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Author
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Topic: The Wings of Eagles
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warren_bergerson
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Member # 262
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posted 05. August 2002 08:43
It is sometimes easy to forget that ‘positive, hard evidence’ supporting a theory can deteriorate over time. Hard direct evidence that was at one time interpreted as supporting a particular theory, may, as new knowledge accumulates, acquire a new meaning or interpretation which not only doesn’t support the original theory, but may actually contradict it. This deterioration of positive, hard evidence, is, IMO, what has happened to the large body of hard, positive evidence supporting Darwinian and neo-Darwinian theories. The wings of eagles, I would suggest, provide an important illustration of the phenomena.
As a recent PBS special pointed out, there are many types of eagles which have different types or shapes of wings. The different types of wings are clearly adapted to the particular environment in which each species lives. Gradual adaptive changes in wing shape provides, almost everyone would agree, direct evidence for the existence of a certain type of evolutionary change. In the past, almost everyone would also have agreed that these examples provided direct evidence for Darwin’s theory of evolutionary change. Given our current greatly expanded knowledge of both genetics and wing design, it is still clear that adaptive changes in wings provides evidence for a type of evolution. It is not at all clear, however, if such evidence is compatible with either Darwinian or neo-Darwinian ‘theory’.
In the absence of knowledge of genetics, and in the absence of detail knowledge of wing design, it was relatively simple to construct a model of adaptive change from the short stubby wings used in forests to long thin wings associated with eagles that hunt in the ocean. For example, defining wing design in terms of two variables (length and width), we could set assumptions for creation of diversity, and differential selection. If we have evidence available on how fast adaptive changes occurred in nature, it would not be difficult to find diversity and selection assumptions that would fit the observed rate of evolutionary change. Given the limited knowledge of Darwin’s day, it would have been relatively easy to simulate evolutionary changes in eagles wings using assumptions compatible with Darwin’s theory.
However, once we introduce our current knowledge of wing design and genetics, the creation of a simulation model that fits both the facts and the theories becomes much more difficult. The number of variables required to define wing design will increase significantly and the degree of precision associated with each variable is likely to increase. In addition, knowledge of genetics imposes severe restrictions on acceptable assumptions regarding creation of diversity. (to my knowledge, the existence of a non-random series of mutations that would produce fine incremental changes in wing length are neither known to exist, nor compatible with existing genetic theory.)
It is almost certain that a ‘mutate-select’ model using realistic assumptions consistent with existing knowledge could not explain or simulate the known evolutionary changes in eagles wings. It is even more certain that no one has actually produced such a demonstration. It is reasonable to conclude that given current knowledge, the known existence of gradual steady adaptive change is not necessarily compatible with Darwinian or neo-Darwinian theory.
It is also not a great leap to suggest that much, if not all, of the ‘positive evidence’ accumulated by Darwin and his successors in support of Darwinian theories has deteriorated as a result of our steadily increasing knowledge. At the very least, any claim of positive evidence supporting evolutionary theory should be reinterpreted in light of current knowledge.
Much of the ID vs evolution debate has focused on the ability of Darwinian and neo-Darwinian theory to explain complex phenomena like the evolution of flagellum or the evolvability of complex redundancy. Recognizing the ‘deterioration of positive evidence resulting from new knowledge’, it may be far easier and far more productive to go back and review the ability of Darwinian and neo-Darwinian theories to explain the seemingly simple occurrences of evolutionary change. Subjects like the adaptive evolution of eagles wings would seem like a good starting point.
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charlie d.
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posted 05. August 2002 15:08
quote:
to my knowledge, the existence of a non-random series of mutations that would produce fine incremental changes in wing length are neither known to exist, nor compatible with existing genetic theory.
This will come to some surprise to breeders of pigeons, dogs, horses etc who have been selecting long- and short-limbed genetic variants for centuries with remarkable success...
