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Author | Topic: The Electric Eel - more evidence against evolution | |||||||||||||||||||||||
Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
The probability of this calcium atom in my arm bone ending up there after being formed on the inside of a star and being blasted across outerspace, landing on the planet, going through the soil and the into the piece of broccoli I ate, and then being incorporating into that particular part of my body is so ridiculously low that I agree that it looks unrealistically implausible. But there it is and that's how it got there (more or less). Yea, unfortunately that's not how molecular evolution specialists look at probability. The literature contains numerous papers on the limits of evolution when it comes to complex adaptations (traits that require multiple mutations to evolve, each mutation not conferring a selective advantage), the kinds of complex adaptations that can plausibly evolve, etc. All of this would be rendered useless by your elementary argument, because basically any trait could evolve if we accepted that your argument applied to molecular evolution. Edited by Genomicus, : No reason given.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
It seems to me an example of this can be found in Douglas Futuyma lactose digestion experiment with bacteria, as described in Ken Miller's pointing out of how 'Irreducible complex' systems can evolve. The experiemnt cuts one of the 3 genes needed for lactose digestion from bacteria, so you have a culture that can not digest lactose. After many generations and letting it grow to be billions, you feed it nothing but lactose, and some of those bacteria survive. They developed , through mutation, another set of 3 genes needed to digest lactose http://www.millerandlevine.com/km/evol/DI/AcidTest.html While talking about how Intelligent Design got it wrong, it also is an example where you have to have multiple traits develop at the same time to provide new function. But only a few mutations were needed. There was no evolution of trait A to trait B wherein the pathway bridging those two traits could only be reached by numerous neutral mutations.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
But are they determining how plausible it is? There are a number of papers in the literature that investigate the rate of emergence of complex adaptations, based on factors like, e.g., population size and the number of mutations the complex adaptation would require. If we accept your argument, then any adaptation is plausible (even if it requires, say, 100 specific substitutions before there is any selective advantage). Actually, the whole "star calcium atoms to body calcium atoms" argument can be refuted in several ways. By that argument, it is perfectly reasonable to suppose that ERVs in specific genomic locations in humans and other primates share those same locations because of chance alone. You sure you want to go down that route?
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
There are a number of papers in the literature that investigate the rate of emergence of complex adaptations, based on factors like, e.g., population size and the number of mutations the complex adaptation would require. And they use that to question the plausibility of evolution? No, that is not the point here. The point is that, firstly, the existence of "complex adaptations," or traits requiring multiple mutations before offering a selective advantage, are known to exist; secondly, studies have been conducted to determine the limit of evolution when it comes to complex adaptations. So, if a complex adaptation required many, many mutations before there was any selective advantage, its evolution would be implausible. These studies do not use the existence of complex adaptations to question the plausibility of evolution, because all of the complex adaptations these studies have considered so far (e.g., the evolution of disulfide bonds) are within the reach of evolution. But we actually have equations we can employ to determine if a complex adaptation is in the reach of evolutionary processes (assuming we have sufficient information about the molecular nature of that trait).
Actually, I was saying that "star calcium atoms to body calcium atoms" is not plausible. The point was that plausibility didn't really matter. Obviously, plausibility does matter when it comes to science. That's why, e.g., molecular evolution specialists will choose phylogeny topologies with strong bootstrap values over those with weak bootstrap values (and the same is true for Bayesian phylogenetics and the associated posterior probabilities): the phylogeny topologies with weak bootstrap support are less probable -- and therefore less plausible -- than the other topologies. There are countless instances where plausibility is taken into consideration to choose one hypothesis over another, so I don't understand why you say that "plausibility doesn't really matter."
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Thanks, I will look into info on various marine organisms and on that paper (pity I do not have the time or resources for purchasing every such publishing!). To be sure, that's not the only paper on the subject. You'd have to do some browsing on PubMed or Google Scholar to look for more papers on the subject. I have institutional access to almost all the papers in Science Direct, so if you want to read one of the full papers, feel free to shoot me a PM with the title of the paper and I should be able to send you the PDF.
