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Author
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Topic: Article in Commentary critiques eye evolution
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Michael Francisco
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Member # 769
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posted 10. June 2003 01:32
There is a great article by David Berlinksi in the April edition of “Commentary” magazine. [ Berlinski, David. “A Scientific Scandal.” Commentary 115 No.4 (April 2003:29-36)]
Berlinski offers an extended critique of a well-known journal article often used to defend the evolution of the eye. [Dan-Erik Nilsson and Susanne Pelger
“A Pessimistic Estimate of the Time Required for an Eye to Evolve,” Proceedings of the Royal Society, London B (1994) ] Perhaps this article and the issue of eye evolution has come up previously on ISCID threads. Even so, this commentary article makes succinct and clear attacks on the original article and then offers excellent criticism of how misused the article has been by evolutionary proponents.
The original 1994 Nilsson and Pelger article claimed that a light sensitive patch could “gradually turn into a focused-lens eye,” and in the space of only a few hundred thousand years-a mere moment, as such things go.” Berlinski critiques the article itself, and specifically how article has been used by defenders of evolution, such as Richard Dawkins in his book River Out of Eden. Perhaps of most interest, many have claimed that the Nilsson and Pelger paper used a computer simulation to demonstrate how the eye could have evolved. Berlinski emphatically demonstrates that no computer simulation was used in the article my Nilsson and Pelger.
Relevance to ID :
Nilsson and Pelger claimed to show how evolution could have produced the lens-type eye. If convincing, the article would be a key argument in demonstrating how Darwinian evolution could produce a complex system – such as the eye. In fact, Richard Dawkins has used the Nilsson and Pelger article for this very purpose.
Berlinski’s Critique of Nilsson and Pelger :
After first offering a detailed summary of the article’s claims and calculations, Berlinski argued that the article’s conclusions are both trivial and unsubstantiated. To highlight a few of the arguments:
1)He pointed out how simplified their calculation was – it ignores biological structure within the initial assumed patch (such as blood vessels, nerves or bones).
2)Nowhere in the paper are details of their key calculations given.
3)They only addressed morphological change of the eye, completely ignoring the necessary biochemical change.
4)Their calculations are based on 1% steps that are never expressed in terms of biological change. (Just how many years are in a 1% step?)
5)Nilsson and Pelger did not utilize selection in their calculations of eye evolution.
6)Berlinski points out the potentially high costs of developing an eye socket for the evolving eye – an issue completely ignored in the paper.
7)Nilsson and Pelger used selection pressure as a constant for 300,000 years, and never offered population figures to justify their figures.
8)Nilsson and Pelger never mentioned randomly occurring changes.
Berlinski then made his key observation:
“It is six pages, their paper contains no mention of the words “computer” or “simulation.” There are no footnotes indicating that a computer simulation of their work exists, and their bibliography makes no reference to any work containing such a simulation.” In fact, Berlinski went so far as to email Dan-Erik Nilsson and confirm that no computer simulations were used in the paper. The senior author confirmed Berlinski’s presumption – no computers had been used.
Berlinski’s Critique of how the article has been used :
Critics of Berlinski have written in previous issues of commentary about the computer simulation of eye evolution (supposedly contained in the Nilsson and Pelger paper). These attacks are undeniably laid to rest by Berlinski’s article. Going on the attack even more, he takes a shot at Richard Dawkins, “who has been responsible for actively misrepresenting Nilsson and Pelger’s work, and for disseminating worldwide the notion that it offers a triumphant vindication of Darwinian principles.”
He quotes Dawkin’s use of the article to demonstrate how widely the false notions about a computer simulation of eye evolution have spread. He even challenges the two authors of the original paper that has been so widely misused for not correcting those scientists and journals who blatantly misrepresented their work.
The article concludes by asking, “What should we call such a state of affairs? I suggest that scientific fraud will do as well as any other term.”
Berlinski thus cast significant doubt on the claims of the Nilsson and Pelger paper and at the same time severely chastised those who try to use the paper as a positive argument for the evolution of the eye. Anyone confronted by those who believe the original paper offers good evidence for evolution of the complex eye would do well to take a look at Berlinski’s piece. It is a shame that more coverage to this issue is not in the professional science journals, instead of commentary magazine.
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Pim van Meurs
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posted 10. June 2003 01:56
Personally the suggestion that Dawkins may have made a mistake in calling it a program is not really that important to the discussion of Pelger's work. Whether the simulation was done on a computer or not is irrelevant to the discussion of the relevance of the work.
