Did evolution take a misstep with large civilizations?

[Dylan Cannisi]

This question has been festering in my brain for a few years now. The idea that evolution in humans took a misstep. I wonder does evolution (Explained by Charles Darwin and Alfred Russel Wallace ) have something like a logic error in the programming of genes? The survival of a species relies on the weak mutations to die out and strong mutations to survive and breed, but, what if a mutation occurs (like that at the divergence from Homo Erectus to Homo Sapiens and Homo Sapien Neanderthalensis) that allows the specimen with weak genes to be supported by the one with strong? I don't mean anything ethical racial just the Homo Sapien Sapien as a race when I say weak. The key genes I'm referring to is the ones that allowed for Homo Sapiens to form civilizations. Will civilizations lead to a genetic evolution dead-end? Or are they a evolution sweet spot?

 

Sorry for the anthropology and the philosophy in the genetics group, but, the question is pointed toward the question how genetics evolve over time.

 

 

 

 

 

[CharonY]

The premise is wrong. There are no weak or strong genes and survival has only a secondary relevance. There are only variants that are a) beneficial, b) neutral or c) detrimental for reproduction under a given set of conditions. The latter can and does change and thus altering the selective pressure that shape genotypes. And on top of the whole thing there are stochastic events that also affect the genomic landscape though not in a structured manner.

[swansont]

It's entirely possible that preserving a wide diversity of genetics would boost survivability of some sub-population under some future environmental conditions. Species that become too specialized are more prone to extinction when conditions change, as they inevitably do.

[Dekan]

" The survival of a species relies on the weak mutations to die out and strong mutations to survive and breed, but, what if a mutation occurs .... that allows the specimen with weak genes to be supported by the one with strong? .... The key genes I'm referring to is the ones that allowed for Homo Sapiens to form civilizations. Will civilizations lead to a genetic evolution dead-end? Or are they a evolution sweet spot? "

 

Dylan, apologies for condensing your post to skirt round the references to "race". That word tends to cause trouble.

 

"Species" is still OK though. And I think you're basically right ,that when the species "Homo Sapiens" came on the scene, evolution took a new step. I wouldn't call it a "mis-step", though, but rather a "step-change". This new species had genes which allowed it create "civilisation". And that 's a new phenomenon, which seems unprecedented in the history of life.

 

Homo Sapiens "Civilisation" brings in the deliberate, organised, widespread - and consciously-directed support of the weaker members of the species, by the stronger ones.

 

At first sight, that looks like a recipe for evolutionary disaster. It tends to preserve such things as weak eyesight. In a precivilised world, genes which cause poor vision would be quickly eliminated. A child born with such defective genes wouldn't last long. He/she would be unable to spot lurking predators, and so get eaten. Or be unable to hunt and forage for food effectively, and so starve to death. That would prevent the child from surviving to reach reproductive age and spreading "weak-eyesight" genes among the population. Thus everyone would have good eyesight.

 

Whereas civilisation - especially technological civilisation - goes right against this. It invents devices such as "spectacles". and reading-glasses. These allow weak-eyed children to grow up, prosper, and reproduce

 

But that's a good thing, because it preserves much more valuable endowments, like a powerful intelligence. And isn't the increase of intelligence something that seems to have been selected for, throughout the course of evolution? As time has passed, organisms have tended to get more intelligent. Any modern mammal is an intellectual giant, compared to the creatures of the Cambrian Period! Evolution seems to go for more IQ.

 

In that light, couldn't Anthropogenic civilisation be regarded not as a "misstep", but as the next, improved, evolutionary step?

 

[PS - I messed up the quote function -sorry!]

Edited March 10, 2014 by hypervalent_iodine

[swansont]

At first sight, that looks like a recipe for evolutionary disaster. It tends to preserve such things as weak eyesight. In a precivilised world, genes which cause poor vision would be quickly eliminated. A child born with such defective genes wouldn't last long. He/she would be unable to spot lurking predators, and so get eaten. Or be unable to hunt and forage for food effectively, and so starve to death. That would prevent the child from surviving to reach reproductive age and spreading "weak-eyesight" genes among the population. Thus everyone would have good eyesight.

It's also possible that genetic encoding for poor eyesight has other implications that might be an advantage under different environmental circumstances.

[chadn737]

As CharonY pointed out, there are some false premises at work. The biggest being the idea that evolution has made a "misstep". This implies directionality to evolution. It is entirely possible that civilization and group cooperation could create conditions under which a species enter a mutational meltdown. However, mutational meltdowns and extinction are as much a part of the natural course of evolution as beneficial mutations and increased fitness.

 

Secondly, it also assumes that what was "optimal" for humans 200,000 years ago is "optimal" for humans today. But we live in a very different environment than 200k years ago. Different phenotypes may prove more advantageous today than they did back when modern humans first evolved.

 

Furthermore, as CharonY pointed out, its not a matter of "survival", but of reproduction. Civilization may ensure that the mentally handicapped or physically disabled survive, but it does not guarantee that they will reproduce. Ultimately, that is what matters, reproductive success. We still very much live in a world where the healthier, sexier, smarter, etc that you are...the more chances you will have of having sex. If you are of legal age, just go to a bar on a Friday night. Actually, the real game changer is contraception (and artificial insemination), which really removes reproduction from the act of sex and so has the chance to really skew the reproductive success of various individuals. Thats an entirely different conversation however.

 

My final point is this, the survival and even reproduction of deleterious mutations is really not of significant consequence as long as those deleterious alleles remain rare in the population. With the increase of human population, there has been a subsequent increase in the number of rare deleterious mutations, however, this has had little impact on the actual genetic structure of the human population as a whole. Mutational meltdown, the situation where a population enters a downward spiral to extinction due to an accumulation of deleterious mutations really only happens in small populations, like endangered species, where the effects of genetic drift are more pronounced. That is not the case with humans however, with 6 billion some people. The larger the population, the more effective natural selection is even on slightly deleterious or beneficial mutations. Furthermore, in large populations, allele frequencies typically remain fairly constant if the conditions of Hardy-Weinberg Equilibrium are applicable.

Edited March 10, 2014 by chadn737