I think we should expect to find some other marine organisms with only some of them. I think so, too. One could probably begin by looking at all the known marine organisms that have electricity-producing organs, and look at their general anatomy.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
P.S. How do I do properly formatted blockquotes on this forum? Just hitting reply on a post doesn't put any text in the box, and pasting it text with blockquote tags indents but with no border/coloration. The standard method used here is enclosing the quote with [qs], and when you come to the end of the quote, [/qs]. Edited by Admin, : Fix quotes.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
So, but it had to be three distinct mutations. Which is pretty plausible when you look at the population genetics of the situation.
And that was just a very minor thing. There is not reason why more complicated structures could not form, particularly if the changes were accumulative. Actually, significantly more complex systems could only evolve if the changes were cumulative (meaning that the changes cumulatively added a selective advantage).
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
As is the electric eel, when you take into account account accumulative change over time, with the filter of the environment the eel was in. Correct -- if there is an evolutionary pathway that consists of steps that provide a selective advantage, there is no real problem for the evolution of that system.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Nonsense. Advantageous changes don't get selected; seriously disadvantageous changes that prevent reproduction get selected. Others have already responded to this. I advise you to study the theory you subscribe to. There is positive selection and purifying selection. This is pretty basic, and actually there are ways to compare DNA sequences and see if purifying or positive selection has dominated their evolution.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Genomicus is also not quite correct for different reasons. I don't mind being wrong, but I'm interested in where you think my arguments above have been flawed.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Again, yes, some changes may give some critters an advantage BUT only in a very limited sense. Citation, please. Positive selection can be weak or it can be strong; so, too, can purifying selection be weak or strong. Where does this "but only in a very limited sense" come into play?
It is only when those critters in a population don't reproduce that a trait gets filter out. Not necessarily. A trait can be lost from a population through genetic drift, or it can be replaced by another, more advantageous trait (positive selection).
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
And this is important in the example of this thread. Traits that are not seriously advantageous or disadvantageous get passed on. Filtering is only at the extremes. Traits that offer neither an advantage or a disadvantage don't all get fixed in the population. This is not the same thing, of course, as merely being passed onto offspring, but fixation (at least the general spreading of the trait throughout much of the population) in a population is hugely important when it comes to the evolution of biological systems. Simply getting the trait passed onto your offspring won't necessarily do the trick since that trait can be lost in the population.
Filtering is only at the extremes. Beneficial traits can get lost, too. Edited by Genomicus, : No reason given.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Which is still irrelevant. No.
In the example in this thread the question is whether or not changes that are not seriously disadvantageous can accumulate over time. No, the question is whether the proposed changes offer a selective advantage.
Can, might, improbable are all still irrelevant. No.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
It does matter, especially when something is proven fact in the face of how improbable it seemed to be. Like with CS's example of the calcium atoms. Except his example actually isn't all that improbable. The probability of the formation of a calcium atom in a star isn't improbable, as that's part of the way the physics of the situation works. The probability of calcium atoms spreading throughout the galaxy (including on Earth) is likewise very high, given the mechanism of calcium formation (e.g., supernovas). The probability of calcium atoms being used in bones is very high, since without calcium, bones would not have evolved. When you look at all the details, the scenario he outlines really isn't improbable. There's a reason why probability is used in science.
He didn't say plausibility doesn't really matter. What he said was probability in the case of the calcium atoms didn't really matter. But probability obviously matters when it comes to biological origins, as evidenced by a number of papers discussing the evolution of complex adaptations, and how these limit evolution the greater the number of individually non-adaptive mutations are required.
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Genomicus Member (Idle past 1941 days) Posts: 852 Joined: |
Yes, when you know ALL the details it's not so improbable any more is it? I believe that was CS's point. And sometimes when you know all the details, the proposed mechanism for a given phenomenon results in that phenomenon's occurrence being improbable.
It does in the general study of biology, to make predictions, etc. But, not in the sense that something couldn't have happened just because it seems improbable. No, the issue here isn't whether something "happened" or not. For example, in the case of the origin of molecular machines, no one denies that they exist, and thus, obviously they originated somehow. But if it is demonstrated that the proposed mechanism for their origin is improbable/implausible, then the efficacy of that mechanism is cast into doubt.
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