evolution’s fight for the y chromosome
Gentlemen, I have good news and bad news. The bad news is that the chromosome that makes us males, the Y chromosome, is deteriorating and some researchers started pondering a future in which biological males as we know them today, could be extinct. The good news is that males are vital for human reproduction and evolution so the forces of natural selection are going to try and maintain the biological setup for males as long as possible. Overly mutated Y’s are getting kicked out of the gene pool and we’re swapping genes with other chromosomes to maintain our existing distinction between the sexes.
To see why this is happening, we need to go back to the first Y chromosome which was a mutation of a normal chromosome pair that gave us the modern XY setup for males and XX for females. But there’s a bit of a problem with this arrangement. The Y chromosomes couldn’t recombine with the X and speed up the editing of genetic defects, making males slightly more prone to harmful genetic conditions. Even worse, they’re losing hereditary information. Over the last 160 million years, between 800 and 900 perfectly good genes pulled a Houdini. The two things slowing the deterioration are the Y’s ability to fix itself by using the many copies of working genes in its structure when the original gets damaged, and the potential to exchange genes with other chromosomes.
So what happens in the next few million years as the Y chromosome keeps unraveling itself? Natural selection will have to kick in to preserve males. Sexual reproduction produces a much greater variety than asexual lineages which represent an extreme form of inbreeding and leave the species much more vulnerable to genetic disorders and environmental changes. This is why some scientists think that either the Y chromosome will be somehow maintained or new sex chromosomes will develop to keep males around. For humans, there’s another reason to preserve males. We can’t go the way of whiptail lizards. We either reproduce the way we always have, or go extinct as the currently slight imbalance between males and females becomes a vast rift which reduces our population by attrition. And if nature doesn’t come to the rescue, the last women on Earth can justifiably blame men for bringing an end to all of humanity.
