What evidence is there for evolution being non-random?
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Schneibster
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I can describe such a criterion: a gene is selected if the creature possessing it reproduces.
mijopaalmc
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How is that gene selected in order for that creature to reproduce?
Obviously, not all vehicles that carry a certain variety of a gene reproduce.
Isn't a bit circular to say (not that I am implying that you, Schneibster, did) "a gene is selected if the creature possessing it reproduces and a creature possessing a gene reproduces if the gene is selected"?
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Schneibster
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The genes carry the information that produces the phenotype; the phenotype interacts with the environment, and either survives to reproduce or does not survive to reproduce.
So? You asked for a mechanism, there's the mechanism. What YOU want is a mechanism that works every time; there isn't one. It works in aggregate, and that's all that's necessary to explain what we see.
You're right, that's not what I said. The content of the genes does not determine whether the creature possessing it reproduces; it merely makes it more or less likely to reproduce. As you well know, this is a statistical process.
articulett
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Your definition wasn't applicable because mijo was asking about Dawkins use of the word which is a word used in response to creationist obfuscation. Moreover, you said that I said evolution is non-random... I didn't say that...I repeatedly said that summing up evolution as random or non-random is uninformative. And you made the claim that there was one definition of random and didn't provide any evidence of that being the case. Moreover, I pointed out a physics definition that pretty much said nothing is "truly random".
It's clear that random is an ambiguous word. And if you use it to describe evolution in general or to sum up natural selection--which is a 2-part system--you are being vague in the same way creationists are vague.
This the only reason that biologists go out of their way to discriminate the relative randomness of the information exchange from the non-random selection of the organism it produces. The Dawkins tape is clear. Mijo's question in the OP was answered. You and he can insist that Dawkins is wrong or replying to the wrong definition-- or that by your definition (which you keep claiming is the only one--without providing evidence or even a definition) evolution is a random process. Maybe so...but that is vague. If everything that contains random components IS random--then Algebra IS random and so is artificial selection and so is the nozzle example.
I was not behaving badly. You were. You kept hearing me say something I never said, and ignored all parts where I said, "YES randomness is important"--you just underplayed the part about "natural selection" being much less so. And I just kept answering the OP--most scientists consider "natural selection" to be the answer to the OP. The Dawkins clip goes into detail much better than I did.
Information changes relatively randomly. Natural Selection can't see the information to select it unless it creates a change to the phenotype. That's the bottom line. None of Mijo's definitions gets it--and you may not either.
But I think anyone can listen to the Dawkins clip and understand him clearly where as mijo just keeps saying "evolution is random because it can be described by a probability chart." What can't? Doesn't that make loaded dices random? Where is this vague definitiion used in the sciences? You keep claiming there is a singular scientific definition and every single scientist I've been able to talk to about this says you're "full of it"--the term is ambiguous for many reasons.
You are asking all scientists to conclude that Dawkins is explaining it wrong while not considering his audience nor offering anything near as descriptive or understandable?
In any case you agree that the componets that affect natural selection (everything in the physical environment that acts on an environment) is not the same kind of "randomness" used when discussing mutation.
So what exactly is your answer to the OP. And to whom is Dawkins wrong or not explanatory to other than you and mijo (I provided a clip and quotes from him). And what do you propose as a better definition. And does anyone find it a clearer way to explain the natual selection component?
I thought you weenied out of the conversatin because you accused me of saying something I never said (I never said evolution was "non-random"--I just said that calling the whole thing random was vague--like calling algebra random because it contains random variables.) Are you arguing that it's informative to call evolution random. Are you arguing that it's informative to call natural selection a "random process". Doesn't that make the evolution of everything a random process? Doesn't that make it vague and a poor definition? Doesn't that fit right in with Behe and the common creationist conundrum that "science thinks this all happened by chance"-- We don't think that. Even if you do or can't define the difference between that and what biologists actually know about the process.
articulett
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Or it can be completely neutral. Most mutations are. Of course most mutations are not even in functional genes. Mutations in highly conserved genes are usually lethal. Mutations can only be selected for or against if the genome they are in (the entire encyclopedia of the information) creates a successful replicator (an organsim that survives to reproduce).
If the organism reproduces, the neutral DNA is passed on...negative mutations get weeded out through time and positive mutations, combinations, etc. bias the evolution of a given species. The changes we observe in the species is due to natural selection including sexual selection and meteors and all the physical conditions that affect this planet and all the other creatures competing in the game.
The changes in the DNA are a record of everything beneficial and neutral (or at least not lethal) that have been passed on. We can tell by how much the DNA is conserved or altered or how many different alleles there are--whether the gene helped drive the evolution of a species or just went along for the ride in successful genomes (selected genomes). NON-randomly selected genomes. Genomes selected by virtue of the fact that they produced organism that made lots of copies of the information that built them.
I just don't see how it's informative to call that random. I'm not saying that random isn't important or that there are not random components or that evolution is non-random. I'm just saying that however you describe it--if you don't distinguish the difference between natural selection and the pool of randomness from which it selects, your definition is as vague as the creationist over simplification.
