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Faith  Suspended Member (Idle past 1475 days) Posts: 35298 From: Nevada, USA Joined: |
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Author | Topic: A Creationist's view of Natural Limitation to Evolutionary Processes (2/14/05) | |||||||||||||||||||
nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: Most genetic changes by mistake are neutral with regards to fitness, actually.
quote: This is also how we get genetic benefits. Bacteria obtain antibiotic resistance in exactly this way, which would certainly be a benefit to the bacteria, right? "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: But if that disease does not hinder reproduction, it doesn't matter with regards to reproductive fitness of the population, as long as the environmental pressures remains the same.
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
Sure bad (and in this case I mean bad to the individual in the long term, like my keratoconus) mutations can slip past the reproduction filter, but so do good and neutral mutations that can counter or modify those bad ones. quote: As I have mentioned several times before, I have a neutral/beneficial mutation. In a gene called "MSX1", I have a mutation which prevented my lower wisdom teeth from ever forming. There is also a mutation which conferrs partial to full immunity to the HIV virus. It turns out that the HIV virus is quite similar to the virus that causes Bubonic Plague, and several families who were survivors of the Black Plague in Europe centuries ago happened to have a mutation that prevented the virus from doing what it did to nearly everyone else. The decendents of those Plague survivors have inherited that mutation and are now benefitting from it now that the environment has had a similar virus introduced into it. The above example is much the same as what happens with antibiotic resistance. Another example of a beneficial mutation is Sickle Cell Disease. From the wiki bold added by me:
The sufferers of the illness have a reduced life span. It is believed that carriers (sickle cell trait) are relatively resistant to malaria. Since the gene is incompletely recessive, carriers have a few sickle red blood cells at all times, not enough to cause symptoms, but enough to give resistance to malaria. Because of this, heterozygotes have a higher fitness than either of the homozygotes. This is known as heterozygote advantage. The malaria parasite has a complex life cycle and spends part of it in red blood cells. In a carrier, the presence of the malaria parasite causes the red blood cell to rupture, making the plasmodium unable to reproduce. Further, the polymerization of Hb affects the ability of the parasite to digest Hb in the first place. Therefore, in areas where malaria is a problem, people's chances of survival actually increase if they carry sickle cell anemia. Due to the above phenomenon, the illness is still prevalent, especially among people with recent ancestry in malaria-stricken areas, such as Africa, the Mediterranean, India and the Middle East. In fact, sickle-cell anemia is the most common genetic disorder among African Americans; about 1 in every 12 is a carrier. The evolution of sickle-cell anaemia is probably an example of Baldwinian evolution, whereby humans modify their environment and thus change the selective pressures. As humans in tropical areas in Africa and elsewhere developed agriculture and animal husbandry, they expanded the niche for Anopheles mosquitoes that could transmit the malaria parasite. In the USA, where there is no endemic malaria, the incidence of sickle cell anaemia amongst African Americans is much lower than in West Africa and falling. Without endemic malaria from Africa, the condition is purely disadvantageous, and will tend to be bred out of the affected population. See the Price equation article for a simplified mathematical model of the genetic evolution of sickle cell anemia. Edited by schrafinator, : No reason given. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: Yes, Percy, hip displaysia is the disorder, and other breeds of dogs get it too. Collies are prone to having retinal problems and certain horse breeds are known to be prone to certain degenerative chronic foot and leg problems for the same reasons. All of these maladies are a result of artificial selection for the whims of human aesthetics, though.
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: Well, mostly I think it is a neutral mutation, because wisdom teeth do not emerge until very late in puberty, long after reproduction would have taken place among human populations 100,000 years ago. No, it could also be viewed as a beneficial mutation if you change the environmental conditions. Fast forward to a time in human civilization before modern dentistry. Now imagine impacted wisdom teeth. Very painful, and they often become infected. My mutation removes all chance of impaction, and if I was able to keep reproducing, better teeth for me means better nutrition for my offspring.
quote: Because some people in family groups have the mutation but most people not in those family groups do not.
quote: Why would a beneficial mutation be selected against? I assume you have now conceded that beneficial mutations do, in fact, exist?
quote: Carriers of SCD rarely have any symptoms. And you continue to ignore the fact that what the SCD mutation does is to stop people from being killed by maleria before they can reproduce. All evolution is concerned with is the passing on of genes. One passes on genes much more successfully if one is alive, destined to die from SCD in one's 40's, compared to if one is dead from malaria at the age of 6 months.
quote: Do you or do you not accept that antibiotic resistance in bacteria is "real evidence of beneficial mutations"?
