natural selection?

[darryl]

http://evolution.berkeley.edu/evolibrary/article/evo_25

This is a very useful link, and after looking at that, there is no way that people can deny that natural selection occurs.

Natural Selection is no more susceptible to disproof than any any other tenet of science. The question is why the focus on this. The answer is obvious. Because it offends fundamentalism. As I said before, why are the fundies not challenging Newton or Galileo? You haven't connected that part of what I said with your opinion that I think science is static.

Aqueous I am not with these fundamentalists or think like them, but the reason comes down to evolution, religious texts are in opposition to it, not what Newton or Galileo said. My problem is not with evolution, I accept it, my problem is with natural selection. I admit I do not believe natural selection has anything to do with evolution, perhaps I can do another thread at some point and discuss this, I do not deny that it occurs, I just think evolution is driven by a more important mechanism.

I am saying that whatever the best evidence reveals, that is where you find science,

I fully agree with that, but when it comes to natural selection I have read 100s of books, studied the topic in depth etc, I see no direct evidence for ns driving evolution.

You haven't said why you think that day will ever come, or - if you're hoping it will - why.

I believe there is already evidence do downplay ns as an evolutionary mechanism, I can discuss that in another thread when I sort myself out and try and get together some kind of case.

Do you think Galileo, or Bruno, or any of the other victims of witch hunts would approve of calling "science" dogmatic? Why the hyperbole?

I do not think science is dogmatic only natural selection. I can talk about this in another thread at some point, but right now I am still trying to ponder on how natural selection can be falsified.

 

[rpenner]

For natural selection to be falsified in a model system, a system must exist where it does not work. For example, natural selection does not work in crystals or stars because these do not have heritable variation.

If the pagan concept of fixity of species were true (it dates back to Plato's essentialism that all Beech Trees were shadows of the eternal Platonic ideal of a Beech Tree rather than accepting that Beech Tree is a convenient label for a population of individuals in the here-and-now and is subject to a shift in meaning if we use it to describe trees from 1500 years ago), then the universe would falsify natural selection.

Basically, to actually falsify natural selection you need evidence that it is not actually at work when heritable variation leads to statistically strong expectations of differential reproductive success. If some goddess of fate actually chose who lived and died based on some other criteria or whim, then evidence of that mechanism would largely falsify Darwin's idea of Natural Selection.

But because we have strong evidence that natural law is not capricious or biased against individuals, it is unlikely that the mathematical model of differential reproductive success based on heritable variation has a counter example in this universe.

Popper's test of falsification does not require any scientific theories to be actually falsifiable in this universe, only that we can conceive of universes where they are not the case and testing would demonstrate this. In this way, Newtonian physics, Maxwell's Equations and Special Relativity have been falsified in certain experimental domains. Quantum Field Theory, General Relativity, and Evolution by means of Natural Selection have better track records.

 

[gmilam]

I fully agree with that, but when it comes to natural selection I have read 100s of books, studied the topic in depth etc, I see no direct evidence for ns driving evolution.

What do you mean "driving evolution"?

Evolution is basically the observation that things change over time.

Natural selection is based on the observation that some changes are undesirable and the organism dies before it spreads it's mutation to the next generation. Seems fairly obvious to me. :shrug:

 

[Buckaroo Banzai]

Definition of natural selection:



The geneticist Waddington commented that natural selection "states that the fittest individuals in a population (defined as those which leave the most offspring) will leave the most offspring".

In other words the "fittest" survive whilst the "unfit" die out. The debate from critics of natural selection, is how can we define the "fittest".

It's even arguable whether there are real, legitimate "critics of natural selection" that are not either just making some emphasis against a naive hyper-adaptationist/selectionist view. And creationists or the like, who don't really fit on "critics of natural selection" anymore than flat-earthers fit on "critics of plate tectonics".

This whole "problem" is akin to some people arguing about the "problem of light" after some unfortunate physicist having made a statement such as that the theory of optics "states that the lightened spots (defined as the spots that receive light) will be charged with more photons", cynically posing the pseudo-problem of how can we define "light".

The reality of nature is not on hold until we come up with the definitions or different wordings that would satisfy creationists or whoever. What happens is that there are different inheritable variations that will give its bearers different odds at reproducing , which changes the frequencies of these traits along the generations and environments. This happens, it's empirically verified in the wild.

