Is there a real neutral theory of evolution?

_{Denyse O'Leary

May 4, 2014

Darwinism, Evolution}

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Or do Darwin’s survivors just not know how to cope with his death? Hey, happens.

Last week, I read with considerable interest Vince Torley’s post, “Will the real neutral theory of evolution please stand up,” and commend it to all.

First, we’ve been hearing about the neutral (or mutationist) theory for years, but explanations vary with the explainer.

That’s okay in principle, given how much is up in the air these days. Torley’s account seems to confirm my guess that neutral evolution is more a movement away from Darwinism in search of a new theory than it is a clearly thought-out theory.

It seems to generally be this:

More recently, neutralists PZ Myers and Larry Moran have spoken out even more boldly, arguing that most of the complexity that we see in the biological world could be largely the result of chance, although they do not wish to rule out a role for natural selection.

Okay, but if natural selection is not a mechanism of change (because it simply cannot create the level of new information needed), what is?

If each and every life form has a vast selection of intricately interlocking possibilities available purely by chance, how did it come to be there in the time available since the Big Bang?

People don’t need to answer these questions in order to research life today of course. But they might want to follow available leads in distancing themselves from current Darwinism.

Okay, let’s be frank. The big news on that front today is a New York Times reporter mounting a defense of good old-fashioned Darwinian racism.

What’s not to not like about that?

This just in: The 1990s phoned and they want the selfish gene back; we say send it express post yesterday.

Note: University of Toronto Prof. Larry Moran has not so far got back to Torley responding to his five questions re neutral evolution, intended to verify the limits and ramifications of the theory. Here they are again:

1. Do you agree or disagree with the view expressed by Motoo Kimura that natural selection is necessary to explain evolution occurring at the morphological level?

2. How do you respond to Dr. Gert Kothof’s claim that the neutral theory “is not a theory of evolution,” because it “is not sufficient to explain complex life and adaptations”? If not, why not?

3. Can you point to any complex structures, functions or behaviors which you believe could not have arisen in the absence of natural selection? (You’ve already nominated the change occurring in the human brain over the past few million years as an event in which natural selection played an indispensable role; what else would you put on your list?)

4. In which of the following events do you see natural selection as having played a decisive role: the origin of eukaryotes, the origin of multicellularity, the 20-million-year Cambrian explosion, the origin of land animals, the origin of the amniote egg, the origin of angiosperms, and the radiation of mammals immediately after the extinction of the dinosaurs?

5. Or is it simply your contention that natural selection, while not playing an important role in the origin of complex structures and novel morphological features, exerts a refining and purifying effect subsequent to their appearance, weeding out non-viable life-forms?

Five questions is enough for one day. In the meantime, I’d strongly recommend that readers of this post familiarize themselves with the articles [here], as they raise a number of interesting issues that will be the topic of future posts of mine.

Reader reflections are encouraged, as always.

