ongoing human evolution (Myers quote)


by Phobos
Tags: evolution, human, myers, ongoing
Phobos
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Aug29-05, 12:58 PM
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I recall there being several past topics where we debated whether evolution is still ongoing for humans. I just found & wanted to share this interesting quote from PZ Myer's blog, Pharyngula...

...the ridiculous idea that evolution has stopped for us. It hasn't, and in fact is probably accelerating, in the sense that we've removed many selective forces that would have culled back variants in the pastówe're accumulating novelties in our genomes faster than before. It should also be self-evident that not everyone has children, and different people have different numbers of children, and people have different levels of success in raising healthy children to adulthood. The only way one could think evolution has stopped is if one has a very poor idea of what evolution is.
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honestrosewater
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Aug30-05, 02:07 AM
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It hasn't, and in fact is probably accelerating, in the sense that we've removed many selective forces that would have culled back variants in the pastówe're accumulating novelties in our genomes faster than before.
Can anyone explain or give some examples of what s/he's talking about here? Does he mean that things like medicine and charity have kept some people alive and reproductive, allowing the population to become more diverse?
selfAdjoint
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Aug30-05, 05:57 PM
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Quote Quote by honestrosewater
Can anyone explain or give some examples of what s/he's talking about here? Does he mean that things like medicine and charity have kept some people alive and reproductive, allowing the population to become more diverse?
Yes. There are two prongs to the argument: first, genetic variation hasn't stopped because of civilization; we all carry around a bunch of gene variations that we have acquired since birth; just random molecular events. We will pass them on to our children who will also acquire their own fresh variations, and so on. So new genes are entering the genome all the time, just as they did in the past.

Second, whereas genes that cause physical difficulties were partly eliminated in the past because the children who inherited them tended to die before having children of their own, medicine now keeps these individuals alive to pass those deliterious genes on. So not only is the common genetic variation going on just as in the past, but deliterious genes are not being weeded out as in the past.

Variation is one half of the evolution mechanism; selection is the other. We don't have a clear picture of what selective gradients exist in modern life, but we can be sure that some do exist and over time - if we have the time - they will evoke adaptations just as with Darwin's Finches.

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Aug31-05, 04:55 PM
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ongoing human evolution (Myers quote)


Last part completely agree with, we have no idea at which levels selection is taking place now, its not just selection at the level of the organism but were also evolving as a society. Once we start to change our genetic makup I think we'll even speed up evolution (for good or better which is really irrelevant).
The notion that evolution has stopped for us is ridiculous, we've only been around for such a short while so theres really no way to tell. Lets wait for the next disaster and see what selection will have for us in store :)


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