Warren, have you read any recent literature on the genetic and developmental control of limb formation? There's actually quite a bit that is known and, interestingly, a substantial amount on birds (granted, chicken are not as romantic as eagles, but still the developmental processes aren't that different). Basically, several mechanisms are known that can yield precisely the progressive type of quantitative variation in limb length you so much puzzle about; in fact bone growth appears very much to be the result of an equilibrium between agonist and antagonist growth and differentiation factors whose expression level is itself finely quantitatively regulated.
I would suggest this review and this one on vertebrate limb formation, and this and this on the skinny about bone development (pardon the pun).
I don't want to seem picky, and the Administrator will forgive me I hope, but a lot of your puzzlement at the insufficiency of natural selection, as in this quote of yours from the redundancy thread:
quote:
If we look at sexual reproduction in complex organism we find an interesting phenomena. Something greater than 99.999% of natural selection or selective survival and reproduction occurs before the male and female sex cells combine and before most phenotype traits appear. Most traits in nature, it would appear, are heavily shielded from Natural selection.
seems to derive more from your apparent lack of familiarity with the current literature than with anything else. This results in potentially interesting threads dieing early deaths as long lists of relevant publications, which should have been checked before any conjecture is made.
[ 05 August 2002, 15:14: Message edited by: charlie d. ]
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warren_bergerson
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posted 06. August 2002 17:35
Charlie,
I intended to ignore your comments because they were off topic. The question addressed here is ‘evidence supporting Darwinian and neo-Darwinian theories’. You comments and references related to ‘evidence for gradual evolutionary change’, a very different topic. Your comments are, however, useful in pointing out a number of interesting points regarding the current state of evolutionary science.
First, it is useful to note that search engines can be as much a hindrance as a help in discussing scientific issues. It is so easy and so common place for individuals to put in a phrase, pull out a list of references, and present those references as a substitute for thinking through the issue. It is important to note that references needed to be interpreted relevant to the topic under discussions. In the absence of such analysis, references are largely useless.
Second, as I pointed out in my original post, the relevance of a piece of evidence relative to a theory or group of theories can change rapidly as new information becomes available. Evidence that seemed to support a theory even a few months ago may now not be consistent with a theory.
Third, hard science is based on the concept of formulating a theory and making it open to ‘king on the hill’ type falsification. Once it is recognized how quickly positive evidence can deteriorate, it becomes apparent that reliance on positive evidence is a very poor substitute for the old fashioned anyone can falsify any theory.
Fourth, it might, IMO, be more accurate to describe current evolutionary biology as ‘systematic accumulation of knowledge’ rather than as a science in the classic sense.
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charlie d.
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posted 06. August 2002 19:23
So are you saying that you stand by your comment that "the existence of a non-random series of mutations that would produce fine incremental changes in wing length are neither known to exist, nor compatible with existing genetic theory"?
I am just arguing that molecular developmental processes that may result in such changes do indeed exist, as widely reported in the relevant literature, and that they are fully compatible with existing "genetic theory", as well as darwinian evolutionary mechanisms. If this is not germane to your claim that "it is almost certain that a ‘mutate-select’ model using realistic assumptions consistent with existing knowledge could not explain or simulate the known evolutionary changes in eagles wings", then maybe I misunderstood what your post was all about, and I apologize. Perhaps, though, you should rephrase your point in a less ambiguous manner, so that the inadvertent reader is not induced to erroneous conclusions about the current state of knowledge on developmental and evolutionary biology, as well as modern genetics.
As for your other comment that "it is so easy and so common place for individuals to put in a phrase, pull out a list of references, and present those references as a substitute for thinking through the issue", I should say that I do not at all wish to substitute references for thinking through an issue, but rather suggest that reading through the references is a necessary pre-requisite to sound thinking about any issue. Especially, because it is now so easy.
[ 06 August 2002, 19:29: Message edited by: charlie d. ]
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warren_bergerson
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posted 07. August 2002 09:59
Charlie,
Quote: I am just arguing that molecular developmental processes that may result in such changes do indeed exist, as widely reported in the relevant literature, and that they are fully compatible with existing "genetic theory", as well as darwinian evolutionary mechanisms.
