Tautology and Natural Selection

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Which, of course, is why I prefer talking in terms of populations or communities rather than organisms

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Yeah, I agree. That's kindof like my first post where I mentioned lineages surviving. But I do feel one should be able to talk about individuals reproductive success and survival coherently.

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Fitness isn't defined in terms of reproductive success
(at least not in the weltenshaung that presents the
phrase 'survival of the fittest').
Fitness is about the ability to survive -- if you are better
able to survive you are more fit.

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When referring to individual organisms, I don't think it is enough to speak of survival, you also have to refer to fecundity. Taking them together you have reproductive success. I mean one organism can survive for 2 days and have many offspring, and another can live for 2 weeks and have much fewer.I'd say the phrase can be interpreted as "The best able to reproductively succeed more often reproductively succeed." And the "best" can be from an engineering perspective looking at a problem. That does seem tautologous, but I don't think it is.It would be like the rule "winning of the best player" in chess. Which is the best player, the one that wins? Not necessarily, it would be the one best able to play the game, and I think you can obtain which is best a priori. I say, he's the best because he knows the most opening theory, middle game strategy, and endgame positions. Someone will say, but why are those the best? And I'll say because they give him a better ability to win. So "winning of the player best able to win" would be the phrase.This is the kindof conversations I'm getting into with some creationist "friends". I think they just read some anti-evolution book and are throwing every argument they read at me.

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One cannot use the word 'purpose' unless there is an intelligent
intent behind a function/feature. That's what purpose means.

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Yeah, I understand that's how it is usually used. It does actually make more sense. I'm reading "Darwins Dangerous Idea" and he equivocates purpose with life, but it seems more like a redefinition of 'purpose'(which I think he admits).I was kindof just rambling in the last post. You're right that purpose shouldn't be used in context to life.[This message has been edited by JustinCy, 07-24-2003]

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I think in the dog example you should look at it as the dogs with the thicker coats have a higher chance of surviving to reproduce and therefore have a higher fitness

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I would say that "they have a higher chance of surviving and reproducing because they are fit", not that "they are fit because they have a higher chance of surviving a reproducing."I remember Stephen Jay Gould talking about this in "Darwin's Untimely Burial." I got it in a library database a while ago, but you might be able to find it online. I think he says I'm saying, presumably in a more coherent and entertaining style.

I would disagree...with Gould as well. The first construction you present, a higher chance of reproducing because they are fit, implies that the individual has somehow pre-adapted and can anticipate what would be fit which smacks of Lamarkism. The second construction does not as you don't know what the fitness of an individual is until it has reproduced i.e. you have one kid your fitness is 0.5...before that you have no way of knowing. That is why fitness is usually a population based measure rather than based on an individual...though it is possible to calculate fitness for an individual or lineage. Also, conditions can change within the lifetime of an organism so what might have conferred an advantage is a disadvantage..think of a new virus entering a population where a small subset of people have natural resistance and the overwhelming majority have a different genetic background at specific loci.I also don't like the engineering concept of adaptation. Nature works more by whatever gets the job done rather than maximizing the efficiency or optimizing function...you can have to piss poor vision systems competing in a population..the one that is less piss poor than the other will likely come to dominate if there is selective pressure for better vision...it does not mean that a good system will come to predominate. In addition, there are a lot of genes and traits that can be in conflict with one another i.e. an allele of a gene which promotes more accurate embryo development but downstream causes cancer with 45 for all individuals bearing the allele may spread throughout the population rapidly if it confers an advantage. Since the individual gets sick after their potential age of reproduction they still have a higher fitness. A lot of theoretical evolution of gerontology is focused on this concept that the tradeoff of aging and dying is a consequence of actually properly developing in the first place so that you can reproduce.cheers,
M

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When referring to individual organisms, I don't think it is enough to speak of survival, you also have to refer to fecundity. Taking them together you have reproductive success. I mean one organism can survive for 2 days and have many offspring, and another can live for 2 weeks and have much fewer.

