most common in the Baltic Sea region, Northern, Eastern and Central Europe, and to a lesser degree in Southern Europe. Blue eyes are also found in parts of the Middle East, most notably in Iran and Afghanistan as well as in the Levant, especially amongst the Jewish population of Israel.
While blue eyes are thought to be exclusive to Caucasoid ethnic groups, the manifestation of blue eyes has been documented in pure-blooded, darkly complected tribal Africans, as well as people of mixed African and European ancestry; the former, usually the result of genetic mutation and the latter most often the manifestation of recessive European genes.
Y-Chromosome DNA testing performed on ancient Scythian skeletons dating to the Bronze and Iron Ages in the Siberian Krasnoyarsk region found that all but one of 11 subjects carried Y-DNA R1a1, with blue or green eye color and light hair common, suggesting mostly European origin of that particular population.
A 2002 study found that the prevalence of blue eye color among Caucasians in the United States to be 33.8 percent for those born from 1936 through 1951 compared with 57.4 percent for those born from 1899 through 1905.
Blue eyes are continuing to become less common among American children, with only one out of every six or 16.6% of the total population, and 22.3% of the White population having blue eyes.