Secondly, I fail to see the relevance to ID, unless ID is based on perceived shortcomings in Darwinian theory? Even assuming that the article is incorrect in its claims, how does this make for a reliable ID interpretation?
Worse is that Berlinski makes many more important mistakes in his assertions.
For example when the Discovery Press release states
quote:
In reality, neither Nilsson nor anyone else has thus far created a computer model for eye evolution. Furthermore, according to Discovery Institute Senior Fellow David Berlinski, the crude
calculations that have been published by Nilsson are not such a model.
Nilsson's own work seems to disagree with this
quote:
Computer modelling of eye evolution
A long standing question has been how variation and selection can produce an imaging eye. We have previously approached this question by theoretical modelling (Nilsson and Pelger, 1994: A pessimistic estimate of the time required for an eye to evolve. Proc R Soc Lond B 256: 53-58) which demonstrate that even with rather weak selection, the structures of a focused camera type eye can evolve in less than half a million generations. We now continue this line of research by computer simulations of eye evolution. These simulations are made to accurately mimic a realistic genetic control, and involves selection from populations of partially mutated offspring. The project has three principal aims: 1, to understand the conditions and criteria that select the fundamental optical types of eye (compound and simple etc) during early eye evolution; 2, to better understand the fine tuning of eyes to special visual requirements and habitat conditions; 3, to provide an insight into the mechanisms of genetic control required for evolution in general and eyes in particular. (Dan-Eric Nilsson, Lars Gislén)
I would love to discuss Berlinksi's commentary versus the paper by Nilsson and Pelger.
Michael, have you read the paper by Nilsson and Pelger?
P.S. I truely find the following 'argument' fascinating
quote:
He even challenges the two authors of the original paper that has been so widely misused for not correcting those scientists and journals who blatantly misrepresented their work.
Blatantly misrepresented... Widely misused? I'd say lots of rethoric to create a scandal where there truely is none.
Michael suggests: Berlinski thus cast significant doubt on the claims of the Nilsson and Pelger paper and at the same time severely chastised those who try to use the paper as a positive argument for the evolution of the eye.
1. I fail to see how Berlinski casts significant doubt on the claims of Nilsson and Pelger but perhaps there is more in the original article to which I have no access.
2. The paper, even if not a computer simulation, is an excellent example of evolution as it applies to the eye. Not only do we have evidence of many of the intermediate steps in a variety of organisms but also quite good models. It may be that Berlinski's scandal goes the same way as Wells' 'scandal of the peppered moth' that really wasn't.
[ 10. June 2003, 02:15: Message edited by: Pim van Meurs ]
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charlie d.
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posted 10. June 2003 08:27
Berlinski's argument is two-sided: first, he says that the Nilsson and Pelger is scientifically unsound, for a number of reasons he enumerates in great detail, and then he accuses a slew of scientists and authors of basically lieing to promote the overinterpretation of the results. Leaving aside that one does not necessarily follow from the other (or everyone who uses certain well-disproven arguments from DBB or IOE would also be engaging in misconduct!), Berlinski is actually right in only one thing: people who used the term "computer simulation" should have used "computer model" or "computer calculations". Big friggin' deal, quite honestly.
His other comments on the original paper's significance and soundness (and thus on the "conspiracy" to overinterpret its results), range from the sophomoric (like that N&P ignored crucial factors like the need to modify the skull structure during eye evolution! ![[Roll Eyes]](rolleyes.gif) ) to the plain lazy (he didn't even bother to go check all the references provided in the paper, where most of the "missing explanations" are).
The only "scandal", if there is one, is that a respectable author like Berlinski would have the presumption to accuse a whole series of academics of misconduct without making any effort to even understand the original work in question. Berlinski's article is so full of basic misunderstandings, and so bad, a public apology by Berlinski would in fact be in order.
[ 10. June 2003, 09:58: Message edited by: charlie d. ]
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Pim van Meurs
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posted 10. June 2003 11:26
Several scientists have responded to Berlinski's claims
Including Nilsson himself who points out that much of the objections by Berlinski are addressed in the same paper.
quote:
At regular intervals he (Berlinski) repeats the phrase: "they do not say". But all the necessary information is there.
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RBH
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posted 10. June 2003 13:10
charlie d wrote quote:
Berlinski is actually right in only one thing: people who used the term "computer simulation" should have used "computer model" or "computer calculations". Big friggin' deal, quite honestly.