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I've always thought of natural selection as a kind of
'survival filter', but if one individual within a population
was able to bear more young more often because of a heritable trait
I suppose that trait set would flourish even if survival rates
were low.

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I'd say the phrase can be interpreted as "The best able to reproductively succeed more often reproductively succeed." And the "best" can be from an engineering perspective looking at a problem. That does seem tautologous, but I don't think it is.

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I think we all agree that reproductive success is the measure of fitness. It's what conferred this fitness upon the organism/allele that your engineering perspective can discern.------------------
Quien busca, halla

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I would disagree...with Gould as well.

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As many do.

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The first construction you present, a higher chance of reproducing because they are fit, implies that the individual has somehow pre-adapted and can anticipate what would be fit which smacks of Lamarkism.

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I'm not sure it implies that. Can you go into that more?You're a dog, your warm climate relatively rapidly changes to a cold climate. The dogs with thicker coats lose less of their energy to the environment, and therefore can survive longer and reproduce more. I would say fit refers to traits of an organism, i.e. thicker coat. Reproductive success would be a result of that design. When you say pre-adapted, do you mean that the alleles are already present in the population, and certain organisms are just accumulating them?

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The second construction does not as you don't know what the fitness of an individual is until it has reproduced i.e. you have one kid your fitness is 0.5...before that you have no way of knowing.

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I think this is still consistent with the first construction. Practically, it probably isn't possible to know which traits are fit before reproduction, but in theory it should be possible. Cold climate, one dog thick coat and the other thin coat, ceteris paribus, the thick coat should be more fit.Survival and fecundity, I would say, are not traits of organisms. The traits should be what we refer to as fit. Seeing which has reproductive success is a good way to figure it out, though.

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Also, conditions can change within the lifetime of an organism so what might have conferred an advantage is a disadvantage..think of a new virus entering a population where a small subset of people have natural resistance and the overwhelming majority have a different genetic background at specific loci.

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I agree. Once the environment changes, the traits that are fit changes

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I also don't like the engineering concept of adaptation. Nature works more by whatever gets the job done rather than maximizing the efficiency or optimizing function...you can have to piss poor vision systems competing in a population..the one that is less piss poor than the other will likely come to dominate if there is selective pressure for better vision...it does not mean that a good system will come to predominate.

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I still think this is constistent with the engineering perspective. The thing to remember is that from the engineering perspective, there is not going to be some progress towards some perfect design. The best vision system can only be made in reference to the environment. So even though we may think of our vision being much better than a thin line of photorecepting cells, the only way to gauge this is to look at the organism in its environment.

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In addition, there are a lot of genes and traits that can be in conflict with one another i.e. an allele of a gene which promotes more accurate embryo development but downstream causes cancer with 45 for all individuals bearing the allele may spread throughout the population rapidly if it confers an advantage. Since the individual gets sick after their potential age of reproduction they still have a higher fitness. A lot of theoretical evolution of gerontology is focused on this concept that the tradeoff of aging and dying is a consequence of actually properly developing in the first place so that you can reproduce.

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I still think this is consistent. You would have to look at an organisms historical contingencies and its multiple functions to theoretically figure the fit.JustinC[This message has been edited by JustinCy, 07-24-2003]

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I think we all agree that reproductive success is the measure of fitness. It's what conferred this fitness upon the organism/allele that your engineering perspective can discern.

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I agree, you can measure what animal is more fit by reproductive success.

Hi Justin

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I'm not sure it implies that. Can you go into that more?
You're a dog, your warm climate relatively rapidly changes to a cold climate. The dogs with thicker coats lose less of their energy to the environment, and therefore can survive longer and reproduce more. I would say fit refers to traits of an organism, i.e. thicker coat. Reproductive success would be a result of that design. When you say pre-adapted, do you mean that the alleles are already present in the population, and certain organisms are just accumulating them?

