What is it that makes one a boy or girl? Our chromosomes hold the answer for this in human beings and many other mammals. A female has two X chromosomes while a male has an X chromosome and a Y chromosome. In fact, the Y chromosome is kind of odd because it’s significantly smaller than X chromosomes and carries much fewer genes.
The surprising part?

Scientists believe that the Y chromosome is slowly disappearing! Over millions of years it lost genes and may soon vanish completely. What will this imply for the human race?

Occupation of the Y Chromosome

It might be small, but it carries a lot of weight. One gene present on Y called SRY behaves like a master switch. SRY activates different genes which begin to form male features such as testes as well as testosterone production at about 12 weeks following fertilization thereby ensuring that the embryo develops as a male.

Why does the Y chromosome disappear?

Most mammals have an X and a Y chromosome arrangement similar to ours. However, there is something strange about this particular gene. Because males have only one copy of X, they receive only half “dosage” of X-genes compared with females. This unequal amount can cause problems.

Interestingly, the platypus, a mammal from Australia, doesn’t share this system. It has completely different sex chromosomes, similar to birds. This suggests that the X and Y in mammals were once ordinary chromosomes, and the Y has been losing genes over time.

At the current rate, the Y is expected to lose all its remaining genes in about 11 million years. This has led some scientists to worry about the future of humans.

A Glimmer of Hope For Y Chromosome

But there’s a twist! Two different rodent groups, mole voles and spiny rats, have already lost their Y chromosomes and are still thriving. This suggests that losing the Y isn’t necessarily a death sentence.

Researchers studying spiny rats discovered something even more fascinating. They found that these animals evolved a new sex-determining gene on a different chromosome. This gene seems to have taken over the job of SRY, even though it works in a different way.

What Does This Mean for Humans?

The spiny rats’ discovery offers hope for the future of humans. It shows that even if the Y disappears, we might be able to evolve new ways to determine sex. However, this process isn’t without risks. Evolving different sex-determining mechanisms could lead to the creation of new species if different groups develop different systems.

So, what does the future hold? While we can’t predict with certainty, the story of the Y chromosome reminds us that evolution is a dynamic process. It’s possible that humans will find a way to adapt and survive even if the Y eventually fades away. However, it also highlights the potential risks and complexities that come with such evolutionary changes.

Here’s some information about the Y chromosome’s evolution:

• In the distant past, mammals, including humans, established a system where sex determination relied on the presence or absence of the Y chromosome.
• Initially, the Y chromosome likely evolved from a pair of standard chromosomes, gradually losing most of its genes over time.
• Presently, humans possess 46 chromosomes, with males carrying one X and one Y chromosome, while females have two X chromosomes.
• However, the human Y chromosome is significantly smaller than the X chromosome and contains far fewer genes, approximately 55 compared to 900.
• Looking forward, scientists estimate that in around 11 million years, if the current rate of gene loss persists, the Y chromosome could lose all its remaining genes and ultimately vanish.