The sex of human and other mammalian babies is determined by the presence of a male-determining gene on the Y chromosome. However, the human Y chromosome is slowly degenerating and could disappear entirely in a few million years, which has led to concerns that this could result in human extinction unless a new sex-determining gene evolves. Interestingly, some rodent species, such as the spiny rat, have already lost their Y chromosome and yet continue to survive, offering hope that humans may also adapt.
In 2022, a study published in Proceedings of the National Academy of Science revealed that spiny rats have evolved a new male-determining gene. Typically, in humans and other mammals, females have two X chromosomes, while males have one X and one Y chromosome. The Y chromosome contains few genes, but it plays a crucial role in determining sex, particularly through a master gene known as SRY (sex region on the Y). This gene activates pathways that lead to the development of male characteristics by producing hormones like testosterone.
The human Y chromosome has been losing genes over the past 166 million years since the divergence from species like the platypus, which has a different sex chromosome system. At the current rate of degeneration, the Y chromosome could lose its remaining 55 genes in around 11 million years.
Despite this, certain rodent species, including the spiny rat, have shown that life can go on without a Y chromosome. In these rodents, most of the genes from the Y chromosome were relocated to other chromosomes, and a new genetic mechanism for determining male sex evolved. In the spiny rat, researchers discovered a small DNA duplication near the SOX9 gene, a critical gene for male development, that compensates for the absence of SRY.
This discovery offers optimism for the future of human evolution, suggesting that new sex-determining genes may evolve. However, this process could lead to complexities, such as the emergence of multiple sex-determining systems, potentially resulting in the evolution of new human species.
Source link: https://www.sciencealert.com/the-y-chromosome-is-slowly-vanishing-a-new-sex-gene-may-be-the-future-of-men
Follow for more.