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What I am implying is that a priori you don't know what is fit or not...the hairy dog's fitness in the cold environment is not known until it reproduces...and actually not until it is past the age where it can reproduce. Fitness ends up being a post hoc analysis since you are measuring the fitness of the previous effective population size i.e. those that have contributed to this generation. You can make calculations based on that to extrapolate what the fitness will be for the present generation and future generations under specific conditions...I am not trying to make a dumb semantics game out of this but I find fitness a fairly complicated and interesting concept that is widely misunderstood.In your thick hair dog example..lets say the extra nutritional requirements of having extra hair in a cold environment where food is limited confers a greater disadvantage to the individuals that have that trait than those that do not...from an engineerig perspective, that extra hair seems like a great idea..but in terms of fitness it could cause the trait to get wiped out. Thus I don't see engineering principles as a model for evolution.

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The traits should be what we refer to as fit.

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Again, I don't know how you can determine which traits are fit as we don't know a priori. If we look at a current population of say African elephants subspecies africana and subspecies cyclotis (the forest elephant) we make our determination of what traits confer fitness based on what we see as predominate traits in the population i.e. cyclotis are smaller and better adapted overall to foraging in dense forests as opposed to the larger savanah elephants...this is determined by looking at them now...the original population(s) that gave rise to the two subspecies would not have been clear how they would have adapted or what traits would be favored...what traits were more fit? We can say now because certain features dominate...but what about before the fact?

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I still think this is constistent with the engineering perspective. The thing to remember is that from the engineering perspective, there is not going to be some progress towards some perfect design. The best vision system can only be made in reference to the environment. So even though we may think of our vision being much better than a thin line of photorecepting cells, the only way to gauge this is to look at the organism in its environment.

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Actually, I disagree. The best vision system can only be made in reference to the other vision systems in the population or in whatever groups are competing i.e. species vs species, population vs. population. The environment is providing selective pressure on the groups with different traits. Again, from an engineering pespective, both vision systems could be absolutely lousy. However, if one is good enough to allow the individuals bearing the trait to survive and reproduce more than those with the even more crappy system, a less crappy but still very crappy system will come to dominate. If there is not further selective pressure on the trait, it will not likely spontaneously evolve into a really good vision system. Biological systems are hugely wasteful and inefficient...but, they got the job done better than their competitors and thus are pervasive...not because of better engineering per se.Hope this rather long post is in any way understandable..have not had enough coffee yet so I can't vouch for clarity cheers,
M

Wow -- de ja vu -- or however you spell it!!!!I have been having this exact discussion with mark24 in the free
for all.If you define fitness as reproductive success you are OK
so long as reproductive success encompasses reproductive output
and survivability.You cannot say that fitness causes reproductive success or
vice versa if on defines the other -- you would be saying
it's blue because it's colour is blue.If you define fitness in some survival oriented way
then fitness promotes reproductive success and is an after
the fact means of assessing fitness.reproductive success doesn't MAKE something fit, it's the
way that we can see the level of that fitness.

I guess I am being dense but I don't understand your last sentence at all.mark24 has done a great job explaining this (even if Symansu will never understand it).In any case, you seem to be saying fitness and reproduction are coupled on the one hand and then saying they cannot be coupled.fitness is not a cause.Simply put, if I produce 50 kids and they produce 50 each while you produce 2 kids who go on to produce 2 each..I have a higher relative fitness than you and my kids have a higher relative fitness than your kids. If there are traits that can be linked to this higher output, then those are the traits that contribute to the relative fitness advantage and have a selective advantage i.e. they are the traits that natural selection is selecting for. I don't have kids yet. I don't know about you. Assuming you do not either (for the sake of arguement in case you do have kids) at this point neither of us know how our relative fitness measure will turn out...and in terms of the population..we are not part of the effective population (Ne) and do not count towards a population based measure of fitness.

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What I am implying is that a priori you don't know what is fit or not...the hairy dog's fitness in the cold environment is not known until it reproduces...and actually not until it is past the age where it can reproduce.

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I would say natural selection is non-random reproductive success of organisms. Since it is non-random, then one should be able to determine, in theory, which organisms will have reproductive success before the fact. Right?

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Fitness ends up being a post hoc analysis since you are measuring the fitness of the previous effective population size i.e. those that have contributed to this generation.

