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starlarvae

starlarvae's thread hijack (from, "Does evolution follow the scientific method? If so, how?")

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MonDie    133

It's akin to circular reasoning, like in Plato's Euthyphro, where, in a nutshell, "piety" is defined as that which pleases the gods. OK, so how do we know which things please the gods? Obviously, it is those things which embody piety. Which is what? That which pleases the gods, of course. And so on.

 

Which traits contribute most to reproductive success (or "adaptation" or "fitness," etc.)? Those which are selected. OK, so how do we know which ones will be selected? Obviously, it is those traits that will contribute most to fitness. But which are those? They are the ones that get selected. And so on.

 

Please use quotes to delineate where the circularity occurred, or else don't insert circularity where there is none.

 

"Fitness" is that which is naturally selected.

 

"Natural selection" is (net) change in allele frequencies due to the interaction between individuals and their (natural) environment.

 

"Allele frequency" is a quantification of how often that allele occupies that locus in that population.

 

"Population" is a group of interbreeding individuals.

 

I can go on, but I cannot go on infinitely.

 

 

I don't see the difference between a stochastic event and a narrowly defined event. Most individual events are random, but the sum of their effects is nonrandom.

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Delta1212    894

It's akin to circular reasoning, like in Plato's Euthyphro, where, in a nutshell, "piety" is defined as that which pleases the gods. OK, so how do we know which things please the gods? Obviously, it is those things which embody piety. Which is what? That which pleases the gods, of course. And so on.

 

Which traits contribute most to reproductive success (or "adaptation" or "fitness," etc.)? Those which are selected. OK, so how do we know which ones will be selected? Obviously, it is those traits that will contribute most to fitness. But which are those? They are the ones that get selected. And so on.

It really boils down to the fact that evolutionary processes are dependent upon the fact that things which make more copies of themselves more frequently wind up with larger numbers of copies of themselves in a shorter period of time.

 

Which, yes, is trivially true.

 

Organisms have traits. A trait is literally any aspect of phenotype that you care to categorize ranging from hair color to having hair to number of limbs to the angle of curvature of the leftmost toenail of your right foot.

 

Some traits are more highly correlated with survival and reproduction than others. The more highly correlated with reproduction a trait is, the more likely that trait is to spread in a population.

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Strange    2479

To put it yet another way, there is variation within a population - this is trivially true by observation.

 

Much of this variation is heritable - this was known by selective breeders for millennia, quantified by Mendel, explained by genetics.

 

Some of these variants will have greater [or lesser] reproductive success than others for a variety of reasons - also true by observation. (This is the fact commonly known, for better or worse, as "natural selection".)

 

Therefore those variants will be come more [or less] common over time.

 

Given those facts, evolution must happen. It would take divine intervention to prevent it.

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starlarvae    11

 

Every trait it has, has been selected.

 

Really? Its bones are white. Why would white bones be selected over some other color? Same with the blood being red. Also, its heart makes a faint noise while it beats. Why was that noise selected, and not some other one? This list could go on and on.

 

EVERY trait has been selected, sayest thou. I think probably not.

 

 

Eventually the favourable traits (sorry, don't know what else to call them) will spread throughout the population and the less favourable ones will cease to exist. One individual crow with a poorly deformed beak might survive and reproduce (ie be selected) if food is plentiful. But no way is the trait going to survive long term.

 

The favorable traits will spread? How can you recognize a favorable trait EXCEPT by watching it spread? The traits that spread are the ones that spread. That's all. There's no need to attribute to them mystical properties, such as their being "favorable" or "adaptive."

 

The possessor of the deformed beak might just fly over to where the unique beak will enable it to exploit a new foodstuff, or attract a kinky mate. Look at all the beak variety among Darwin's finches. Which finch beaks are "deformed"?

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Ophiolite    1811

The favorable traits will spread? How can you recognize a favorable trait EXCEPT by watching it spread? The traits that spread are the ones that spread. That's all. There's no need to attribute to them mystical properties, such as their being "favorable" or "adaptive."