Cyborg says it simply. And Dawkins says it eloquently. And everytime Mijo says anything about it, it just sounds vague and meaningless.
mijopaalmc
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I'm not sure what you thought I was arguing in my post, but I was asking questions based on my assumption of what "deterministic". To me "deterministic" means that the same initial conditions yield the same results. I realize that there is some disagreement on what exactly the initial conditions are. The replicators that the vehicle is given when it is created seems like reasonable place to start; however, the "non-randomites" seems to want to include every interaction of the vehicle before its replicators replicate. In this case, it is incontrovertibly true that each vehicle is unique. Therefore, we need not be worried the replicators in one vehicle replicate while the same replicators in a different vehicle will not replicate, because each vehicle is unique.
I do not want a mechanism that works the same way all the time because the point of a probabilistic mechanism is that it doesn't work the same way all the time, and the probability of selection is how often the mechanism works in a defined way.
I apologize if it appeared as if I was being contradictory; that was not my intent. I do think that your response migth have more impact because it is not coming from someone who is a confirmed creationist.
Schneibster
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This proves that mijo was SPECIFICALLY NOT asking about Dawkins' description, which is ADMITTED EVEN BY YOU not to be directed to the technically or scientifically minded individual, but to the general public WITH THE SPECIFIC INTENT TO ADDRESS THE CREATIONIST "RANDOM" STRAWMAN. Don't make me go find your exact quotes; I will if you insist, but the longer you keep this up, the more you piss me off.
There is no question about this, there is no doubt, it is there in plain English, for all to see. You have specifically and repeatedly (for over thirty pages!!!) ignored this obvious fact, and managed to piss me off pretty seriously in doing so. You have wronged mijo, and refuse to admit it, and you are arguing for the sake of arguing, twisting words, and ignoring anything you don't want to hear. It is a rather unpleasant spectacle to watch, and now you have placed words I did not say in my mouth and directly insulted me in so doing.
OK, here we go:
The last one is three times in a single post. Do I need to go on? You DID say that, in as many words, many times.
Actually, I provided two long posts full of evidence, all of which you ignored using precisely the same type of sophistry you are using here.
No, you didn't provide a physics definition; you provided a definition by a physicist writing for a non-technical audience, a far different thing. And more sophistry.
It's clear that you've confused your audience with children who are unsophisticated enough to believe that. Presented with ample proof that there is in fact a single well-accepted scientific definition, and a far less specific common definition, and that the audience you were talking to is and was using the scientific definition and not the common one, you have nevertheless confounded the two and pretended that the scientific one doesn't exist, or is somehow not "informative" despite being presented with overwhelming evidence that this is not the case.
Only if I use the common definition; and I never have, and you have never admitted that. Nor has mijo, at least not on this thread. You are confusing two definitions; as I have repeatedly stated, you don't seem to know the difference between them. While this is only semi-serious, it is also a pointer to a fundamental dishonesty on your part, that you are using to "prove" your point. I don't accept sophistry as proof, and I don't think anyone else should either.
Of course they are- and they are also ordered. Not disordered, which is what I proposed you use instead of not random, which you were repeating with alarming regularity, many, many pages ago.
No one is insisting Dawkins is wrong; merely that he is talking for an unsophisticated audience. What we're insisting on is that the current audience is not unsophisticated.
Mijo's question in the OP was NOT answered, has not been answered, and cannot be answered; by the definition he makes it clear he is using IN THE OP, as demonstrated by the quotes from the OP I reproduced above, evolution IS random. Ordered; stochastic; but driven by RANDOM events in the environment, acting on RANDOM combinations of genes. At the individual level, evolution is and always must be random. You might argue that evolution does not exist at the individual level; and I might listen to that argument, and eventually agree based on that that evolution is, in fact, not random. But you have not presented that argument. Instead, you have descended to sophistry and dishonesty. See above; "I never said evolution is not random."
You said something over and over, and then claimed you had not said it (and are still claiming you did not). I provided proof of my assertions, and you ignored it. I tried to give you honorable ways to acknowledge the truth of what I said, and you ignored that too. If that's not behaving badly, I don't know what is.
You did not answer it, you have not answered it, and you cannot answer it. Its very content makes it clear that you are answering a different question than is being asked, and refusing to acknowledge that it is different.
Natural selection is based on a randomly changing fitness landscape, which is dependent upon natural events that are affected by the species in question, natural events that are affected by other species, and natural events that are unconnected to any species. The last two are, with respect to a particular genome, effectively random; when a large asteroid will hit the Earth, or when another species will adapt to a particular adaptation that the current species has developed to obtain food or avoid predation, for two of the most obvious examples. That fitness landscapes change randomly, at least with respect to the genome, is unquestioned in the literature. The criteria of selection, therefore, change randomly, and the genome also changes randomly. What is really interesting about this system is that it produces such elegant results; but you cannot deny that it is random.
And another insult. Tell me again how you're not behaving badly.
Since you obviously haven't read my previous posts, or if you did you didn't understand them, I will refer you back to them. If you have specific questions about how they are applicable, please feel free to ask- but until you show that you have read them and understood at least some of them, I have no intention of wasting further time reproducing the arguments. You didn't read them then; why should I believe you will read them now? And that makes it a waste of time.
But his audience there is not scientists; it is popular media, intended for the consumption of the reasonably well educated, not the consumption of other scientists, or even the heavily educated. And that is precisely what I have been saying for many posts now. And precisely what you have been ignoring for an equal amount of time.
