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Humans haven't stopped evolving

harvardmagazine.com

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Re: Humans haven't stopped evolving

#111

Post by HarHarVeryFunny »

prologic wrote: post #7

If that's true. Why haven't we evolved into a species that doesn't harm each other or the environment?

Maybe that's what Tibetans are evolving into?

That's the way evolution works - isolated sub-populations that mostly don't breed with outsiders necessarily diverge.

Of course evolution is essentially directionless, just "survival of the survivors", although over time whole ecosystems of co-evolving animals and plants will necessarily settle into dynamic "attractor states" of semi-stable co-existence, until a spanner is thrown into the works.

Re: Humans haven't stopped evolving

#112

Post by saltcured »

seanmcdirmid wrote: post #104
HarHarVeryFunny wrote: post #103

Earlier quoted context omitted.

As long as all offspring aren't 100% exact clones of the parents then you'll get evolution. In practical terms it would be impossible to genetically engineer away genetic variation (assuming you could convince people to stop having sex and visit your cloning lab instead). There are all sorts of things like DNA damage, horizontal gene transfer, and just the inherent error potential of reproduction that you would never…

You’ll get mutations, not evolution. You still need natural selection to sort out the mutations which gives us evolution, and that’s a bit harder now that we don’t have to worry about being hunted down by tigers. Anyone can reproduce and pass down their genes, so what mutations are we currently selecting? Maybe looks, but I doubt even that.

You're saying that as if survival doesn't remain an evolutionary pressure. Life is inherently demanding, and many mutations are lethal.

So, at best, the argument seems to be that the surviving gene pool may get more complex with lots of optional mutations which all coexist? Could we end up like some plant species full of cultivars where larger swathes of genes are expressing differently out of a very convoluted library?

If you're envisioning medical science to allow people to survive with otherwise lethal mutations, I would say that is not an escape from evolution. Instead, you've revised the reproductive cycle to include more epigenetic components. The species is still the survivable set of genes and cultural practices which are evolving together, and which terminate when they no longer function as a system.

Re: Humans haven't stopped evolving

#113

Post by HarHarVeryFunny »

mhurron wrote: post #14
prologic wrote: post #7

If that's true. Why haven't we evolved into a species that doesn't harm each other or the environment?

Because we became an incredibly successful species doing just that.

On an evolutionary timescale it's a bit early to call humans a success. We only diverged from other apes about 5 million years ago, and have existed in modern human form for much less. Mitochondrial Eve lived only 100-200K years ago.

In the last few hundred years since industrialization we've been destroying our own environment - the one we'd previously adapted to - at a rather remarkable rate, an "experiment" that is still playing out. Will it turn out to be successful, or will we end up modifying the environment so much (or just fail to evolve quickly enough to adapt to changes outside of our control) that in another million years we'll all be gone?

We'll certainly not last forever, even if we manage to have a run as long as the dinosaurs. Whether it's climate change, disease, or some unforeseen change in our fortunes, eventually we'll either go extinct or branch off into a bunch of other species that would be unrecognizable to ourselves.

Re: Humans haven't stopped evolving

#114

Post by HarHarVeryFunny »

seanmcdirmid wrote: post #104
HarHarVeryFunny wrote: post #103

Earlier quoted context omitted.

As long as all offspring aren't 100% exact clones of the parents then you'll get evolution. In practical terms it would be impossible to genetically engineer away genetic variation (assuming you could convince people to stop having sex and visit your cloning lab instead). There are all sorts of things like DNA damage, horizontal gene transfer, and just the inherent error potential of reproduction that you would never…

You’ll get mutations, not evolution. You still need natural selection to sort out the mutations which gives us evolution, and that’s a bit harder now that we don’t have to worry about being hunted down by tigers. Anyone can reproduce and pass down their genes, so what mutations are we currently selecting? Maybe looks, but I doubt even that.

I'm sure if you looked at fertility rates across the globe, broken down by location/race/religion and other demographics, you'd find plenty of differences - some very large.

Yes, ability to fend off (or avoid) a tiger attack is not much of a factor nowadays, but even something as simple as a religion that encourages having large families, and encourages marrying within religion (you don't need to live on an island to be somewhat genetically isolated) will have an effect.

As far as survival (not dying) goes, I'm guessing that risk appetite, and certain specific forms of it (e.g. fear of heights) has a genetic component, and it looks like base jumpers and free soloists are experiencing selection pressure!

In the modern world there is also a lot of truth to the premise of the nominally satirical movie "idiocracy", where it's not things we regard as positive (strength, intelligence, etc) that drive reproductive success, but in fact the opposite, with birth rates among the unintelligent often higher than that among the intelligent (who are prone to worrying about having kids).

What tends to drive evolution the most seems to be occasional rapid shifts in the environment rather than stable selection pressures. For example, we were lucky that COVID-19 wasn't worse than it was, but nonetheless by definition those who died were those with immune systems less well prepared for the new threat, and the human species as a whole has now slightly "evolved" to be better able to survive that selection pressure.

Re: Humans haven't stopped evolving

#115

Post by ninthcat »

seanmcdirmid wrote: post #104
HarHarVeryFunny wrote: post #103

Earlier quoted context omitted.

As long as all offspring aren't 100% exact clones of the parents then you'll get evolution. In practical terms it would be impossible to genetically engineer away genetic variation (assuming you could convince people to stop having sex and visit your cloning lab instead). There are all sorts of things like DNA damage, horizontal gene transfer, and just the inherent error potential of reproduction that you would never…

You’ll get mutations, not evolution. You still need natural selection to sort out the mutations which gives us evolution, and that’s a bit harder now that we don’t have to worry about being hunted down by tigers. Anyone can reproduce and pass down their genes, so what mutations are we currently selecting? Maybe looks, but I doubt even that.

Evolution happens even without any selection pressures, for example with genetic drift.

Re: Humans haven't stopped evolving

#117

Post by asdff »

johnthewise wrote: post #91
asdff wrote: post #75

Earlier quoted context omitted.

You can observe evolution on much narrower timescales. People were following how covid was evolving after all. Evolution just means some changes to dna. Even identical twin children have some differences between them.

It's more of a function of selection pressure applied to genes per unit time based on some environmental factor, so you'd expect to observe less evolution in narrower timescales simply because it takes few decades for humans to pass on genes versus bacteria or viruses. In the same fashion, if some gene pool is locally optimal(?) against the environmental pressures, it may just stop evolving meaningfully. E.g, If male…

You can have evolution even within your own lifetime. Cancer progression, for example, is governed by selective pressures on the tumor.

Re: Humans haven't stopped evolving

#118

Post by gweinberg »

"Most research during the past two decades hinted that human evolution has largely slowed or changed so subtly that existing tools couldn’t detect it; evidence seemed to suggest that civilization put humans beyond the reach of natural selection."

There has never been the slightest shred of evidence to that effect, anywhere, ever.

Re: Humans haven't stopped evolving

#120

Post by dTal »

vitally3643 wrote: post #99
chaz6 wrote: post #93

Does anybody think that evolution just stops? A species only stops evolving when it is wiped out.

Or when they develop a society which removes all evolutionary pressures. Evolution isn't magical, it's purely probabilistic. You can drive the probabilities down real low and then genetically engineer the rest away.

Do you really believe that everyone in society is precisely equally likely to reproduce? No inheritable traits liable to move the needle one way or another?
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