What color does human skin depend on? Pigment melanin
People are different: black, white, and still brown: from light to dark. Skin color varies from continent to continent. Where did this diversity come from? What determines the color of the human skin? What is melanin? Let's figure it out.
Melanin. What is it?
In medical terms, melanin is a pigment synthesized in skin cells called melanocytes. It is interesting that it is present in the bulk of animals, including humans. It is the pigment melanin that gives the skin a variety of shades. It is synthesized in two leading forms, the color of which can vary from yellow to dark brown and black. Eumelanin is a form of melanin, which gives the skin a brown color. The second form of melanin is pheomelanin, which has a reddish-brown hue. Thanks to pheomelanin people have freckles or fiery red hair.
Today almost everyone knows about genetics. Each of us inherited from his parents a set of chromosomes, including those responsible for the color of the human skin. The more active cells in cells, the darker the skin color. Not so long ago it was possible to observe a unique case in one family, where twins with different skin color were born. But in addition to the genetic predisposition to the production of melanin affect and external factors.
Effect of melanin on human
Any person on our planet has an approximately equal number of melanocytes. This fact proves that all people on the planet, whether white men or black girls, have the same skin. The question arises in the synthesis of melanin by a separate organism and some external factors. Under the influence of ultraviolet radiation, human skin begins to produce more melanin. This helps to prevent damage to DNA in the skin of a person.
So far, this process has not been fully investigated, but thanks to the protective reaction of the body, our skin remains undamaged. And among people living in the equator, where the sun's rays burn mercilessly, the skin has acquired its characteristic dark color.
failed. Unfortunately, there are exceptions to the rules. Today you can observe a rare disease - albinism. It is characterized by the lack of melanin in the skin cells. This process is observed in animals as well as in humans. We are happy to watch white animals, for example, you can see a white lion or a magnificent white peacock, but if this happens to a person, it is really a tragedy. A person can not stay in the open sun for a long time, his skin instantly burns. The body suffers from severe irradiation.
There is one more malfunction in the genetic program caused by the progressive loss of melanocytes, vitiligo. In this case, the skin becomes spotty. Whichever color of a person's skin predominates, with this disease it sometimes becomes completely white. And as a result, a black man by nature can become completely white. Unfortunately, for today genetic failures are incurable.
Light-skinned inhabitants of the planet
It is interesting that representatives of the white population make up 40% of all mankind. As we have already said, the genetically light color of the human skin is due to the activity of melanin in the cells. If we consider that people settled around the planet had features of a certain group and the color of the dermis, then in due course the isolation of the group led to the formation of a light-skinned race. Most of these people live in Europe, Asia and North Africa.
The color of a person's skin, as already mentioned, also depends on external factors. For example, in Northern Europe, people have a lighter derma than Asians. The sun's rays are less active in the north, and therefore, it's easier for white people to get the vitamin D necessary for the body. Although it should be noted that there are northern nationalities that have rather dark skin. According to the scientists, this also depends on food.
It is interesting that in people with light skin melanin in the upper layers of the epidermis is present in single specimens. The color of the eyes also depends on the layer of the iris in which a large amount of melanin is located. If this is the first layer, then the eyes will be brown, and if the fourth to fifth layers, then, respectively, blue or green.
The general population with dark skin color lives in Central and South Africa. People in this climatic zone are subject to intense sun exposure. And the effect of ultraviolet radiation causes in the human body a synthesis of melanin, which has a protective function. The result of constant exposure to the sun and became dark skin.
A distinctive feature at the gene level in people with black skin is that their cells produce melanin in large quantities. In addition, as scientists have found out, the top layer of the epidermis in such people completely covers the skin with a pigment. This fact gives the skin color from brown to almost black.
An interesting fact is that the melanin pigment appears in humans in embryonic development. But by the time of birth melanocytes practically disappear from the baby's body, and after birth begin to develop intensively in the skin. Many people are surprised when they see light kids at a black mother. The fact is that children are born light and darken over the next few months.
At this time, science is based on the fact that human skin color is the result of the adaptation of a certain group of people to the intensity of solar radiation in their habitat. Melanin in this case exercises protective functions from the ultraviolet radiation of the sun, in the absence of its skin would grow old very quickly. In addition to aging, the possibility of skin cancer is increased.
It is interesting that women have a slightly lighter skin than men. That's why black girls look much lighter than guys. In people with a light dermis this difference is almost not noticeable. Unfortunately, in today's world, skin color often breeds stereotypes. The division of humanity on this basis often leads to racial discrimination. But we all belong to the same species and we are people.