Tautology and Natural Selection

Natural Selection1. Organisms produce more offspring than can survive
2. Organisms vary from one another in heritable ways
3. Some of heritable variations will affect and organisms ability to reproduce in a given environment
4. Variations which increase an organisms ability to reproduce viable offspring in a given environment will be passed on through the next generationSo basically this states that there is non-random survival in nature (not-including genetic drift).So if you deny this then you feel all organisms survive randomly, and that properties such as speed, coordination, and intelligence have nothing to do with reproductive success.The trouble comes in the Spencer's phrase "survival of the fittest".Some have said to drop the phrase altogether; that its tautologous, and not an accurate description of natural selection. I would like to, but it does seem (to me....I could be wrong)to describe natural selection accurately. Here's my interpretation (influenced by many authors)of it:No organism survives indefinately, so what survives? Lineages survive, more specifically lineages distinguished by a certain trait (compared to the ancestor lineage). So how can we define fitness? It would be nonsensical to say that fitness is defined by what increases a certain lineages survival, because the lineage would be different once a new heritable trait (that affects reproduction) emerges in it. So can fitness be defined as an organisms ability to leave a certain amount of viable offspring in a given environment?So the phrase now would be interpreted as "survival of the lineage with a certain trait that allows its members to leave the most offspring in a given environment"Is this all viable analysis?I've always had a bit of trouble resolving the tautological issue, so I'd like some input if anyone wouldn't mind.JustinCAlso, for the record I'm an Evolutionary Biology Major (sophomore).

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I believe that is exactly how it is currently defined. Fitness is a measure of the reproductive success of an individual

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If we changed "survival" to mean reproductive success, so that the phrase was "reproductive success of the fittest", would that still make sense? It seems to me that it would. But it would seem to become a tautology, since fitness is a measure of reproductive success.Bringing the subject down to the individual level, as opposed to lineages, how can we measure fitness? Can it be just from an engineering perspective, and some designs are a priori better suited for certain environments?So the phrase would be "reproductive success of the better engineered for a particular environment." This seems to make sense and seems how it is pragmatically used in evolutionary biology.I stated this definition to a pseudo-creationist friend of mine, and he asked "Why do the better engineered have reproductive success?" Is this a valid question? Does the best engineered just survive a priori? Should the answer be "Because they are best engineered to reproduce?" The phrase would now be "reproductive success of the best engineered for reproductive success." This seems tautologous, but is it?JustinC[This message has been edited by JustinCy, 07-21-2003]

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Natural selection is not a tautology, but it can be described in a way that makes it sound like circular reasoning. Yes, if 'fitness' refers to the ability to reproduce most effectively, then the fittest organisms in a population will indeed leave the most offspring. That's not saying anything about fitness.

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I understand that in most situations, the interaction between the environment and organism are too complex to make any accurate prediction about what is fit.But I'm talking about a theoretical framework for fitness. Can it be described as reproductive success? Or does there have to be an independent criterion for fitness not involving reproductive success, such as in engineering.I guess you can say that a replicating molecule has a purpose, which is to replicate. And then, from an engineerinig perspective, there is a best way to replicate in a given environment. And this way isn't arbitrary is it? Once something has a purpose, there is a best way to actuate that purpose isn't there? And since our purpose is reproductive success, the best engineered to reproductively succeed will reproductively succeed. Is this tautologous?Would the analogy be something like:"Easier pounding of the nail by the best hammer." The hammers purpose would be to pound in nails. And from an engineering perspective, there would be an absolute best way (multiple ways maybe) to pound in nails. So it's saying the best engineered to pound in nails will pound in nails easier. Does that make sense?So is it tautologous to say to say, "The best engineered to perform action x, will perform action x the best." It seems like a truism, but it also seems like it makes predictions. I mean, if I have 2 different hammers, I'd be able to know which one would be best engineered and pound in nails easier, right?I don't know, any thoughts?JustinCSorry if I sound like I'm rambling, i'm trying to work these ideas out in my head. I'm not saying anything definatively either, I'm just tentatively expressing some things.

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In contrast, the humble peacock carries plumage that no one would consider advantageous in the fitness equation except for the fact that peahens are attracted to it. An organism can be not-well-adapted to its environment and still win the reproductive lottery.

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But I would consider the peahens apart of the peacocks environment (am i using the term too loosely?). And if ones purpose is to reproduce, then they'd have to be a factor in the equation. So wouldn't the peacock with the flamboyent plumage be the best adapted to its environment?I'm not asking for an objective set of traits that make an organism fit. I understand that you can't say "speed" is a fit characteristic without reference to the environment. Couldn't you say that a walrus and cactus are fit because they are best engineered for reproductive success for their environments, factoring in their historical contingencies?I understand that natural selection isn't a tautology. Like I said before, you'd be denying that an organisms traits have anyting to do with reproduction. I just get into alot of these conversations with creationists, so I just wanted to see what other people think about it.

