Amazing Facts About Eye Colors You Probably Didn't Know

Fact about Eye Colour

Fact about eye color: 
Today, there is an infinite number of variations in eye color, and the prevalence of this or that shade differs in different geographical areas. But has it always been so?

Scientists have proved that about 10 thousand years ago the entire population of the Earth was brown-eyed. This color of the eyes and now occurs most often - in 70-90% of people. The second after the blue appeared a blue hue. This was due to a mutation - a reduction in the amount of melanin in the iris. 

Scientists distinguish from 12 (according to the system of the Soviet anthropologist V. V. Bunak ) to 16 (on the scale Martin-Schulz, adopted in the West) eye shades. Among them - all kinds of variations of blue, blue, brown, gray, yellow, green and even black (which is actually dark-dark brown) and yellow.                                                       

The overwhelming majority of children in Europe are born with blue eyes, and this shade persists for about a year, although dark pigmentation may appear already in the fourth month of life. The reason for the changes is that melanin begins to accumulate in the iris. But only by three years to judge the color of the child's eyes can for sure, although to ten or twelve years the shade can still continue to change. In the elderly, the iris can again turn pale due to reduced pigment production. Also sometimes the shade varies due to some diseases. For example, with melanoma, it darkens, and with leukemia lightens. 

The degree of prevalence of this or that color of eyes in different corners of the planet is explained by the gene pool of this or that nationality. For example, the majority of the blue-eyed population comes from Northern Europe, Ireland, and England. And among the representatives of the Negroid race in America, the percentage of people with black eyes is relatively high (11.9%). 

The rarest color of the eyes on the ground is green if one does not take into account its variations (gray-green, green with yellow-brown impregnations). Only 2% of the world's population can safely call themselves green-eyed. Another very rare shade - red - is solely the consequence of albinism. In such cases, the melanin pigment is completely absent in the mesodermal and ectodermal layers of the iris, so the color of the blood in its transparent vessels is visible. Sometimes the shade of the eyes in albinos is even violet if the red is superimposed on the blue color, which is reflected when the light is scattered in the stroma - the transparent part of the cornea.

By the color of the eyes, you can identify some diseases. For example, an absolutely black shade of the eye indicates the absence of the iris - aniridia, which leads to a reduction in visual acuity, photophobia, and other problems.

 yes can be of different colors, and sometimes only a single part of the iris can have a different shade. These are two variants of heterochromia, which is much more common in animals than in humans. Most often, the bearers of this deviation are white cats of some breeds and Siberian husky.  

There is a direct relationship between the eye color and the degree of their protection from ultraviolet, which in large doses can have a destructive effect on the retina.