The error of evolution
Where do blue-eyed blondes disappear to
Blue—eyed blondes are mutants that appeared 6 thousand years ago among brown-eyed brunettes. Since then, they have gained insane popularity. But geneticists predict a steady decline in their numbers. Can blond and light-eyed inhabitants of the planet disappear?
The color of the eyes, hair, skin is affected by melanin — a special pigment. Depending on its quantity in special cells of melanocytes, a certain color is obtained. The end result depends on the genes.
From the point of view of evolution, melanin is a useful pigment, it protects the body from excessive ultraviolet radiation, which can cause the growth of cancer cells.
"In Africa, this is relevant, people have dark eyes, hair and skin. Otherwise, with such an amount of light, there would be a lot of cancerous tumors," he said Sibnet.ru Head of the Museum of the History of Genetics in Siberia Ivan Sinitsyn.
Initially, all people on Earth were dark-haired and brown-eyed, but about 6-10 thousand years ago an unusual mutation appeared in northern Europe. There were people with blond hair, skin and eyes.
This mutation does not give a special advantage in terms of survival, but blue eyes and blond hair turned out to be very attractive to the opposite sex. Therefore, the mutation began to spread. Especially in the northern latitudes, where there is not so much dangerous solar radiation.
Blue -eyed rarity
Gradually, a variety of hair and eye colors was formed. Two types of melanin are responsible for this diversity. Eumelanin (DOPA-melanin) is a black-brown pigment. It is its quantity that creates different shades.
If there is not enough eumelanin, then the hair is light, and if there is a lot, dark. The situation with the eyes is similar: with an abundance of eumelanin, a person has brown eyes, and with a small amount — blue or gray. The average amount of pigment gives green eyes.
Another variety is pheomelanin (yellow-red pigment). Thanks to this pigment, red hair is obtained. This is the rarest hair color, in order for it to turn out, there must be little eumelanin (dark pigment) and a lot of pheomelanin (red).
A person may completely lack melanin — then it is an albino. He has white hair and reddish eyes. The thing is that the iris of the eye in this case is not colored and blood vessels are visible through it.
In any case, except for albinos, the color of the iris is heterogeneous, even in black-eyed people. The fact is that the melanin level in the cells is slightly different and because of this, darker and lighter areas are obtained.
Previously, it was believed that eye color obeys the classical laws of genetics. That is, a lot of melanin is a dominant (leading) sign, and a little melanin is recessive.
"It turned out that everything is much more complicated, more than one gene is involved in this process, so it cannot be said that two brown—eyed parents cannot have a blue-eyed child," Sinitsyn noted.
But still dark shades dominate over light ones. And now, when people are actively moving around the world and mixing genetic material, the probability of blue-eyed people is decreasing. Blondes, redheads, people with light eyes are becoming less common.
However, scientists do not assume the complete disappearance of blondes. "These signs cannot completely disappear. They could disappear only if they had a negative impact on the survival of the species. Then the number of alleles would decrease, but there is no such thing," the geneticist predicted.
And it's too early to call this mutation an evolutionary mistake. Blue eyes and blonde hair appeared only 6 thousand years ago, and this is very little by evolutionary standards for nature to come to some final conclusion about the benefits of change.
"It cannot be ruled out that a new mutation will arise, which will once again change pigmentation, and people will like the new option," the interlocutor concluded.
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