Your above statement is not an argument, but a simple claim or assertion which you have not backed up with 1)logical arguments, 2)evidence, or 3)citations in the literature. I am well aware that popular culture appears to permit unsubstantiated claims relating to
‘evolutionary theory and evidence’, but the discussion here is intended to be on a somewhat more rigorous/technical level.
Your claim relates to two very complex questions:
1. Is it possible to construct a scientific theory which is both compatible with the body of existing knowledge and the general principles of Darwinian and neo-Darwinian theory?
2. If such a theory could be constructed would it/could it stand up to rigorous scientific testing/validation?
Pop culture waves its hand and claims to have simple answers to both questions. Serious scientists realize there is currently no clear answer to either question. Stephen J Gould wrote a very long detailed analysis of the first question. The conclusion of his analysis was essentially(to paraphrase) - I hope I can make some small contribution to the development of a positive answer to the first of the above questions.
Constructing scientific theories and constructing simulation models can be described as a ‘connect the dots’ problem. The more knowledge available, the more dots, and thus the more difficult the task. The ‘wings of eagles’ problem provides a relatively clear demonstration that it is not currently possible to construct either a simulation model or a scientific theory that 1)fits known facts, and 2)is consistent with the principles of Darwinian and neo-Darwinian theory.
The rather obvious conclusion that ‘no one currently knows how to construct a Darwinian model or theory of evolution’ may be controversial in our pop culture but there is no reason why this conclusion should be controversial from a rigorous scientific perspective. [Note: If my conclusion is wrong, then it would be a relatively simple task to prove me wrong by producing the simulation/demonstration I claim is impossible.]
Rather than veer off into the ‘pop culture’ versus ‘real science’ issue, it is probably better to consider the usefulness of the ‘wings of eagles’ demonstration on the ID versus evolution issue.
To begin, most proponents of ID would recognize that 1)an eagles wing is an example of biological design, and 2)small modifications in these designs may be explainable in terms of materialistic mechanisms. At the same time, these changes in design do not appear to be logically consistent with Darwinian and neo-Darwinian principles. Eagles wings, it appears, provide an opportunity to study a non-Darwinian design mechanism.
To briefly review, changing the design of a wing involves small incremental changes/variations in variables such as wing length. We have lots of evidence that biological systems can produce such incremental variations and that the occurrence of such variations can result in changes in phenotype traits (selective breeding experiments).
If we view genes in terms of ‘assembly instructions’, as I suggested earlier, then it is not at all difficult to envision a genetic mechanisms which could account for the observed types of variations.
The problem, of course, is that such gradual change/variation mechanisms are totally inconsistent with both the logic and the mathematics of random mutations. [Given even a little knowledge of mathematical modeling, this should be obvious.] Modeling changes in these variables ‘suggests’ that ‘when wings evolved, the design included a handy quick change devise that allows eagles to quickly change from short wings to long wings if they ever decide to move from the forest to an ocean side home.’ In more formal terminology, the analysis of eagles wings suggests that the development or evolution of wings included the development or evolution of some as yet unidentified mechanisms to quickly adapt the shape of the wings to fit environmental conditions.
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charlie d.
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posted 07. August 2002 13:51
quote:
To briefly review, changing the design of a wing involves small incremental changes/variations in variables such as wing length. We have lots of evidence that biological systems can produce such incremental variations and that the occurrence of such variations can result in changes in phenotype traits (selective breeding experiments).
....
The problem, of course, is that such gradual change/variation mechanisms are totally inconsistent with both the logic and the mathematics of random mutations. [Given even a little knowledge of mathematical modeling, this should be obvious.]
With all due respect for mathematics (and your logic), given a little (and I truly mean little here) knowledge of current molecular developmental biology and genetics, you'd realize that it is actually quite well established that
1) most, if not all organs (such as limbs, as it is relevant here, or fruit size, see below) whose development and growth are under the quantitative control of soluble growth and differentiation factors, can indeed progressively change size by changes in the level of expression of such factors;
2) most traits related to gross developmental processes (such as height, limb length, stubborn refusal to accept obvious facts) are inherited as quantitative traits, that is are the product of the additive, subtractive and epistatic interactions of multiple genes. Such characters usually display extended, continuous phenotypic ranges and it is their precise nature to vary progressively by accumulation of mutations with small individual effects.