I agree to nothing of the kind. The fitness landscape varies randomly; the genome varies randomly. Both acting together produce wonderful adaptations. Order emerges. But that order is not present in any of the components; that is the nature of emergent order. That this sort of randomness can result in such order is truly the most amazing part of it all, but by denying the randomness of the underpinnings, you deny that wonderfulness. It's not surprising, says you; it's not wonderful. It's inevitable. Well, you may be right about that- Stuart Kauffman certainly agrees that it's inevitable. But he doesn't agree it's not wonderful, and beautiful, to see such order emerge spontaneously from the underlying chaos- and neither do I.
My answer is, there is no evidence for evolution being non-random- and there is no evidence for evolution being disorderly, either. It is order emerging from chaos- the very essence of the thing. Just as the order of thermodynamics emerges smoothly and naturally from the chaos of quantum mechanics. Just as the order of a mountain range emerges from the random kneadings of the Sun and Moon, and the random swirlings of convection in the mantle. Just as the order of life emerges from the random pounding of the waves and the tides at the edge of the ocean. Just as the order of intelligence arises from the random firing of neurons.
He's not wrong- just simple. He's not explanatory of the amazing emergence of the order of life we see around us from the underlying chaos of random genetic changes and random fitness landscapes- but he's not trying to be. It's you who insists that it's not random- not him. He's just explaining it for everyone. Sit down and talk to him, and if you know about emergent order, and fitness landscapes, and molecular biology, I expect he'd probably agree with what I've said. But that's not who he's talking to on TV, nor in popular science books. He's fighting the good fight there, and I respect him for it- but I don't make the unwarranted assumption, as you do, that that's all there is to the story.
See above.
Mijo seems to- and so do jimbob and Meadmaker. We'll see about cyborg.
More to the point, do I recommend trying to explain this to everyone? Not really. Most people aren't interested enough to bother. For them, "evolution is not random" is probably sufficient. If they're interested to ask more, then perhaps you should go into it- then again, perhaps not. It might be better to ask, "Well, what precisely do you mean by 'random?'" And depending on the answer, you might educate them a bit on what random means. It's a matter of judging your audience. Which I say you have done a particularly bad job of here.
But I'm just repeating myself. I've said all that already, more than once.
No, when you denied that you had said "evolution is not random," and I looked at the quotes I have reproduced above, and they are not as far as I recall the only ones, just the first five or six I found in a quick search of this thread, I decided that you were not being reasonable any more, and I don't waste much time on unreasonable people.
Depending on the audience, yes, I am. You need to check what they mean by "random," and be alert for the strawman, but given an audience that "gets it," I think it's far more informative than saying "evolution is not random" to an audience that obviously knows you're wrong over and over like it means something.
See immediately above.
Yes, it does. Interesting, isn't it? Take a hard look around you- EVERYTHING is random. But it's also orderly. Isn't that interesting? Doesn't that look like the operation of a few simple principles on a few simple components to create amazing complexity and order? With all this order springing up for free, isn't it stupid to attribute it to some supernatural entity? Isn't that actually denying how wonderful and interesting our world really is? Isn't that leading straight down to the question, "where did all the order come from?" You better have an answer for that one; if you don't the cretinists are going to bury you.
Not particularly; it explains a hell of a lot more than evolution, in case you hadn't noticed. It's a much more satisfying and systematic explanation for things. You want to go at it piecemeal; I'm after the whole enchilada. You want to counter the cretinists; I'm after the whole religion thing. Cretinists are just a small part of that. They're some of the loudest and most irritating parts of it; but never forget who and what you're dealing with here. Pulling leaves off is a waste of time; try ripping it right out by the roots. That's what I'm after, and you're up my nose about it.
Ahhhh, but you see, the fact is, we DO think it all happened by chance. Not that that's the first thing to say; and that mistake's already been made. As I've said repeatedly on this thread, most people don't understand what random really means. They think that random is random, top to bottom. They don't look around them and see random turning into orderly as you move from level to level- they're not even sure there IS any level but the one they see directly, and when they encounter something that makes them question what's going on, it scares them. So they hide from it, and pretend it doesn't exist- and they never see the beauty of things as a result. They read some book written by neolithic sheep herders and think they know it all- the sekrit knowledge of how everything works. As if neolithic sheep herders would know that. The sekrit knowledge is what the scientists have- and they don't try to keep it secret, but you have to learn math to know what they're talking about, and we don't teach math very well. And so it goes.
articulett
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Actually it was your frequent insults of Dawkins and then your calling him wrong and then biased...and your reference to Kimura as though it refuted Dawkins. The evolution of information (DNA) is not the same as evolution of life--the variation of the species. Probabilities and known mutation rates are used all the time to tell whether a DNA stretch was crucial or just went along for a ride as part of a particularly fruitful stretch of DNA. But if you want to know what Dawkins or any biologist means when they say natural selection is not random, it's because it is entirely determined by what DNA in the pool of randomness creates the best replicator in whatever environment it finds itself in. What we SEE in regards to speciation is from this determined SELECTION. Whether something is "determined" or not depends on what exactly you are asking and from what perspective. Technically, every physical event is determined by the interaction of matter and the forces acting on it. Physical things don't happen without a cause of some sort. But genome changes are relatively random; wheras which DNA changes produce the most prolific replicators cannot be. It must involve a change in phenotype. Or else the selection process is blind to it. If you want to say it's random as to whether a genotype changes a phenotype, that's fine... But saying that natural selection is random or stochastic is as descriptive as if you used those terms to describe a loaded dice, the nozzle evolution, or artificial selection. The interaction between the information carrier and the environment is doing the choosing--whether it's a conscious choice or not.
