Original article (in Slovenian) was published on 8/7/2024; Author: Lara Drugovič
Most of the genes on the Y chromosome have not changed over the last 25 million years, according to the authors of a peer-reviewed paper published in the scientific journal Nature in 2012.
“The Y chromosome is disappearing, experts say, and with it the male sex and the human species,” claimed an article in Planet Lepote on 12 June, which argued that the Y chromosome is deteriorating and could disappear in a few million years – as will humans.
The author was referring to a study published in 2022 in the Proceedings of the National Academy of Science, in which the authors investigated new mechanisms for sexual reproduction in rats without a Y chromosome.
The study found that in a rat population in Japan that lacks a Y chromosome, sex is determined by a gene on chromosome 3, which is not a sex chromosome. However, the authors did not find that a similar change can occur in humans, nor did they predict that such a change would lead to the end of the male sex or of the human species.
The human X and Y sex chromosomes evolved from a pair of ordinary chromosomes over the last 200 to 300 million years, but during this period they stopped exchanging genes, leading to the partial genetic decay of the Y chromosome, according to the authors of a peer-reviewed paper published in 2012 in the scientific journal Nature.
The authors compared the Y chromosomes in humans and macaque monkeys and found that gene loss over the past 25 million years has occurred only on the most recent part of the human Y chromosome, which makes up less than three percent of the entire chromosome. Other parts have not lost genes in the past 25 million years.
Peter Dovč, professor at the Department of Genetics, Animal Biotechnology and Immunology at the Biotechnical Faculty, University of Ljubljana explained to Razkrinkavanje.si that over the last 160 million years the Y chromosome has only retained 45 of the approximately 1,700 genes it had initially.
Not a single gene on the Y chromosome has been lost in the 6 million years since humans and chimpanzees split into two biological species, he pointed out. The shortening of the Y chromosome would also be slowed down by natural selection, which would eliminate people with a non-functioning Y chromosome faster than those with a functioning one.
“It is theoretically possible that the process of Y-chromosome shortening will continue, but we cannot predict the speed or the extent of this process, and therefore the consequences for the reproduction of the human species,” Dovč said.
He noted that the shortening or loss of the Y chromosome has occurred in relatively small populations of mammals that have evolved alternative mechanisms for sex determination. This suggests the possibility of another chromosome or a new gene taking over this function in humans.
Y chromosome shortening or loss has occurred in small mammalian populations such as the rats analysed by the authors of the 2022 study referred to by the website, but such changes take several generations, a time span much longer in humans than in short-lived rats.
We shared our findings with Planet Lepote and will publish their response when we receive it.
According to the methodology of Razkrinkavanja.si, the claim that the Y chromosome is disappearing, and with it the male sex and the human species, constitutes pseudoscience.
Because the title of the article does not reflect its content, we have also designated it as click bait.
