In humans and many mammals, the male Y chromosome has begun to degenerate. However, humans can still survive without it, say scientists at the Setagaya-ku National Institute for Child Health and Development Research in Tokyo. The study is published in the journal PNAS.
Most mammals have two sex chromosomes, X and Y. Females carry the XX set and males carry the XY set. It is the second Y chromosome that carries the SRY genes, which "turn on" the development of male genitalia in the embryo, resulting in the birth of a male.
According to scientists, in some animals, the Y chromosome loses some of its genes and completely disappears. In humans, the same thing happens, leading to its complete disappearance in a few million years.
"The good news is that we know of two rodent lines that have already lost their Y chromosome and are still surviving. These are voles from Eastern Europe and barred mice from Japan. There are new species of these animals whose males and females have only the X chromosome," the scientists said.
The researchers found that most of the Y genes in spiny mice had been moved to other chromosomes. In doing so, the SPY gene was missing and its function was taken over by the SOX9 gene set.
"In humans, the Y chromosome is also reduced, this is inevitable from an evolutionary point of view. Hence the question of how we will give birth to men. This could lead to the end of humanity. Of course, like other species, we can develop new genes, but what if those genes are different all over the world? This could lead to new species of humans," the researchers explained.