You can call it whatever you want. But if you actually want to have a comprehensive, useful understanding of how species diverged, I suggest you listen to what Dawkins is saying rather than calling him wrong. He's not using your definition, and I don't see any evidence that your definition is an accepted definition. It seems too vague to inform anyone about anything.
Do you understand why the nozzles aren't selected randomly? This is true, even though not every possible mutation was made. This would be true if an artifact gave the selectors "false results". Those are incidentals. This is true even if a better starting design would give a better result. The interaction between the organism and the environment is doing exactly that kind of selection. It's no more random than the the nozzle scenario. A blind algorhithm does better than "planned" design. Easily. All the time. Especially when inumrable replicators are making prototypes for endless selection experiments and honing through the eons.
Schneibster
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That's where you went wrong- you're talking about the classical definition of determinism. We're very close to working out the math to understand many other types of determinism; and we already have the math to understand some. Most people would say the Second Law of Thermodynamics is deterministic. And they'd be right. But the Second Law of Thermodynamics turns out to be derived from the Fluctuation Theorem; it's a special case of it, what happens when you consider large ensembles. Somewhere above the molecular scale, the 2LOT stops being accurate- and the FT predicts where. But does that mean that the determinism of the FT disappears? Why, not at all- in fact, it predicts just how likely it is that a particular situation will violate the 2LOT. It's been confirmed in the laboratory.
Similarly, it's incorrect to state that quantum mechanics is non-deterministic. When a quantum event takes place, there is a certain set of possible outcomes that might happen- but it is absolutely determined that ONE of those outcomes will be seen. You might see this one or that one, but you WILL see one of them, for certain.
As far as classical determinism, well, it looks like that doesn't really exist in our world. There is no tractable solution to the n-body problem; there is a solution to the three-body problem, but it doesn't generalize, and it contains singularities, which means there are situations that can physically occur that it cannot describe.
Based on this, I would argue that the type of determinism you're talking about doesn't actually exist, except as an artifact of over-simplified mathematics that don't describe the real world.
You can't sensibly talk about one replicator; what happens to one replicator is random, and I mean that in the common sense of the word: disorderly. It's not until you're talking about the species, or at least a population, that you see the order emerge. I think the time is coming quite shortly when the math to describe this emergence of order may be available; we may actually be able to define the point at which a population has enough members to be likely to develop novel characteristics quickly enough to survive a major landscape shift, and we may actually be able to quantify such shifts in such a way as to apply a probability to them. We may already be doing so; I don't follow biology closely enough to know.
We played with the 2LOT, and the Maxwell-Boltzmann statistics it's based on, for damn near 140 years before we figured out the FT. I see that as a watershed event; many questions are resolved by knowing that entropy is essentially meaningless on the atomic and molecular scale of individual interactions. Knowing that entropy can be destroyed at the quantum level tells us that we might be able to do some really amazing things with nanotechnology; and opens up a whole new world with respect to molecular biology. Consider that genes might be right at the edge of the scale where it becomes likely that anti-2LOT processes take place spontaneously, and you might begin to see what I mean. And this is not mysticism; it's proven scientific fact. The experiments that define this scale, and confirm the FT, were done years ago.
So when you say "random," remember that might mean orderly. And it may mean "deterministic," too- you just can't tell until you look at the particular situation. If you're dealing with individuals, likely it doesn't- but if you're dealing with a population, then likely it does.
You asserted that evolution is not deterministic- I stated that, in fact, it is, and showed the mechanism. I think it's just wrong to use words like "deterministic" in the classical sense when talking about the real world- there is no determinism in the classical sense in the real world. But there is determinism- real world determinism, that works on populations.
Never fear; you don't need to apologize. I see the fight you're fighting, and I partly share it- but be aware, you have to take the nature of chaos into account. I'd suggest At Home in the Universe, if you haven't read it already- and if you have, go read it again.
BTW, you've labeled yourself, probably inadvertently, a "confirmed creationist," at least by implication. You might want to fix that if it's not right.
Fine posts, #1428 and #1430 Schneibester: http://www.internationalskeptics.com/forums/showthread.php?postid=2732834#post2732834
Especially: #1428:
I thought he had fixed it, in response to specific questions that I had asked, to clear up this question.
http://www.internationalskeptics.com/forums/showthread.php?postid=2727715#post2727715
"All models are wrong, some are useful." -George Box (another statistician)
I'd argue that saying natural selection is probabilistic is useful in making predictions and explaining features.
I'd say that arguing that fighter aircrft evolved is not useful, is misleading, and really plays into the hands of ID proponents.
Articulett, do you see the essential difference between artificial selection and natural selection, and evolutionary algorithms and natural selection?
As (I think) steenkh, has said, farmers are good at only letting those organisms breed that they wish to. Of course natural selection modulates this, but artificial selection has a set of predefined goals.
Jim
Especially: #1428:
Schneibster said:
I thought he had fixed it, in response to specific questions that I had asked, to clear up this question.
http://www.internationalskeptics.com/forums/showthread.php?postid=2727715#post2727715
mijopaalmc said:
"All models are wrong, some are useful." -George Box (another statistician)
I'd argue that saying natural selection is probabilistic is useful in making predictions and explaining features.
