The Y chromosome disappears: will this be the end of humanity?

It is well known that biological sex In humans, as in other mammals, this is described by their sex chromosomes. As for women, they have two X chromosomeswhereas men have one X accompanied by a Y chromosome. But what happens if the Y chromosome disappears? Will we be there until the end of humanity? What about the human race? These may all seem like pointless questions, but they’re actually not that pointless because there are studies that show that it actually disappears.

This is not something that should concern us much since it is estimated that some of them are missing. 11 million years for his disappearance. If we don’t destroy the planet by then, people as we know them could disappear. And the human race would do this to him, since there is only one thing for which women, without exception, need men: breed.

Some animals, especially reptiles, They have the ability to reproduce by parthenogenesis. This occurs when females do not have the opportunity to interact with a male, so they initiate another form of reproduction that does not require sperm. But in the case of humans, this would not be feasible, since the embryo needs to receive some genes that must necessarily come from the father. Hence loss of Y chromosome Can mean end of the human race. Luckily, if we go the way of some rats, things aren’t too bad. They had already lost the Y chromosome and their species lived to… scream about it?

Why does the Y chromosome disappear?

Chromosomes are like little packets of DNA. This may be encoding or non-encoding. The first type includes genes containing information necessary for protein synthesiswho make us who we are and give us everything we need. For non-coding DNAdoes not contain information that can be translated into proteins, although it may be necessary, for example, to regulate when these proteins should be used.

In the case of sex chromosomes 900 geneswhereas the Y chromosome consists only of 55 genes and a large amount of non-coding DNA.. Now among these 55 genes on the Y chromosome, there is one that is vital for the existence of males and females. And all embryos initially develop as female, until the moment comes when, under the influence SRY genethey start to form testicles. They also secrete hormones responsible for the formation of other male characteristics.

Although this differentiation is actually regulated by another gene called SOX9which must first be enabled FRY. In short, they work well as a team.

None of this would be possible without the Y chromosome. platypus chromosomes, they were quite surprised. This is a mammal, despite the beak and the method of reproduction by eggs. It must have a genetic distribution similar to ours. However, the content of their two sex chromosomes is very similar.

This leads us to think that humans have been losing genes on the Y chromosome since the common ancestor of platypuses. 166 million years ago this marked the beginning of the separation of platypuses from humans. If during this time we went from 900 to 55 genes, this would mean a loss 5 genes every million years. To summarize, in only After 11 million years, the Y chromosome will be completely lost.

Good news about the rat genome

This may all seem crazy. How does a species lose its Y chromosome? Well, it’s not such a strange thing. In fact, this has already happened to two species of rodents: spiny rat and Eastern European mole.

The best studied case is that of the spiny rat. It has been observed that he has completely lost his Y chromosome, so that females are XX and males are X, nothing more. It also does not retain the SRY gene. However, they can continue to reproduce. How is this possible?

The key point, as reported in 2022 in a study published in PNAS, consists of two factors. On the one hand, the spread of genes from the Y chromosome to other chromosomes. On the other hand, changes in the use of the SOX 9. SRY gene were not found anywhere, it was not even moved to other chromosomes. However, near the SOX 9 gene, located in chromosome 3there is something that only occurs in men.

This is a small dub. That is, the small number of letters that make up DNA, duplicate. These modifications to non-coding DNA can act as switches, changing the way nearby genes are used. In this case, SOX 9 will not require SRY to be included since it already has a unique male duplication.

They were saved from extinction thanks to this little trick. Will the same happen to people? We do not know. In any case, for now it would be better to worry about leaving a habitable planet for those who come here. Otherwise, what happens to this species in 11 million years should not matter to us, since it will have nowhere to live.