Evolution and complexity

And selective pressure also causes stasis (ie, no change) and the more pressure also leads to more stasis.I don't think we can equate evolution with change, but rather with adaptation. If a population is not well adapted to its environment to start with, then selective pressure would result in change. But if a population is already well adapted to its environment, then selective pressure will act to resist change and hence keep the population in stasis.So how does evolution know to change gears like that? Like the thermos, which keeps hot things hot and cold things cold. How does the thermos know which is which? It doesn't. All the thermos does is block the transfer of heat in either direction and the "keeps hot things hot and cold things cold" effects are the natural consequence.A thought experiment suggested by a 1980 Science article on the conference where punctuated equilibria was introduced. Picture a population as a bell curve with the horizontal axis representing the genome and the vertical axis the number of individuals possessing that genome. Most of the population will be clustered around a mean (read "average") genome. The wider the curve the more diversity the population has. Now also picture that for the environment there exists some ideal genome with which the population would be optimally adapted; actually there are probably several such "ideal" genomes, with some being more ideal than others but each being just fine. Next picture reproduction being represented by the drawing of a new bell curve which would be larger than the parent curve, exist around pretty much the same mean genome as the parent curve, and be spread out wider (more diverse) than the parent curve. Then that new generation undergoes selection in that not all the children will survive to reproduce.What I see happening in the selection step is that the portion of the child curve which is closest to an "ideal" genome will have a higher percentage of survivors than will the portion(s) farthest away from an "ideal" genome. Over generations, this will result in the bell curves' mean genomes to shift towards the closest "ideal" genome. This will have one of two different outcomes, depending on where the population is positioned on the horizontal axis.If the population is not on an "ideal" genome, then selective pressure will cause it to shift towards the closest "ideal", thus resulting in change. This is what people commonly regard as evolution meaning change.But if the population is already on an "ideal" genome, then selective pressure will cause it to stay there, thus resulting in stasis.What I see as the effect of greater or lesser selective pressure is that the population would possess less or more genetic diversity. A high degree of selective pressure would result in a narrow bell curve clustered tightly about the ideal genome, whereas a low degree of selective pressure would allow for a much wider distribution about the mean, which would not necessarily need to be centered about an ideal. An effect of this is that generalized species will tend to have higher genetic diversity and be able to weather through changes in their environment, whereas specialized species that are finely tuned to their environments will have less genetic diversity and will most likely not be able to survive changes in their environments.

I would agree that when selective pressure is causing change to occur, then greater selective pressure should generally result in more rapid change.The main reason for my quibble is that for many, the definition of evolution is change over time. I've especially seen creationists use this definition, such that they then try to use examples of stasis as evidence against evolution. Which is, of course, wrong, but as long as they are using a faulty definition for evolution they will be convinced (and will convince others) that they are disproving evolution.As for determining whether something is more or less evolved, or whether everything is equally evolved, it's all relative. To my mind, it's how well adapted a species is to its environment, which would then equate degree of specialization as a measure of how evolved something is. But what about less-highly specialized species able to function in several different environments? Could they really be considered less highly evolved?I think that the only instance that we can truly and safely described one species as being more highly evolved than another, or more primitive, would be when we consider a transitional series and compare earlier and later stages of the development of a particular trait.And again, I quibble because I've seen how the misunderstandings created by such usage of the terms "more evolved" and "primitive" are exploited by creationists.More directly regarding the statement, "All living things on Earth have experienced the same amount of evolution.", I would also quibble. Not all species are at the same point in adapting to their environments; some are relatively new to their niche while others have been there for a long time. Some traits are much more recent developments than others. I think that what he was trying to convey was that we cannot speak of certain species being more evolved than others.The only other sense in which that statement would be true would be that, if all life descended from a common ancestor, then all life has been evolving for the same amount of time. Which brings us to a claim made by Michael Denton.Denton compared the differences between species of a given protein (it's been nearly 20 years, so I forget the details as I relate this from memory). If you compare the same protein between different species, you will find differences in the amino acid sequences. We would expect more closely related species to have more similar sequences and less closely related to have less similar sequences and that is precisely what we find. Denton refuted that by expecting to see a ladder-of-life progression of the modern protein sequences and he failed to find that. Instead, he found grouping-together of similar species and that all the groups were about equidistant from each other (I had done a decent write-up on this on CompuServe, but don't know where it is right now).The irony is that, while he thought that he was refuting the "tree of life", what he had actually done was to recreate it. Because one of the ideas about genetic drift is that random changes in amino acid sequences will occur at a relatively constant rate over time. So given two modern species, one having descended from the other, we would find that both differ by the same amount from the ancestral species from which both are descended. In other words, just because amphibians evolved from fish doesn't mean that fish stopped changing; ie, modern proteins are not identical to what the ancient proteins were. This was demonstrated by "green fossils", tree leaves preserved in mud in which genetic material survived. "Green fossils" of magnolia leaves show changes in proteins over generations while the physical form of the leaves had remained constant.This also came into play in Walter Brown's imfamous "rattlesnake protein" claim. Using a study that compared cytochrome c in various species, Brown claimed that it showed that the rattlesnake is more closely related to humans than to any other animal. Strictly speaking, and stated in precisely that manner, that was true. Because no other snakes were included in that study, all other animals were equally different from the rattlesnake; it was pure coincidence that humans were one amino acid less different. Of course, if he had explicitly stated what he was implying, that, based on this protein comparison, the animal closest to humans is the rattlesnake, then that would have been grossly false. The macaque monkey differs from humans by one amino acid, compared to the 14-amino-acid difference (from memory) with the rattlesnake. And although chimpanzees weren't included in that study, their cytochrome c is identical to humans.

