Buh?

[rowyn]

'Three hundred million years ago the Y chromosome had about 1,400 genes on it, and now it's only got 45 left, so at this rate we're going to run out of genes on the Y chromosome in about five million years.”

… I really hope, for the sake of my faith in science, that this professor is basing her conclusion on something a lot more complicated than that statistical trendline.  Because that reasoning strikes me as akin to saying “A billion years ago, the ancestors of humans had four legs, and now humans have only two!  At this rate, in another billion years we’ll have none!”  Showing that natural selection favors a Y chromosome with fewer genes isn’t the same as saying natural selection favors the Y chromosome not existing.  But this is a mainstream newspaper ‘science’ reporting.  And just because an idea makes absolutely no sense at the surface level doesn't mean it's wrong. Surely there’s more to it than that. 

Surely.

o_O

Comments

[pyat.livejournal.com]

I read a newspaper article once where a politician claimed that Japan's negative birthrate meant that, in 200 years, Japan would be an empty island.

[rowyn]

Heeheehee! Even the phrase "negative birthrate" is funny when you think about it. How do you get negative births? Babies crawl back into the womb and then regress to fetuses and finally unfertilized eggs? Is that what happened to the backwards-living Merlin?

[ceruleanst.livejournal.com]

1. Arithmetic: Fewer babies were born today than yesterday.
2. Geometric: More babies were born today than yesterday, but the increase in births from yesterday to today is smaller than the increase from the day before.
3. Exponential: The increase in births is increasing, but the increase of the increase is not as much as it was.
4. Ridiculous: The increase of the increase is increasing, but the increase of the increase of the increase is decreasing.

3 is "negative birth rate". 4 is "the birth rate is falling". While the world population continues to skyrocket, "the birth rate is falling" is enough to convince most people that humanity is in danger of dying out from lack of interest within a few generations if we don't all Duggar it up posthaste.

[rowyn]

There seem to be plenty of people who really want to have babies. I am more than happy to leave it to them to reproduce. Personally, I think "I am happy having kids" is just the sort of trait that ought to be bred into the population, as opposed to "Have kids because it is your duty" or "have kids because birth control is immoral". If the former yields fewer kids but ones who are happier about breeding -- hey, win/win!

[terrycloth.livejournal.com]

Well, from the article, there's only one gene on the Y chromosome that's really essential and there are several other candidates that could replace it. Apparently this has already happened in a few other mammal species.

Then instead of having a bright-line 'XX' vs 'XY' it'll be 'how many copies of the lots-of-testosterone gene on chromosome 12 do you have'?

[rowyn]

Or maybe we'll evolve into hermaphrodites!

I never have understood what the evolutionary advantage of distinct male/female genders over hermaphrodites is.

[shockwave77598.livejournal.com]

principly the effect of "Only the strongest survive" is multiplied by two when sex is added. So ANY progeny will gain the genes of the two survivors. Offspring of a hermaphrodite is essentially just a clone of the mother - a genetic dead end lacking in variation.

[rowyn]

I don't know offhand, but I didn't think all hermaphrodites were self-fertilizing. Is there necessarily a genetic advantage to two parents, one male + one female, versus two parents, both hermaphrodites?

[terrycloth.livejournal.com]

Yeah, they're not the same thing. But preventing parthenogensis might be why male/female works better, since parth offspring are going to be severely inbred if it was accidental breeding-with-yourself and not an actual clone.

[rowyn]

I was wondering if male+female might just be the easiest way to prevent self-fertilization without requiring each individual to have two sets of reproductive organs.

[tuftears.livejournal.com]

I think that's conflating self-impregation with the ability of a being to participate in either sexual role!

[terrycloth.livejournal.com]

I kind of like the amphibian thing, where you switch from one to the other over the course of a few days depending on what's needed.

The main advantage...

[tahkhleet.livejournal.com]

...is energy. Herms burn LOTS of calories. One of the main energy budget items in the body is the gonads, because they get insane biological "copy protection" and "data integrity" measures. Dwayne (who's a microbiology major) says herm on a physical level is a wild gamble, evolution wise, because it adds a huge survival burden (a lot more food) for a very minor benefit (higher reproduction rate) (the point is, you still can't have too many of the species pregnant at the same time so you can't make everyone into a mother...)(and a higher growth rate means more bodies and more stress on the niche)

Re: The main advantage...

[rowyn]

I can see where herms with two sets of gonads would burn more calories, but it seems like you could dual-purpose one set of gonads (as Terrycloth pointed out some amphibians do) so that they could do either job, without expending tons more energy on it. Maybe we just didn't go down that branch, though, and it's too hard for mammals now to get back to that path.

[shockwave77598.livejournal.com]

Whah?

Our genes are growing longer, with more and more garbage code with every mutation. They aren't getting smaller! And besides, 300,000,000 years ago precedes even the dinosaurs. Y chromosome? Gotta have a mammal to stick it in first.

Er, I'll double check with Dwayne...

[tahkhleet.livejournal.com]

...but I've seen this before and I don't think the underlying claim was based on statistical manipulation. The Y chromosome is very unhealthy. Its basically deformed. This used to be a significant issue in my misandry and radical feminist convictions. Now, admittedly, I may have been misled and its a perfectly healthy thing. But iirc, the sources I read on this weren't feminist tracts but a couple of neutral articles in magazines. So she might be right for the wrong reasons, but there's a significant chance she's right. Its worth noting that almost all sex-linked diseases affect males.

[koogrr.livejournal.com]

For thirty seconds I forgot males suck.

[sebkha.livejournal.com]

A I understand, the Y chromosome has developed a redundant error correction coding which staves off the deterioration.

[rowyn]

Ooh cool!

[koogrr.livejournal.com]

That is pretty cool.