I'd say that arguing that fighter aircrft evolved is not useful, is misleading, and really plays into the hands of ID proponents.
Articulett, do you see the essential difference between artificial selection and natural selection, and evolutionary algorithms and natural selection?
As (I think) steenkh, has said, farmers are good at only letting those organisms breed that they wish to. Of course natural selection modulates this, but artificial selection has a set of predefined goals.
Jim
articulett
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Is your contention that the process they are describing in this link is random, Mijo--Schneibster?
Fast-Reproducing Microbes Provide a Window on Natural Selection
http://www.nytimes.com/2007/06/26/science/26lab.htm
Really?
How about this?
http://video.on.nytimes.com/?fr_story=3ba8ecaed1cf130c1d0ea4baa3876356bea3bb58
Would you contend that the creatures are changing shapes, "randomly".
When you see this clip, do you think that he is describing a "random process"?
A "stochastic process"? Anybody?
(Are they not understanding natural selection or am I not understanding the usefulness of the term random?)
Fast-Reproducing Microbes Provide a Window on Natural Selection
http://www.nytimes.com/2007/06/26/science/26lab.htm
Really?
How about this?
http://video.on.nytimes.com/?fr_story=3ba8ecaed1cf130c1d0ea4baa3876356bea3bb58
Would you contend that the creatures are changing shapes, "randomly".
When you see this clip, do you think that he is describing a "random process"?
A "stochastic process"? Anybody?
(Are they not understanding natural selection or am I not understanding the usefulness of the term random?)
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articulett
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I know random processes explain a lot more than evolution...I just don't think they do justice to the natural selection part of the evolution equation. Random processes other than evolution do not involve information that builds organisms to copy the information.
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This seems a real example of the hypothetical examples I posted earlier:
articulett's New York Times article
This is exactly the sort of probabilistic information that I was talking about.
Two-thirds of the cold-adapted bacteria did worse at high temperature, but one third did as well or better.
Jim
articulett
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This is from evo-devo biologists review of Behe's new book:
http://www.sciencemag.org/cgi/content/full/316/5830/1427
Behe thinks that evolution is too complex to come about randomly...
He thinks the answer is top down design--biologists say the answer is "natural selection"--bottom up "design"
Behe, a professor of biochemistry at Lehigh University, has found an audience among various flavors of creationists who find Darwinian evolution incompatible with their religious views and see scientific validation in Behe's claims. ...
The problem is what Behe asserts Darwinian evolution can't do: produce more "complex" changes than those that have enabled humans to battle malaria or allowed malarial parasites to evade the drugs we throw at them. Behe's main argument rests on the assertion that two or more simultaneous mutations are required for increases in biochemical complexity and that such changes are, except in rare circumstances, beyond the limit of evolution. He concludes that "most mutations that built the great structures of life must have been nonrandom." In short, God is a genetic engineer, somehow designing changes in DNA to make biochemical machines and higher taxa...
My goal here is to point out the critical flaws in Behe's key arguments and to guide readers toward some references that illustrate why what he alleges to be beyond the limits of Darwinian evolution falls well within its demonstrated powers....
Behe's chief error is minimizing the power of natural selection to act cumulatively as traits or molecules evolve stepwise from one state to another via intermediates. Behe states correctly that in most species two adaptive mutations occurring instantaneously at two specific sites in one gene are very unlikely and that functional changes in proteins often involve two or more sites. But it is a non sequitur to leap to the conclusion, as Behe does, that such multiple-amino acid replacements therefore can't happen. Multiple replacements can accumulate when each single amino acid replacement affects performance, however slightly, because selection can act on each replacement individually and the changes can be made sequentially....
Behe begrudgingly allows that only "rarely, several mutations can sequentially add to each other to improve an organism's chances of survival." Rarely? This, of course, is the everyday stuff of evolution. Examples of cumulative selection changing multiple sites in evolving proteins include tetrodotoxin resistance in snakes (3), the tuning of color vision in animals (4), cefotaxime antibiotic resistance in bacteria (5), and pyrimethamine resistance in malarial parasites (6)--a notable omission given Behe's extensive discussion of malarial drugresistance.
Behe seems to lack any appreciation of the quantitative dimensions of molecular and trait evolution. He appears to think of the functional features of proteins in qualitative terms, as if binding or catalysis were all or nothing rather than a broad spectrum of affinities or rates. Therefore, he does not grasp the fundamental reality of a mutational path that proteins follow in evolving new properties.
This lack of quantitative thinking underlies a second, fatal blunder resulting from the mistaken assumptions Behe makes about protein interactions. The author has long been concerned about protein complexes and how they could or, rather, could not evolve. He argues that the generation of a single new protein-protein binding site is extremely improbable and that complexes of just three different proteins "are beyond the edge of evolution." But Behe bases his arguments on unfounded requirements for protein interactions. He insists, based on consideration of just one type of protein structure (the combining sites of antibodies), that five or six positions must change at once in order to make a good fit between proteins--and, therefore, good fits are impossible to evolve. An immense body of experimental data directly refutes this claim. There are dozens of well-studied families of cellular proteins (kinases, phosphatases, proteases, adaptor proteins, sumoylation enzymes, etc.) that recognize short linear peptide motifs in which only two or three amino acid residues are critical for functional activity [reviewed in (7-9)]. Thousands of such reversible interactions establish the protein networks that govern cellular physiology.
