Scientists have been talking for a long time about the fact that people can lose the chromosome that determines male affiliation. A recent study by biologists from Denmark and the United States reopened this topic: according to their calculations, the Y chromosome in humans could completely disappear in 4.6 million years. What will happen to men?
To begin with, a short excursion into the school biology course Most of our hereditary information is contained in the chromosomes that are in the nucleus of each cell, and a person’s sex is determined by the combination of two sex chromosomes (or gonosome).
They are usually designated by the letters X and Y. This sex determination system works not only in humans, but also in the vast majority of mammals. The combination XX sets the development of the body according to the female type, XY – according to the male.
These two chromosomes are not similar to each other either in shape or in gene composition, although they were originally the same size and contained the same genes. The problem is that the Y chromosome is passed only from father to son, which means that the genes in it cannot combine, which is why negative mutations accumulate. With each generation, they are increasingly leading to the degradation of this chromosome. As biologists say, it becomes shriveled. In any case, against the background of the X chromosome.
In general, the male chromosome contains very few useful genes. The most important of them is the SRY gene, which determines the male sex of an organism and serves as a genetic “switch” for its development in the male pattern. There are also genes necessary for normal sperm formation. All the rest are genetic trash. Over the entire period of the existence of Homo sapiens, its Y chromosome has already lost 1393 of the 1438 genes originally present in it. And this process continues. Therefore, scientists have repeatedly expressed fears that the human Y chromosome may completely disappear in a few million years.
For example, Jenny Graves, a professor at Australian National University, likes to talk about it. “Men will lose completely in the battle of the sexes. The process is already running, ”she says. The researcher spends 5 million years on everything about everything. And he refers to examples from the animal kingdom.
Some species of rodents have already lost the Y chromosome: the Japanese spiny rat, the Transcaucasian mole vole, etc. And now a group of scientists from Denmark and the United States has published a new study, where an even shorter period is named: 4.6 million years. And, although the Y chromosome has developed several mechanisms that should slow down the process of its disappearance, the researchers are sure that this will not save it, although there has been a long debate about this in the scientific community. But will it save men?
“It is not the first time there are reports that the Y chromosome will disappear and men will disappear with it. As a justification, they put forward the fact that once the human ancestors had two sex chromosomes of the same size, and then one of them, which determines the male sex, began to lose genes and decrease in size, – says the head of the genome analysis laboratory of the Institute of General Genetics. – Do you need to fear such prophecies? No, men shouldn’t expect tricks from the Y chromosome.
First, not every process is going in one direction all the time. For example, a child is actively growing after birth. Should we conclude from this that it will grow throughout its life and grow to such a size that it will not crawl through any door? In evolution, the decrease and increase in size is also not infinite, they have their limits. Secondly, the very presence of a separate chromosome that determines the male mole is not at all necessary in nature.
There are species in which males do not have such a chromosome, they just have one less chromosome than females. Or sex is generally not determined by chromosomes, but by external conditions. Therefore, the study of the evolutionary history of the Y-chromosome is very interesting, but does not give any frightening predictions.”
Again, some species of rodents have already gone through this scenario. They still have males and females, and the breeding method is still the same, and the SRY gene, which determines sex, simply moved to another chromosome. It is not excluded that humanity will follow the same path.