Y Chromosomes Are Slowly Getting Disappearing

A male-determining gene on the Y chromosome determines the sex of newborn humans and other mammals as in contrast, the human Y chromosome is deteriorating and may vanish in a few million years, causing our extinction unless a new sex gene is developed. The good news is that two species of rodents have already experienced Y chromosome loss and survived.

About 900 genes in the X perform various tasks unrelated to sex. However, there are only about 55 genes in the Y, and most of the DNA is non-coding, or just repetitive DNA that doesn't appear to accomplish anything. However, the Y chromosome is powerful because it has a crucial gene that initiates male development in the embryo. This master gene activates other genes that control the growth of a testis at around 12 weeks after conception. Male hormones are produced in the embryonic testis to guarantee the infant will develop into a boy.

SRY was recognised as the master sex gene in 1990. It operates by initiating a genetic pathway that begins with the SOX9 gene, which, despite not being located on the sex chromosomes, is essential for the determination of male gender in all vertebrates.

The majority of animals have X and Y chromosomes that are comparable to ours; the X has many genes, while the Y has SRY and a few additional genes. Due to the uneven dosage of X genes in males and females, this system has issues. Although the alleged impending demise of the human Y chromosome sparked a controversy, and to this day, estimates of the Y chromosome's predicted lifespan range from infinity to a few thousand years.

Researchers are aware of two rat lineages that have already lost their Y chromosome yet are still thriving, which is fantastic news.

Both the Japanese spiny rats and the Eastern European mole voles exhibit species in which the Y chromosome and SRY have totally vanished. In either a single or double dose, the X chromosome is still present in both sexes. A team led by Hokkaido University biologist Asato Kuroiwa has had more success studying the spiny rat, a group of three species that are all endangered and found on different Japanese islands. It is still unclear how mole voles determine sex without the SRY gene.

Meanwhile, the majority of the genes on the Y chromosome of spiny rats have been moved, according to Kuroiwa's study. However, neither SRY nor the gene that can replace it were detected by her.