A basic problem with high school biology textbooks is that most of them are written by professional textbook writers, not by biologists. Their works have a reputation for containing inaccuracies and misinformation. In addition, creationists have long exerted grassroots pressure on textbook publishers to minimize or remove their coverage of evolution.I've long wanted to do a writeup on the events in California as reported in the NCSE's Creation/Evolution Newsletter of the mid-1980's. During that time, California was selecting new biology textbooks. William J. Bennetta organized a panel of scientists to review the textbook offerings. That panel found none of the candidates to be acceptable, all containing numerous inaccuracies, misconceptions, and outright false information. For the least horrible candidate (or the top few; I don't quite remember that detail), they submitted a long list of the errors they had found and how those errors could be corrected. One of the publishers made a few of the corrections and resubmitted their book. Without informing the scientists, the board met and approved the new version, despite their knowledge that it was still filled with erroneous teachings about science.So one must be careful when one turns to high school textbooks. One source of information on the quality of textbooks is William J. Bennetta's website for "The Textbook League" at Text Book League -- I'm not certain how recent it is. It contains several reviews. As I recall, BSCS textbooks are considered higher quality (indeed, that they were written by scientists who aren't afraid to present evolution is what caused Epperson vs Arkansas, 1968, which resulted in the 1920's "monkey laws" being struck down, which resulted in "creation science" and its claims of being based solely on scientific evidence). Glencoe textbooks of all stripes do not fare well.As a slight aside, in viewing Hovind's seminar tapes that he used to post on his drdino.com (no longer there, last I checked), I saw him use a Glencoe textbook in a "bait and switch" (something he kept accusing "evolutionists" of doing). From my notes on Tape IV:

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1:00:39
quotes Merrill Earth Science, 1993, pg 451 that human embryo has gills like a fish
this after pointing to BSCS book (BSCS Biological Science, 1978[?]) pointing out the SIMILARITIES between embryos' development
this after having belabored accusation that evolutionists use "bait and switch"
Also points out Glencoe Biology, 1994, pg 312

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His claim basically was that modern textbooks were still using Haeckel's doctored drawings, yet the only such example was from a Glencoe text; he never did show what the other books had to say about Haeckel nor whether they also display the drawings.Wouldn't undergraduate college textbooks be better?

Agreed that Darwin up straight should not be the first choice. Kind of like reading the Bible straight through from the beginning -- turned me into an atheist before I even got half-way through Genesis.The more modern popularizers should be the first choice. I'm not up on the recent contributions, but a couple good ones:Darwin for Beginners by Jonathan Miller and Borin van Loon. Comic-book format, but it presents an overall history of the development of the ideas. It's available on amazon.comBlueprints: Solving the Mystery of Evolution by Maitland A.; Johanson, Donald C. Edey . Apparently no longer in print, but can be bought through amazon.com. Another historical perspective, only this one goes through the development of the ideas behind evolution, including how genetics and mutation were at first thought to contradict Darwin (mainly his ideas of inheritance, which were wrong) but then it was found that genetics supplied the missing piece to Darwin's puzzle. It also went through how scientists arrived at their conclusions, something that's largely missing in science education.