 

The possessor of the deformed beak might just fly over to where the unique beak will enable it to exploit a new foodstuff, or attract a kinky mate. Look at all the beak variety among Darwin's finches. Which finch beaks are "deformed"?

Your posts reveal, repeatedly, that you have learned the vocabulary of evolution, but have no understanding of its meaning.

 

A deformed beak is a rather useless term in this context. In some environments a specific beak shape may be advantageous, in other environments, deleterious, or neutral.

 

Contrary to your assertion we can certainly look at features and predict whether or not those features would be positive or negative in a given environment. If you searched the literature with an open mind you would find plenty of examples. (Don't ask me for citations: this evolution 101 and you claim to be passed that point. Do the work yourself.) The majority of the identification of desirable traits is post hoc, but that is because we live in a post hoc world, not because it impossible, as you assert.

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Strange    2479

Really? Its bones are white. Why would white bones be selected over some other color?

 

They are white because of the material they are made from, which is a product of millions of years of selection.

 

 

Same with the blood being red.

 

Ditto.

 

I'm tempted to ask what your alternative explanation is, but I suspect it is even more idiotic than creationism. So please keep it to yourself.

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starlarvae    11

 

You have overlooked the nature of selection pressure - it does not necessarily work first or directly on whatever aspect of a trait you have decided to label. White bones have been selected, first because they are easily available in the trait space as byproducts of selected strength and so forth, and then because any other color would incur a cost without a benefit. All the other colors would have been been selected against, in other words, as and when they occurred.

 

 

". . . . whatever aspect of a trait you have decided to label." Oh, brother. Here we go: What's qualifies as a "trait" and what qualifies as merely an "aspect" of a trait? You're just making it up as you go. Can you give me some logic, and not just a list of assertions? The fact that evolution occurred is plain from the fossil record. But the putative mechanism of natural selection is just plain incoherent.

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Essay    89

 

". . . . whatever aspect of a trait you have decided to label." Oh, brother. Here we go: What's qualifies as a "trait" and what qualifies as merely an "aspect" of a trait? You're just making it up as you go. Can you give me some logic, and not just a list of assertions? The fact that evolution occurred is plain from the fossil record. But the putative mechanism of natural selection is just plain incoherent.

 

Perhaps this quote will add some perspective on 'defining' a trait, or what qualifies as a trait. From:

– E. O. Wilson, from Chapter One (loc.71), The Meaning of Human Existence

 

Where Wilson is talking about the "the prevalence of some genes (more precisely alleles, variations in codes of the same gene) over others,"

Wilson describes that prevalence as, "the result of environmental forces, most of which are beyond human control or even understanding."

===

 

...my emphasis.

 

~

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starlarvae    11

Where Wilson is talking about the "the prevalence of some genes (more precisely alleles, variations in codes of the same gene) over others,"

Wilson describes that prevalence as, "the result of environmental forces, most of which are beyond human control or even understanding."

===

 

 

Gulp. Aren't you afraid you're giving ammo to . . . the . . . dreaded . . . Creationists !!?? >:D

 

If Wilson is right, then what's up with the theory of natural selection? Why is it so central to evolution theory? I suspect he's right, to a point. I'd like to know how he thinks epigenetics ultimately will re-cast evolution theory. Plus, in the light of evo-devo, phenotypes might have far less to do with endogenous (environmental) forces than with endogenous (physiological) forces.

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CharonY    1604

What Wilson refers to is the complexity of the elements and contrasts it with our potential ability at some point in the future to manipulate genes (or something to that extent).

Why is natural selection important? Because we know it exists and that it shapes allelic distributions. This can be demonstrated experimentally quite easily, although it is difficult in the field. Just because we cannot explain it completely for every populations does not mean that it is worthless. If that was the case we would ditch the concept of gravity as even as concept it is not completely understood (at least afaik).

