Scientists are raising alarms about the potential disappearance of the Y chromosome in a few million years, which could lead to human extinction unless a new sex-determining gene evolves.

In humans, males possess one X and one Y chromosome (XY), while females have two X chromosomes (XX), with the Y chromosome containing approximately 55 genes compared to the 900 found on the X chromosome.

The SRY gene on the Y chromosome is crucial for male reproductive organ development, activating around 12 weeks post-conception by stimulating the SOX9 gene.

Over millions of years, the Y chromosome has lost a staggering 1,393 of its original 1,438 genes, indicating a significant decline in its functionality, as noted by genetics professor Jennifer A. Marshall Graves.

Professor Jenny Graves emphasizes that the Y chromosome's gene loss is a part of a historical trend regarding sex chromosomes.

Research led by Asato Kuroiwa has shown that spiny rats have adapted by relocating genes from the Y chromosome, with a DNA duplication near the SOX9 gene on chromosome 3 compensating for the missing SRY gene.

This study highlights that two rodent lineages, the mole voles and spiny rats, have successfully developed alternative mechanisms for male sex determination after losing their Y chromosomes.

Future research will delve deeper into these genetic changes, aiming to provide insights into sex determination and the implications for the survival of male offspring.

If the trend continues, there is a possibility that only female offspring could be born, raising serious concerns about the long-term survival of the human species.

Should humans evolve separate sex determination systems, future visitors to Earth might encounter multiple human species with different sex chromosomes instead of a single type.