As long as I'm Posty McPosterson...

[moominmuppet]

A friend emailed me the following link:

Redheads set for extinction
From: The Courier-Mail
August 22, 2007
PETER Beattie, Nicole Kidman and Michael Voss are. So were William Shakespeare, Christopher Columbus and Queen Elizabeth the First.

But the future doesn't look bright for people with ginger hair.

According to genetic scientists redheads are becoming rarer and could be extinct in 100 years.

Click here to read the full article on the website

And I wrote the following reply (I should note that I think the "100 year" estimate is probably substantially off, but the overall effect is certainly happening):

I have such weirdly mixed feelings about it (the same is apparently happening to true blondes). I've actually been thinking about the idea since I was a pre-teen, when I read some relatively lousy Piers Anthony young adult SF, where the entire population of the world had homogenized in terms of skin and hair tone, except these last few kids, who were being herded into breeding only with those who had the same traits, so they could be 'preserved'. Of course, people fell in love across the boundaries, and adventure was had.

But it did make me think a lot. It made me realize that something could seem both tragic, and wrong to prevent at the same time. I love all the unique weirdnesses that biological isolation has caused, and I value them, but I don't know if I see any true benefit to trying too hard to maintain them, and I definitely see downsides to doing so. Of couse, this isn't all that different from all the questions about how we handle the same issues culturally, and I have a much harder time answering that one.

On the positive side, one of the few easy bonuses of the types of genetic tinkering we may be able to do in the relatively near future is that it wouldn't be all that hard to artificially maintain those traits if we choose to, without playing "breeding program" games, and I'm sure some people would.

Comments

[moominmuppet.livejournal.com]

Really not utter nonsense, though. Although 'extinct' is a headline term, because 'statistically negligible' doesn't sell papers, the basic idea is true. As we function more and more as a planet, and less and less as isolated groups, all phenotypical extremes, especially the recessives (and particularly recessives that already are only carried by a very small proportion of the planet) are going to become radically less common, especially in terms of the constellations of traits that we tend to identify as the notable physical traits of particular ethnic groups (although obviously traits that are carried close together on the same chromosome will take longer to dissociate from each other). Whether the original cause was simple genetic drift or evolutionary pressures of a particular environment, either way those we're going to see radically fewer of the extremes. Of course we'll always see variation, but it's not going to be at all in the way that we currently think about ethnicity, and people with vivid red hair (recessive trait), or deep black skin (which requires inheriting alleles for dark skin on all or almost all of the requisite genes), or body morphology extremes such as the Masai or Inuit, will become very, very rare.

To use an artificially induced example, any "purebreed" dog has a specific constellation of traits that we identify as that breed. Mixed-breeds have a much more random assortment of those traits, and they tend much less toward the extremes. I think this is generally a good thing, given all the health problems that often accompany those extremes, either as a direct result of the extreme itself (stomach torsion in large breeds, for example), or as an unfortune side-effect of in-breeding. However, it doesn't change the fact that two thoroughly Heinz 57 mixed-breeds don't produce chihuahas or Great Danes.

I love the current phenotypic variety among humans on our planet on a purely aesthetic level, but it's impossible not to be aware that the variety itself is fundamentally a result of isolation that is becoming less and less common.

As for mutations, yes, of course. However, the way mutations successfully spread is either through evolutionary pressure, or through genetic drift. In either case, small population size makes it a lot more likely, and a lot faster.

*off to read the snopes article now*

[tasharowan.livejournal.com]

or deep black skin (which requires inheriting alleles for dark skin on all or almost all of the requisite genes),

IIRC, skin coloration, including the deep black, is partially climate induced. It takes something like a 1000 generations to make a shift from pale to dark, but it happens. So as long humans keep living in a variety of enviroments, people will look dramatically different from one another. Evolution demands no less.

[moominmuppet.livejournal.com]

Only to the extent that they're producing offspring with other people who've continued to live in those same climates for extended periods of time. As our population becomes more mobile, that's a lot less certain. And if some generations of your family have lived in equatorial areas, and 10 generations later, they're living in five other places around the globe, you're not going to see consistent evolutionary pressures (especially considering the extent to which we mitigate those environmental pressures with modern technology). As I recall, skin tone is essentially an additive effect; there are some number of gene locii, and the more dark alleles you have between all of them, the darker your skin. I think the effects of direct heredity in that regard are going to be much, much more powerful than evolutionary selection. Given statistical distributions, there will continue to be variation, just as too people can produce a child that is either darker or lighter than them, depending on how those alleles sort out, but I think it'll gradually get closer to a normal distribution, rather than specific geographic areas that have consistently substantially darker or lighter skin. I'm talking very long-term here, obviously. Even if we all up and shuffled across the planet this minute, it'd take a while, and our interactions are still heavily within our own geographic regions, but it's been a continual process (hell, the vast majority of American citizens are examples of that), and I think it will continue in this direction pretty inevitably, barring societal collapse that stops the progressive increase of mobility.