Is The Y Chromosome Vanishing?

In humans and mammals, the critical determinant of a baby’s sex is a gene that resides on the Y chromosome. This chromosome might be minuscule, containing roughly 55 genes-many of which are non-coding DNA sequences.¹ Yet, it’s vital for it houses the gene responsible for kick-starting male development in embryos. This sex-determining gene, identified as SRY (sex region on the Y) in 1990, fires up a genetic pathway that triggers the creation of a testis about twelve weeks after conception.
Contrarily, females possess two X chromosomes, each loaded with nearly 900 genes associated with a plethora of functions not directly linked to sex determination. These genes perform vital roles within the complex machinery of our bodies, contributing to everything from regulating our metabolisms to producing specific proteins. However, the humble Y chromosome carries the heavyweight: the all-important SRY gene.
The SRY gene works in tandem with another key gene named SOX9, which is crucial for male determination in all vertebrates, even though it isn’t situated on sex chromosomes. After the SRY gene initiates the process, it hands the baton to the SOX9 gene, which regulates the development of the testis. This embryonic testis then produces male hormones, primarily testosterone, and its derivatives, setting the stage for the embryo to develop as a male.
Is The Y Chromosome Vanishing? A New Sex Gene Might Be On Its Way

1. “The Y Chromosome Is Vanishing. A New Sex Gene Could Be The Future of Men.” Science Alert. Jenny Graves. June 2, 2023.