3) With few exceptions, it is mostly quantitative genetic traits that have been exploited in breeding novel animal and plant varieties over centuries. Such selection processes have brought about cattle that were progressively fatter, or gave progressively more milk, sheep with progressively longer and thicker wool, wheat and corn with progressively higher per-acre yields, progressively faster horses, and so on.
Interestingly, several of the genetic loci underlying these quantitative traits are now being identified, research pushed forth by the enormous financial stakes behind the genome projects of species of agricultural interest, including several crop plants and farm animals. You'd be surprised to learn, I bet, that so far, all of these recently identified quantitative loci have been found to correspond to old-fashioned genes, those that code for proteins, rather than the fancier, newer model you seem so attached to, that supposedly encode "assembly instructions". One example is fw2.2, a tomato gene responsible for part (30%) of the difference between large and small size tomato varieties, which appears to encode for a signaling molecule, with some similarity to an animal oncogene, and to work by affecting cell division during flower development. Interestingly, the different activity of large fruit size- vs. small size-associated alleles is not in the gene's coding sequence, but in its level of expression (as I discussed in point 1). Another example is the DGAT-1 acyl-CoA:diacylglycerol acyltransferase gene, in which a known, specific point mutation is responsible for up to 10% of the milk fat differences in some cow breeds.
Quantitative trait loci involved in everything from crop yields, animal body size, fertility, disease resistance, hypertension, cancer susceptibility, milk yield, obesity etc are currently beginning to be identified.
Whether the amount of evidence that complex characters can and do change progressively under selection by well-characterized genetic mechanisms, compatible with darwinian evolution, represents a more likely explanation of eagles’ wingspan variation than your cogent argument that ‘when wings evolved, the design included a handy quick change devise that allows eagles to quickly change from short wings to long wings if they ever decide to move from the forest to an ocean side home" I'll leave to others to decide.
My expectation is that, with enough time and money, selective breeding and genetic analysis of eagles would identify QTLs involved in wing span, corresponding to allelic variants in the structure or expression levels of genes. If you were interested in putting your theories to the test, you could actually try pursuing this kind of investigation, although I realize that nitty-gritty science is much slower, and can be less rewarding, to some, than the intellectual freedom allowed by speculation unrestrained by data.
[edited as per moderator's request]
[ 07 August 2002, 16:37: Message edited by: charlie d. ]
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posted 07. August 2002 14:30
Charlie d.,
This is just a "tone warning." Comments like "You could actually try doing that, though that’d be science" are demeaning, insulting, and unacceptable on this forum.
I appreciate your comments on the science behind certain types of evolutionary change. But I require that you refrain from the gratuitous jabs. Please edit your post accordingly.
[ 07 August 2002, 14:36: Message edited by: Moderator ]
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warren_bergerson
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posted 08. August 2002 11:28
Charlie,
If I understand your argument, you are pointing out there is obvious evidence from selective breeding for ‘gradual, graduated, change in a trait such as wing length’. Such evidence supports the ‘proposal’ that evolutionary/adaptive changes in wing shape involves a multi-stage gradual change. I think I made it clear from the beginning that the argument I am presenting is based on the existence of gradual, multi-stage adaptive change.
Second, you are presenting evidence that different forms or alleles of a gene can produce measurably different variations in an observed variable such as wing length. Again this is a fact that is implicit in the argument I am presenting.
The factual information you are presenting provides support for some of the points underlying my argument. As far as I can determine, the information you are providing simply documents facts or assertions that are not in question. If I am missing some point in your argument I would appreciate clarification.
Your argument, again as I am reading it, then leaps to the conclusion that Darwinian and neo-Darwinian genetic theory can explain the evolution of the types of adaptive change under discussion. I apologize if I am nit-picking, but I don’t see where you have presented either evidence or arguments relevant to your conclusion.
