Rebuttal To Creationists - "Since We Can't Directly Observe Evolution..."

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Since when does one particular selection condition make the entire environment constant? Did the weather remain constant? Were there no droughts or floods? Did they have any wars? Any famines? Other diseases? I don't think you have thought through your argument.

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No, you haven’t thought through my argument. It is not necessary that the environment remains absolutely constant, only that it does not change in ways that make the new allele disadvantageous before it fixes. You will note that none of these things have removed the advantages of the sickle cell allele.Of course if you had thought though your argument you would realise that it assumes that such is the case. You are arguing that recombination does not give an advantage in fixing two advantageous alleles. If either of the two alleles cease to be advantageous your argument is moot.

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You clearly aren't thinking through your argument. You are posing an argument based on a particular environment and a particular population

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No, I am offering an actual example of an environment staying stable enough to allow cumulative evolutionary change. Which demonstrates that such is possible.

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The sickle cell allele is not advantageous in the non-malaria environment. Otherwise, it would fix. Your example is not valid

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On the contrary - it is valid for that exact reason. We know an environmental change - eliminating malaria - could wipe out the advantage. But it hasn’t happened - despite all the other changes that have gone on. That is the point.Indeed if my point were invalid sickle cell shouldn’t exist - or should be very rare. It has remained advantageous - in malarial regions - for many human lifetimes. That is why it is as common as it is in the world

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You make the same mistake that Taq makes that multiple alleles can fix simultaneously.

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They can certainly increase in frequency simultaneously - in a sexually reproducing species - which is all I am claiming.

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That's what the Desai experiment shows. The adaptive alleles increase in frequencies but before fixation occurs, they induce sexual reproduction. If they had waited longer, only a single allele would have fixed and all the other alleles would have been eliminated by the competition and fixation process.

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So the Desai experiment shows that you are wrong.

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Then everyone would have the sickle cell allele. It only has benefit in malaria endemic regions. In non-malaria regions it is not a beneficial allele.

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Mixing up examples made to illustrate different points is not going to help you. Multiply-resistant bacteria demonstrate that cumulative evolution is possible. Sickle cell demonstrates only that environments can be constant enough to maintain allele frequencies - and I am not claiming any more for it.(Besides that you are wrong. Even if malaria was everywhere, we wouldn’t all have the sickle cell allele. As predicted by the mathematics of evolution).

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Sure, but it isn't advantageous outside the malaria environment. It gives no advantage to those living in northern Europe

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Which does not change the fact that it is advantageous in malarial regions, and that that advantage is constant enough to spread the allele there.

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It isn't as common in northern Europe where malaria is not endemic. And if it is homozygous for the sickle cell allele, it is harmful. I treated a patient many years ago who was homozygous for sickle cell and this patient was hospitalized many times for sickle cell crisis.

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Which still does not change the facts.

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Only in a constant environment will they increase and only within a limit. If an adaptive recombination event doesn't occur, competition and fixation will eliminate all but one of the adaptive alleles. If the environment is not constant, who knows what alleles will increase in frequencies.

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As usual you haven’t thought out your argument. If the two alleles do not come into contact they cannot interfere. If they do then recombination becomes a possibility - and the greater the contact the greater the probability of it occurring.It does not require an absolutely constant environment, only that the alleles remain advantageous which is implicit in your original argument.

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You are confused

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Not at all. As you admit the Desai experiment proves the point:

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The Desai experiment behaves exactly as expected. 90 generations of a constant environment with asexual replication gives increases in frequencies of adaptive alleles, then at 90 generations, sexual reproduction is induced and adaptive recombination events occur. Sexual reproduction is induced before fixation has occurre

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I didn't bring up the Malaria example, you did.

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I see. I am it supposed to bring up valid examples because you’ll make stupid mistakes?

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Multiply resistant bacteria requires a population size much greater than that for singly resistant bacteria. It take much larger populations because they have to diverge more to get variants with double mutants. And to get triple mutants requires such large populations that even HIV does not achieve such population size. That's why 3-drug therapy works.

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Which does not change the fact that hospitals are a stable enough environment for the evolution of multiply-resistant bacteria.

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And that's your proof for UCD?

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If you’d read my posts you’d know it wasn’t - and you’d know the point I was making.

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What facts are those?

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The ones I mentioned earlier in the post:

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Your own example, the Malaria gene shows that it is not advantageous in every environmenT

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The point is the stability of the environment where it is found. I guess you think we shouldn’t worry about malaria because any time soon it’s bound to just vanish.

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… but you have to pretend that there are some alleles that remain advantageous in any environment.

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No, I really don’t have to pretend anything of the sort. And I don’t.

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The point is the experiment is performed in a constant environment, something which doesn't exist in reality for humans. You are so confused, you think it does because the Malaria allele appears. Why aren't they resistant to Tuberculosis, or Small Pox, or Plague, or of a number of other infectious diseases?

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No, I don’t think that the environment remains constant. I just accept the facts that it is constant enough for sickle cell to exist and even be common in quite large areas.

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Not at all, you bring up invalid examples because you are confused. Try bringing up what is in your imagination, like those alleles that are advantageous in any environment.

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Yes, I get it. You think telling the truth is a sign of confusion. That’s why you lie. Not a surprise coming from a Satan-worshipping nutcase.

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So humans can create an environment for bacteria to evolve resistance to drugs

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Which is yet more evidence that environments do not have to radically change in they way you assume.