How do you want to evolve tomorrow?

Caesarean sections are on the rise.

Taking the stat only of C-sections required due to a woman's birth canal being too narrow to let the baby though, and only in some developed nations, they're up about 3% since the 1970s.

The explanation is that women who'd have died in childbirth not too long ago, now can give birth more or less safely and multiple times, therefore they're passing on genes for a too-narrow birth canal. This means there's a positive selective pressure on these genes, or that the negative selective pressure against them has vanished. Either way, more C-sections in the future as more women pass on such genes to their offspring.

Now, countries where hospital births are not the norm, and where reaching a hospital in an emergency during birth is hard or impossible, won't see this happen (and will see more women die in childbirth, alas).

This is an easy example of how different human populations might evolve in different ways. Of course, it gets more complex because there will be some mixing of the two very broad groups.

But suppose human populations were scattered more widely, say in different worlds. Suppose we had a permanent population on the Moon, Mars and Titan, plus in habitats out in space (maybe by the asteroid belt, maybe on Earth orbit, maybe around Jupiter, etc.)

We can't say what selective pressures will be found, not for sure. There is much speculation, especially in science fiction, to the effect that adaptations to low gravity will prove desirable. We don't know what kind of mixing will go on, either.

Now imagine we manage to colonize a few habitable worlds around other stars. The more Earthlike the environments, the more familiar selective pressures there will be. But "habitable" could mean lots of things. Larry Niven has imagined some strangely habitable worlds, including ones with higher gravity. He has also made use of a known thing called the founder effect.

Suppose we start with a small number of colonists, say 100, who will be rather isolated for decades. Now suppose one of them has a rare genetic mutation, say violet eyes. In succeeding generations, this mutation will be over-represented in the new world (if it succeeds).

Mixing will be slow and rare, assuming light speed to be the ultimate speed limit in the universe. Within a few millennia, humanity could separate into different species, eventually perhaps being unable to interbreed.

Quote: Nareed

The explanation is that women who'd have died in childbirth not too long ago, now can give birth more or less safely and multiple times, therefore they're passing on genes for a too-narrow birth canal.

You can expand that argument to a lot of medical intervention. We may be producing more and more people who need assistance to survive normally.
But what should we do instead? That's the problem.

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Suppose we start with a small number of colonists, say 100, who will be rather isolated for decades. Now suppose one of them has a rare genetic mutation, say violet eyes. In succeeding generations, this mutation will be over-represented in the new world (if it succeeds).

You should be able to mitigate this by taking along the basic material for test tube babies. Settlers could produce children with a much wider variety of genetic information.

Quote: rxwine

You can expand that argument to a lot of medical intervention. We may be producing more and more people who need assistance to survive normally.
But what should we do instead? That's the problem.

I don't see a problem.

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You should be able to mitigate this by taking along the basic material for test tube babies. Settlers could produce children with a much wider variety of genetic information.

That would depend on the means used for colonization and the technologies available at the time. It may be taking frozen embryos along wouldn't be the best idea (story idea: the embryos are sabotaged by a hidden radiation source, but it's too weak to kill them so it just mutates them "X-Men in space!!!" <w>).

Quote: Nareed

I don't see a problem.

One might be the cost of providing various medical interventions. Both long term and short term.

Of course, one day we may be able to completely cure people of most things that are chronic or debilitating.

Quote: rxwine

One might be the cost of providing various medical interventions. Both long term and short term.

Humans come with minds as well as bodies. Many people with severe disabilities, whether congenital, genetic, or acquired, have made great contributions to humanity. It would be short-sighted and self-destructive to classify disabilities and defects as problems.

Quote: Nareed

Humans come with minds as well as bodies. Many people with severe disabilities, whether congenital, genetic, or acquired, have made great contributions to humanity. It would be short-sighted and self-destructive to classify disabilities and defects as problems.

Not asking you to be Hitler. Or even practice China's one child policy.

The Earth isn't yet in a sinking Titanic position where painful decisions have to be made, but we could be one day.

What would you do when volunteerism is no longer resolving a serious problem?

How much increased risk would you put 99 people of your space colony to save one, who might be depleting supplies of medicine, if you only have supply ship every two years?

Quote: rxwine

The Earth isn't yet in a sinking Titanic position where painful decisions have to be made, but we could be one day.

Conceivably so. but absent some major natural disaster like an asteroid/comet impact, gamma ray burst, coronal mass ejection or super-volcano, we should be ok. One telling statistic is that population growth first slows then reverses in direct correlation to rising prosperity.

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How much increased risk would you put 99 people of your space colony to save one, who might be depleting supplies of medicine, if you only have supply ship every two years?

A colony in another star should expect a supply ship every few decades. once per year sounds too good to be true ;)