I have just reread both the Nilsson & Pelger (1994) paper and the section (pp 78-83) of Dawkins' River Out of Eden in which he describes and discusses that paper. Contrary to the implicit claim in the OP, Dawkins never once refers to a "computer simulation." His consistent phrase is "computer model." The only place a form of the word "simulation" appears is when Dawkins says that N&P did not "simulate the internal workings of cells" (p. 79). Given the complexity of the calculations (changes were calculated in multiple morphological dimensions, for one complexity) that Nilsson & Pelger performed, I can readily believe that they were performed on a computer. But it's irrelevant: The calculations could have been performed on a slide rule or an abacus or on their fingers and their main finding would still hold. Berlinski's point, on the other hand, reduces to the complaint that Nilsson & Pelger used a different device to make the calculations of their mathematical model than was assumed by, say, Dawkins. Gee. Fraud, indeed!
Most of Berlinski's other complaints are that the paper did not do things it didn't claim to do and that were not claimed for it. That's a bit strange. Nilsson & Pelger did what they set out to do in that paper, namely estimate the number of small incremental morphological steps required to get from a light-sensitive patch to a focused lens eye, taking into account the minimum number of (pessimistic) assumptions about the process. That is, they did not simulate (nor does Dawkins claim that they simulated) precisely how the invertebrate eye evolved; rather, they were attempting to estimate what an evolutionary process would have to accomplish if the eye evolved. And that they did.
I too commend the several letters in the URL Pim provided to Mr. Francisco's attention.
RBH
Added in edit Rereading Dawkins for a fourth time, I find I made a misstatement above. Dawkins uses "simulating" in one other place: "The beauty of simulating an eye, as distinct from, say, the leg of a running cheetah, is that its efficiency can be easily measured, using the laws of elementary optics" (p. 80). In that usage, "simulating" and "modeling" are virtual synonyms.
[ 10. June 2003, 13:42: Message edited by: RBH ]
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yersinia
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posted 10. June 2003 15:55
Most of the basic comments have already been made. Michael Francisco really should read the letters written in response to Berlinski's "A Scientific Scandal", particularly the response from Nilsson himself, and then see how many of his/Berlinski's claims are left standing.
I, for one, would really like to know why Berlinksi thought that the skull would have to be "reconstructed" when (1) eyes developed in the invertebrate (and therefore skull-less) chordate ancestors of fish, not in some kind of mythical blind fish, (2) skulls therefore developed around pre-existing eyes, not vice-versa, (3) the evolutionary model was of an invertebrate eye anyway, and (4) most of the camera eyes on the planet are in critters without skulls anyhow. This is basic biology that Berlinski misunderstands, and yet it is Berlinski who has the gall to go around accusing people of scandal.
The bit about the equations not being in the paper is really embarrassing for Berlinksi, as (1) some of them are, and (2) each of the others that are not is specifically referenced to previous literature either by Nilsson himself or in the optics literature.
I would also like to know why Commentary felt that publishing such an underinformed and misleading piece was appropriate.
Regarding Dawkins, RBH argues that even his referral to a "simulation" is ambiguous. There is, however, a bit somewhere where Dawkins refers to Nilsson and Pelger as undergoing random variations. Lesse, here are the quotes that Berlinski cites from Dawkins:
quote:
[Their] task was to set up computer models of evolving eyes to answer two questions ... [:] is there a smooth gradient of change, from flat skin to full camera eye, such that every intermediate is an improvement? ... [and] how long would the necessary quantity of evolutionary change take?
In their computer models, Nilsson and Pelger made no attempt to simulate the internal workings of cells.
... Nilsson and Pelger began with a flat retina atop a flat pigment layer and surmounted by a flat, protective transparent layer. The transparent layer was allowed to undergo localized random mutations of its refractive index. They then let the model transform itself at random, constrained only by the requirement that any change must be small and must be an improvement on what went before.
The results were swift and derisive. A trajectory of steadily mounting acuity led unhesitatingly from the flat beginning through a shallow indentation to a steadily deepening cup, as the shape of the model eye deformed itself on the computer screen... And then, almost like a conjuring trick, a portion of this transparent filling condensed into a local, spherical region of higher refractive index.
... This ratio is called Mattiessen's ratio. Nilsson and Pelger's computer-simulation model homed in unerringly on Mattiessen's ratio.
There is pretty clearly the implication of a stochastic simulation there I think. Dawkins let his imagination of what Nilsson and Pelger did overstep the bounds of what they actually did.
