Men may disappear: what's happening to the Y chromosome and what science says about it

The Y chromosome is responsible for determining sex in humans and other mammals. However, studies show that this chromosome is gradually degenerating and may disappear in a few million years.

This may lead to the extinction of humanity, or people will have a new gene responsible for sex, according to ScienceAlert.

For now, the only good news is that two groups of rodents on Earth have already lost their Y chromosome and continue to exist. A recent scientific study found that the first to experience this were baggy rats, which have developed a new sex-determining gene.

Women have two X chromosomes, while men have one X and a small Y chromosome. The X chromosome contains about 900 genes that perform a variety of functions not related to sex. At the same time, the Y chromosome has a much smaller number of genes (approximately 55) and a lot of non-coding DNA, often called "junk", which is simply a repeating sequence without any functional role.

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Nevertheless, the Y chromosome contains a key gene that determines male sex in the early stages of embryo development.

At 12 weeks after conception, this gene activates other genes responsible for testicular development. The embryonic testes then begin to produce male hormones, such as testosterone and its derivatives. It is this process that determines whether a boy will be born.

In 1990, a major sex gene called SRY was identified, which initiates a genetic pathway through the SOX9 gene that is central to determining male sex in all vertebrates.

It is known that in most mammals, including humans, the X chromosome has more genes than the Y chromosome, which leads to inequality in gene dosage between males and females.

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But how did such an unusual system come about? Scientists believe that a study of Australian platypuses, which have completely different sex chromosomes, may shed some light on this question. In platypuses, the XY pair is an ordinary chromosome with an equal number of genes.

This suggests that in mammals, the X and Y chromosomes were once a common pair. It also means that the Y chromosome has lost 900-55 active genes over 166 million years, a time in which humans and platypuses have evolved separately. Thus, the Y chromosome has lost approximately 5 genes per million years. If this process continues, the Y chromosome could lose its last 55 genes in the next 11 million years.

From an evolutionary point of view, the disappearance of the Y chromosome seems inevitable. However, humanity still needs men and their sperm to reproduce. Does this mean that the disappearance of the Y chromosome will lead to the extinction of humanity?

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A new study has shown that there is a possible alternative - people may develop a new sex-determining gene. But the evolution of a new sex gene carries certain risks. For example, if different sex determination systems emerge in different regions of the world, it could lead to several different kinds of people on the planet.

Thus, in 11 million years, humanity may either disappear or there will be several different kinds of people with different sex determination systems on Earth.

Earlier, we told you that scientists have discovered a hidden code in human DNA that could be the key to developing new treatments.

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