To repeat, the point of my argument is that given current technology and knowledge, it is possible to construct a reasonably detailed simulation model of the evolutionary/adaptive processes which produce changes in the wings of eagles. Such simulations can be constructed using 1)known/documented features of the changes involved, and 2)Darwinian and neo-Darwinian theory. In constructing such a simulation one will need to make assumptions regarding the number of genes, the number of genetic changes or mutations, mutation rates, and selection rates.
If Darwinian and neo-Darwinian theories are valid, then the assumptions used to produce the simulation should be consistent with or should ‘validate to’ known genetic characteristics. I claim that even a relatively rough attempt at creating such a simulation will clearly show that it is logically impossible to construct such a simulation using assumptions that will validate. Most obviously, mutation rates would have to be 1000’s possibly even millions of times greater than they are known to be in nature. Second, it seems likely that mutations would have to be highly focused or directed rather than random. Third, it seems likely that the simulation would have to assume the existence of a variety of non-Darwinian processes and mechanisms.
Almost everyone, scientists and academics included, seem to take it for granted that Darwinian and neo-Darwinian theories can explain and are compatible with the simple gradual adaptive change that can be produced artificially by selective breeding. I am suggesting that 1)it is relatively easy to test the validity of this widely accepted assumption, and 2)if you perform the test you will find Darwinian and neo-Darwinian theories fail. The issue or issues being raised here will not, IMO, be addressed by referring to the literature because the issues have not been addressed there.
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charlie d.
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posted 08. August 2002 13:50
Warren:
this is taking way too much time and effort.
Now, you seem to be agreeing that gross anatomical and physiological traits are often quantitative in nature, that such quantitative traits are largely genetic in origin, and hence heritable, that the underlying genetic variability can be ascribed to conventional mutations processes (aminoacid substitutions, changes in gene expression levels), and finally that such traits can be, and have been, selected, e.g. under artificial breeding conditions, to dramatically alter the phenotype of organisms, even in the span of a few hundreds to thousands generations.
Well, this is all Darwinian models ever need: variability, heritability, selection.
It is up to you, now, to provide details of your mathematical models, purportedly showing that darwinian evolution of quantitative traits cannot happen (while, for some reason, artificial evolution works!), so that an informed discussion can take place about their validity, if any. Otherwise, I, for one, will keep thinking you are pulling these anti-darwinian dogmatic statements out of thin air.
Personally, I'd love to see a "reasonably detailed" mathematical model of wing evolution, keeping track of the hundreds of genes likely involved in wing development and bird flight aerodynamics, their additive and epistatic interactions, their mutation rates, and the effects of selective forces in unknown environments over the course of millions of years. Excuse me if I am skeptical.
[Edit: I have pulled the "phantom" out, but I stand by my statement that in the absence of any verifiable support, which warren steadfastly refuses to provide in most of his threads, pronouncements like quote:
much, if not all, of the ‘positive evidence’ accumulated by Darwin and his successors in support of Darwinian theories has deteriorated as a result of our steadily increasing knowledge.
...
The rather obvious conclusion that ‘no one currently knows how to construct a Darwinian model or theory of evolution’ may be controversial in our pop culture but there is no reason why this conclusion should be controversial from a rigorous scientific perspective...
honestly amount to little more than trolling.
I have little interest, and less time to waste, in pursuing a specific discussion in a skewed situation in which abstract statements are repeated over and over as fact, and empirical evidence is ignored. I do feel however that references to the amount of actual data out there, and to the bona fide scientific work being done to address certain issues, may perhaps be of some use to interested readers.]
[ 09 August 2002, 12:26: Message edited by: charlie d. ]
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posted 09. August 2002 12:03
Charlie D. and Warren.
