Is The Y Chromosome Vanishing? A New Sex Gene May Be The Future of Men

Evolutionary biologist Jenny Graves in 2002 shared A. controversial calculation. human Y chromosome, it wrote “time is running out,” one comment two years later said.

The sex chromosome, which determines males, has lost 97 percent of its ancestral genes over the last 300 million years. Graves calculated that if this rate continued, several million more people could perish.

The inevitable fate of the Y chromosome quickly gripped the media, in most cases without the nuance Graves intended.

Relating to: Many Men Lose Their Y Chromosomes as They Age. We Now Know Why It’s So Deadly

His evolutionary ideas were not expected to predict the ‘end of men’ or the end of the human species; These were ‘back of the envelope’ calculations in an academic paper, yet produced “a hysterical reaction”.

“It really surprises me that people are worried that men will become extinct in 5 or 6 million years,” Graves told ScienceAlert. “After all, we’ve only been humans for 0.1 million years. I think we’ll be lucky if we make it through the next century!”

But if Graves’ calculation is correct, what does this mean for the Y chromosome and what does it mean for the future of men?

The good news is that similar chromosomes in other mammals, as well as fish and amphibians, have lost their sex-determining status during genetic changes, and the species continues to tell the story.

For example, in some rodents the Y chromosome has been completely and silently replaced. For example, three species of Y-less mole vole, ellobius talpinus, Ellobius tancreiAnd ellobius alaicus, they only have X chromosomes now. The sex-determining genes on the Y chromosomes were shifted to other locations.

spiny rats (Tokudaia osimensis), Meanwhile, They lost their Y We transfer the chromosome to a new version that now serves as the sex marker instead.

Relating to: Humans Share a Surprising Genetic Link with Golden Retrievers

“If a new variant emerges that works better than our poor old Y, it could come into play very quickly,” Graves predicted. “Maybe it already exists in some human populations somewhere; how do we know?”

Ultimately, the variables that determine gender not routinely screened Because in genome studies, if the role of the Y chromosome was transferred to another chromosome in a population, there would be no significant difference. There will still be males and they will still be able to reproduce.

The fate of the Y chromosome has captured the world’s attention for years, but beneath the sensational headlines, many people are unaware that a powerful scientific debate is brewing that brings two incompatible views of evolution into direct conflict.

One school of thought that Graves subscribes to frames the sex chromosome as a dilapidated old part that is doomed to extinction and can be replaced at any time. The other view positions the Y chromosome as a survivor, ultimately safe and stable.

Jenn Hughes, an evolutionary biologist at MIT’s Whitehead Institute, agrees with the latter interpretation. For over a decade Hughes and Graves I respectfully disagree. by participating in open academic debate about how to interpret the same evidence.

In 2012, Hughes and colleagues found: very few core Y genes lost in the human lineage for the past approximately 25 million years.

More latest evidence to have reinforced This argument suggests that there is deep protection core Y genes in primates – compared to fish and amphibiansIt exhibits a gradual deterioration of the Y chromosomes, and some scientists, such as Hughes, interpret this as long-term evolutionary stability of the Y chromosome in primates.

“Our study comparing Y gene content across many mammals showed that gene loss was rapid at first, but quickly stabilized and gene loss essentially stopped,” Hughes told ScienceAlert.

“Genes retained in the Y serve very important functions throughout the body, so the selective pressure to preserve these genes is too great for them to be lost.”

Graves disagrees with these comments. He argues that just because a gene is deeply conserved does not mean that it cannot be changed.

He also says that additional genes found in the human Y sequence in recent years are largely duplicates, some of which are inactive.

Graves in the past in the name The Y chromosome is the “DNA junkyard.” Making multiple copies of a gene can at least increase the likelihood of a gene surviving, Graves explains, but can also accidentally create evolutionary “gaps.”

It’s kind of like a telephone game. The more a message is shared, the more likely it is to stick, but also the more likely it is to be distorted.

So why is the Y chromosome like this?

Evolution is to blame.

“In the ancestor of placental mammals, the X and Y chromosomes were identical and had about 800 genes,” Hughes told ScienceAlert.

“When Y specialized to determine male sex (about 200 million years ago), X and Y stopped recombining in males and Y began losing genes. Meanwhile, X was still able to recombine in XX females, so it remained largely unchanged.”

Related: Male Brains Shrink Faster Than Female Brains, Study Finds

Today, the human Y chromosome has only 3 percent of the genes it once shared with the X. But these genes did not disappear at a constant rate. Hughes argues that this is the biggest misconception.

Graves agrees.

The estimated extinction date of around 6 million years is based on a straight, cold-blooded disruption of the Y chromosome, but he says that’s unlikely, meaning the estimate has a wide margin of error.

“From now on, it’s everything, never,” Graves told ScienceAlert. “I’m surprised it’s being taken so seriously!”

Although the Y chromosome appears to stabilize at certain moments, Graves argues that these snapshots will not be permanent, even if they appear to persist for 25 million years.

“I don’t see any reason to assume that Y decay has stopped or could stop in primates or any other mammal group,” Graves said. “It is moving slowly and intermittently for reasons we understand very well.”

After a public contention In the 2011 debate between Hughes and Graves over whether the Y chromosome was fixed or doomed, the audience at the 18th International Chromosome Conference voted 50/50. They were split down the middle on which hypothesis was correct.

Let’s hope it doesn’t take 6 million years to break the tie.

Related News