 

With regards to physiolgy, that is a weird statement, as physiology does not happen in a vacuum. Our understanding of molecular physiology has sky-rocketed, yet the interplay with the environment has not kept up (as it is much harder to research), It is possible that this may have skewed your view a bit). However, one just need to look at the most prevalent organisms (i.e. bacteria) to see that it is certainly no the case. Environmental factors play a huge role in their genotype, which is much more fluid than in more complex organisms.

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starlarvae    11

OK I'll give you that one. "Now a rockslide kill 25 individuals, independent of their alleles." That does make it clear there was no selection advantage, but I'll be a Devil's Advocate and ask how was this determined that it was just random and independent in the first place?

Think of the Chicxulub Meteor it wiped out a high percentage but some animals survived.

 

But this exchange just highlights a problem with natural selection theory. There's no way to know if the survivors were cowardly and avoided precarious landscapes. Or if those killed were dumb and didn't sense the danger. You can make up all kinds of stories about why this one got killed and that one survived, about whether the event and its consequences for the gene pool were random or reflected some aspect of fitness. There's no way to know.

 

And yet, we keep talking about fitness, adaptation and such as shapers of phenotypes, when we can't tease apart any such considerations from the endless contingencies that bear on the kinds of situations we're interested in.

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MonDie    133

 

But this exchange just highlights a problem with natural selection theory. There's no way to know if the survivors were cowardly and avoided precarious landscapes. Or if those killed were dumb and didn't sense the danger. You can make up all kinds of stories about why this one got killed and that one survived, about whether the event and its consequences for the gene pool were random or reflected some aspect of fitness. There's no way to know.

 

And yet, we keep talking about fitness, adaptation and such as shapers of phenotypes, when we can't tease apart any such considerations from the endless contingencies that bear on the kinds of situations we're interested in.

 

This is not a unique problem.

 

https://en.wikipedia.org/wiki/Type_I_and_type_II_errors

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arc    296

 

Really? Its bones are white. Why would white bones be selected over some other color? Same with the blood being red. Also, its heart makes a faint noise while it beats. Why was that noise selected, and not some other one? This list could go on and on.

 

EVERY trait has been selected, sayest thou. I think probably not.

 

The favorable traits will spread? How can you recognize a favorable trait EXCEPT by watching it spread? The traits that spread are the ones that spread. That's all. There's no need to attribute to them mystical properties, such as their being "favorable" or "adaptive."

 

The possessor of the deformed beak might just fly over to where the unique beak will enable it to exploit a new foodstuff, or attract a kinky mate. Look at all the beak variety among Darwin's finches. Which finch beaks are "deformed"?

 

 

 

". . . . whatever aspect of a trait you have decided to label." Oh, brother. Here we go: What's qualifies as a "trait" and what qualifies as merely an "aspect" of a trait? You're just making it up as you go. Can you give me some logic, and not just a list of assertions? The fact that evolution occurred is plain from the fossil record. But the putative mechanism of natural selection is just plain incoherent.

 

 

 

But this exchange just highlights a problem with natural selection theory. There's no way to know if the survivors were cowardly and avoided precarious landscapes. Or if those killed were dumb and didn't sense the danger. You can make up all kinds of stories about why this one got killed and that one survived, about whether the event and its consequences for the gene pool were random or reflected some aspect of fitness. There's no way to know.

 

And yet, we keep talking about fitness, adaptation and such as shapers of phenotypes, when we can't tease apart any such considerations from the endless contingencies that bear on the kinds of situations we're interested in.

 

starlarvae, the methodology that natural selection operates by is not some obtuse convoluted idea from someone's imagination 150 years ago. It is at its most fundamental and basic form something that you do every day of your life. You probably own a car. Do you know why it has a motor instead of a horse tied to its front end? It is because the same methodology that selected changes in the evolution of life selected a motor over a horse for the locomotion of a car.

