What is this nonsense I keep hearing about the death of the Y chromosome and the "extinction of men"? I cannot believe that responsible scientists can have suggested this, except in the most tongue-in-cheek fashion, as being a valid interpretation of the facts. The latest "news" is that it's not going to happen after all — well, a child could have told them that! Last I heard, men are necessary for new babies, and the extinction of men would be followed in pretty short order by the extinction of women, and that's that!
The really crazy thing is that some reports have allegedly suggested that after the extinction of men, women would "evolve" to not need them for procreation. Though how they are going to evolve if they can't get pregnant in the first place is beyond me; these people do understand that it takes millions of years for a species to achieve parthenogenesis, right? This particular strand of idiocy also confuses cause and effect: it's one thing for species that has adopted parthenogenesis as its main strategy to subsequently lose its males, it would be quite another thing for a species which has somehow lost its males to achieve parthenogenic abilities!
The facts in this case appear to be these: that the Y chromosome began to evolve separately from the X chromosome some 200 to 300 million years ago, and that in that time it has gone from having about 1,400 genes to only having 45 genes now. Those seem to have been the only facts considered by the original study that made all this noise, and which somewhat naively assumed a constant rate of loss, leading to an empty Y chromosome about five million years from now.
Let's think about this. Implicit in the notion that "the Y chromosome began to evolve separately from the X chromosome" is that, just before this, the Y chromosome actually was the same thing as the X chromosome. [That's not earth-shattering, many species have their sex genes scattered all over their chromosomes, presumably some kind of switching mechanism turns some of them on or off to achieve the required sex. This can be seen for example in some reptiles, where the temperature of the egg during incubation determines the sex of the hatchling: obviously, in such cases, both sexes must have the full complement of genes available to them as fertilised eggs.]
We know two other things as background information. One is that genes can shuffle around the genome, moving around inside a single chromosome or even leaping from one chromosome to another. This isn't the kind of thing that happens every day, but it is quite common given evolutionary time. Very common, in fact. The other is that, in humans, females get one X chromosome from their father and the other from their mother, making them very resilient to diseases caused by faults on a single one of these chromosome: assuming some faulty protein is made from one of the chromosomes, a good version of that protein is still going to be made from the other one (unless they are really unlucky and get two X chromosomes with damage in the same place), and that will very likely be enough for them not to be troubled by the disease in question. Males however only get one copy of the Y chromosome, from their father, and so would tend to accumulate damage to it without its being repaired [this is linked to the fact that males are more likely than females to die in utero, and indeed at all stages of life thereafter].
Given those extra facts, it makes sense that non-sex-related genes might tend to migrate off the Y chromosome and onto the X chromosome; that is to say, that this would be selected-for when and if it should randomly happen, because the resultant males would be more likely to have a healthy X chromosome off their mother [again, what we really mean here is that a male could get either of his mother's X chromosomes, her father's or her mother's, and that a male that got a healthier X chromosome would be more likely to survive].
It's quite clear however that sex-related genes really can't migrate from the Y chromosome to the X chromosome, at least not without a simultaneous evolution of some kind of off-switch to silence it in the female; not impossible, but a much rarer case. There is therefore a certain minimum size for the Y chromosome, and the latest studies suggest that we have already arrived at it.
The outlook therefore is for more of the same: higher mortality in human males at all stages of their lives, together with more variability as compared with females (because the double copy of female genes will lead to a kind of reversion to the mean).
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