Every inhabitant is well aware that in the summer you need to walk in white. Because things of light shades are much weaker basking in the sun. Pulling on black clothes in the summer heat is not the best idea. But the question arises: if black absorbs the sun's rays so well, then why did evolution make the indigenous people of Africa not white, like albinos, but black as night? Let's try to figure it out.
So, the darker part of the color spectrum, the worse it reflects and the better it absorbs the sun's rays. It is for this reason that dark objects heat up a lot, and light ones much less. However, things are not so simple with humans. No matter how much we love the sun's rays, the light of a distant star is dangerous for a person. The main enemy of health in this matter is ultraviolet radiation, which has an extremely negative effect on humans. In the short term, long-term UV exposure to the skin creates burns and wrinkles. In the long term, it changes the DNA structure of human integument cells and leads to the development of cancer.
Evolution has endowed man with many protective tools that allow him to adapt to an aggressive environment. For example, skin cells produce a substance called melanin. The stronger and the longer ultraviolet exposure to human skin, the more melanin is produced in its cells. Melanin, in turn, increases the level of absorption and the degree of neutralization of ultraviolet radiation. So, when a girl returns from the beach beautifully tanned, know that right now her body is screaming: “What are you doing?! Ultraviolet is dangerous! Urgently send us 15 more trucks with melanin!!!” In other words, skin darkening is the body's response to the effects of ultraviolet radiation. And yes, as you might have guessed, it is melanin that makes the skin dark.
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What does all this have to do with the indigenous inhabitants of Africa? The most immediate. The fact is that in representatives of the Negroid race and numerous mulattoes, the genetic structure differs from representatives of the Caucasian race precisely in the issue of melanin production in skin cells. Indigenous Africans have lived for so long in conditions of aggressive exposure to sunlight that for many millennia increased production of melanin in skin cells has turned from a situational response of the body into its normal condition. Without such an evolutionary solution, our distant common ancestors who lived in Africa most likely simply died out. At the same time, the evolutionary process turned out to be reversible. When ancient people migrated from Africa to other parts of the planet with less UV exposure, their skin gradually lost its dark hue, as the normal production of melamine in cells from generation to generation decreased.
Why, then, do not modern black Americans “turn white”? Firstly, they gradually “turn white”, if only because the process of mixing people with different sets of genes is going on in society. Fortunately, apartheid in the United States was more or less able to win in the 1960s. And now, marrying “black” to “white” and “white” to “black” is not considered something reprehensible in society. However, now there is some gloomy ironic bias in public relations in the opposite direction. Secondly, for such a radical evolutionary transformation as a complete change in skin color, not even centuries are needed. The necessary thousands of years, if not tens of thousands of years, as well as hundreds and thousands of generations of people.
If you want to know even more interesting things, then you should read about "dark-skinned horsemen": who are they and where did they come from in Abkhazia.
Source: https://novate.ru/blogs/080322/62360/