Sorry, simonsays, not even close. As in a negative-feedback control loop, the selective pressure is there all the time; the perceived effect of that selective pressure depends on where you are relative to the set-point.

Oh! You're complaining about the thermos!The only purpose served by that thermos analogy was to demonstrate that the exact same mechanism can produce two very different and apparently contradictory results. That was all.Don't worry about the thermos. It was in no way intended to model any part of evolution.

What non sequitur are you talking about? I had written none.Here's the thermos paragraph that seems to have caused you so much heartburn, along with the preceding paragraph that it refers to:

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I don't think we can equate evolution with change, but rather with adaptation. If a population is not well adapted to its environment to start with, then selective pressure would result in change. But if a population is already well adapted to its environment, then selective pressure will act to resist change and hence keep the population in stasis.

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So how does evolution know to change gears like that? Like the thermos, which keeps hot things hot and cold things cold. How does the thermos know which is which? It doesn't. All the thermos does is block the transfer of heat in either direction and the "keeps hot things hot and cold things cold" effects are the natural consequence.

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I started thinking about that several years ago when it was stated on a PBS show about evolution that when a species is not well adapted to its environment then evolutionary change is rapidly, but then as it approaches being well adapted evolutionary change slows down. My reaction was, of course, "say what?". Just how is evolution supposed to know when to speed up and when to slow down?The thermos analogy is from an old joke where a dim-witted individual says it's the most wonderous invention because it keeps hot stuff hot and cold stuff cold, but how does it know the difference? The full extent of the analogy is that the same mechanism just operates the same in both cases; it doesn't need to know anything. The thermos does not need to know whether it contains hot liquid or cold liquid, because its mechanism of preventing the transfer of heat into or out of the thermos bottle has the seeming contradictory effect of keeping hot liquids hot and cold liquids cold. Evolution doesn't need to know how well adapted a particular species is in order to regulate how rapidly it changes; the same mechanisms (not the same mechanism as the thermos'; I never ever claimed that it did) cause different rates of change in different circumstances.Evolution and stasis are not opposites. Stasis is not the absense of evolution, but rather an expected effect of evolution.And of course I'm talking about populations.As you should be able see clearly, there is no non sequitur there. If you still have a problem, could you please state it clearly?