 

In the latter case the "selection" methodology utilized the unnatural mechanism of consumer choice, buyers preferred motors over horses. And then the "unnatural selection" mechanism continued on over the next century to choose starters over hand cranks, steel wheels over wood, electric lights over acetylene lights, and so on until today.

 

Why does life evolve?

 

It has no choice, you yourself make selections for not only what products consumers will have to choose from in the future but even what individual features or conveniences they will have, simply by buying something today. Every seemingly insignificant choice you make influences future events by increasingly greater significance the farther ahead that the observed selection projects.

 

The selection methodology forms the basis of modern societies. Their democracies, economies, cultural changes, educational systems and business practices all are mirrored on the natural selection methodology.

 

You are it and it is you. YOU CANNOT ESCAPE IT! ^_^

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starlarvae    11

If you don't know what "trait" means, or "aspect", look them up in the dictionary. I just write in English, using a simple vocabulary most native speakers of English should be familiar with. Do you deny the existence of traits? Aspects? If not, whatever you take them to be, in agreement with a decent dictionary, will do.

 

 

 

Nobody's having much trouble with the basics of it except you. The word "selection" is clear, right? - from a set, certain members continue and others don't, so that later on you have lost some members you used to have, the remainder is "selected". Is the word "natural" difficult for you to comprehend? It means anything following the laws of the physical universe but not directly constrained or caused by human beings.

 

So we start with a population, we don't do anything to it, and later notice that some kinds of members have disappeared while others become more common. Natural (we didn't do it) selection (some gone, some still in the population) has happened.

 

Yow. Don't get your undies in a bundle. The comment you quote goes back to my characterizing the whiteness of bones as a trait, and I was informed that the bones are a trait and the whiteness merely an aspect of that trait. Nothing in a dictionary is going to settle that indeterminacy of usage.

 

And your explanation of natural selection just makes the point I've made several times already -- namely, that natural selection is a superfluous concept and we can just drop it.

 

Because, what we actually observe is differential reproductive success and its consequences on the genotypes and phenotypes of succeeding generations. That's all you've said. Nobody's arguing with that.

 

The dispute enters when we try to explain the observation. Many people invoke something that they call "natural selection" to explain it. But, as your comments above illustrate, "natural selection" is just a synonym for differential reproductive success. So, all I'm doing is trying to be a good scientist and stick with what is empirically verifiable: differential reproductive success. Occam's razor cautions against inviting superfluous ingredients into our theorizing, which I think is sound advice. So, let's drop "natural selection".

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Arete    1152

 

Yow. Don't get your undies in a bundle. The comment you quote goes back to my characterizing the whiteness of bones as a trait, and I was informed that the bones are a trait and the whiteness merely an aspect of that trait. Nothing in a dictionary is going to settle that indeterminacy of usage.

 

And your explanation of natural selection just makes the point I've made several times already -- namely, that natural selection is a superfluous concept and we can just drop it.

 

Because, what we actually observe is differential reproductive success and its consequences on the genotypes and phenotypes of succeeding generations. That's all you've said. Nobody's arguing with that.

 

The dispute enters when we try to explain the observation. Many people invoke something that they call "natural selection" to explain it. But, as your comments above illustrate, "natural selection" is just a synonym for differential reproductive success. So, all I'm doing is trying to be a good scientist and stick with what is empirically verifiable: differential reproductive success. Occam's razor cautions against inviting superfluous ingredients into our theorizing, which I think is sound advice. So, let's drop "natural selection".

 

 

Except "differential reproductive success" is not what natural selection is. Selective forces are environmental conditions which lead to differential reproductive success. Therefore, natural selection describes the process by which environmental phenomena result in differential reproductive success within a population, and thus, evolution.

 

Natural selection is not superfluous - in fact it's one of the most observationally verified parameters of evolutionary theory.