I understand Charlie D.'s desire to see Warren back up some of his Warren's claims regarding a mathematical analysis, etc. I also understand the natural tendency to turn to rhetoric such as 'phantom mathematical models’, and ‘anti-darwinian dogmatic statements’ to evoke a more detailed and sufficient response. However, I would like to provide the following warning:
charlie d., I would appreciate it if, in the future, you could resist the urge to make such demeaning remarks, and instead simply persist in your demand for more concrete details.
I have actively, in the past, tried to harness in the critics of Darwinism from an excess of rhetoric and would appreciate it if you could do the same.
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warren_bergerson
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posted 09. August 2002 16:00
I started this thread with the suggestion that evolutionary/adaptive changes (like the redesign of eagles wings to adapt to new environments), may not be compatible with Darwinian theory if we take into account current knowledge of genetics. I then suggested that this logical incompatibility, inconsistency, or incompleteness might be demonstrated by constructing simulation models. Reasonably enough, some doubts exist as to whether the proposed approach is practical and whether it will actually produce the predicted result.
Recognizing the difficulty of demonstrating incompatibility with all possible Darwinian theories, let me modify my initial proposal to "Simulation models will demonstrate that the adaptive redesign of eagles wings is compatible with a non-Darwinians model of evolutionary change".
To demonstrate that the proposed approach is workable, let’s consider a single variable in wing design such as length. In the hypothetical example, let us assume wing length changes to adapt to changes in the environment in which the eagle lives. For the sake of discussion, assume that the starting point wing length is denoted by L0 and the redesigned wing length is L10. Further assume that there exist intermediate wing lengths L1 to L9. Based on both selective breeding experiments and on analysis of the fossil record, it is reasonable to assume that some types of evolutionary change from L0 to L10 can involves steps or stages such as L0 changes to L1, then L1 changes to L2, …L9 changes to L10.
There are a large number of neo-Darwinian genetic models that might fit the pattern of change described above. The simplest would be a gene H which defines length and where H has different alleles associated with length L0, L1, ..,L10. As should be obvious, there are a lot of problems with this or any known model of gradual genetic change. The two most obvious are 1)how does the organism ‘direct mutations’ or that L2 produces the L3 mutation and not the L9 mutation and 2)how do you get mutation rates high enough to account for the rates of change that can be produced in selective breeding.
If you think about the problem for a while, you can probably find 100 ‘possible’ neo-Darwinian genetic models that might fit the gradual change process. Chances are good that all of them either 1)don’t work or 2)require the introduction of non-Darwinian processes and mechanisms. To my knowledge, no one has yet figured out how to simulate Darwinian gradualism using genetic assumptions that are realistic and compatible with neo-Darwinian theories. [I would be glad to see any suggestion on how to make such a model work.]
The above analysis suggests, at the very least, that we currently don’t know how to explain Darwinian gradualism in terms of neo-Darwinian genetic concepts. It is not therefore appropriate to suggest that gradual evolutionary change provides direct evidence for Darwinian theory. A reasonable conclusion, IMO. Such analysis doesn’t prove neo-Darwinian theory can’t work, but it demonstrates that gradualism does not, given current knowledge, provide positive evidence supporting Darwinian theory.
As I stated at the beginning, it is difficult and possibly impossible to prove that Darwinian and neo-Darwinian theory can’t explain evolutionary gradualism. It is, however, relatively easy to formulate a non-Darwinian ‘teleological’ model or theory which explains the phenomena.
To begin, as Charlie pointed out earlier, in many instances we know the mechanism that control at least some of continuous variables such as length. In simplistic terms, growth processes involve a start process, a grow process, and a stop process. Again in simplistic terms, the size of something can be changed by changing factor that triggers the stop process(or by changing the factor that triggers the start or by changing the rate of growth). In other words, size is controlled by some type of biological growth clock.
Given a biological growth clock, all that is needed to explain gradualism are mechanisms to add or delete units from the clock. Some individuals, under this assumption, are born with clocks for longer growth periods than their parents, some are born with clocks for shorter growth periods. Given appropriate environmental conditions, this add/delete mechanism would produce relatively rapid step by step change. If you want to get fancy, you could suggest mechanisms that control the speed and magnitude of the add/delete units mechanisms.
