Male and female, XX and XY. It seems like the basis of the genetic ABC that we all learned in school. But what if they told you that this apparently granitic distinction is destined to crumble in the course of evolution? That the Y chromosome, the distinctive mark of the male sex, is progressively losing pieces like a wreck adrift in the sea of time?
What if they told you that, hypothetically, in 11 million years (since we exist!) the Y chromosome could disappear completely, throwing humanity into an unknown reproductive scenario? Would you think it's science fiction or just the natural evolution of an ever-changing species?
AAA chromosome desperately sought
Imagine our genome as an immense puzzle of chromosomes. In each cell, two special pieces determine sex: XX for females, XY for males. It seems like a perfect system, proven by millions of years of evolution. Except that one of these pieces, the Y chromosome, is slowly vanishing.
Yes, because while women indulge in their 900 copies of X genes, men have to settle for just 55 measly Y genes. An asymmetry that cannot help but make us think. How did we get to this point? And above all, where will it take us?
To understand this, we need to take a leap into the past. A dive of 166 million years, when our very distant ancestors split from the platypuses. Well, in these funny animals the sex chromosomes are still equal: a nice full-bodied X chromosome and a Y chromosome, each with its own set of genes.
But then, in the long evolutionary journey that led us to become human, something changed. The Y started to lose pieces, like a wastebasket that is emptied gene by gene. A slow but inexorable hemorrhage: about 5 genes every million years, according to the geneticist's calculations Jenny Graves (I'll link the study here).
If this trend continues, in 11 million years the Y could disappear completely. Puff, dissolved into thin air. So? Would this be the end of men? The extinction of the human species? The apocalyptic movie scenario?
Nature always finds a way
Calm down, don't panic. Before we resign ourselves to a dystopian future populated only by women, it is worth looking at nature once again. Because, surprise surprise, there are already several species of rodents that have completely lost the Y. Yet, somehow, they continue to produce offspring of both sexes.
How do they do it? Simple: moving the "control unit" that determines sex elsewhere. In some cases, scientists have found that the critical region has migrated to another chromosome, without getting lost along the way. In short, nature always finds a way.
And then, let's face it: 11 million years is an eternity on a human scale. Who can say what we will have become by then? Perhaps we will have learned to clone, to reproduce in test tubes, to hack our own genome. Or maybe we will have already become extinct for very other reasons, who knows.
Of course, as Professor Graves points out, there is also the possibility that humanity has in the meantime divided into different species, each with its own sex determination system. A bit like platypuses and rodents without a Y chromosome. An explosion of biological diversity which perhaps, if you think about it, wouldn't be so bad after all.
The future is an enigma wrapped in a Y chromosome
Let's be clear: all of this is just speculation. An exercise of imagination based on partial data and extrapolated trends. No one has a crystal ball to predict how we will evolve in the next few million years. The only certainty is that we will change, as we always have.
Perhaps reflecting on these distant scenarios can help us look at our present with different eyes. To understand that the categories of "male" and "female", however rooted in our imagination, are not absolute and immutable truths. That life always finds a way to reinvent itself, to adapt, to surprise us.
What a wonderful spectacle evolution is. This dance of genes and forms that has brought us this far, and which will continue far beyond us. With or without a Y chromosome, the future is an enigma. Who knows what the next page will be.