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starlarvae    11

 

 

Except "differential reproductive success" is not what natural selection is. Selective forces are environmental conditions which lead to differential reproductive success. Therefore, natural selection describes the process by which environmental phenomena result in differential reproductive success within a population, and thus, evolution.

 

Natural selection is not superfluous - in fact it's one of the most observationally verified parameters of evolutionary theory.

 

Wrong. Differential reproductive success is observationally verifiable. You can count offspring. You can tally up their traits. You can do all kinds of statistical analyses on their genes.

 

But you cannot observe natural selection. The most you can do is observe differential reproductive success, and once you've observed it, then you can dance around chanting, "Natural selection."

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Arete    1152

Wrong

 

Nope, sorry. This is basic evolution 101. Your definitions are simply incorrect. Again, selection is the force which results in differential reproductive success. Measuring a change in allele frequency and comparing it to a null model is one of the ways of identifying the impacts of selection.

 

Analogously, you can measure a change in the speed of an object to infer the impact of wind resistance, however wide resistance is not a change in speed or vice-versa. One can cause the other, but they are distinct terms.

 

 

But you cannot observe natural selection.

 

 

Again, nope.

 

You can quantify selection - actually quantifying the force of selective pressure, and the genetic/phenotypic response to selection pressure is a significant area of study in evolutionary biology. To suggest that biologists simply hand wave about selection is to ignore decades of quantitative research.

 

e.g.

 

http://myxo.css.msu.edu/lenski/pdf/1997,%20Nature,%20Sniegowski%20et%20al.pdf

http://onlinelibrary.wiley.com/doi/10.1111/j.0014-3820.2003.tb00326.x/abstract

http://faculty.virginia.edu/brodie/files/publications/Brodie%20et%20al%2095%20TREE.pdf

http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000698

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022881

 

etc.

Edited by Arete
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starlarvae    11

 

Again, selection is the force which results in differential reproductive success. Measuring a change in allele frequency and comparing it to a null model is one of the ways of identifying the impacts of selection.

 

You can quantify selection - actually quantifying the force of selective pressure, and the genetic/phenotypic response to selection pressure is a significant area of study in evolutionary biology. To suggest that biologists simply hand wave about selection is to ignore decades of quantitative research.

 

Thanks for the links to references.

 

If selection is a quantifiable "force," and its unit of measure is a change in allele frequency, and the signifcance of that change is statistical (does it exceed or not some statistically defined threshold relative to the null hypothesis?), then the question remains as to cause and effect. The difference between natural selection and genetic drift rests on a statistical threshold. The assignment of causation (selection or drift) is done by convention (by defining statistical thresholds and seeing whether the thresholds are exceeded or not). Statistics is a descriptive tool, and useful for that. It can produce suggestive correlations. But causality is something else.

 

This is not a unique problem.

 

https://en.wikipedia.org/wiki/Type_I_and_type_II_errors

 

Quite.

Edited by starlarvae
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MonDie    133

I think starlarvae's shtick is that differential success actually arises from physiology and the interaction of sequences rather than the environment. Of course differential success must ultimately trace to genetics, or else it wouldn't be selection. Yet Starlarvae doesn't see the modifying-role of environment that has diversified life on Earth.

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starlarvae    11

I think starlarvae's shtick is that differential success actually arises from physiology and the interaction of sequences rather than the environment. Of course differential success must ultimately trace to genetics, or else it wouldn't be selection. Yet Starlarvae doesn't see the modifying-role of environment that has diversified life on Earth.

 

It's not clear how much "environment" should be credited with the diversity of life. Early photosynthesizers dramatically reconstituted the proportions of gases that composed the atmoshphere. Bacteria nucleate raindrops and fix nitrogen in the soil. Calcium sea shells help regulate the ph of the oceans. Beaver dams.

 

And so on. Creatures construct their niches, and those of neighbors and descendants, as much as they adapt to whatever situation they're born into.

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Ophiolite    1811

 

It's not clear how much "environment" should be credited with the diversity of life.