What actually happened seems to be widely misunderstood. Here is my understanding (going from memory). Nilsson and Pelger started out with a common observation, that quantitative traits (traits that vary in an effectively continuous manner, like e.g. height, even though we all know inheritance is particulate at bottom) usually fall out in a distribution with a bell-shaped curve, i.e. a normal distribution.
See these lecture notes on Quantitative Genetics. Here is how particulate genes can add up to continuous variation with a normal distribution:
These distributions can be fully described by the mean and standard deviation, which makes a number of things simple. Namely, if you have selection acting on a continuously-varying trait of a population, and you have the heritability (h) of the trait, you can calculate how much the mean of the trait in the population will change with each generation. Nilsson and Pelger used these very simple fundamentals, making conservative assumptions about selection (1% IIRC), heritability, etc., and that's how they got their total number of generations.
Berlinski explains it well enough:
quote:
The chief claim of their paper now follows: to achieve the visual acuity that is characteristic of a "focused camera-type eye with the geometry typical for aquatic animals," it is necessary that an initial patch be made 80,129,540 times larger (or greater or grander) than it originally was. This number represents the magnitude of the blob's increase in size. How many steps does that figure represent? Since 80,129,540 = [1.01.sup.1,829], Nilsson and Pelger conclude that "altogether 1,829 steps of 1 percent are required" to bring about the requisite transformation.
These steps, it is important to remember, do not represent temporal intervals. We still need to assess how rapidly the advantages represented by such a transformation would spread in a population of organisms, and so answer the question of how long the process takes. In order to do this, Nilsson and Pelger turn to population genetics. The equation that follows involves the multiplication of four numbers:
R = [h.sup.2] x i x V x m
Here, R is the response (i.e. visual acuity in each generation), h is the coefficient of heredity, i designates the intensity of selection, V is the coefficient of variation (the ratio of the standard deviation to the mean), and m, the mean value fur visual acuity. These four numbers designate the extent to which heredity is responsible for visual acuity, the intensity with which selection acts to prize it, the way its mean or average value is spread over a population, and the mean or average value itself. Values are assigned as estimates to the first three numbers; the mean is left undetermined, rising through each generation.
As for the estimates themselves, Nilsson and Pelger assume that [h.sup.2] = .50; that i= 0.01; and that V = 0.01. On this basis, they conclude that R = 0.00005m. The response in each new generation of light-sensitive patches is 0.00005 times the mean value of visual acuity in the previous generation of light-sensitive patches.
Their overall estimate--the conclusion of their paper--now follows in two stages. Assume that n represents the number of generations required to transform a light-sensitive patch into a "focused camera-type eye with the geometry typical for aquatic animals." (In small aquatic animals, a generation is roughly a year.) It, as we have seen, the mean value of visual acuity of such an eye is [1.01.sup.1,829] = 80,129,540, where 1,829 represents the number of steps required and 80,129,540 describes the extent of the change those steps bring about; and if [1.00005.sup.n] = [1.01.sup.1,829 ] = 80,129,540, then it follows that n = 363,992.
It is this figure--363,992--that allows Nilsson and Pelger to conclude at last that "the time required [is] amazingly short: only a few hundred thousand years." And this also completes my exposition of Nilsson and Pelger's paper. Business before pleasure.
What is bizarre is that Berlinski appears to understand the above, but then begins to talk about the importance of random variations later on:
quote:
Nilsson and Pelger assert that only 363,992 generations are required to generate an eye from an initial light-sensitive patch. As I have already observed, die number 363,992 is derived from the number 80,129,540, which is derived from the number 1,829--which in turn is derived from nothing at all. Never mind. Let us accept 1,829 pour le sport. If Nilsson and Pelger intend their model to be a vindication of Darwin's theory, then changes from one step to another must be governed by random changes in the model's geometry, followed by some mechanism standing in for natural selection. These are, after all, the crucial features of any Darwinian theory. But in their paper there is no mention whatsoever of randomly occurring changes, and natural selection plays only a ceremonial role in their deliberations.
I can only think that Berlinski would have been far less confused if he had made the connection between the population genetics equation and the Gaussian distribution that describes the variation in typical biological traits.
We could go into more detail about the equations (I have the pdf of the paper from JSTOR) if people really want to, but it's pretty clear that Berlinski never even got this far in his understanding of the calculations.
Berlinski's various recent papers in Commentary are online here (sometimes just excerpts). Here is A Scientific Scandal.