Very simple calculations indicate how easily such motifs evolve at random. If one assumes an average length of 400 amino acids for proteins and equal abundance of all amino acids, any given two-amino acid motif is likely to occur at random in every protein in a cell. (There are 399 dipeptide motifs in a 400-amino acid protein and 20 mult 20 = 400 possible dipeptide motifs.) Any specific three-amino acid motif will occur once at random in every 20 proteins and any four-amino acid motif will occur once in every 400 proteins. That means that, without any new mutations or natural selection, many sequences that are identical or close matches to many interaction motifs already exist. New motifs can arise readily at random, and any weak interaction can easily evolve, via random mutation and natural selection, to become a strong interaction (9). Furthermore, any pair of interacting proteins can readily recruit a third protein, and so forth, to form larger complexes. Indeed, it has been demonstrated that new protein interactions (10) and protein networks (11) can evolve fairly rapidly and are thus well within the limits of evolution....
For instance, Behe once wrote, "if random evolution is true, there must have been a large number of transitional forms between the Mesonychid [a whale ancestor] and the ancient whale. Where are they?" (12). He assumed such forms would not or could not be found, but three transitional species were identified by paleontologists within a year of that statement.
My question is, why do you think this reviewer is being very clear in distinguishing motifs arrising "at random" from motifs evolving via random mutation coupled with natural selection? Do you see the difference in the examples of each? The latter is much faster due to a bias, right? How does a randomite distinguish the former from the latter and/or how do randomites address Behe's errors? And if your definition can't or doesn't do either--you've got a definition that nobody will care about but creationists.
It doesn't matter how right you think you are or how sure you are that evolution can rightly be described as a random or stochastic process--your definition is just too vague to be useful in conveying what evolution is.
http://www.sciencemag.org/cgi/content/full/316/5830/1427
Behe thinks that evolution is too complex to come about randomly...
He thinks the answer is top down design--biologists say the answer is "natural selection"--bottom up "design"
Behe, a professor of biochemistry at Lehigh University, has found an audience among various flavors of creationists who find Darwinian evolution incompatible with their religious views and see scientific validation in Behe's claims. ...
The problem is what Behe asserts Darwinian evolution can't do: produce more "complex" changes than those that have enabled humans to battle malaria or allowed malarial parasites to evade the drugs we throw at them. Behe's main argument rests on the assertion that two or more simultaneous mutations are required for increases in biochemical complexity and that such changes are, except in rare circumstances, beyond the limit of evolution. He concludes that "most mutations that built the great structures of life must have been nonrandom." In short, God is a genetic engineer, somehow designing changes in DNA to make biochemical machines and higher taxa...
My goal here is to point out the critical flaws in Behe's key arguments and to guide readers toward some references that illustrate why what he alleges to be beyond the limits of Darwinian evolution falls well within its demonstrated powers....
Behe's chief error is minimizing the power of natural selection to act cumulatively as traits or molecules evolve stepwise from one state to another via intermediates. Behe states correctly that in most species two adaptive mutations occurring instantaneously at two specific sites in one gene are very unlikely and that functional changes in proteins often involve two or more sites. But it is a non sequitur to leap to the conclusion, as Behe does, that such multiple-amino acid replacements therefore can't happen. Multiple replacements can accumulate when each single amino acid replacement affects performance, however slightly, because selection can act on each replacement individually and the changes can be made sequentially....
Behe begrudgingly allows that only "rarely, several mutations can sequentially add to each other to improve an organism's chances of survival." Rarely? This, of course, is the everyday stuff of evolution. Examples of cumulative selection changing multiple sites in evolving proteins include tetrodotoxin resistance in snakes (3), the tuning of color vision in animals (4), cefotaxime antibiotic resistance in bacteria (5), and pyrimethamine resistance in malarial parasites (6)--a notable omission given Behe's extensive discussion of malarial drugresistance.
Behe seems to lack any appreciation of the quantitative dimensions of molecular and trait evolution. He appears to think of the functional features of proteins in qualitative terms, as if binding or catalysis were all or nothing rather than a broad spectrum of affinities or rates. Therefore, he does not grasp the fundamental reality of a mutational path that proteins follow in evolving new properties.
This lack of quantitative thinking underlies a second, fatal blunder resulting from the mistaken assumptions Behe makes about protein interactions. The author has long been concerned about protein complexes and how they could or, rather, could not evolve. He argues that the generation of a single new protein-protein binding site is extremely improbable and that complexes of just three different proteins "are beyond the edge of evolution." But Behe bases his arguments on unfounded requirements for protein interactions. He insists, based on consideration of just one type of protein structure (the combining sites of antibodies), that five or six positions must change at once in order to make a good fit between proteins--and, therefore, good fits are impossible to evolve. An immense body of experimental data directly refutes this claim. There are dozens of well-studied families of cellular proteins (kinases, phosphatases, proteases, adaptor proteins, sumoylation enzymes, etc.) that recognize short linear peptide motifs in which only two or three amino acid residues are critical for functional activity [reviewed in (7-9)]. Thousands of such reversible interactions establish the protein networks that govern cellular physiology.
