One of the two sex chromosomes, the Y chromosome is present in some mammals, including humans. Every cell in the body contains one set of sex chromosomes. Males have one Y and one X chromosome, and the Y chromosome is found in them. Females, on the other hand, have two X chromosomes.
An embryo's sex is determined by the existence of the Y chromosome, however research indicates that it has aged and diminished with time. (Today, it has roughly 45 genes compared to the estimated 1,000 genes on the X chromosome.) So, the question is: Is the Y chromosome disappearing?
How is the Y Chromosome Behaving?
According to Melissa Wilson, an evolutionary scientist at Arizona State University, "our sex chromosomes weren't always X and Y." They were not directly connected to whatever determined maleness or femaleness. She says that when the first animals originated 100 or 200 million years ago, they lacked any sex chromosomes. The X and Y structures, however, were the same as those of any other set of chromosomes.
Remember that some animals still today don't require sex chromosomes. Geneticist Jennifer Graves from La Trobe University in Melbourne, Australia, notes that each chromosome contains a variety of genes, not all of which are sex-related. Only the SRY gene stands out in the Y chromosome as producing male rather than female development. The sex of the embryos in turtles and alligators, however, is determined by their environment's temperature; there is no switch. Before the SRY abruptly formed and persisted, according to Graves' theory, a similar configuration existed.
There is an easy reason for the Y's degeneration. Genes evolve detrimental mutations throughout time, but they have a mechanism to prevent passing them on to offspring. Chromosomes unite and recombine as the body makes sperm and eggs to enhance the likelihood that only functional copies will be passed on during reproduction. With the exception of the Y chromosome, which lacks an equal to recombine with, the paternal and maternal chromosomes can mix and match.
"Normally, you'd be able to exchange with your companion if a nasty mutation happened. Wilson remarked, "But the Y can't do that. Because they were forced to maintain the mutations, Y chromosomes gradually shrunk in size.
"Y will vanish entirely in 4.5 million years."
According to Graves' research, there may have been 1,669 genes in the Y 166 million years ago. She responded, "Same as the X chromosome. Therefore, it doesn't take a brilliant mind to understand that the entire Y will vanish in 4.5 million years if the rate of loss is uniform (10 genes per million years) and we only have 45 genes remaining.
Recent studies have discovered that the Y's degeneration has slowed, probably to a standstill. For example, a Danish study that looked at the Y from 62 men discovered that it can carry out structural rearrangements to enable gene amplification, which improves sperm performance and lessens gene loss. The investigation also discovered that the Y has developed a special palindrome structure for self-defense. Palindromic sequences essentially have a process that duplicates genes to replace broken ones.
According to Graves, numerous species have already experienced the Y's removal. In Japan, three vulnerable species of spiny rats as well as two species of mole voles have lost the Y. These species also continue to live, demonstrating that the removal of the Y does not necessarily equal extinction. Mole voles and spiny rats still have separate males and females, in fact. Rasmus Nielsen, a geneticist in University of California, Berkeley, United states said: "People think that sex is sort of a really determined thing. That if you have Y chromosome, then you're a guy, or if you don't have Y chromosome, then you're a woman. But that's not how it operates.
The Y Chromosome's Future
Despite the fact that the Y chromosome is the one that gets all the credit for determining sex, 95% of the genes that distinguish between males and females don't come from the Y or X chromosomes. For instance, chromosome 6 has the gene that encodes estrogen receptors, which are essential for the growth and development of females.
Nielsen said, "Losing the Y chromosome doesn't equal losing the masculine." Graves said that if the Y gene ever lost its ability to determine an embryo's sex, it is likely that another gene would take its place. While others think that the Y chromosome will always exist because of built-in safeguards like the palindrome structure that prevent it from losing its genetic material, the Y chromosome cannot stop being, they claim. Since the anticipated expiration date is more than 4 million years in the future, it doesn't matter whether it occurs or not.
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