People are different: black, white, and brown: from light to dark. Skin color varies from continent to continent. Where did such a variety come from? What determines the color of a person’s 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. Interestingly, 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 that gives the skin a brown color. The second form of melanin is pheomelanin, which has a reddish-brown tint. Thanks to pheomelanin, people have freckles or fiery red hair.
Today, almost anyone knows about genetics. Each of us inherited from our parents a set of chromosomes, including those responsible for the color of human skin. The more active genes in the 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 colors were born. But in addition to a genetic predisposition, external factors also influence the production of melanin.
Human exposure to melanin
Any person on our planet has an approximately equal number of melanocytes. This fact proves that all people on the planet, whether they are white-skinned men or black-skinned girls, have the same skin integument. The question arises in the synthesis of melanin by an individual organism and some external factors. Under the influence of ultraviolet radiation, human skin begins to produce a greater amount of melanin. This helps prevent DNA damage in the skin of a person.
Until now, this process has not been fully studied, but thanks to the protective reaction of the body, our skin remains intact. And in people living in the equator region, where the sun's rays scorch mercilessly, the skin has acquired its characteristic dark color.
Program crash
But unfortunately, there are exceptions to the rules. Today you can observe a rare disease - albinism. It is characterized by the absence of melanin in the skin cells. This process is observed both in animals and in humans. We are happy to watch snow-white animals, for example, you can see a white lion or a magnificent white peacock, but if this happens to a person, this is really a tragedy. A person can not be in the open sun for a long time, his skin burns instantly. The body suffers from severe exposure.
There is another malfunction in the genetic program caused by a progressive loss of melanocytes - vitiligo. In this case, the skin becomes spotty. Whatever the color of a person’s skin prevails, in this disease it sometimes becomes completely white. And as a result, a black man by nature can become completely white. Unfortunately, genetic failures are incurable today.
Fair-skinned inhabitants of the planet
An interesting fact is that representatives of the white-skinned population account for 40% of all humanity. As we have already said, the genetically light color of human skin is due to the activity of melanin in the cells. If we consider that people who settled on the planet had facial features and the color of the dermis characteristic of a certain group, then over time the isolation of the group led to the formation of a fair-skinned race. Most of these people live in Europe, Asia and North Africa.
Human skin color, as already mentioned, also depends on external factors. For example, in Northern Europe, people have a lighter dermis than Asians. The sun's rays are less active in the north, and therefore it is easier for white people to get the vitamin D needed by the body. Although it should be noted that there are northern nationalities that have fairly dark skin. According to scientists, this also depends on food.
Interestingly, in people with fair skin, melanin in the upper layers of the epidermis is present in single copies. Eye color also depends on which layer of the iris contains a large amount of melanin. If this is the first layer, then the eyes will be brown, and if the fourth to fifth layers, then, respectively, blue or green.
Black people
The main population, with dark skin color, lives in Central and South Africa. People in this climate zone are exposed to intense sun exposure. And exposure to ultraviolet radiation causes the synthesis of melanin in the human body, which has a protective function. The result of constant exposure to the sun and became dark skin.
A distinctive feature at the genetic level in people with black skin is that their cells produce large amounts of melanin. In addition, as scientists have found out, the upper layer of the epidermis in such people completely covers the skin with pigment. This fact gives the skin a color from brown to almost black.
An interesting fact is that the pigment melanin appears in humans even in embryonic development. But by the time of birth, melanocytes practically disappear from the baby's body, and after birth they begin to intensively develop in the skin. Many people are surprised when they see light babies with a black mother. The fact is that children are born light and dark over the next few months.
In conclusion
At this time, science is starting from the fact that the color of a person’s skin is the result of the adaptation of a certain group of people to the intensity of solar radiation in their habitat. In this case, melanin carries out protective functions from the ultraviolet radiation of the sun, in the absence of which its skin would senile very quickly. In addition to aging, the risk of skin cancer increases.
Interestingly, women have slightly lighter skin than men. That is why black girls look much lighter than guys. In people with light derma, this difference is almost not noticeable. Unfortunately, in today's world, skin color often generates stereotypes. The division of humanity on this basis often leads to
racial discrimination. But we all belong to the same species and are human beings.