Very simple calculations indicate how easily such motifs evolve at random. If one assumes an average length of 400 amino acids for proteins and equal abundance of all amino acids, any given two-amino acid motif is likely to occur at random in every protein in a cell. (There are 399 dipeptide motifs in a 400-amino acid protein and 20 mult 20 = 400 possible dipeptide motifs.) Any specific three-amino acid motif will occur once at random in every 20 proteins and any four-amino acid motif will occur once in every 400 proteins. That means that, without any new mutations or natural selection, many sequences that are identical or close matches to many interaction motifs already exist. New motifs can arise readily at random, and any weak interaction can easily evolve, via random mutation and natural selection, to become a strong interaction (9). Furthermore, any pair of interacting proteins can readily recruit a third protein, and so forth, to form larger complexes. Indeed, it has been demonstrated that new protein interactions (10) and protein networks (11) can evolve fairly rapidly and are thus well within the limits of evolution....
For instance, Behe once wrote, "if random evolution is true, there must have been a large number of transitional forms between the Mesonychid [a whale ancestor] and the ancient whale. Where are they?" (12). He assumed such forms would not or could not be found, but three transitional species were identified by paleontologists within a year of that statement.
My question is, why do you think this reviewer is being very clear in distinguishing motifs arrising "at random" from motifs evolving via random mutation coupled with natural selection? Do you see the difference in the examples of each? The latter is much faster due to a bias, right? How does a randomite distinguish the former from the latter and/or how do randomites address Behe's errors? And if your definition can't or doesn't do either--you've got a definition that nobody will care about but creationists.
It doesn't matter how right you think you are or how sure you are that evolution can rightly be described as a random or stochastic process--your definition is just too vague to be useful in conveying what evolution is.
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articulett
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I'm all for probabilities when you can say what those probabilities are. I just am not sure of how you distinguish random mutation from probable selection .
For example, in the Behe review, how would you differentiate between the motifs that evolve randomly and the ones that evolve much quicker due to bias produced by natural selection? In the nozzle example--would you say, the nozzles evolved through random mutation and probable selection? Or would you go into the algorithm details where only modifications that performed better than the parent got selected for the next elimination round? Do you think you could review Behe's book with more precise (correct?) language than Sean Carroll? Do you understand what he is saying and how Behe is wrong from the excerpts? Is he using the word random in the way you would use it? He's talking to a scientific audience and Behe has a biochemistry degree.
Also, would you call the evolution of the internet a random process? A probable process? or Something else. How would you convey the algorithmic increasing complexity over time in terms of probability and bottom up design. As you type, you create part of the entity the internet is becoming (you are part of the internet's emergence). That's not your goal--but that is what is happening every time someone uses the internet, right? Nobody has a complete understanding of the internet and nobody envisioned what it is today when it was in its infancy. What is random and what is determined about the internet...and at what point does something go from random to determined...from probable to actual? Prior to your conception you were amazingly improbable, but as events started lining up, your existence got closer and closer to being "determined"--So probability changes through time until it becomes determined, right? At what point does probable selection become determined?
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If a mutation increases the probability of an organism reproducing, there will be a selection pressure in faviour of it. The larger the population, and the larger the probability improvement, the "greater the pressure" i.e. the higher the probability of this trait "standing out from the noise" and being selectied for. With geological time and global populations, one is dealing with big numbers, so the probabilities are high.
with geological time and global populations one is dealing with big numbers, soagain these probabilities are large, not small
And I would say that a quantitative assessment should include a quantitative assessment of the actual probabilities, when applied to the large populations and timescales (or generations).
The probabilities are large, not small, and can be calculated in many situations.
Because fossils are rare, fossiliation is unlikely, Once a scavanger has crunched up the bone marrow, there isn't much left to fossilize. These scavangers are efficient because of evolution. Dead food doesn't run away.
I would discuss the actual probabilities, which are far higher, as natural selection is definitely a biased probability distribution.
The larger the numbers, the easier it is to seperate the advantage for a mutation from the general noise.
I didn't see this before posting my previous reply.
I would not disagree with anything that Sean Carroll has written, if one wanted to discuss the probabilities I would attempt to do so in a similar fashion to my previous post.
Behe has, through ignorence or malice, guess which I suspect, completely ignored how selection works. He seems to be arguing that selective advantage is all or nothing, whereas I would point out that it is a percentage game, and increasing the probabilities of survival is all that is needed. Sean Carrol says something similar too.
Small populations and short time: the advantages need to be big. Large populations or many generations, the advantages can be slight and still be selected for.
I don't really understand how Behe uses the word random. I suspect this is not through any inadvertant faiure of communication on his part. It seems to me like "telling lies for Christ" or dishonesty in what he percieves to be a just cause.
In the nozzle example I would say it shows how evolution can work, just remember that in natural selection the "goal" is reproduction and that is not boiled down to a simple measurable predefined trait, only how many offspring actually breed, the measure of success of a bee colony is how many queens it produces.
I would say the selection was non-random in the nozzle example, as the "fitness environment" is fixed, and the selection criteria are fixed. There might be some "random" selections in the algorithm to avoid being stuck in local optima. But I would be failrly sure that the best is always selected as a parent.
I slightly prefer selective breeding, as the raw material is the same as in natural selection.
To select a dog for speed, one would eventually come up with something like a greyhound. To select a dog for reproduction one could just leave alone.
