A new analysis has revealed that the Y chromosome has been losing most of its genes over the last 166 million years. As a result, a theory has been proposed that the Y chromosome will completely disappear in 4.5 million years.

The X chromosome holds more genes than the Y chromosome does. The X chromosome spans 155 million DNA building blocks. As a result, it is about 5% of all the DNA found in a human’s cells. This also results in the X chromosome containing about 900 to 1,400 genes.

Evidence has suggested that, over the past 166 million years, the Y chromosome in humans has begun to vanish. It’s also begun to lose much of its genes, as it had much more than the 70 to 200 seen now.

Luckily, the vanishing of the Y chromosome doesn’t necessarily mean that human men will cease to exist. Thanks to our body’s evolutionary ways, it’s likely the genes on the Y chromosome will relocate to other chromosomes instead.

Instead of a Y chromosome or the SRY gene, researchers discovered something different in these rats’ SOX9 gene. The SOX9 gene helps with the animal body’s development of testes.

Thanks to evolution, many species on the planet have changed over millions of years. This has resulted in many genes being lost to time. However, humans haven’t lost nearly as many genes as other species have.

Many times, genes are lost because of evolutionary change. This loss happens slowly over millions and millions of years. However, some geneticists say that gene loss could happen just from a mere accident or because of a better evolutionary event.

When it comes to the evolutionary standard of the Y chromosome in humans, it isn’t great. The Y chromosome has a few issues. For example, the Y chromosome cannot swap out bad DNA with the X chromosome.

Studies have also shown that the Y chromosome can have more mutations. However, gene mutations aren’t always harmful or bad. Whether a mutation is beneficial or harmful depends on what it is, and where it’s located.

Some studies have even gone as far as to show that there could be a link between a Y chromosome and cancer. According to one study, the loss of the Y chromosome in specific bladder cancer cells actually helped the cancer spread.

While the Y chromosome is slowly vanishing, people shouldn’t start worrying. Even if the Y chromosome does fully disappear, this won’t happen for another 4.5 million years.

The loss of the Y chromosome could also lead humanity to a new sex-determining system, thanks to evolution. There’s no telling what a future like this would hold. After all, evolution doesn’t impact every single being in a species all at once — it often occurs slowly, over time, in certain areas.