People are different: black, white, and also brown: from light to dark. Skin color varies from continent to continent. Where did this diversity come from? What determines the color of a person's skin? What is melanin? Let's find out.
Melanin. What is this?
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 that range in color from yellow to dark brown to black. Eumelanin is the form of melanin that gives skin its brown color. The second form of melanin is pheomelanin, which has a reddish-brown hue. Pheomelanin gives people freckles or fiery red hair.
Today almost everyone knows about genetics. Each of us inherited a set of chromosomes from our parents, including those responsible for human skin color. The more active genes in the cells, the darker the skin color. Not so long ago it was possible to observea unique case in one family where twins with different skin colors were born. But in addition to the genetic predisposition, external factors also influence the production of melanin.
The impact of melanin on humans
Every person on our planet has approximately the same 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 prevent DNA damage in human skin.
Until now, this process has not been fully explored, but thanks to the protective reaction of the body, our skin remains intact. And people living around the equator, where the sun's rays scorch ruthlessly, have acquired a characteristic swarthy skin color.
Crash in the program
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 in both animals and humans. We enjoy watching snow-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 cannot stay in the open sun for a long time, his skin burns instantly. The body suffers from strong radiation.
There is another failure in the genetic program caused by the progressive loss of melanocytes - vitiligo. In this case, the skin becomes patchy. Whatever color of a person's skin prevails, with this disease it becomes completely white in places. And as a result, a dark-skinned person by nature can become completely white. Unfortunately, today genetic failures are incurable.
The light-skinned inhabitants of the planet
An interesting fact is that representatives of the white population make up 40% of all mankind. As we have already said, the genetically light color of human skin is due to the activity of melanin in the cells. If we take into account that the people who settled on the planet had facial features and dermis color characteristic of a certain group, then over time 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.
Human skin color, as already mentioned, also depends on external factors. For example, people in Northern Europe have lighter skin 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 necessary for the body. Although it should be noted that there are northern peoples who have rather dark skin. According to scientists, it 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 athis is the first layer, then the eyes will be brown, and if the fourth or 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 solar 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 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 pigment. This fact gives the skin a brown to almost black coloration.
An interesting fact is that the melanin pigment 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 develop intensively in the skin. Many people are surprised when they see light-colored babies from a dark-skinned mother. The thing is, babies are born light and darken over the next few months.
And finally
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 performs protective functions from the ultraviolet radiation of the sun, in the absence of its skinwould fade very quickly. In addition to aging, there is an increased risk of skin cancer.
Interestingly, women have slightly lighter skin than men. This is why black girls look much lighter than guys. In people with a light dermis, this difference is practically not noticeable. Unfortunately, in today's world, skin color often gives rise to stereotypes. The division of mankind on this basis often leads to racial discrimination. But we all belong to the same species and are human.