You know, it really would help if you didn't use arcane language. Dammit, Jim, I'm a programmer, not a philosopher or a lawyer (or whatever field you're drawing your jargon from)! The only use of the noun, "warrant", that we've seen has been in and about the field of law enforcement. We're more familiar with the verb, "warrant", from which I'm trying to decipher your meaning. Please note that I'm not the only one wondering just what you're going on about. It would really help if you would try to communicate it to us in a coherent manner and in standard English. You miss the mark. What I was using that analogy for was to describe something that produces opposite and even contradictory results just by doing the same thing. Your example has the same result being produced. A better form of your example would be an area that the water flooded and then subsided, leaving debris distributed both at the high-water mark and at the lowest point. Same mechanism resulted in different results, but despite the different results the mechanism was still the same. Same as with the thermos.Now, consider a voltage regulator, which operates by a negative feedback loop. It has a set-point which is the desired output voltage that is to be maintained. When the voltage is not at that set-point, then the regulator drives it towards that set-point. When the voltage is at the set-point, then the regulator keeps it there. Guess what. The regulator is operating in exactly the same manner -- it's doing nothing different -- both when it's changing the voltage and when it's keeping the voltage at stasis. The regulation mechanism is exactly the same in both cases. Sure, we can describe it in terms of the regulator being in different states, but it is still operating exactly the same in those different states; it doesn't change what it's doing. And the only thing that is keeping that voltage in stasis is the regulator continuing to perform its function. In the case of the voltage regulator, the only way to keep the voltage constant, AKA "in stasis", is for the regulator to be actively operating. If, once the voltage is in stasis, the regulator were to suddenly cease functioning altogether, then the voltage would no longer remain at its set-point, but rather it would drift away from that set-point.That is somewhat the model that I'm following, except that we can't really identify an explicit negative feedback loop. Also, my understanding of evolution is that it's the observed results of how life works. Populations consist of individuals who are very similar to each other, though a bit different, some more different than others. Some of these individuals though not all, in conjunction with others, reproduce off-spring who are very similiar to their parents, though a bit different. Then some, but not all, of these off-spring, in conjunction with others, produce the next generation of off-spring who are very similar to their parents, though a bit different. That is how life works.I visualize the population as a bell curve with many of the individuals clustering about a mean, or average, and the rest differing by different degrees from that mean -- I trust that we all have some feel for a bell-curve distribution. The production of off-spring would initially increase the amplitude and width of the distribution, but then survival issues would trim it back down. Those who are better adapted would be more likely to survive and to contribute to the next round of reproduction; I visualize that as meaning that individuals in different parts of the bell-curve distribution would have differing probabilities of surviving and reproducing.At that point, I hypothesize that for that particular environment there would be some ideal phenotype that would be best adapted to that environment. That ideal would act as the set-point. The members of the population who are closest to that ideal would have the greatest probability of surviving and reproducing and producing off-spring who are also better-adapted and so their genes would be better represented in the next generation. This would shift the mean of the new generation in their direction.Now, here's where that thermos analogy and the voltage regulator analogy come into play. Does this shifting of the population mean result in change or in stasis? It depends on where the population mean is currently relative to the set-point. If the population mean is away from that ideal mean, then the population mean will shift towards that ideal, resulting in change. If the population mean is already at that ideal mean, then it will lock onto the point and not move, AKA "stasis".Please note that it is the exact same processes, life doing what life naturally does, which can result either in change or in stasis. Life's not doing anything different, but it's just doing the same thing in both cases.Now, selective pressure. I visualize that as affecting the width of the bell curve. The more selective pressure there is, the tighter the requirements for survival are. When the population is at its ideal (please note that in reality there are many such "ideal" means, most of them "good enough" means since good enough will still enable a population to survive), then those individuals who have the highest probability of surviving and reproducing will be those at the population mean already and so the next generation's population mean will pretty much stay at the same point. If the selective pressure is high, then the population will have a narrower distribution -- the curve will be narrower -- and the population mean will track the "well-adapted" set-point more tightly. Thus selective pressure will keep a population in stasis.Now consider what would happen to a population in stasis if selective pressure were removed. All individuals in the population would have roughly equal probability of surviving and reproducing. The width of the distribution would increase as greater variability is tolerated. And the population mean will no longer have to track the "well-adapted" set-point, so the population mean will start to drift. It will no longer be held in stasis.Consider a naval analogy. If the ship is laying at anchor, it may shift a bit, but it will remain attached to that anchor which is attached to the sea bottom. It's not moving; it's in stasis. Hoist the anchor and the ship will start to drift. It's no longer in stasis; it's drifting.Does that help any?

Well, that blows my hypothesis that he's a non-native speaker of English. Foreigners may have odd phrasing and use the wrong words (and insist on using the exact same wrong words repeatedly when asked to rephrase), but they at least know how to spell those wrong words that they're using.It takes a native speaker to really screw up, such as writing "know" as "no".

Basically, evo-devo looks a lot like what Dawkins was saying in The Blind Watchmaker. His Mac program, Blind Watchmaker (in Chapter 3), was based on the idea of small changes in the genotype resulting in large changes in the phenotype.Slightly tangentially, it seems that a lot of standard creationist misrepresentations about mutations is that they concentrate largely on developmental mutations, in which the mutation is in the phenotype, not necessarily in the genotype. Rather the only mutations that are of interest in evolution are the mutations in the genotype -- ie those that will be carried in the genetic material in the gametes -- , because only those can be inherited.So part of the name of the game is that the only mutations that count are in the genotype, but selection does not act upon the genotype but rather on the phenotype. So how do we get the phenotype from the genotype? Through development. So in that sense, evo-devo is nothing new; we've known about it all along. What it does appear to contribute, though, is that it tries to figure out just how the genes direct development.Edited by dwise1, : Added the slight tangent.

