The Y Chromosome is Vanishing

Image credits: (Illustration by Stephen Kelly / Getty Images)

Over the course of human evolution the Y chromosome has gone through a number of significant changes. The Y chromosome is much smaller in size compared to the X chromosome, and only one Y chromosome is needed to make a person a male.

In the past, the human Y chromosome used to possess the same number of genes as the X chromosome but has lost them in the past 166 million years. This caused most of the current Y chromosomes to be composed of repetitive junk DNA. Junk DNA does not encode proteins, so it cannot produce proteins in the cell.

Males usually only have 1 copy of the Y chromosome, making it unable to go through genetic recombination or the shuffling and mixing of genetic material. The Y chromosomes will begin to disappear without recombination. “This significant gene loss over the centuries has led scientists to predict that the Y chromosome might vanish entirely in about 11 million years," as is stated in an article from Earth.com. The Y chromosome contains the master sex gene called SRY, which triggers a fetus’s development as a biological male. Long ago, the X and Y chromosomes were just an ordinary pair of chromosomes.

Now, what would happen if the Y chromosome were to vanish? Humans might become extinct or even evolve a new sex gene. There is evidence of evolving new sex genes found in rats: "We could simply evolve a new sex-determining gene. That's what we've already seen happen in some types of rodents, and it seems to have worked successfully," said Graves to Science Focus.

But human males are not going to disappear in the foreseeable future. Some scientists argue that the Y chromosome will not disappear at all as it has several defense mechanisms in place.

Though this extreme change in human evolution can lead to a new human species, it will take millions of years.