Weird…
I assumed it was a sloppy reference to the shrinking Y, but they’re talking about cells in elderly (over 70) men just straight up missing the entire Y.
I feel like the article was on the right track but missed the obviously conclusion:
When DNA is duplicated before cell division, if mistakes arise, they can usually be eliminated in something like a copy-checking process, where one chromosome is compared to its partner.
But because the Y is different to the X, it cannot be checked in this way, and so genetic mistakes have crept in during evolution.
This is why the Y is full of genes with mutations that make them defunct and why it is among the smallest of our chromosomes, with many mutated genes having been jettisonned in the past.
Scientists describe the Y as “genetic garbage”. Some have even predicted that over millions of years, it might dwindle to nothing, leading to the end of men.
The Y keeps changing, and the resulting sperm keeps changing as well.
But after 70 years of random changes at every cell division, a lot of shit is going to break.
There might be a built in clock that just stops including the Y to be safe. Or maybe some mechanism that can tell when it’s so mutate the cell line is better off without the Y.
It’s likely the same mechanic that makes men over 35 more likely to have daughters than sons. If thebY is dropping off in cell lines, then sperm is going to have a higher % without Ys.
It might not be even something that happens to all men, just human variation and circumstance.