"Y Chromosomes Are Shrinking" : A recent study proposes a 'sex gene war' which occurred with spiny rats, but are males here to stay? : A Complete review

A new study has revealed that one of the main factors influencing male sex is the progressive shrinkage of the Y chromosome. With the possibility that the Y chromosome will completely vanish, this reduction raises concerns about the future of human reproduction.

In humans, the Y chromosome, which is essential for defining male sex, is getting shrink. It has lost 1,393 of its 1,438 original genes over the last 300 million years, leaving only 45 genes. Jennifer A. Marshall Graves, Vice Chancellor's Fellow and Distinguished Professor of Genetics, believes that the Y chromosome is "running out of time." Concerns regarding the survival of humans and male progeny in the future have been raised by the possibility that the Y chromosome would completely vanish in 11 million years if current trends continue. A future where only female children are born is one of the many significant ramifications of such a development.

Y Chromosome: What Is It? 

One of the two sex chromosomes in humans is the Y chromosome (the other is the X chromosome). One of the 23 pairs of human chromosomes in each cell is made up of the sex chromosomes. The Y chromosome makes up over 2 percent of all the DNA in cells and spans more than 59 million base pairs, the basic units of DNA.

Every human cell typically contains one pair of sex chromosomes. Males have one X and one Y chromosome, while females have two X chromosomes. Males also have one Y chromosome.

What function does the Y chromosome serve? 

Despite being smaller and having fewer genes than the X chromosome, the Y chromosome is crucial for the development of males. It carries the SRY gene, which initiates the development of testes and other male reproductive organs. Typically, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome plays a crucial role in determining male traits in embryos, despite its small size.

A Review of Evolutionary Shifts:

The shrinkage of the Y chromosome is not a novel phenomena, according to genetics expert Professor Jenny Graves. She draws attention to the fact that the XY chromosomal pair manifests as regular chromosomes with equal members in platypus. "This suggests the mammal X and Y were an ordinary pair of chromosomes not that long ago," Graves said. Between 900 and 55 active genes have been lost from the Y chromosome over 166 million years; at this rate, the Y chromosome could completely vanish in 11 million years.

The Y Chromosome's Declining:

Over millions of years, the Y chromosome, which initiates male development, has shrunk dramatically in size. The scientific community has begun talking about the future of human sex determination as a result of this reduction. According to a study that was published in the Proceedings of the National Academy of Sciences, male-determining genes had already evolved in spiny rats, suggesting that humans may have evolved along a different evolutionary route.

Y Chromosome Shrinkage: Imminent extinction? 

The decrease of the Y chromosome has long been a source of scientific controversy. The 1990 discovery of the SRY gene is known to activate the SOX9 gene, which is essential for male determination in all vertebrates. Despite not being on the sex chromosomes, SOX9 is essential for male development because SRY activates it. But during the course of the last 166 million years, the human Y chromosome has lost almost 900 genes; about 55 genes are still active. There are worries that the Y chromosome may vanish in the next few million years as a result of this loss.

The Y chromosome may continue to exist indefinitely, according to some scientists, but its demise is certain. There is some optimism because certain rodent species, such as the spiny rat and mole vole, have survived without a Y chromosome. The fact that these rodents have adapted and procreated suggests that other means of sex determination may be found by animals, including humans.

A Ray of Hope: The Adaptation of the Spiny Rat 

A recent study that was published in the Proceedings of the National Academy of Sciences has given rise to hope among growing fears over what may happen to the human Y chromosome. Researchers have shown that after completely losing its Y chromosome, the Japanese native rodent species known as the spiny rat acquired a new gene that determines male status. This adaptation may provide information on how humans could live if their own Y chromosome disappears.

The majority of the Y chromosome genes in spiny rats had moved to different chromosomes, according to a study led by Asato Kuroiwa of Hokkaido University. On chromosome 3, the researchers discovered a little DNA duplication close to the SOX9 gene that is present in all male spiny rats but not in females. The SOX9 gene appears to be activated by this duplication, assuming the function of the absent SRY gene in male development. "The Y chromosome's loss has not been fatal for the spiny rat; instead, it has adapted by finding an alternative way to determine sex," according to the research.

For humans, what does it mean? 

If the Y chromosome vanished, the spiny rat's capacity to live and procreate in the absence of a Y chromosome raises the possibility that humans would develop a new gene that determines sex. This discovery holds significance since it indicates that mammals have the ability to evolve substitute systems for determining sexual orientation, so providing optimism that humans could potentially adjust to a similar genetic change.

That being said, the evolution of humans may be significantly impacted by this shift. Experts warn against the possibility of the birth of new human species due to the diversification of sex-determining systems among various human groups. Scientists hypothesize that "we could see the rise of several distinct human species, each with its own unique sex-determining mechanism," underscoring the possibility of various evolutionary routes.

Human Reproduction's Future:

Significant evolutionary advancements may result from the Y chromosome gradually being extinct, which could drastically alter human reproduction. Although the details of this process are yet unknown, the consequences are enormous for the survival of our species. Researchers are still looking into these possibilities since they know that the loss of the Y chromosome might either result in the evolution of new systems that determine sexual orientation or the emergence of completely new human species.

As investigations continue, scientists are still trying to figure out how these genetic shifts can affect human populations in the future.

A Complicated Future:

There is hope that humans may evolve a new gene that determines sex, but there are risks involved as well. Significant genetic variation could arise from the emergence of distinct sex-determining mechanisms, perhaps giving rise to new human species. "A 'war' of the sex genes could lead to the separation of new species, which is exactly what has happened with mole voles and spiny rats," researchers warn.

There may be multiple distinct human species on Earth in 11 million years, each with its own genetic composition. On the other hand, the loss of the Y chromosome can have disastrous effects and even bring about the extinction of the human race. Though the future is still uncertain, there is some hope that humans may be able to adapt and survive in light of the discovery of alternate sex-determining systems in other mammals.

Although the possible loss of the Y chromosome is a serious worry, new findings on the spiny rat provide optimism that humans may develop to overcome this obstacle. The results of the study open up new directions for our understanding of sex determination and evolution in the face of an uncertain future. Although the prospect of the emergence of new human species is fascinating, it also poses significant concerns regarding the survival and diversity of human species in the future.

Final outcome:

In spite of this, scientists predict that men will probably continue to make up a constant portion of the population. According to the report, the Y chromosome has been receding for millions of years, but if it keeps getting smaller, other genes or processes could be able to make up for its loss.

In the distant future, the impacts of a diminishing Y chromosome could force us to rely on other genetic pathways for determining sex and fertility, however it would probably take millions of years for this to happen. Discussions concerning the future of human reproduction and genetic evolution are sparked by this research, which emphasizes that while changes are happening, they are happening gradually and that there isn't any immediate reason to be concerned about the extinction of men.