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If you want to make the charge of tautology even more acute, sure. In terms of susceptibility to predation, however, the peacock with the biggest plumage is at a disadvantage, regardless of its popularity with peahens.

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I'm not sure it makes it any more acute. I'm just saying that in certain environments, certain features aid in reproduction a priori. The environment would be everything in its surroundings.You defined fitness as 'having most reproductive success'. I might of missed this, but do you think "reproductive success of the fittest" would be an accurate description of Natural Selection?

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I don't actually think that 'survival of the fittest' as
a phrase is tautological unless you assume that the fittest
are the one's that survive -- rather than just treat the phrase
as a summary of an observation

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I'm not trying to be a dick here, I actually do know alot about evolutionary biology.But how can you define fitness without reference to reproductive success? If I say that a thick coat for a dog is fit in a cold environment, do I have to explain why? For instance, should I say it's fit because it increases reproductive success? So the phrase would read "Reproductive success of the organisms better equipped for reproductive sucess." Or is that not necessary?Or should fitness be purely decided from an engineering perspective of a problem. For example: Our goal is reproductive success, this organism lives in this environment, what can we do to help it out.If we can equate some purpose to life (not some ultimate purpose), then wouldn't some things follow a priori that would help it out. For example, a hammers purpose is to pound in nails, so if we modify a the hammer so it does this action with greater efficiency, how do we describe what we did to it? We made the hammer more efficient because we made the head heavier. Why does that make it better? Because it can pound in nails easier. So we have "Easier pounding of the nails by the hammer that can pound in nails the easiest." Can anything that acutates somethings purpose or makes it more efficient be stated as a tautology? Could the beauty of life be that it's autotelic? But is there a non trivial way to dichotomize things as purposeful or unpurposeful?Any thoughts?JustinC

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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.

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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.

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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]

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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]

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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.

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I dont' see how you can say that. 'Reproductive success of the fittest' seems like a valid description of natural selection. If fittest is reproductive success, then the phrase is a tautology. Shouldn't fitness be 'best engineered for reproductive success'?JustinC

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The problem is that it is an observation i.e. that some individuals or variants produce more offsrpring than others. The traits that allow this to occur confer a fitness advantage to the individual bearing them. The science is trying to identify the individuals in a population that contribute the most to the next generation and then determine which traits are providing the advantage in that environment.

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Agreed.

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One can of course make predictions that need not be so drastic as dropping a fish in a desert and seeing if it reproduces more or less than a gila monster. Here is an experiment in survivial of the fittest that I do almost every day...I often clone PCR products into a vector that then gets electroporated in bacteria competent to recieve said vector. The vector includes the gene for ampicilin resistance. Only a tiny fraction of the bacteria will take up the vector of the millions of bacteria electroporated. The selective force of their environment come when I plate them on an agar plate consisting of everything that makes bacteria grow happily plus a crap load of ampicilin...of the millions of bacteria that I plate, who has the selective advantage? what do you think I will see the next day on my plate? Will all the bacteria I plated grow equally?...the answer is that only the bacteria that took up my vector grow and form colonies on the plate because they can survive the antibiotic...survival of the fitest. There are natural examples of this as well rather than this experiment.

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Yes, i'm not arguing that survival of the fittest doesn't happen. I've actually done that experiment in my Biology lab (although we didn't prepare the vectors ourselves). You can make the prediction before hand because you are figuring out what is best engineered for reproductive success (ceteris paribus) in the ampicilin agar environment. There are features in environments that a priori are better for reproductive success. The same thing goes for any other object with a function. If one thinks that "survival of the fittest" is tautologous and unuseful, they'll have to concede that all of engineering is the same way.

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This is again why I don't like even using the word engineering in describing nature...all biological life wastes huge amounts of energy on all sorts of things that are unecessary..but merely get the job done. Oxidative phosphorylation is extremely sloppy i.e. we only use a small fraction of the potential energy from the food we eat. Most genomes are chock full of DNA that are relic retrotransposons..while some are biologically important, many are inert..yet they get copied (again a huge waste of energy) in every cell division...if engineering principles were used to guide (since I guess you are ultimately trying to argue intelligent design here) not a single life form would pass the muster regarding optimized design principles....

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If I was arguing optimally engineered for energy utilization, then I would see your point. But I'm just arguing better engineered for reproductive success.And let me clear things up, I am not arguing for intelligent design.
I've been reading books on evolution since I was 12, I am an Evolutionary Biology major, and I am an evolutionist/atheist.I understand natural selection, i'm just trying to figure out a better way to articulate it.

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what you see in nature is what left more offspring behind than something else for multiple reason from selection, to catastrophic climate change, to just plain random chance...much like my amp resistant bacteria and the catastrophic climate change of mean Mammuthus plating them on nasty antibiotic containing food.

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Agreed.EDIT: Has anyone read Elliot Sober's "The Nature of Selection"?[This message has been edited by JustinCy, 07-28-2003]