Chromosome Y in red, next to the much larger X chromosome. /National Human Genome Research Institute Photo
The Y chromosome, which plays a critical role in the sexual reproduction of men, is degenerating rapidly. Research suggests that the Y chromosome may disappear in less than five million years, leading to a future without males, who carries two different kinds of sex chromosomes (XY).
According to an article published by scientists from the University of Kent last week on The Conversation, although the Y chromosome contains the "master switch" gene SRY, which can determine the gender of the embryo, it carries very few other genes and is the only chromosome not necessary for life.
Women, who typically have two of the same kind of sex chromosome (XX), manage just fine without the chromosome.
When the very first mammal emerged, the Y chromosome had the same size and the gene combination as the X chromosome. However, since the Y chromosome has a fundamental flaw, it can only present as a single copy passed from fathers to their sons.
Therefore, genes carried by the Y chromosome cannot undergo genetic recombination, the "shuffling" of genes that occurs in each generation which helps to eliminate damaging gene mutations, said scientists.
If the Y chromosome keeps degenerating at the same rate, it will disappear in 4.6 million years.
Jenny Graves from La Trobe University in Australia pointed out in a 2016 paper that Japanese spiny rats and mole voles have lost their Y chromosomes entirely, claiming that the loss of genes would lead to fertility issues.
Luckily, assisted reproduction techniques can make up for the lack of Y chromosome, meaning that genetic engineering may soon be able to replace the gene function of the Y chromosome, allowing same-sex female couples or infertile men to conceive.
"Although this is an interesting and hotly debated area of genetic research, there is little need to worry. We don't even know whether the Y chromosome will disappear at all," scientists said at the end of the article.