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I would agree that the best way to determine which features are fit would be a post hoc analysis. But if fitness is defined by the post hoc analysis, then I think that only strengthens the claim of tautology, i.e survivors survive.

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I find fitness a fairly complicated and interesting concept that is widely misunderstood.

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I agree, I think the subject is alot more interesting then people suppose.In your criticism of my dog example, I think you miss the point. The perfect engineer would have to examine the nutritional requirements, and every other aspect of the organism. From this it should be possible to determine which animal will have the most reproductive success, barring genetic drift.I'm saying the phrase should be, "The probable reproductive success of the best able to reproductively succeed." It should be possible to determine the best able to reproductively succeed before hand. Industrial melanism would be an example. If one knew before hand all the information about the environment, it seems it would be possible to determine the peppered moth population frequency shift.

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Again, I don't know how you can determine which traits are fit as we don't know a priori. If we look at a current population of say African elephants subspecies africana and subspecies cyclotis (the forest elephant) we make our determination of what traits confer fitness based on what we see as predominate traits in the population i.e. cyclotis are smaller and better adapted overall to foraging in dense forests as opposed to the larger savanah elephants...this is determined by looking at them now...the original population(s) that gave rise to the two subspecies would not have been clear how they would have adapted or what traits would be favored...what traits were more fit? We can say now because certain features dominate...but what about before the fact?

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Again, it may not be practically possible to determine what traits are fit due to the extreme complexity of interactions within the organism and the organism to its environment. But it seems like it should logically be possible to determine what traits are more fit.This may an absurd example (maybe erroneous, you can correct me). Say I drop a Gila monster(desert lizard) and any fish in the desert, would I not be able to figure out a priori which which reproductively succeed before the fact?

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Actually, I disagree. The best vision system can only be made in reference to the other vision systems in the population or in whatever groups are competing i.e. species vs species, population vs. population. The environment is providing selective pressure on the groups with different traits.

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I don't know if I can agree with that. The optimal optical(Poet and didn't even know it) system would be made in reference to the interactions with the environment and within the organism. How would comparing two different systems to each other determine which is best unless there is a reference to how they function in the environment.

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Again, from an engineering pespective, both vision systems could be absolutely lousy. However, if one is good enough to allow the individuals bearing the trait to survive and reproduce more than those with the even more crappy system, a less crappy but still very crappy system will come to dominate. If there is not further selective pressure on the trait, it will not likely spontaneously evolve into a really good vision system. Biological systems are hugely wasteful and inefficient...but, they got the job done better than their competitors and thus are pervasive...not because of better engineering per se

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You do not need a non-lousy system from the engineering perspective. Like you said, only the system less crappy would survive. But how can we determine which is less crappy? I think it should be possible theoretically to determine which is the best design for reproductive success before hand.Maybe this may clarify something. I'm not saying best engineered vision system, best engineered energy utilization system, or anything like that. I'm saying best engineered to reproductively succeed.JustinC[This message has been edited by JustinCy, 07-25-2003]

Peter, Fitness & reproductive success are one & the same, they are equal, neither is measured by the other. I boobed when I said (words to the effect of) fitness is a measure of rs, poor English on my part.Mark------------------
Occam's razor is not for shaving with.

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I would say natural selection is non-random reproductive success of organisms. Since it is non-random, then one should be able to determine, in theory, which organisms will have reproductive success before the fact. Right?

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In a perfect world, we could get very close. We'd have to have perfect knowledge of every relevant variable-- weather patterns, etc. Needless to say, we have nowhere near that level of knowledge. Then, we'd have to restrict the prediction to the few generations only. If we reach too far into the future the system will change and what was adaptive ceases to be so. An animal adapted to ice, wouldn't do well where I live.

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But if fitness is defined by the post hoc analysis, then I think that only strengthens the claim of tautology, i.e survivors survive.