If the proposed mechanism exists( or is already known to exist), would its existence contradict Darwinian or neo-Darwinian theories. The existence of non-random or directed genetic changes (if in fact the clock is coded in genetic material) would seem to contradict the concept of ‘random mutation’. Supporters of Darwinian theory would have to decide for themselves if ‘directed or teleological evolutionary change’ is compatible with their theory.
The point or points of my original proposal were 1)it is possible to model/simulate relatively complex evolutionary phenomena such as the redesign or adaptive change in eagles wings, 2)such models suggest that (knowledge of genetics and knowledge of evolutionary processes) is not necessarily compatible with (Darwinian theory and neo-Darwinian genetic theory), and 3)the development of such simulation models can lead to the development of non-Darwinian models and theories. I believe I have at least outlined above, a demonstration of all three points. If any part of the above demonstration is unclear, I am more than willing to try to clarify it
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charlie d.
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posted 09. August 2002 20:05
Warren:
Let me focus on your mathematical model, and forget the rest. Basically, you are treating wing evolution as if the were the chance of random elongation of a bridge. That's not the way biology works.
The relevant variables in biology are things like number of involved genes, their mutation rate, frequency of beneficial alleles, selective advantage of beneficial mutations, effective population size (i.e. numbers of reproducing individuals in a population), etc etc.
The groundwork has been done already more than half a century ago. For instance, it can be calculated that if the population is large, the probability of an allele to completely take over the population ("fixation") is P=2s (about), with s the selective advantage. That is, for instance, a new mutation that gives a very small selective advantage, like 1% (i.e. carriers leave on average 1% more offspring than non-carriers), has a probability of spreading throughout the population of 2%. We also know that the number of generations required for fixation equals (2/s)ln(2N) generations (N is the effective population size). That is, if the population is large (10^6), an allele with 1% advantage will become fixed in just a couple thousands generations (to be honest, I am going by memory, you should re-check this).
To be clear, even with this knowledge neither you nor I can sit down and come up with a reasonable model of how something as complex as eagle wing evolution worked. No one can, for now. However, much mathematics has been put already into evolutionary modeling, and darwinian models have been shown to be effective in scores of examples, indeed to be rather efficient at picking up advantageous mutations. Developmental genetics has shown that multiple, defined, often quantitative molecular pathways effectively contribute to organ development. Quantitative genetics teaches us that most populations have large stores of genetic variability for complex phenotypic traits (due to genetic drift), which can have major contributions to phenotypic changes, if selection is applied: that's why artificial selection works so quickly and efficiently. There is really nothing insormountable, in principle, in eagle wing evolution, at least until we have all the necessary knowledge and the data to prove otherwise.
If you want to do some reading about the basics, I suggest you try some textbooks first, like Graur and Li's "Molecular Evolution" - short on math, but good on genetics (that's why I like it, I guess. ![[Wink]](wink.gif) )
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warren_bergerson
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posted 10. August 2002 16:12
Charlie,
I proposed yesterday what I characterize as a ‘non-Darwinian’, ‘teleological or directed’ model of wing design(more accurately of one feature of wing redesign). Your comments relate to the issue "Should, would, or can the academic/scientific community objectively evaluate this or any model which competes with Darwinian models and theories?" rather the specific merits of the model I proposed.
In addressing your comments let me first note I recognize you are expressing your personal opinions not necessarily those of some broader group. Second, it is generally recognized by most individuals involved in the various aspects of science that the rules of science require that alternative/competing models and theories be objectively compared and evaluated. Finally, although there will undoubtedly be a period of resistance, a theory of biological design which competes with Darwinian theories, will eventually be objectively evaluated, and if it passes testing/validation will eventually be accepted by the academic/scientific community. In the context of the above qualifiers, your comments reflect some of the arguments that can and have been used to ‘resist or reject the need for’ objective evaluation of design concepts, models, and theories.
