World is losing Y chromosomes slowly. Will it lead to the extinction of men?

The Y chromosomes, which have been the male-determining gene, have been degeneratingand are likely to disappear in some million years. But would the vanishment of the Y chromosomes lead to the extinction of men?

Maybe not, because scientists have observed that the two branches of rodents have survived after losing their Y chromosomes.

In a paper published in Proceedings of the National Academy of Science in 2022, it was explained how the spiny rat evolved a new male-determining gene.

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So, scientists now believe that the evolution of a new sex gene can stop men from becoming extinct.

What led to the shrinking male-determining chromosome?

The Y chromosome started decaying after it was first formed around 180 million years ago when a segment reattached with the same chromosome after breaking off but in the reverse orientation.

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This “reduced the Y chromosome’s ability to recombine with the X chromosome across the majority of its length and subjected its genes to the erosive forces associated with reduced recombination,” read the study, which was published inNature.

So, by accumulating the bad mutations, Y chromosomes got smaller over time which led it to lose 97 per cent of its ancestral genes.

Meanwhile, the X chromosome conserved its gene content and has around 900 genes currently in comparison to the Y chromosome's meagre 55.

What makes the Y chromosome special?

In mammals and humans, two X chromosomes are present in females while males have one X and a Y.

The Y chromosome is special, even though it has fewer genes in comparison to its X counterpart, because it contains the SRY gene which can begin the male development in the embryo.

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This is done by the chromosome by acting as a switch which starts the development of testes.

"Our sex chromosomes weren't always X and Y," said Melissa Wilson, who is an evolutionary biologist at Arizona State University, in a paperpublished back in 2014.

"What determined maleness or femaleness was not specifically linked to them," she added.

(With inputs from agencies)