Y chromosomes: Finally the answer is out that why lots of female child are getting born these days. a recent study has thrown light on the gradual shrinking of Y chromosomes, a key factor in determining male sex. This phenomenon has raised questions on the future of human reproduction, with the possibility of complete disapprearance of y chromosomes. There is a possibility that in future only female offspring are born.
Dissapearing Y chromosome.
The Y chromosome, which plays a crucial role in initiating male development, has experienced a substantial reduction in size over millions of years. This shrinking has led to debates within the scientific community regarding the future of human sex determination. A study published in the Proceedings of the National Academy of Sciences points to spiny rats, which have already evolved a new male-determining gene, potentially offering insight into an evolutionary direction that humans might also follow.
How y chromomes determine human sex?
The Y chromosome is one of the two sex chromosomes in humans, the other being the X chromosome. These chromosomes are crucial in determining an individual’s sex. In humans and most mammals, females have two X chromosomes (XX), while males possess one X and one Y chromosome (XY).
Interestingly, the names of these chromosomes aren’t based on their shapes; the “X” originally represented something “unknown,” as noted by The Conversation.
The X chromosome is home to about 900 genes that perform various functions not directly related to sex. In contrast, the Y chromosome, although much smaller with around 55 genes, includes the vital SRY gene. This gene is responsible for initiating the development of male characteristics in embryos, making the Y chromosome essential for male sex determination.
Spiny rat adaptation theory
The spiny rat adaptation theory revolves around the evolutionary changes observed in certain species of spiny rats, particularly in how they have adapted to the loss of the Y chromosome. Unlike most mammals, some species of spiny rats have completely lost their Y chromosome, yet they continue to reproduce normally. This intriguing adaptation has sparked interest in the scientific community as it provides a glimpse into how sex determination mechanisms can evolve in the absence of the Y chromosome.
Key Points of the Spiny Rat Adaptation Theory:
- Loss of the Y Chromosome: Some species of spiny rats, particularly those in Japan, have completely lost their Y chromosome, which is typically responsible for male sex determination in mammals.
- New Male-Determining Mechanism: Despite the loss of the Y chromosome, spiny rats have developed an alternative mechanism for male determination. Research suggests that a different gene, possibly located on another chromosome, has taken over the role of the SRY gene that is normally found on the Y chromosome.
- Evolutionary Implications: The adaptation of spiny rats raises questions about the long-term viability of the Y chromosome in other species, including humans. It suggests that if the Y chromosome were to disappear in humans or other mammals, alternative mechanisms might evolve to ensure sex determination continues.
- Potential Human Insight: This adaptation in spiny rats could offer valuable insights into the future of human sex determination, particularly in light of the ongoing reduction in the size of the human Y chromosome. It opens up the possibility that humans might also evolve new mechanisms for sex determination if the Y chromosome were to diminish further.
But why is this happening? A report previously published in *The Week* suggests that much of the Y chromosome consists of repetitive “junk DNA.” Due to this unstable composition, the Y chromosome is at risk of vanishing entirely over multiple generations.
The report also notes that because males only have a single copy of the Y chromosome, it lacks the opportunity to undergo genetic recombination—the process that shuffles genes in each generation and helps eliminate harmful mutations. Without recombination, the genes on the Y chromosome gradually deteriorate over time.
The potential disappearance of the Y chromosome raises significant concerns about the future of humanity. Would the loss of the Y chromosome result in human extinction?
According to Professor Jenny Graves, “When humans eventually lose the Y chromosome, they could either face extinction—assuming we haven’t already gone extinct by then—or they might evolve a new sex-determining gene that creates a new set of sex chromosomes.”
She further clarified that, unlike certain species of lizards and snakes, which consist solely of females, this scenario is not possible for humans or other mammals. This is because mammals, including humans, rely on at least 30 crucial “imprinted” genes that function only when inherited from the father through sperm.
Before jumping to apocalyptic conclusions about the fate of humanity, take a moment to consider recent findings that offer a more hopeful perspective. A study published in the *Proceedings of the National Academy of Sciences* reveals that the spiny rat has successfully developed a new male-determining gene, despite losing its Y chromosome.
The research highlights that both mole voles in eastern Europe and spiny rats in Japan have lost their Y chromosome and the crucial SRY gene, yet they continue to thrive. The team, led by Asato Kuroiwa at Hokkaido University in Japan, discovered that the essential genes from the Y chromosome in spiny rats have been relocated to other chromosomes. This suggests that even if the Y chromosome were to disappear, a new method for determining sex could emerge.
This discovery has significant implications for the future of humanity. Scientists speculate that if someone were to visit Earth 11 million years from now, they might find a planet devoid of humans—or populated by multiple human species, each with its own unique sex-determination system.
For now, however, there’s no need to worry with y chromosomes dissapearing—the human race remains secure.