I do not believe that selective pressure could be represented by a heat differential. Selective pressure would come from the survival requirements exacted by the environment. A lush environment in which food is relatively plentiful and predators are relatively few would exert a lower selective pressure; the standards would be more lax. A harsher environment would exert a higher selective pressure with tighter standards of what it would take to survive and reproduce.Rather, what the temperature difference between the air and the coffee would represent would be how different a population is from an optimal set of characteristics for survival in that environment. The further away that population is from that optimal set of characteristics, the more rapidly we would expect it to move in the direction of that set of characteristics.But once it has arrived at that set of optimal characteristics, then selective pressure will hold it there. In that harsher environment, selective pressure never lets up, even though the perceived results of that selective pressure is different. Regardless whether a population is moving towards a set of optimal characteristics or it is holding tight to that set of optimal characteristics, it is as a result of the continuing application of selective pressure. Regardless of where the population is with respect to that optimal set of characterisics, selection happens!If you really feel so strongly that stasis is due to the absense of selective pressure, then perhaps you can offer an explanation for how evolution magically turns on and off. As in the thermos joke, how does evolution know when to turn on and when to turn off?My answer is, as in the case of the thermos, evolution never turns off.

No, I haven't been missing that. That is exactly what I've been arguing for all along.Your earlier exposition in #87 makes a lot more sense now. However, no model or analogy is complete nor completely applicable. What I have been thinking of all along are two cases -- one where the population is not well-adapted to its environment and the other where it is -- and that the same evolutionary processes are active in both cases. But rather than the ball bearing being at equilibrium by coming to rest at a stable lowest point (what I recall as being called "static equilibrium"), it is at an unstable high point with the forces working to keep it there (which I recall as being called "dynamic equilibrium").In the example of the coffee being at equilibrium with the surrounding air, we find that as the temperature of the surrounding air changes, the coffee's temperature will try to track it, but if the air remains at a constant temperature then the coffee will remain at in static equilibrium. But there all the changes that would throw the coffee out of equilibrium are changes in the environment, not in the coffee itself.But what I see as happening in a population is that the population itself will tend to throw itself out of equilibrium -- it is in dynamic equilibrium. With each generation, the population mean will drift away out of equilibrium. Selective pressure is needed to hold it at that equilibrium point.Instead of a ball bearing

I have described it to you repeatedly. Could you please explain what problem you're still having with it? In plain English with as little obfuscational vocabulary as possible.

OK, that helps to explain why SimonSays has been using unrecognizable language. That's an ID book. ID uses language and invokes concepts that sound really impressive to the general public, while at the same time the IDist is saying nothing. ID Jive.Like the airline stewardess, we don't speak Jive.

Describing science as working differently than it actually does seems to be all to common in ID.My first exposure to ID founder/co-founder lawyer Phillip Johnson was on a 1981 Nova -- as I recall after he had written "Darwin on Trial" -- where he was insisting that science had to follow courtroom rules of evidence. My immediate and enduring reaction was "What an idiot! Science isn't a courtroom proceeding in which a case is being made and argued, but rather an on-going police investigation in which clues are sought and found and from which hypotheses are formed and tested -- tested in large part by trying to figure out what other clues there should be and where to find those clues." Johnson was trying to force science to be something very different from what it is and to force it to operate by a foreign set of rules and standards. Pretty much what ID is continuing to do as it tries to force science to employ supernaturalistic explanations.According to amazon.com, one of the authors of SimonSays' book has an advanced degree in theology. Theology does indeed rely almost exclusively on formal logic, since it has no real evidence to work with -- the only evidence theology has are what the religion's founders and leading theologians had said and written, hence only argument by authority. I suspect that that author had written the passage in question. Now, SimonSays, in the book did that author go on to insist that these rules of formal logic must be applied to science? That only those findings of science that can be expressed in terms of rigorously devised syllogisms may be deemed acceptable? In other words, was that book's author also insisting that a foreign set of rules and standards must be applied to science?BTW, I did come across that book in a bookstore some years ago. I browsed through it and recognized it as yet another load of anti-evolution taurine coproforms, little different from standard creationist fare except that it left out young-earth claims and was more adept at shovelling taurine coproforms than most creationist hacks.