NPR aired a brief segment this morning on the evolving nature of the Y chromosome. Apparently:
“A few years ago, scientists began wondering whether [the Y chromosome] was in trouble. When they compared it to the X chromosome, which is carried by both men and women, the Y chromosome didn’t seem to measure up.”
When they say “didn’t measure up,” they mean that the Y chromosome has been shedding genes like crazy, and now has only 70 or 80 or so. Compare that to the X chromosome, which carries hundreds of genes. White science-y dudes everywhere are worried because the type of evolution the Y chromosome is doing – gene shedding – “can’t go on forever.”
But rather than delving into the implications of the incredible shrinking Y chromosome, NPR reporter David Page chose instead to wrap the package up with a neat little bow, concluding that the Y chromosome (which is really just a fun science-y way of saying menfolk) is a paragon of agility, and should be commended for its innovative evolutionary techniques.
Left unanswered were several questions any reasonable listener, and indeed any self-respecting journalist, would ask:
• Why are the genes evolving in this disparate fashion?
• Why can’t the gene-shedding carry on forever?
• What happens if said gene-shedding continues? Do men become obsolete, or somehow less complete? Or do they just get EVEN MORE AWESOME, as the story would have us believe?
• Why isn’t the X chromosome evolving this way?
• What are the benefits and drawbacks of the different forms of evolution for these two genes?
• What are the freakin’ implications, huh?
The story brought up more questions than answers – questions that the reporter could’ve easily used the segment’s two minutes of airtime to address, rather than just reassuring his male audience that they needn’t worry about obsolescence, but instead should congratulate themselves on their superior evolutionary skills.
White male scientist David Page, of MIT’s Whitehead Institute, summed it up this way:
“It shows quite a degree of inventiveness and creativity that maybe the rest of the genome could learn something from.”
Thanks for the edification, white guys! I guess I should set about training my inferior X chromosomes to adopt an unsustainable pattern of evolution, huh?
Listen to the full segment here.
We've known about this for years, which makes the NPR/NYT response additionally idiotic. Anyhow, the problem with the Y chromosome is redundancy. There are 23 pairs of chromosomes (all X-like) in the human genome, unless you're a man, in which case half of one of those pairs is mismatched. Normally if there's an error in DNA transcription, it's okay because you have another, very similar, chromosome to use instead, and your most successful offspring are most likely the ones who got the undamaged chromosome. But since men have XY sex chromosomes, if there's any error in the Y, it will be passed down to all male offspring. Thus, over the course of about 166 million years, the Y chromosome has gradually become more error-prone and tiny. (For perspective, humanity is 200 thousand years old.) However, this is a self-limiting effect. Eventually, the Y will be so damaged that any further damage will end the genetic line, and only those who copy it correctly will be able to procreate. Either that, or we'll evolutionarily adapt into producing males if you have X and females with XX.Further notes: Most insects use XX/X (in two categories: XX/X0 and haplo/diploid), and birds (and some fish, reptiles, and insects) use ZZ (male) and ZW (female).Let me know if you have more questions here.
I wonder how different a single-X male would look/act from an XY male. For that matter, does this mean that males are more prone to congenital issues?If only an entire newsroom full of highly educated, bespectacled "serious" journalists had taken the time to do the research of a single internet blog commenter, these questions could've been brought up in the minds of listeners, instead of just having their fluff-filled brains reinforced with more fluff.
Well in first world nations the nature of what men do has changed alot. Maybe that has something to do with it. I'm not an expert so this is a big guss on my part.
Obviously, since internally we're working so hard to improve our awesome man genes that explains the problematic externals.
@Ian There are problems with the externals? Do tell.@Matt That would make sense to me. Further research needed!
"Simplicity is the ultimate sophistication" -Da Vinci"It seems that perfection is reached not when there is nothing left to add, but when there is nothing left to take away" -Antoine de Saint Exupéry"Everything should be made as simple as possible, but no simpler" -EinsteinI do concede that these are "Y" folk … perhaps they are advocating simplicity subconsciously, aware of there own genetic downsizing.Although, It may be that "X" folk are those lagging, holding tight to depreciated information.Another good question would be: Have the X chromosomes been acquiring new genes?
@Byron It would be kind of cool if the Xs were getting new genes, but only if they were stealing them from the Ys. Genetic parasitism!