It is clear to me and, I believe, to several others posters in this thread. The difficulties of comprehension appear to lie with yourself.

 

Early photosynthesizers dramatically reconstituted the proportions of gases that composed the atmoshphere.

But their actions were wholly constrained by the physical and chemical properties of that atmosphere.

 

Bacteria nucleate raindrops and fix nitrogen in the soil.

If the environment lacked water vapour bacteria could not perform that function. If there were no nitrogen in the atmosphere there would be no opportunity for nitrogen fixing bacteria to evolve.

 

Calcium sea shells help regulate the ph of the oceans.

Which they could not do without oceans and oceans that contained sufficient dissolved calcium. The diversity of environment provided for the opportunity for a diversity of life.

 

Beaver dams.

Which are formed from trees, which are part of the natural environment. No one is claiming that life does not change the diversity of the environment, or that life is not part of the environment.

 

Creatures construct their niches, and those of neighbors and descendants, as much as they adapt to whatever situation they're born into.

Their creation of niches is wholly dependent upon the opportunities afforded by their environment and genetics.

 

You don't appear to be presenting a reasoned argument so much as farting into a headwind. What is your central thesis?

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Strange    2479

 

It's not clear how much "environment" should be credited with the diversity of life. Early photosynthesizers dramatically reconstituted the proportions of gases that composed the atmoshphere. Bacteria nucleate raindrops and fix nitrogen in the soil. Calcium sea shells help regulate the ph of the oceans. Beaver dams.

 

And so on. Creatures construct their niches, and those of neighbors and descendants, as much as they adapt to whatever situation they're born into.

 

So, life creates greater diversity of environments which drives greater diversity of life. What was your point again?

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starlarvae    11

 

So, life creates greater diversity of environments which drives greater diversity of life. What was your point again?

Right. Life creates a diversity of environments. The whole planet has been made over by the presence of life, made over to support diverse life. So, do environments select adapted organisms? Or do organisms select/create favorable environments? Do environments shape phenotypes, or do phenotypes shape environments?

 

It's a little artificial to say that environments "select" when environments themselves get made over to meet the needs of their inhabitants.

 

Anytime you interact with anything, I could say that that thing "selected" whatever behaviors your interaction with it consisted of. But that wouldn't tell us anything useful. Likewise, neither does the theory of natural selection tell us anything useful.

 

It is clear to me and, I believe, to several others posters in this thread. The difficulties of comprehension appear to lie with yourself.

 

But their actions were wholly constrained by the physical and chemical properties of that atmosphere.

 

If the environment lacked water vapour bacteria could not perform that function. If there were no nitrogen in the atmosphere there would be no opportunity for nitrogen fixing bacteria to evolve.

 

Which they could not do without oceans and oceans that contained sufficient dissolved calcium. The diversity of environment provided for the opportunity for a diversity of life.

 

Which are formed from trees, which are part of the natural environment. No one is claiming that life does not change the diversity of the environment, or that life is not part of the environment.

 

Their creation of niches is wholly dependent upon the opportunities afforded by their environment and genetics.

 

You don't appear to be presenting a reasoned argument so much as farting into a headwind. What is your central thesis?

 

Ok, how far back do you want to trace the causal chain? Organisms are able to do what they do only because the Earth is a certain distance from a sun of the requisite size, and that's possible because we're the right distance from galactic center. and so on. I suppose you could say that organisms are "adapted" to the mass of the proton. After all, look at how well the creatures operate in this world in which the mass of the proton is whatever it is.

 

Maybe we need to tackle the Anthropic Principle.

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Strange    2479

So, do environments select adapted organisms? Or do organisms select/create favorable environments? Do environments shape phenotypes, or do phenotypes shape environments?

 

Yes.

 

 

Likewise, neither does the theory of natural selection tell us anything useful.

 

what would you like it to tell you? It seems to be a remarkably successful theory.

Edited by Strange

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