Your first argument is in effect, your analysis shouldn’t be taken seriously because it is not in the format and using the variables we use. This is the issue of approaches, perspectives, and assumptions. Almost every innovative new solution to a problem is based on the use of new approaches, perspectives, and assumptions. It is a part of the nature of many individuals to doggedly argue that a particular approach, perspective or set of solutions should be used even though the individual has been able to solve the problem. Despite the passion these issues some times evoke, they generally are not difficult to overcome.
The second issue you raise relates to the difference between ‘fact and theory’. You present some notation which is part fact and part theory and you are not drawing a clear distinction between which is which. Much of the confusion in the popular discussion of evolution arises from failure to clearly distinguish what is fact and what is theory. This problem, IMO, should not normally arise in rigorous technical discussions.
The third issue, the complexity of mathematics, I find particularly interesting. In effect you are arguing my model can’t be valid because the math isn’t complex enough. Mathematics, as the mathematician are fond of saying, is a logically precise art form. Unfortunately, relatively few people really understand the different forms of mathematics and even fewer actually know how to work them. If, as I am doing, you introduce analysis based on somewhat unconventional mathematical modeling concepts and techniques you have an extremely small initial set of individuals with the technical skills to evaluate the approach.
Finally, you raise the ‘some expert has already done it’ argument. If to paraphrase, you want to introduce a new idea you should first find the three experts who already introduced the idea and get them to approve your idea as original.
I apologize if in the above discussion I have used phrases or expressions with inappropriate or offensive connotations(I did try to avoid them). Whether it was your intention or not, I think you have pointed out that the major roadblock to a fair and objective evaluation of design theory is the lack of individuals with the precise technical skills needed to perform evaluations. Science is a highly technical set of skills which individuals spend years learning. A new science and new scientific concepts require the highly technical sets of skills, but without the years available to learn them.
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charlie d.
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posted 10. August 2002 18:36
warren:
Let me clarify: your mathematics, as far as I am concerned, could even be of Nobel Prize level. It's just your biology that has no relationship with the real world.
Oh, and, from where I am standing, the major roadblock to a fair and objective evaluation of design theory is not the lack of individuals with the precise technical skills needed to perform evaluations, but in fact the dearth of individuals with the precise technical skills to put it into practice, who are seemingly interested in doing so, and the resulting complete absence of biologically meaningful work.
[ 10 August 2002, 19:39: Message edited by: charlie d. ]
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warren_bergerson
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posted 11. August 2002 05:02
Charlie,
Out of curiosity, what part of my biology to you see as unrealistic. Eagles?, Wings? Step by step changes in near continuous variables? Mechanisms that control growth? Evolutionary/adaptive redesign of wings? Can you actually provide a single example of where my biology has no relationship to the real world? You certainly leave the impression the you are making blanket accusations to cover your own lack of knowledge of biology.
The only area where I depart from traditional biological views is with respect to ‘random mutation and natural selection’ and the hypothesis that these mechanisms can account for the known occurrences of wing redesign. RM&NS is theory, hypothesis, conjecture not fact.
The biological reality that I have been pointing out is that 1)RM&NS has not, and apparently can not be reconciled to the known facts regarding the redesign of eagles wings, and 2)a ‘directed’ design model is consistent with known facts and is explainable in terms of likely physical mechanisms. Design theory, in the example being discussed, appears to describe biological reality. Neo-Darwinian genetic theory, it appears does not and can not describe biological reality.
No one expects that every individual involved in biology is going to be qualified to express an informed, intelligent, objective, supportable, scientific opinion on every subject. In science, one does expect individual to be a bit cautious about expressing opinions on topics on which they do not entirely qualified. If one doesn’t understand a comment or opinion one should ask questions. If someone expresses an opinion on a topic he should be willing and able to provide back up detail.
I have made and continue to make statements which are unconventional and which I expect are not fully understood by many readers. I will gladly attempt to clarify and support any of comments and opinions.
You make claims that "your biology has no relationship with the real world". You make such comments with the suggestion you have at least an elementary knowledge of science and biology. You should therefore be able to provide some substantiation for your comment.
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