Will men be wiped out from Earth? The case of disappearing Y chromosomes

Aug. 27, 2024, 11:17 a.m.

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Is a future with only female births on the horizon? A recent study suggests that this could be a possibility, implying a future dominated by women.

What is the basis for this prediction? A recent study has unveiled that the Y chromosome, crucial for defining male sex, is progressively shrinking and might eventually vanish. This could lead to a world where only girls are born.

Let's delve deeper into the findings of the study and its implications for humanity.

What is the Y chromosome and how does it determine a person's sex?

The Y chromosome is one of the two sex chromosomes in humans, the other being the X chromosome. Most mammals, including humans, possess two sex chromosomes — X and Y — that together dictate an individual's sex. Females have two X chromosomes in their cells, while males have one X and one Y.

Interestingly, the names "X" and "Y" are not related to their shapes; the "X" simply stands for "unknown".

The X chromosome carries approximately 900 genes that perform various functions unrelated to sex. However, the Y chromosome, which contains around 55 genes, holds the crucial SRY gene that triggers the development of male characteristics in embryos.

This image from the National Institutes of Health (NIH) displays the X and Y chromosomes. What is this about the fading Y chromosome?

A widely shared recent study has revealed that the Y chromosome is deteriorating. Professor Jenny Graves, using the platypus as an example, explained this concept. “In the platypus, the XY pair is just a regular chromosome with two equal parts,” she stated. “This suggests that the mammalian X and Y chromosomes were a regular pair not that long ago.”

“This means that the Y chromosome has lost 900 to 55 active genes over the 166 million years that humans and platypus have been evolving separately. That’s a loss of about five genes per million years. At this rate, the remaining 55 genes will be gone in 11 million years,” she explained.

Advertisement But why is this happening? An earlier article in The Week reported that the Y chromosome contains a large amount of repetitive, non-coding DNA, often referred to as 'junk DNA'. The report stated, “Due to its unstable makeup, the Y chromosome faces a risk of complete disappearance over time, spanning multiple generations.”

The report also explains that because males only have one copy of the Y chromosome, it doesn't undergo genetic recombination. This process, known as “shuffling of genes”, occurs in each generation and plays a crucial role in eliminating harmful gene mutations. Without recombination, genes on the Y chromosome deteriorate over time.

The potential disappearance of the Y chromosome raises questions about the future of humanity. Representational image/Pixabay Does this mean there will be no men in the future?

Advertisement The possibility of the Y chromosome vanishing raises concerns about the future of the human species. Could the loss of the Y chromosome lead to human extinction?

Professor Graves said, “When humans run out of Y chromosome, they might become extinct (if we haven’t already gone extinct ourselves long since), or they might evolve a new sex gene that defines new sex chromosomes."

She further elaborated that while some lizards and snakes are exclusively female species, this scenario is not possible in humans or other mammals. This is because we possess at least 30 vital “imprinted” genes that function only when inherited from the father through sperm.

Advertisement Is there any hope for men?

However, before succumbing to the bleak outlook for humanity, consider this: a research paper published in Proceedings of the National Academy of Science showcases how the spiny rat has evolved a new male-determining gene.

The study demonstrates that the mole voles of eastern Europe and the spiny rats of Japan have lost their Y chromosome and the SRY gene but continue to thrive. Researchers led by Asato Kuroiwa at Japan’s Hokkaido University discovered that most Y chromosome genes in spiny rats have migrated to other chromosomes. This finding suggests that even with the disappearance of the Y chromosome, a new mechanism for sex determination could emerge.

Advertisement This discovery has significant implications for the future of humanity. Researchers state that if extraterrestrial beings were to visit Earth in 11 million years, they might find no human beings — or perhaps several distinct human species, differentiated by their unique sex-determination systems.

But until then, the human race is safe.

With inputs from agencies