I think that this wording already escapes the supposedly problematic situation of a tautology or whatever. The "fittest" are those who reproduce the most or perhaps specifically those who reproduce the most due to having a particular inheritable trait -- depending of how you prefer, or how it seems more proper to analyse/model a certain question. Natural selection is just that "this happens", one does not need to phrase it in such pseudo-problematic way.

Edward Drinker Cope the great American palaeontologist wanted to know what the origin of the fittest was. This is still the trouble.

Robert Broom wrote that "Natural selection certainly eliminates the unfit and establishes the fit, but in my opinion it has nothing whatever to do with the creation of the fit".

What he means here is simply that inheritable variation comes before natural selection, even though perhaps he may be underestimating the effect of cumulative selection.

So for natural selection to be falsified there needs to be some examples of where "unfit" or "less adapted" organisms are not eliminated but instead are indeed surviving and transmitting their genetic characteristics to suceeding generations? Correct?

Not quite. That would refute only a particular hypothetical particular of natural selection, not natural selection in general, or a rather naive view of natural selection as a omnipresent and omnipotent force. Just like showing that sheep don't eat rabbits does not refute predation.


There's no way natural selection could be falsified "as a whole", it's simply absurd, it's more or less like wondering what would be required to falsify friction, or planetary orbits, or parasitism. You simply can't, you can only test particular situations to see how much they satisfy certain criteria. With natural selection what can be done is only to assess (or try to) if certain instances/particulars of natural selection are happening, like finches of different beak sizes having different survival and reproduction odds and whether it affects the frequencies of such traits in the following generations. Other sort of "test" would be regarding some traits that already evolved a long time ago, what were the "selective forces" specifically, or even whether some traits evolved mainly in a "classic" gradual process of natural selection, or if there were more relevant contributions of random, not-that-gradual mutations. And that's it. There's no way to have things much more different than that and still be realistic.

 

[Buckaroo Banzai]

Originally Posted by Rhaedas
Fossilized rabbits in the Jurassic layers.

I think this is an example of how evolution can be falsified not natural selection.

Not if we posit time-travelling rabbits

 

[darryl]

There's no way natural selection could be falsified "as a whole",

I am still looking into that. But let me make it clear, no one has any argument with natural selection as such, nobody denies that it occurs. But to claim "nature selects the fittest" is far from explaining where the "fittest" come from. It is remarkable that Darwin failed to notice the truth in the converse of what he said; the catastrophes that end lives - drought, flood, starvation, plague - are non-selective. The so called "strong" are struck down with the "weak". Is the blackbird's early worm less fit?

It has been shown that by night-time photography, lions do not seek out the smallest weakest buffalo. They may take fully adult males. Nor does a predator overkill or extinguish its prey becuase, if it did, it would die itself. Also if there was no mutant prey, it would catch fit prey.

Mutants are either left to die at birth of from such a small proportion as to make natural selection completely meaningless. This just shows that all forms that continue to survive (both the apparently "weak" and vulnerable) have the same survival value.

It appears that natural selection is all a matter of personal perspective. I have seen no evidence that it is evolutionary.

 

[wellwisher]

Here is a new angle that came to me. Consider a mother animal fiercely protecting her young. Is this natural selection based on age? Rather than select herself, she places herself at risk to protect the child.

This is not about a selfish gene, since her child only contain half her genes and she contains 100%. Nor is there any certainty that her child will be more worth selecting than herself; the child may not be as good a specimen in the final analysis, under normal natural selection.

All and all it appears this behavior broadly selects the future over the past, because over time the natural selection progresses?

 

[Buckaroo Banzai]

Protecting the offspring is a "selfish gene" thing, it's probably even some textbook example. It's individual sacrifice for genetic reproduction, the genes being "selfish", "not caring" for the good of the individual.

The notion does not predict that an individual will always favor himself for having "100% of his own genes" over the offspring that has only 50% as if the behavior were a result of a democratic decision of the 100% of the genes in the progenitor who prefer to save "themselves".