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: No, it really doesn't.
quote: What makes you think that evolution requires a species to "survive in the long run"? Indeed, the history of evolution on Earth is that over 99% of all species have gone extinct.
quote: I am not sure what you refer to here. What "incredible rate of mutation" do you speak of?
quote: But it has has already been explained, most mutations are neutral. Neutral mutations don't do anything.
quote: It does. I am healthy, and I have a mutation. And "healthy" WRT evolution simply means "able to pass on one's genes successfuly."
quote: Antibiotic resistance in bacteria has produced "superbugs" which are very healthy, wouldn't you say?
quote: No, they are not. That this has been explained to you multiple times seems to have done no good at all, so I'm going to leave it to someone else to slog on ahead and try again. Edited by schrafinator, : No reason given. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: Did you read my wiki on Sickle Cell?
In the USA, where there is no endemic malaria, the incidence of sickle cell anaemia amongst African Americans is much lower than in West Africa and falling. Without endemic malaria from Africa, the condition is purely disadvantageous, and will tend to be bred out of the affected population. Edited by schrafinator, : No reason given.
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: There is no selection pressure in favor in the US since there is no endemic malaria here. There is selection pressure against it because people who get two copies of the mutation tend to have lower reproductive success. On balance of these two selection pressures, the incidence of SCD would tend to decrease withing the population.
quote: Sure, that is certainly a possibility, although this does not explain why the incidence is declining in the US. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: Then you agree that beneficial mutations exist.
quote: You are willfully ignoring everything everyone has said to you in this thread. You are simply repeating your initial objections without having addressed the vast majority of the points people have raised. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
The real reason SCD is so interesting within the Evolutionary framework is that it is such a great example of how the ToE can explain this seeming paradox of why a genetic disease would be retained within a population.
"Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: No problem, we all do that.
quote: SCD in the "overall population" was never under discussion. Again, from the wiki:
Due to the above phenomenon, the illness is still prevalent, especially among people with recent ancestry in malaria-stricken areas, such as Africa, the Mediterranean, India and the Middle East. In fact, sickle-cell anemia is the most common genetic disorder among African Americans; about 1 in every 12 is a carrier.
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
The real reason SCD is so interesting within the Evolutionary framework is that it is such a great example of how the ToE can explain this seeming paradox of why a genetic disease would be retained within a population. quote: Not irrelevant, on at least these two points: 1) your claim that there are no beneficial mutations is refuted. 2) your claim that the retention of genetic diseases in a population runs counter to the ToE has been refuted.
quote: Not quite. It also needs to confer a reproductive advantage to remin prevalent in a population. That's why SCD continues to flourish in places where malaria is endemic, and also why it is tending to decline in the US among populations with recent ancestry in places where SCD confers reproductive advantage. Edited by schrafinator, : kan't spel "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
Faith, you are begining to become belligerant.
You are simply repeating your initial assertions and willfully ignoring or selectively misinterpreting what everyone has been trying to say to you. Intelligent, productive conversation is impossible with one such as you, since you refuse to learn or. All you do is project personal incredulity in place of rational argument while twisting what everyone tries to tell you about science. The same thing has happened in every thread you attempt in the science fora. Perhaps it really isn't "everybody else" who refuses to accept your obvious brilliant understanding of Evolution and the scientific method, but your own inability to debate the issues in good faith. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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nator Member (Idle past 2200 days) Posts: 12961 From: Ann Arbor Joined: |
quote: And this is why you should probalby not venture into the science fora, faith. You have a stroke any time your ideas are treated just like we would treat each others'. You do not appear to be listening. You appear to be repeating your initial claims and redefining terms and words into your own special meanings as fast as can be to keep up with all of the demolition of your objections. You may flail and shout and exasperate all you want, but it is simply not the case that you have adequately addressed any of the responses to your claims. If you can't take the heat of scientific inquiry, then maybe you should stay out of the Biology lecture hall, so to speak. "Science is like a blabbermouth who ruins a movie by telling you how it ends! Well I say there are some things we don't want to know! Important things!" - Ned Flanders "Question with boldness even the existence of God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson
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