There were new data refuting theories that men are threatened with extinction
Last reviewed: 16.10.2021
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Earlier, several researchers published data that the Y chromosome, which is found only in men, undergoes so rapid genetic degradation that it can disappear altogether after 5 million years.
In the mid-twentieth century it was found that the Y chromosome plays a crucial role in determining the sex of the embryo during embryonic development. It was also known that it contains a series of genes responsible for the processes of spermatogenesis. It was found that the chromosome Y contains only 78 genes (against thousands contained in other chromosomes).
However, judging by the results of a study published in the journal Press Nature, the genetic degradation of the sex chromosome of type Y practically ceased. Forecasts of genetic catastrophe
The author of the 2003 book Curse of Adam: the future without men, Professor Bryan Sykes predicted the disappearance of men in 100 thousand years.
Similar predictions, made by many geneticists in the late 90s, were based on comparisons of X and Y chromosomes in humans. The female X chromosome has 800 genes, compared to only 78 in the male Y chromosome.
Jennifer Hughes and her colleagues at the Whitehead Institute in Cambridge, Massachusetts, decided to test the validity of these claims about the imminent death of the Y-chromosome.
In an article published in the journal Nature in 2005, they compared the human Y chromosome to the chimpanzee's sex chromosome, whose evolutionary line was separated from the human about 6 million years ago.
In the current study, they studied the Y chromosome of monkeys of the Rhesus type, which are separated from humans by 25 million years of evolution.
The researchers concluded that over the last 6 million years, the degradation of the human Y chromosome was minimal - it did not lose a single gene, and over a period of 25 million years the number of genes decreased by one.
"The Y chromosome does not disappear anywhere, and the loss of genes has practically stopped," says Dr. Hughes, "We can not rule out the possibility that this might happen in the future, but the genes that are present on the Y chromosome will remain with us."
"Apparently, they carry out some critical function, which we are only guessing about, but these genes are well preserved in the process of natural selection." Men are not in danger
Genetic degradation of the Y-chromosome was due to a very limited exchange of genetic material between the male and female chromosomes during reproduction. And between a pair of female X chromosomes such an exchange is very active. This means that mutations in the Y chromosome persist from one generation of men to another.
"There is no problem with the X chromosome, because it continuously recombines with its pair, but the Y chromosome never recombines, which makes it vulnerable to all these degenerative factors," explains Dr. Hughes.
Professor Mark Pagel, dealing with the problems of evolutionary biology at the University of Reading, believes that the future of men in the long term is not threatened.
"This article convincingly shows that the loss of genes in the Y chromosome in the early stages of evolution occurs relatively quickly, but then reaches the point at which breeding makes this process stop."