Brown eyes – deep, attractive, about them sing songs, and writers select refined epithets in the works. But very few people think what is responsible for color of eyes at the person and why brown eyes brown?
Color of eyes directly depends on pigmentation of an iris of the eye. The iris consists of two layers – ektodermalny and mesodermal. Color of eyes also depends on the nature of distribution of pigments between these layers. The external layer of an iris of the brown-eyed person comprises melanin more, than an iris of the owner of light eyes. The external layer of an iris of the eye absorbs low-frequency light, and reflected gives dark, brown color. And, the concentration of melanin is higher, the eyes will be more dark. Most often owners of brown eyes live or are closer to the equator, or in the north. It is explained by the fact that dark light of eyes protects from bright sunlight more effectively. Protection, sunlight is also necessary for northerners, being reflected from snow, will stick together not worse, than the sun in the south. Eyes become brown not at once. Often babies are born with light eyes, and only by two-three years of their eye become brown. To this age at them in a front layer of an iris of the eye enough pigment of melanin is developed. Color of eyes is the inherited sign passing from father to son. And brown color is prepotent sign. Scientists consider that brown color of eyes was the basic at far ancestors of recent people until about 10 thousand years ago one person had a mutation as a result of which color of his eyes became light. This first blue-eyed person also gave the mutating gene to all generations of light-eyed people. Color of eyes at the person can change during all life. There is it not only in infancy when the iris of the eye accumulates melanin, but also in old age when the mesodermal layer loses the elasticity. An eye can change color because of the postponed disease and also play options of shades depending on clothes, cosmetics and even mood of the person.