The Evolutionary Puzzle: Theories explaining why the Y chromosome is shrinking

Research has confirmed that the “Y” chromosome, which is crucial for human sex determination, is actually shrinking over time due to genetic decay.

This could lead to the Y chromosome no longer existing in the future as it would continue to lose genes that are not necessary for survival.

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However, a 2022 study on Amami spiny mice that lack the Sry gene suggested that humans may have evolved a new male-determining gene, offering hope for survival under the decline of the Y chromosome.

Y Chromosome: An Introduction

The Y chromosome plays a crucial role in human biology, particularly in determining male sex and developing male-specific traits.

It carries the SRY gene, which triggers the development of male characteristics by initiating the formation of testicles and the production of male hormones. This process distinguishes males from females, who normally have two X chromosomes.

The Y chromosome is unique in that it is passed down from father to son almost unchanged, allowing scientists to trace paternal descent through multiple generations. This makes it a valuable tool for understanding human ancestry and studying how populations evolve over time.

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Because the Y chromosome doesn’t undergo the same type of genetic mixing as other chromosomes, it provides a stable genetic record that helps researchers track ancient human migrations and explore our evolutionary history.

In addition to determining sex, the Y chromosome also affects male fertility, and certain genetic conditions associated with it can affect male fertility.

Theory of Y chromosome decay

Recent studies have found that the Y chromosome, which determines male sex, is gradually shrinking, raising concerns about the future of human reproduction and the possibility that the Y chromosome may eventually disappear.

If this happens, there could be only female offspring in the world. A study published in the Proceedings of the National Academy of Sciences of the United States of America points out that some animals, such as spiny rats, have evolved new genes that determine maleness, which points to a possible path for the future of mankind.

Genetics expert Professor Jenny Graves explained that the shrinking of the Y chromosome is not a new problem. In some animals, such as the platypus, the X and Y chromosomes look the same as normal chromosomes.

Over the past 166 million years, the Y chromosome has lost more than 900 genes, and in about 11 million years, it may disappear entirely. As the Y chromosome shrinks, new sex-determination systems may evolve, but the process could be risky.

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This could have led to different sex determination systems evolving in different regions, potentially creating different human species. Scientists are closely studying these changes to understand their implications for the future of human reproduction.

The future of the Y chromosome

The potential disappearance of the Y chromosome has raised concerns about the future of humanity.

Unlike some lizards and snakes that can reproduce without males (through a process called parthenogenesis), humans and other mammals need sperm and males to reproduce.

If the Y chromosome disappears, human survival will be threatened. However, if a new method of sex determination emerges, this problem may be avoided.

This new system could potentially lead to different methods of sex determination in different regions, giving rise to several new human species.

Eleven million years from now, there will either be no humans on Earth, or there will be several different human species, each with its own method of sex determination. While the future of the Y chromosome is uncertain, adaptations in other animals suggest that evolution may provide a solution.

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Source: https://dinhtienhoang.edu.vn
Category: Optical Illusion