[ 10. June 2003, 16:09: Message edited by: yersinia ]
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Michael Francisco
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posted 10. June 2003 22:58
Thanks for the many insightful comments on the article – I have certainly been educated through many of them.
First regarding the relevance of this article to ID. I think that the complexity of the eye, and whether it can be produced by evolutionary means is directly applicable to complex systems. The eye is one of the more common examples of a complex organ that may or may not be producible by evolutionary means. Thus, it seems that one of the popularly discussed articles on the issue would be worth bringing up – even if it turns out to be false. Admittedly not experienced in the field, I ran across the Commentary article and thought it would be worth at least discussing the merits of the criticisms of one the commonly referred to papers in the field.
After carefully weighing through the various linked material, it seems clear that Mr. Berlinski makes many criticisms of the paper, particularly those in the form of questions, that are dismissed by further research into the literature. I probably associated myself with the arguments of Berlinski’s piece too much in the original post – I was primarily interested in seeing the article, and perhaps the Nilsson and Pelger article discussed on this forum.
There are, it seems to me, still part of the criticism raised by Berlinski that is still of interest. Most commentators on the issue agree that those who have cited the 1994 paper as a computer “simulation” are in error. This is the only part that Nilsson agreed with in his response previously posted. “Berlinski is right on one point only: my paper with Pelger has been incorrectly quoted as containing a computer simulation of eye evolution” (Linked in Pim's post)
Just how significant is this mix-up? In many contexts, computer simulations and computer models are nearly synonymous, but it seems to me that when strong claims are made about potential time frames for eye evolution in terms of years, that referring to the paper as a computer simulation could easily lead readers to believe that the simulation was in some way a comprehensive evolution of the eye. However, the paper itself makes it clear, “the only real threat to the usefulness of our model is that we may have failed to introduce structures that are necessary for a functional eye.” Interestingly, the end of the paper also brings up how aspects such as neural processing and optic lobes were deliberately ignored. (This is offered as part of an explanation as to why there are still intermediate eyes if the eye could have evolved so quickly.)
The paper, to its credit, is fairly open about the assumptions and aspects of the eye not considered. (Mr. Berlinski’s rhetoric does seem to be overly strong, given the papers clear statements about assumptions.) Because the paper does not include these aspects, and indeed the authors never claimed the paper did, it does seem that citing the paper as a definitive computer model or simulation of the eye evolving in a ‘mere 300,000 years’ overstates the case. It may be the case that a few of Berlinski’s criticisms of the papers’ technical aspects are correct (I am not convinced either way), but ultimately, even if the paper is sound in its conclusions, the way in which these conclusions are used seems to be misleading.
Even the close of the paper itself implies that more has been said about eye evolution, “In this context it is obvious that the eye was never a real threat to Darwin’s theory of evolution.” As far as I can tell, their paper certainly shows that morphological changes as related to spatial resolution is not a problem – but the other aspects of eye development could still potentially pose a problem. As others have noted, you can judge for yourself whether Richard Dawkins overstates the conclusions of the paper. Perhaps this issue is not at all relevant for the ISCID forum, as members of the forum understand the limits of what the Nilsson and Pelger paper concluded, but it does seem that the paper is presented as having settled the whole issue of eye evolution – which does not seem to be the case.
Briefly, I’m still confused about the validity of Berlinski’s criticism regarding units in the paper that relate to years. Perhaps someone could post clarifying the issue, but it does seem that the paper makes assumptions about how the assumed one-year generations relate to the necessary number of 1% steps. It’s likely that I simply do not understand this point fully. I understand, as per Nilsson’s response, that Berlinski has confused the 1% steps and .005% evolutionary change per generation.
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yersinia
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posted 11. June 2003 04:28
Hi,
I've been thinking of doing this for some time. Here is a brief summary of the calculations and reasoning of Nilsson & Pelger (N-P) in a step-by-step fashion. Hopefully this will be helpful for Mike.
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The model
The first step is to set up a model of the evolutionary sequence from light-sensitive patch to camera eye. This is the portion of the inquiry where the existence of a "gradual route" to a camera eye is investigated. Studies of the variations in eyes in the animal kingdom (e.g., Darwin 1859, Salvini-Plawen and Mayr 1977) already indicated that such a route existed.
Nilsson and Pelger (1994) begin by arguing that the whole eye series can be seen as a continual improvement in visual acuity, specifically spatial resolution. They argue that the various uses of eyes, i.e. "measuring self-motion, detection of small targets, or complicated pattern recognition", are all fundamentally dependent on the information-gathering capacity possible with a given spatial resolution.