It boils down to, in some cases, depending on parameters such as longevity, richness or scarcity of environmental resources, typical number of spring, progenitors who protect their offspring even putting themselves at risk or sacrificing themselves, will leave more offspring in the long term than those who don't. Then the behavior is passed on. It does not depend on a perfect assessment from the individual, it's just the safest bet, as it is the one that was selected over time. With different parameters, the extreme opposite would be the safest bet, and with intermediate parameters the selected behavior would be more complex and somewhere in between. And here I'm not suggesting that as the parameters change, the species will always adapt, with the alternative behaviors being selected in whatever degree is the most suited. As the parameters change, there's always the possibility that the adaptation will not accompany it and it will become maladaptive, leading to extinction.

It has something to do with "the future over past" though, because those who "don't care for the future" won't have offspring in the future perpetuating this behavior.

 

[Buckaroo Banzai]

I am still looking into that. But let me make it clear, no one has any argument with natural selection as such, nobody denies that it occurs. But to claim "nature selects the fittest" is far from explaining where the "fittest" come from.

What even "would be" explaining where the fittest comes from?

"Fittest" can be seen as the ones who reproduce the most by virtue of both conditioning and genetically inheritable traits, or specifically of genetically inheritable traits, depending on what you want to model/study. It certainly won't be any sort of "universal" trait that will determine fitness, it will vary immensely depending on the environment and the species.

It is remarkable that Darwin failed to notice the truth in the converse of what he said; the catastrophes that end lives - drought, flood, starvation, plague - are non-selective. The so called "strong" are struck down with the "weak". Is the blackbird's early worm less fit?

I don't believe Darwin thought that all death or reproductive advantage were selective, or that the less fit would all be ultimately wiped out. Even if he did, this is not a position held by current biology, and it does not affect the status of natural selection which does not depend on these assumptions to have the effect of being the main "driver" of adaptive change.

It has been shown that by night-time photography, lions do not seek out the smallest weakest buffalo. They may take fully adult males. Nor does a predator overkill or extinguish its prey becuase, if it did, it would die itself. Also if there was no mutant prey, it would catch fit prey.

No one believes that the organisms are all purposefully engaged in selecting out the unfit, natural selection is not nature's "goal", not anymore than erosion is wind's goal, which does not negate erosion as there are observed instances of sub-optimal erosion. It's just "something that happens". Not something that happens all the time, perfectly, without "noise", but that does not mean that it's all random and that all individuals have the same odds of reproducing or dying regardless of their physical constitution, with only a few exceptional and meaningless correlations in this regard.



And sometimes predators do overkill and extinguish their prey, and/or competitors on the same niche.

Mutants are either left to die at birth of from such a small proportion as to make natural selection completely meaningless. This just shows that all forms that continue to survive (both the apparently "weak" and vulnerable) have the same survival value.

You're equating "mutants" with "deleterious mutants", when the view is that we are all mutants, and that all the extant genetic variation -- between and within species -- ultimately arose from mutations. You're also missing one of the key observations leading to the theorizing of natural selection (but perhaps by Wallace, not Darwin). The offspring is often more numerous than the population that effectively reproduces, and the difference is not constituted only by "failed mutants that die at birth", but mostly by individuals that were perfectly healthy. Sometimes, not always, there are inheritable differences in some traits making a difference. It won't change a species in a single generation, but the effect adds up over the generations.

It appears that natural selection is all a matter of personal perspective. I have seen no evidence that it is evolutionary.

What would constitute such evidence, in your opinion? And how exactly would it be limited? Like "ok, it's possible that natural selection drove a divergence between species like wolves and coyotes, but natural selection couldn't have driven the evolution of cheetahs from a cougar-like ancestor or the evolution of humming birds from a swift-like ancestor, because [...]".

 

[Buckaroo Banzai]

An interesting summary (I'm quoting just the conclusion but there's more) I've found while trying to search for some Darwin quote that implied that he didn't view natural selection as omnipresent and omnipotent:

[...] Conclusion

The common conception of evolution focuses on change due to natural selection. Natural selection is certainly an important mechanism of allele-frequency change, and it is the only mechanism that generates adaptation of organisms to their environments. Other mechanisms, however, can also change allele frequencies, often in ways that oppose the influence of selection. A nuanced understanding of evolution demands that we consider such mechanisms as genetic drift and gene flow, and that we recognize the error in assuming that selection will always drive populations toward the most well adapted state.

http://www.nature.com/scitable/know...election-genetic-drift-and-gene-flow-15186648

 

[Aqueous Id]

Yes I think Galileo, or Bruno, or any of the other victims of witch hunts would approve of calling "science" dogmatic, because those are the best scientists of their era and they really did a lot of searches in their specific fields.