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articulett
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Oh come on... it's not as bad as the annoying creationist thread yet.
So, how do you weight in? Is evolution a random/stochastic process or is that too ambiguous?
Is natural selection "random", non-random, "depends of your definition of random", or "something else"?
articulett
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Oh Look--from the National Academy of the Sciences--and published very recently. Gee, Schneibster, it doesn't look like they share that singular definition of randomness you keep telling me exists. In fact, this definition looks more like Cyborg's
http://www.pnas.org/cgi/content/abstract/104/suppl_1/8567
Published online before print May 9, 2007, 10.1073/pnas.0701072104
PNAS | May 15, 2007 | vol. 104 | Suppl. 1 | 8567-8573
Colloquium Papers
COLLOQUIUM PAPERS
Darwin's greatest discovery: Design without designer
Francisco J. Ayala*
Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA 92697
Darwin's greatest contribution to science is that he completed the Copernican Revolution by drawing out for biology the notion of nature as a system of matter in motion governed by natural laws. With Darwin's discovery of natural selection, the origin and adaptations of organisms were brought into the realm of science. The adaptive features of organisms could now be explained, like the phenomena of the inanimate world, as the result of natural processes, without recourse to an Intelligent Designer. The Copernican and the Darwinian Revolutions may be seen as the two stages of the one Scientific Revolution. They jointly ushered in the beginning of science in the modern sense of the word: explanation through natural laws. Darwin's theory of natural selection accounts for the "design" of organisms, and for their wondrous diversity, as the result of natural processes, the gradual accumulation of spontaneously arisen variations (mutations) sorted out by natural selection. Which characteristics will be selected depends on which variations happen to be present at a given time in a given place. This in turn depends on the random process of mutation as well as on the previous history of the organisms. Mutation and selection have jointly driven the marvelous process that, starting from microscopic organisms, has yielded orchids, birds, and humans. The theory of evolution conveys chance and necessity, randomness and determinism, jointly enmeshed in the stuff of life. This was Darwin's fundamental discovery, that there is a process that is creative, although not conscious.
They are saying exactly what I am saying. You are not speaking for all scientists...and maybe not any scientist. You and your fellow randomites and all creationists just don't seem to be able to describe natural selection in a clear way...and it seems like you are stuck on the randomness of the process without a real understanding of the force that acts as the engine or catalyst for the process. You are so bent on saying evolution is random that you have an utter inability to see how you just aren't conveying anything of value --because you just aren't communicating the power of natural selection.
It's YOU schneibster. It truly is just ambiguous and vague to describe evolution the way you are--It's not that I don't understand random--it's that you don't understand natural selection enough to convey anything about it in your tortured definitions and rants. And that goes double for you, mijo.
Determinism--the opposite of random...right? Natural selection is determined by which genomes create the most successful copying "machines" for themselves in whatever environment they find themselves in. Meteors and thorns are part of nature and part of natural selection.
Ha.
http://www.pnas.org/cgi/content/abstract/104/suppl_1/8567
Published online before print May 9, 2007, 10.1073/pnas.0701072104
PNAS | May 15, 2007 | vol. 104 | Suppl. 1 | 8567-8573
Colloquium Papers
COLLOQUIUM PAPERS
Darwin's greatest discovery: Design without designer
Francisco J. Ayala*
Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA 92697
Darwin's greatest contribution to science is that he completed the Copernican Revolution by drawing out for biology the notion of nature as a system of matter in motion governed by natural laws. With Darwin's discovery of natural selection, the origin and adaptations of organisms were brought into the realm of science. The adaptive features of organisms could now be explained, like the phenomena of the inanimate world, as the result of natural processes, without recourse to an Intelligent Designer. The Copernican and the Darwinian Revolutions may be seen as the two stages of the one Scientific Revolution. They jointly ushered in the beginning of science in the modern sense of the word: explanation through natural laws. Darwin's theory of natural selection accounts for the "design" of organisms, and for their wondrous diversity, as the result of natural processes, the gradual accumulation of spontaneously arisen variations (mutations) sorted out by natural selection. Which characteristics will be selected depends on which variations happen to be present at a given time in a given place. This in turn depends on the random process of mutation as well as on the previous history of the organisms. Mutation and selection have jointly driven the marvelous process that, starting from microscopic organisms, has yielded orchids, birds, and humans. The theory of evolution conveys chance and necessity, randomness and determinism, jointly enmeshed in the stuff of life. This was Darwin's fundamental discovery, that there is a process that is creative, although not conscious.
They are saying exactly what I am saying. You are not speaking for all scientists...and maybe not any scientist. You and your fellow randomites and all creationists just don't seem to be able to describe natural selection in a clear way...and it seems like you are stuck on the randomness of the process without a real understanding of the force that acts as the engine or catalyst for the process. You are so bent on saying evolution is random that you have an utter inability to see how you just aren't conveying anything of value --because you just aren't communicating the power of natural selection.
It's YOU schneibster. It truly is just ambiguous and vague to describe evolution the way you are--It's not that I don't understand random--it's that you don't understand natural selection enough to convey anything about it in your tortured definitions and rants. And that goes double for you, mijo.
Determinism--the opposite of random...right? Natural selection is determined by which genomes create the most successful copying "machines" for themselves in whatever environment they find themselves in. Meteors and thorns are part of nature and part of natural selection.
Ha.