The eye cup
NP therefore begin by calculating how optical resolution changes as (1) the light-sensitive patch curves inward and becomes cupped and (2) as the aperture narrows. Both of these changes improve resolution by narrowing the angle at which light can strike the retina. Nilsson calculated in a 1990 paper (referenced in NP 1994) that the most efficient (in terms of minimal morphological change) way to increase resolution at first is to deepen the pit. Once the pit depth equals the pit width, however, it becomes more efficient to increase resolution by constricting the aperture. Although some further improvement of resolution is gained by deepening the pit, the returns diminish rapidly (Figure 1a).
The eye aperture
The disadvantage of narrowing the aperture is that fewer and fewer photons are able to enter the eye. For reasons of optics, the fewer photons that are available, the less "signal" there is relative to the "noise". There is therefore an optimum aperature width, below which further narrowing cuts off too much light. This optimum width depends on light intensity, so the authors calculate it for several orders of magnitude of intensity (Figure 1b, and equation 1).
The lense
From here, the only way to further improve resolution is via a lense. All along, as the eye pit has deepened, it has been filled with "vitreous mass" (transparent cells) derived from the initial protective surface layer of the light-sensitive spot. A lense can be developed simply by varying the density of the vitreous mass. N-P cite Fletcher et al. (1954) for the calculations. Spatial resolution improves very rapidly with morphological change at this stage (Figure 1c).
Quantifying the amount of morphological change
In order to quantify the amount of morphological change, N-P constructed graphical models of various stages in the process (Figure 2) and decided to calculate the number of 1%-change steps in-between each stage. As an example, it takes 70 1% steps in order for a structure to double in length (due to the compounding of change think compound interest -- it takes only 70 steps rather than 100 in order for doubling to occur). They admit that there is some subjectivity in deciding *how* to measure morphological change, but they decide on the following as simple measures:
[*]length of straight structures
[*]"arc length of curved structures"
[*]"height and width of voluminous structures"
[*]changes in radius of curvature use the arc length of the inside and outside of the curved structure
[*]changes in lens refractive index above the starting point of 1.34
With this method they came up with 1829 1% morphological steps for the evolutionary sequence. They note that in actual evolution, some of the changes could happen simultaneously (e.g., lense development and aperture narrowing could occur together), but because they are being pessimistic, they restrict the steps to happen in series.
Calculation of the number of generations
Nowhere up to this point have the authors made *any* consideration of selection or the number of generations required. All of the preceding work served simply to establish that (1) a gradual route of continual improvement from eyespot to camera eye actually existed and (2) to quantify how much morphological change this entails. Knowing this, N-P can use a simple population genetics equation for continuous traits to calculate how many generations it would take for this set of transformations to occur. Here is the equation:
R = h^2 * i * V * m
Terms:
h^2 = heritability (genetically determined proportion of the variance in the phenotype)
i = intensity of selection
V = the coefficient of variation in the continuous trait (std. dev./mean), assuming the variation in the population has a normal distribution (a common situation)
m = the mean
R = response in 1 generation
The values they use:
h^2 = 0.5 (a common value for heritability -- half of the variation due to genes, half to environment; only the genetic component can be inherited & retained by selection)
i = 0.01 (deliberately low; selection coefficients of 0.3-0.5 are commonly found, e.g. in peppered moths)
V = 0.01 (also low; if the mean adult human male is 6 feet tall, a V=0.01 value would mean that 95% of the male population had height of 6 feet +/- 1.44 inches).
When these variables are plugged in, one gets:
R = 1.00005m
...which means that the change per generation is only 0.005%.
N-P note that 1829 1% steps amounts to morphological change by a factor of 1.01^1829 = 80,129,540. Instead of height doubling (x2), imagine height being multiplied by 80,129,540 (keep in mind, of course, that in our actual example a number of different traits are being modified).
The Time Estimate
As the change per generation is 1.00005, the number of generations (n) can be calculated via:
1.00005^n = 80,129,540
Resulting in...
n=363,992 generations
If we assume one generation per year (and many animals reproduce much faster than this), we get a pessimistic time for the origin of the eye of ~364,000 years, which is a geological eyeblink.
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[ 11. June 2003, 04:33: Message edited by: yersinia ]
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warren_bergerson
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posted 11. June 2003 07:39
Michael,
As discussed in your initial post, Berlinski points out that at the very least the Pelger article is subject to misinterpretation. As I understand it, the Pelger article describes a sequence of gradual phenotype changes which ‘could possibly’ have produced the evolution of the eye. The misinterpretation arises when it is suggested that ‘the proposed series of changes could have been produced by Darwinian processes’ or ‘the described sequence supports Darwinian theory’.
