Idea that some species have stopped evolving is finally going extinct (2015) | Hacker News Reader

Idea that some species have stopped evolving is finally going extinct (2015)

nautil.us

59 pointsdnetesn25 comments

Unless your species is smart enough to prevent pre-reproduction death and cure infertility.

If you are snarkily trying to imply that humans have stopped evolving, the genetic evidence points in the utterly opposite direction. Here's a pop science take on the matter but you can dig "human rapid evolution" into Google and read plenty of takes on the matter from many different papers: https://www.wired.com/2007/12/humans-evolving/

And of course even if you could avoid all selection pressures, the species would continue to evolve to take advantage of that change. We will simply evolve out of the adaptions we developed to cope with the threats we have mitigated technologically, and it seems likely to me those changes could be far more profound.

Right, the lack of selection pressure is in itself a selection pressure, in that those individuals more inclined to devote energy to breeding that might have been devoted to survival will out-reproduce the others.

Rapid changes are expected after a selection bottleneck. There is less genome diversity between native European and native Australians than between apes in one herd.

Being alive and fertile does not imply that you will reproduce. There are other genetic factors that may lower chances of reproducing, like having any kind of flaw that makes given specimen "unattractive" for other specimens.

Evolution is only guided by survival alone in situations where as survival approaches 100%, so does fertility. In humans this is very much not the case for an immense number of reasons even beyond sexual selection. One of the biggest is simply social decisions. For instance there are ever more people that are fully capable of reproducing are 'responsibly' choosing not to. At the same time other populations, including in developed areas, are recklessly reproducing without much concern for anything at all other than themselves.

This means the genetic pool of the future will begin to select against the 'responsible' group. Outside of genetic evolution this also has a major effect on cultural evolution. There are strong correlations between fertility and low income, low education, and high religiosity. 'Responsible fertility' means children from these groups will make up an ever larger percent of all new births. Makes one question the notion of 'responsibility' in this regard.

There are also survival factors that are not so in your face as e.g. being eaten alive by a predator or starving to death. For instance obesity is becoming ubiquitous, yet it is strongly connected with a wide array of factors leading to infant death - including neonatal. Having a child means nothing if that child is not ultimately able to, in turn, also able to procreate. Another example of this issue would have been in olden times when royalty would sometimes inbreed to the point of committing genetic suicide. See, for instance, the Habsburgs.

To bring this point to the extreme, after some time we may have two races of humans, one "higher" race, that would be more intelligent, educated, cultural, and would rule over a much more numbered "lower" race that would be physically stronger, has better mass-reproduction ability, but lower intellect, becoming less and less intelligent over time.

In even more far distant future, those two races may even split so much, that they become separate species, without ability of cross-breeding. Higher species would continue to call themselves humans, and the lower species will quickly drop to the status of animals in the eyes of the higher species.

Then someone will learn that there was once Home Sapiens, which was an ancestors of Home Modernus, and Home Animalis, which is an evolutionary dead end.

> after some time we may have two races of humans, one "higher" race, that would be more intelligent, educated, cultural, and would rule over a much more numbered "lower" race that would be physically stronger, has better mass-reproduction ability, but lower intellect

Since you've stipulated that in this scenario the two classes are still interfertile, in what sense is this not the case right now?

> which is an evolutionary dead end

Just to provide a different perspective

In this contest the likely evolution of Home Modernus would be through a slight abuse of eugenics and genetic manipulation dictated by a sense of aristocratic entitlement. This is likely to produce (almost literally) peacock tails in the higher humans. Evolutionary dead ends happens indeed when traits and behaviours necessary for the survival of an healthy community lose their utility against the environment (in the case of peacock the vivid colours are a signal of an healthy individual able to provide more that enough food).

Meanwhile Home "Animalis" lives outside the upper society, but close to advanced and cheap technology (old by that time standard, but new for us) essentially in a condition not distant from the countryside of many developing nations today.

In the long term I would bet on the "lower" race

No, this will never happen. Genetic isolation of the kind you describe is impossible. Even attempts to maintain racially pure castes are stymied by people's propensity to fuck the wrong person, never mind this happening through passive means.

also if you consider the fact that the process would last quite a few centuries of stable society and that illegitimate "hybrids" would be stronger and healthier. (the split would not be 50/50, but more like 99.99/0.01 so the "upper humans" would be a terrible bottleneck)

> This means the genetic pool of the future will begin to select against the 'responsible' group. Outside of genetic evolution this also has a major effect on cultural evolution.

I doubt that there is a relevant genetic difference between the "responsible" and the "irresponsible" group. As for the cultural evolution, it seems to me that the "responsible" culture has evolved from the "irresponsible" one in the first place, and that it is constantly recruiting people from the "irresponsible" group.

>This means the genetic pool of the future will begin to select against the 'responsible' group.

This idea, called "devolution", is dead wrong. First, it presumes some sort of genetic basis for being "responsible", which is hardly in evidence. Second, it presumes no gene flow between these groups, decidedly false as class mobility is nonzero. Finally and most egregiously it posits some form of group selection, whereas selection acts on individual variants.

There's every reason to think that personality traits such as religiosity, and indeed simple desire to have children, are genetically influenced. (Not that it's been proven, but that's where one should bet.)

There's no need to assume there's no gene flow between sub-populations. Indeed, the existence of gene flow would be why some genetic variants favouring desire to have children could become dominant. There's also no need to assume group selection - individual selection is obviously quite sufficient.

And there's no call for describing this as "devolution". You're maybe confusing the original poster with one of the replies...

No, none of that stops evolution. If an species keeps reproducing, it keeps evolving.

I'm not sure what you mean by that, if you're talking about animals then reproduction death is pretty rare (compared to people), and if you're talking about people then reproduction death and infertility have not been cured. Even if they were that would just reduce two selection pressures, leaving every other pressure in place.

pre-reproduction death. And in humans that is not something that necessarily needs a cure :)

There's sexual selection to account for too.

I always found the idea of species "frozen in time", as crocodiles were often described, highly doubtful and uneducated.

Rather, phenotypes may be similar. What we know for sure, very similar phenotypes evolve via very different paths, e.g. eyes.

I never thought of crocodiles as frozen in time as much as they have a body plan that is so well suited for their environment it is simply kept for want of any better design.

Yeah, if you are constantly evolving, but those offshoots aren't as effective as the root, evolution is still occurring, and if the environment changes the species will, but if you're at a high level of suitability, you'll remain as you are.

The fossils actually are quite limited regarding whether the phenotype has not changed much. Many traits, such as the nature of the immune system, do not fossilize well.

By scrutinizing understudied and recently uncovered fossils, Brochu and other paleontologists demonstrated that ... Crocodiles were once as diverse as dinosaurs.

Another fine example of how holding fast to preliminary models and conceptions is a good way of holding back science, not defending it.

And so it was a fine thing that physics did when it built probability and uncertainty into model-building ... formal recognition of how important it is to stay open-minded.

What a great story

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