I think this is a reference to my post #20.

In those days Honora they didn't really have fields. These two men were trying to help explain the solar system. One of Bruno's offenses against the Church was that he believed the Sun was a star and that there were other worlds that circled other stars. He allowed that they might be inhabited, so that violated the dogma of the Church. Galileo was trying to understand epicycles, which are loops that some of the "stars" were known to circle in their larger movements. Galileo found out that they were not stars at all, but moons of Jupiter. This he discovered after inventing his telescope. At the time, the Church was trying to protect the literal interpretation of Genesis, which both men were proving untrue.

The question is: when scientists make discoveries like Galileo did, or when they develop correct theories, like Bruno did, are they to be dismissed as "dogmatic"? In the case of evolution by natural selection, the teaching is developed around such a vast array of evidence, from so many fields, that it has become one of the most universally adopted principles of science.

How is that dogma? My point was: wouldn't the men who suffered severe punishments under an actual dogma (i.e. that Genesis is the literal truth)--wouldn't they stand up for science, and wouldn't they resent the way "dogma" is being used here to attack science?

 

[Fraggle Rocker]

Yes I think Galileo, or Bruno, or any of the other victims of witch hunts would approve of calling "science" dogmatic, because those are the best scientists of their era and they really did a lot of searches in their specific fields.

That may have been true in their day, but today the meaning of "dogma" has narrowed. Its basic meaning is a code, doctrine, etc., that lacks adequate supporting evidence and because of this is enforced by sheer authority. Its primary use is in (usually critical) discussions of religion and, by extension, to any field in which the Fallacy of Argument from Authority is used to stifle dissent.

Obviously the word is thrown around in the discussion of scientific endeavors. In any human activity there are bound to be people with so much at stake that they'll bend the rules to get their way. "Corporate science" immediately comes to mind because rather than testing hypotheses until they find the correct one, corporate scientists search for evidence that supports the hypothesis that the corporation's product is what we all need. Nazi and Soviet science also fall into the same category.

But to call all of science "dogma" is to completely reject the scientific method. It would be claiming that its rules of empirical evidence, logical reasoning, experimentation, peer review, etc., simply don't work. Either that, or that those rules are simply not followed and that literally everybody is in on the scam.

 

[iceaura]

I fully agree with that, but when it comes to natural selection I have read 100s of books, studied the topic in depth etc, I see no direct evidence for ns driving evolution.

That is the wrong question.

Clearly if some variations are inherited (observed fact), and natural selection among them occurs (likewise an observed fact), then evolutionary change is all but inevitable on grounds of chance alone - for the same reason that random walks lead away from the starting point, on average.

Nothing about "fitness" needs to be invoked. We can assume natural selection by meteor strike, if we want to. "Fitness" considerations merely enlighten us about the most likely selection mechanisms, and explain the patterns in the evolutionary lineages we see all around us.

The question would be: if natural selection has not driven evolutionary change, what prevented it?

 

[quadraphonics]

for the same reason that random walks lead away from the starting point, on average.

Er... your standard, vanilla random walks end up exactly at the starting point, on average. Maybe you meant something different or more specific? I don't think the usual (symmetric) random walk is a good model for a "selection," since it has no preference for any one direction over another.

Or maybe invoke high-dimensional random walks, wherein the probability of returning to the starting points goes down with increasing dimensionality?

 

[darryl]

Ok some interesting posts here and when I get the time I will respond to some of the comments, but going back to the OP very briefly I recently sent some emails out to some biologists and some admitted that natural selection is a tautology to me, others no opinion on it. Theres also a 12 page critique of natural selection written by the biologist Stanley Salthe which can be found here:

http://www.nbi.dk/~natphil/salthe/Critique_of_Natural_Select_.pdf

Has anyone read it?