There are in fact no scientifically defined Darwinian causal processes which could have produced the sequence of changes described. There are simplistic models which could simulate Darwinian changes in one variable, but as Berlinski points out, the evolution of the eye had to have been a complex multi-dimensional process, and there is no Darwinian model or theory capable of explaining such complex changes.
Properly interpreted, the Pelger study suggests that 1)given appropriate conditions it is theoretically possible the eye could have evolved fairly rapidly, but 2)there is no known or defined causal process capable of producing such complex design changes.
We know from selective breeding programs that under some conditions selective breeding can produce small gradual changes in variables. Pelger demonstrates that it may be possible to represent the evolution of the eye as a series of small gradual changes. We know from mathematical analysis that ‘Darwinian type variation-selection processes’ can produce gradual changes in one dimensional models’. These ‘facts’ combined, however, are not sufficient to support the conclusion that ‘the eye evolved by Darwinian processes’.
The Pelger demonstration is one small component in an argument supporting a scientific explanation of the evolution of complex organs such as the eye. This is very different than the claim or misinterpretation that ‘Pelger demonstrates that complex organs such as eyes could have evolved via Darwinian processes’.
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RBH
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posted 11. June 2003 14:59
warren wrote quote:
There are simplistic models which could simulate Darwinian changes in one variable, but as Berlinski points out, the evolution of the eye had to have been a complex multi-dimensional process, and there is no Darwinian model or theory capable of explaining such complex changes.
First, Berlinski didn't point out that the evolution of the eye was multi-dimensional, Nilsson and Pelger did and took it into account in developing their model. Berlinski merely parrotted them.
Second, my company designs, builds, and deploys evolutionary algorithms that "simulate evolutionary changes" in up to 72 variables. That's a lot more than one. Those EAs autonomously make decisions on which tens of millions of dollars ride every day. (Today it's a bit more than $40mm.) Our clients would be real unhappy if the EAs couldn't model evolutionary processes in more than one dimension.
Third, please read these three papers (the second one is a handout for a class, so it shouldn't be hard going for you) and say again that "there is no Darwinian model or theory capable of explaining such complex changes," supporting your claim with a detailed refutation of their content. You repeatedly make the same kind of extravagant claim about the (in)capabilities of evolutionary theory, but it is not at all clear that you're sufficiently knowledgeable about that body of theories to support the claim. Therefore, I ask you to support it rather than merely repeat it. An accurate claim might be "warren does not know of a Darwinian theory or model ..." but to make of it a universal claim ("there is no ...") requires that your readers believe that if there were such a theory you'd know about it. I don't believe that.
Here is a bit of raw material on which you can base an analysis in support of your claim.
1. Landscapes and Molecular Evolution
2. Adaptation as a Polygenic Process
3. Fitness Landscapes and Evolvability
There are many many more that I could provide, but these should give you a start. Please support your claim that there is no "Darwinian model or theory capable of explaining such complex changes" or quit making it.
RBH
[ 11. June 2003, 15:11: Message edited by: RBH ]
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Argon
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posted 11. June 2003 15:46
RBH asks Warren:
"Please support your claim that there is no "Darwinian model or theory capable of explaining such complex changes" or quit making it."
FWIW - He should feel free to support any of his claims.
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Pim van Meurs
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posted 12. June 2003 00:02
Warren suggests "Properly interpreted, the Pelger study suggests that 1)given appropriate conditions it is theoretically possible the eye could have evolved fairly rapidly, but 2)there is no known or defined causal process capable of producing such complex design changes. "
Begging the question, ignoring the evidence. Your denial of Darwinian processes that can produce information and complexity is not very conducive to creating a climate in which ID and Darwinian evolution can be explored.
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warren_bergerson
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posted 12. June 2003 08:03
Berlinski’s complaint, as I understand it, was that 1)the Pelger article was flawed and incomplete and 2) the article is being misused and misinterpreted proponents of Darwinian evolution.
RBH and Pim/Frances are interpreting the article as providing evidence supporting some not explicitly defined form of Darwinian causal process. If the Pelger article does not, in fact, provide direct evidence supporting evolution by some defined causal process, then the accusation that the article is being misused and misinterpreted is confirmed.