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hmmmm.... survivors DO survive. It is a tautology. Not all tautology is fallacious. Here is a tautology for you. 1 = 1. Tautology? Yup. Fallacious? You tell me.A fallacious tautology is a form of argument where one draws a conclusion which is assumed in the premises. The key is that it must be an ARGUMENT. Axioms-- such as that of identity ( 1 = 1 )-- and observations-- that critter died, that one didn't-- don't count. They AREN'T arguments.Back to the topic. It is hard to argue with the idea that the survivors did in fact survive. By definition, if you survive you are a survivor. It isn't an argument, but an observation. The question then becomes, "Why did these survivors survive, and the other animals did not?" The answer is that each individual animal is slightly different than any other, and these slight differences give some animals an edge.

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But it seems like it should logically be possible to determine what traits are more fit.

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With perfect knowledge and in relation to a particular environment, perhaps so. Notice this is relative fitness, not absolute. In your fish/gila monster example, you drop both into a desert. The gila monster wins. But a hundred thousand years later, the desert floods. Suddenly the gila monster's 'good' adaptations are no longer all that good.

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I don't know if I can agree with that. The optimal optical(Poet and didn't even know it) system would be made in reference to the interactions with the environment and within the organism. How would comparing two different systems to each other determine which is best unless there is a reference to how they function in the environment.

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It doesn't matter how well one can see, if everything else is blind. You can have 1% of 20/20 vision and be king of the hill if everything else has no eyes.------------------
No webpage found at provided URL: www.hells-handmaiden.com

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In a perfect world, we could get very close. We'd have to have perfect knowledge of every relevant variable-- weather patterns, etc. Needless to say, we have nowhere near that level of knowledge. Then, we'd have to restrict the prediction to the few generations only. If we reach too far into the future the system will change and what was adaptive ceases to be so. An animal adapted to ice, wouldn't do well where I live.

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I'm not saying that we are ever going to get enough information to make accurate predictions. I'm saying in principle, it's possible. I don't disagree at all.

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hmmmm.... survivors DO survive. It is a tautology. Not all tautology is fallacious. Here is a tautology for you. 1 = 1. Tautology? Yup. Fallacious? You tell me.

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Whose arguing tautologies are fallacious? I'm not. But tautologies do not make predictions and are not scientific statements. I'm saying if "survival of the fittest" is defined by a post hoc analysis, you get "survivors survive". That isn't a scientific statement, it's an empty statement. Saying "Survivors survive" doesn't give any clue as to the direction of evolution. The statement would be true under any scenerio, i.e. if all organisms survive randomly.

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Back to the topic. It is hard to argue with the idea that the survivors did in fact survive. By definition, if you survive you are a survivor. It isn't an argument, but an observation. The question then becomes, "Why did these survivors survive, and the other animals did not?" The answer is that each individual animal is slightly different than any other, and these slight differences give some animals an edge.

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I wouldn't even say its an observation, it's a logical necessity. It's good for a definition, but not good for science. The second part should be how we define fitness. It should be the traits of the organism that help in reproductive success.

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With perfect knowledge and in relation to a particular environment, perhaps so. Notice this is relative fitness, not absolute. In your fish/gila monster example, you drop both into a desert. The gila monster wins. But a hundred thousand years later, the desert floods. Suddenly the gila monster's 'good' adaptations are no longer all that good.

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Again, I'm not arguing with the first part about perfect knowledge. I'm not even arguing with the second part, if by relative fitness you are saying that fitness is relative the environment. Where did I say it wasn't? Where did I say that if the environment changes the Gila monster will still be the fittest? I'm showing that it is possible to make predictions not based on post hoc analysis. Other scenerios are going to be much more complex and being able to make predictions will be much more difficult, if not practically impossible. So the best way is by using a post hoc analysis.

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It doesn't matter how well one can see, if everything else is blind. You can have 1% of 20/20 vision and be king of the hill if everything else has no eyes.

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Again, I don't disagree with this, except that you have to make a reference to the environment. Did you read my posts? I would say that if an optical system is good for reproductive success, it does matter how well one can see. In your scenerio, can't the organism with 1 percent 20/20 see better than the blind one?Also, in that case where you live in a complete darkness, you are just wasting resources developing organs which have no use. You have to have a reference to the environment.JustinC[This message has been edited by JustinCy, 07-26-2003]