It's hard to believe, but ten thousand years ago, all people on earth had the same color - brown. Later, the gene responsible for eye color began to mutate. This led to a decrease in the production of melanin in the iris of the eye. The more this substance, the darker the eyes. Less melanin resulted in blue eyes.
This discovery was made in 2008 by Danish scientist Hans Eiberg. After research carried out under his leadership by a group of scientists from the University of Copenhagen, it was precisely established that the saturation of melanin, the iris "gives out" a different eye color.
Basic eye colors
There are two main colors - blue (gray, blue, blue in its range) and brown (brown, green). Brown eye color is dominant. However, most of the world's population is born with blue or grayish eyes, and only then they change their color.
This is due to the fact that at birth, melanin is completely absent in the iris. Only some peoples of Asia are born immediately with dark eyes - scientists explain this by the peculiarities of the gene structure. With a change in the pigmentation of the iris of the eyes (and this just depends on the saturation of melanin), the color also changes. Scientists have found that the final color of a person's eyes is formed by 2–3 years of age.
We know from our high school biology course that eye color depends on a specific set of genes. Who in school did not solve the problem of determining the color of the eyes of a child, whose mother has brown eyes, dad with blue eyes, and grandparents have gray, blue and green eyes.
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What determines eye color
However, Dutch scientists have conducted research denying the existence of a specific gene that affects eye color and which is inherited.
The experiment, conducted by scientists, involved volunteers, including many twins and their closest relatives. In the final report, the scientists noted that the mononucleotide chains in the gene, which was considered hereditary, strongly influence the final result, but they are not directly related to variations in eye color.
That is why, in school biological problems, the solution looked like a certain percentage of the child's possible eye color, but not an absolutely precise definition.
Disease by eye color
In some people, the iris changes color depending on the weather, lighting, clothing color, and even the state of the body. Why this is not characteristic of all people - specific answers to these questions have not yet been found.
But there is some research in this area too. Since ancient times, a method for diagnosing human diseases by changing the color of his eyes has been known. It is called iridology. In China, India, diseases were defined in this way three thousand years ago. Hippocrates also knew about him.
The first scientist of our time to seriously study this method was Ignacy Pekceli, who lived near Budapest at the turn of the 18th and 19th centuries. Once in his childhood he knocked down an owl with a stick.
When I began to lift it, I saw that a dark line appeared in the eye, which corresponds to the broken paw. The boy took the owl home and began to treat her broken paw. As he recovered, the streak disappeared.
Later becoming a doctor, Ignacy Pekceli began to seriously study this diagnostic method. In parallel with him, the pastor from Sweden Nils Liljekvist worked on the same. He developed a whole theory of recognition of various diseases by changes in the iris of the eyes.
Soviet scientists conducted research on this method on the basis of the Peoples' Friendship University of them. P. Lumumba. In parallel, they found that the color of the iris changes not only depending on those or other diseases. This can happen, for example, with age, when the work of all organs slows down, including the production of melanin decreases.
Nutrition can be another reason. For example, if you consume foods rich in beta-carotene, selenium, vitamin A daily, the production of melanin will increase.
Maria Pavlova