 

[Aqueous Id]

Ok some interesting posts here and when I get the time I will respond to some of the comments, but going back to the OP very briefly I recently sent some emails out to some biologists and some admitted that natural selection is a tautology to me, others no opinion on it. Theres also a 12 page critique of natural selection written by the biologist Stanley Salthe which can be found here:

http://www.nbi.dk/~natphil/salthe/Critique_of_Natural_Select_.pdf

Has anyone read it?

Yes. Again, you have an essay, not anything substantive.

Here is an example of how Salthe furnishes opinion to reach a conclusion:

Here we find an estimate that about 1547 human genes have evolved adaptively in 5,000,000 years. That would be (given a generation time of somewhat less than 20 years), say, 1547 selectively mediated genetic changes per 300,000 generations.That would be about 0.005 such changes per generation, or about 1 adaptive change in about 200 generations -- rather slow to be associated with such large phenotypic changes! And humans are supposed to have evolved especially rapidly, with smallish population sizes! With rates like this in such populations, it would seem that we can reasonably visualize selection on only one or two genes mediating all of adaptive evolution.​

This is a typical fallacy in every kind reasoning that appeals to an intuitive sense of probabilities, rather than the mathematical or scientific treatment. Obviously, a single small aberration can be severe in impact, whereas a huge one can be minor.

Consider for example, the telomere end caps that failed, introducing a chromosomal aberration which alone appears to link apes to humans, at least through common descent.

One of the most central themes to natural selection is niche filling. He doesn't even address it. He does make a passing remark about niche building, which isn't even treated scientifically.

There are really two questions that are running in tandem in your OP:

1. Whether natural selection is falsifiable, and
2. Whether natural selection is false.

The answer, yes, that it is falsifiable has nothing to do with evolution per se. It merely has to do with the natural gravitation of science towards best evidence. Religion, on the other hand, is emblematic of non-falsifiable teaching, since the dogma is not based on evidence. Falsifiability merely addresses the failure of religion to correctly explain natural history. It has no actual bearing on the progress of science, which is evidence based. It's merely a descriptive reference to the existence of the scientific method, nothing more.

In order to show that evolution does not depend upon natural selection, the investigator would have to disprove that niche filling occurs. That's impossible. I think the central fault in the OP is that it does not distinguish between impossibility and falsifiability. They are from completely different causes. The first arises from evidence. The second arises from learning.

You might want to contemplate how all the niche filling that has already occurred can suddenly vanish from the body of evidence. As you see, it has nothing to do with learning and everything to do with collective amnesia.

Thus, a scientific conclusion remains falsifiable even if it is impossible to disprove.

 

[billvon]

It is indeed about a selfish gene. Take two cases:

1) Mother protects her litter; three survive, she dies of her wounds.

2) Mother does not protect her litter; none survive. She survives and has no further young.

The mother in case 1) is, speaking in terms of evolution, more successful.

Nor is there any certainty that her child will be more worth selecting than herself; the child may not be as good a specimen in the final analysis, under normal natural selection.

That is indeed the case. And there are indeed mothers who will not care for (or even actively kill) mutated offspring.

 

[darryl]

One of the most central themes to natural selection is niche filling

Niche filling? I have never heard of this term before, I tried to look it up but found nothing? No biologist or ecologist has ever mentioned it to me? Is this a new idea?

I am interested in this though:

http://en.wikipedia.org/wiki/Niche_construction

 

[Aqueous Id]

Niche filling? I have never heard of this term before, I tried to look it up but found nothing? No biologist or ecologist has ever mentioned it to me? Is this a new idea?

I am interested in this though:

http://en.wikipedia.org/wiki/Niche_construction

Yes that is interesting.

Niche-filling:

http://www.pnas.org/content/107/4/1265.full.pdf

More basic presentation:

http://www.physicalgeography.net/fundamentals/9g.html

An animated tutorial. I really like this publisher:

http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter20/animation_-_mechanisms_of_evolution.html

What I'm trying to get across is that evolution by natural selection is deeply tied to the way creatures find and compete for resources wherever niches open.

 

[Trippy]

Aqueous I am not with these fundamentalists or think like them, but the reason comes down to evolution, religious texts are in opposition to it, not what Newton or Galileo said.

Atcually, religous texts are/were also in opposition to what Galileo said.