The Pelger article, as described, appears to provide a Disney like artistic representation of the evolution of the eye. We have all seen some form of the ‘fish crawling out of the water and transforming into a human" Such artistic representations can be educational and useful, but they do not, by normal scientific standards, represent scientific evidence.
If an artistic representation predicted the existence of intermediate stages of development, and if evidence for such intermediate stages was subsequently found, then the artistic representation/confirmed prediction of intermediate stages could be interpreted as evidence supporting the occurrence or ‘fact’ of evolution. The representation/confirmed prediction says nothing about the process or mechanism of evolutionary change.
To provide evidence relating to the causal processes producing evolutionary change, Pelger and company would have, at the very least, been required to offer precise definition of the beginning and ending states, proposed a process or mechanism capable of producing the defined change in state, generated testable/verifiable predictions using the proposed evolutionary process, and finally showed that the ‘predictions’ generated could be independently verified as accurate. Given the current state of scientific knowledge, we can be quite confident that the Pelger study did not and could not produce evidence supporting the causal processes or mechanisms responsible for evolutionary change.
The Pelger study, it appears, simply represents another variation of the demonstrations presented by Darwin and Disney. The Pelger study, like the Lenski study, it appears, only achieves scientific significance when interpreted or misinterpreted.
Quote RBH: Second, my company designs, builds, and deploys evolutionary algorithms that "simulate evolutionary changes" in up to 72 variables.
It is not difficult to design search routines that search 72 or 72,000 variables. It is, however, a bit more difficult to translate such search models into ‘evolutionary theories’ and then to demonstrate that such models or theories actually fit evolutionary data and generate verifiable predictions.
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RBH
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posted 12. June 2003 12:14
warren wrote quote:
RBH and Pim/Frances are interpreting the article as providing evidence supporting some not explicitly defined form of Darwinian causal process. If the Pelger article does not, in fact, provide direct evidence supporting evolution by some defined causal process, then the accusation that the article is being misused and misinterpreted is confirmed.
For my part, that's false, as I think it is for Pim. I have not interpreted the Nilsson & Pelger paper (don't forget the senior author, warren) as providing evidence for any any causal process, Darwinian or otherwise. I'd really like to see warren provide some support for his false claim about my interpretation. I'm not going to hold my breath until he provides it, though.
I interpret the paper as showing exactly what it claimed to show, namely that the morphology of the invertebrate focused lens eye is accessible to an evolutionary process, and that on pessimistic assumptions about rate of change and heritability, the time required for an incremental process of construction of that morphology is surprisingly short. I said above quote:
Nilsson & Pelger did what they set out to do in that paper, namely estimate the number of small incremental morphological steps required to get from a light-sensitive patch to a focused lens eye, taking into account the minimum number of (pessimistic) assumptions about the process. That is, they did not simulate (nor does Dawkins claim that they simulated) precisely how the invertebrate eye evolved; rather, they were attempting to estimate what an evolutionary process would have to accomplish if the eye evolved. And that they did.
If one actually reads that, far from interpreting the study as evidence for an evolutionary causal process, I specifically said that Nilsson & Pelger did not simulate the evolution of the eye. That warren so badly misrepresents what I have written here further erodes my confidence in his general claims about evolutionary theory. And I note that warren has not provided any support for his extravagant claims about that theory's alleged lack of capability.
RBH
[ 12. June 2003, 12:27: Message edited by: RBH ]
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Pim van Meurs
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posted 12. June 2003 12:18
Warren: The Pelger article, as described, appears to provide a Disney like artistic representation of the evolution of the eye.
I find it fascinating that Warren seems to be critiquing a paper which he has not seen or read. Warren's assertions and accusations seem to lack in reality and familiarity it seems to me.
Warren's speculations "then the accusation that the article is being misused and misinterpreted is confirmed" could easily be confirmed by Warren if he were to read the paper. Rather than making irrelevant claims about Darwinism, Darwinian mechanisms etc I suggest that Warren familiarizes himself with the actual literature on these topics before jumping to conclusions that may likely not be supported by them.
In case of Warren's claim that "2)there is no known or defined causal process capable of producing such complex design changes", Warren may want to explain his claim in light of the paper by Nilsson. I am looking forward to such an approach.
Thus when Warren concludes that " The Pelger study, like the Lenski study, it appears, only achieves scientific significance when interpreted or misinterpreted. "
I agree about the misinterpretation part but probably for different reasons than Warren himself. Like Lenski, the Nilsson/Pelger paper address some very common claims against Darwinian explanations in a scientific manner.
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