June 26, 2024 at 9:26 am

There’s Something Strange Happening With The Y Chromosome As Scientists Observe That It’s Shrinking In Size

by Trisha Leigh

Source: Shutterstock

It’s no secret that the concept of gender has been at the forefront of societies mind over the past several years.

And while many believe it’s nothing more than a construct, most can see that there are typical male and typical female traits in a majority of people, while admitting there is plenty of room for outliers on both sides.

Now, scientists say the Y chromosome – the one that determines a male baby’s biological traits at birth – is changing.

This is leading some to wonder whether or not it could ever disappear altogether.

Most human beings are born with 23 pairs of chromosomes, and one of these pairs is either XX or XY.

The Y chromosome contains a gene called SRY, which triggers the development of testes, but isn’t the only thing that determines a person’s biology.

The Y chromosome is smaller than the X, and while the latter has remained stable since chromosomes that express female or male biological traits first evolved in mammals around 180 million years ago, the Y has shrunk.

It’s about a third of the size of the X chromosome and contains just 106 protein-coding genes compared to X’s 900.

Researchers think the reason for this shrinking is down to the body’s attempt to ensure genetic variation and to avoid passing mutations onto offsprings.

shutterstock 2308656957 Theres Something Strange Happening With The Y Chromosome As Scientists Observe That Its Shrinking In Size

The process is called meiosis.

Meiosis is when spermatozoa and egg cells are created and pairs of chromosomes swap bits of their arms. Y can’t swap, though, so is left paired with its own mutations – mutations evolution would like to eradicate according to Dr. Jennifer Hughes.

“The X is fine because in females it gets to recombine with the other X but the Y never gets to recombine over almost its entire length, and shutting down that recombination has left the Y vulnerable to all these degenerative forces, which is why we’re left with the Y we have today.”

But while it’s not impossible to think the Y might disappear altogether, a 2012 study found that it had only lost one gene in the 25 million years since humans and rhesus monkeys diverged, and not one since we diverged from chimps.

Another study found that Y chromosomes have developed structural changes that help protect it against degradation.

“The Y is not going anywhere and gene loss has probably come to a halt. We can’t rule out the possibility it could happen another time, but the genes which are left on the Y are here to stay.”

Even if the Y chromosome did disappear, experts say that doesn’t mean the male population would go with it.

Source: Shutterstock

There are many genes involved with development that are found on other chromosomes, including SOX9, which plays a critical role. It, or another, could potentially take over the Y chromosome’s role in the process, as researchers have seen happen in the Amami spiny rat.

In the end, most experts believe that the evolutionary process is so slow that this is unlikely to be an issue for human beings as long as they populate the Earth.

So that’s comforting, at least.

If you squint.