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Comments

wd400 @55:
Evolution is a contingent process, sure. So what?
Great, that's all I want. An acknowledgement that we are dealing with a contingent process. An acknowledgment that natural selection doesn't somehow make the contingent process non-contingent. We're on the same page. Thanks.Eric Anderson_{May 13, 2014
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And selection is key to understanding that “integration” part: what happens to new variants, from what starting place is variation created in subsequent generations.
I do not deny what happens to a novel variation after it arises is of interest and especially how it affects the viability of the organism is very important. But for the evolution debate it is much more important to understand how the variant arose and how it became functional. For without this there would never had been anything but very simple microbes around after OOL. So far no one has been able to provide a coherent rationale as to how life changed since the first cell. It is all stories.
I really think that if you can concoct a story that makes natural seleciton “meaningless in the evolution debate” then you need to check your premises.
I have been following this debate for 15 years and I have read a lot by people on both sides of the debate and have yet to see anyone make a good case for natural selection resulting in anything meaningful. Perhaps those who support this concept should provide the rationale for why it is important. Sarcastic remarks don't seem to do it. When one resorts to them, it is a sign of a lack of a rationale as opposed to it being obvious or even that there is one. It is the sign of a non-serious comment. Caveat: Probably in the next few years the whole debate will turn away from how elements in the coding region arose and turn to how the regulatory regions arose and just what these sequences do.jerry_{May 7, 2014
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wd400:
Selection is a process by which organisms become better-adapted to their environment.
How does it do that? Whatever is good enough survives to get the chance to reproduce. Populations wobble but don't change very much. That is the "strength" of natural selection. From Chapter IV (Wobbling Stability) of "Why is a Fly Not a Horse?":
Sexuality has brought joy to the world, to the world of the wild beasts, and to the world of flowers, but it has brought an end to evolution. In the lineages of living beings, whenever absent-minded Venus has taken the upper hand, forms have forgotten to make progress. It is only the husbandman that has improved strains, and he has done so by bullying, enslaving, and segregating. All these methods, of course, have made for sad, alienated animals, but they have not resulted in new species. Left to themselves, domesticated breeds would either die out or revert to the wild state—scarcely a commendable model for nature’s progress.
(snip a few paragraphs on peppered moths)
Natural Selection, which indeed occurs in nature (as Bishop Wilberforce, too, was perfectly aware), mainly has the effect of maintaining equilibrium and stability. It eliminates all those that dare depart from the type—the eccentrics and the adventurers and the marginal sort. It is ever adjusting populations, but it does so in each case by bringing them back to the norm. We read in the textbooks that, when environmental conditions change, the selection process may produce a shift in a population’s mean values, by a process known as adaptation. If the climate turns very cold, the cold-adapted beings are favored relative to others.; if it becomes windy, the wind blows away those that are most exposed; if an illness breaks out, those in questionable health will be lost. But all these artful guiles serve their purpose only until the clouds blow away. The species, in fact, is an organic entity, a typical form, which may deviate only to return to the furrow of its destiny; it may wander from the band only to find its proper place by returning to the gang. Everything that disassembles, upsets proportions or becomes distorted in any way is sooner or later brought back to the type. There has been a tendency to confuse fleeting adjustments with grand destinies, minor shrewdness with signs of the times. It is true that species may lose something on the way—the mole its eyes, say, and the succulent plant its leaves, never to recover them again. But here we are dealing with unhappy, mutilated species, at the margins of their area of distribution—the extreme and the specialized. These are species with no future; they are not pioneers, but prisoners in nature’s penitentiary.
Joe_{May 7, 2014
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Frankly, Im amazed you would spend so much effort saying so little. Evolution is a contingent process, sure. So what? If selection always made things {larger, smaller, faster...} then it wouldn't help us understand biology since the world is fill of large and small and fast and slow organisms. Theories of adaptation have to explain why organisms fit their environment so well. Selection is a process by which organisms become better-adapted to their environment. If environments change selecton may help populations track that change, I don't know why you would think that is a weakness of natural selection.wd400_{May 7, 2014
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wd400:
I’m afraid this is just a longer version of one of Joe’s catechisms, and hardly worth more time.
Joe's catechisms come from the high priests of evolutionary biology, for example Mayr in "What Evolution Is":
To be fit means to possess certain properties that increase the probability of survival. This interpretation is equally applicable to the “nonrandom survival” definition of natural selection. Not all individuals have an equal probability for survival because the individuals that have properties making survival more probable are a restricted nonrandom component of the population.- p 118
Certain properties means it all depends and it obviously can be more than one.
The fundamental difference between the first and second steps of natural selection should now be clear. At the first step, that of the production of genetic variation, everything is a matter of chamce. However, chance palys a much smaller role at the second step, that of differential survival and reproduction, where the "survival of the fittest" is to a large extent determined by genetically based characteristics. To claim natural selection is entirely a chance process reveals a total misunderstanding. p 120
Yes chance plays a much smaller role but much smaller in relation to 100% is what, 70%? 50%? Fitness can be from any number of characteristics, again, it all depends. All wd400 has is wd400 and is failing to make a point.Joe_{May 7, 2014
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wd400: Well, I realize it is unlikely I will be able to cut through years of indoctrination that natural selection is actually doing something or imparting a non-random direction to the process. So you are right, maybe not worth much more time. But hopefully some lurker will be reading and say, "Wait a minute, hmmmmm . . ." :)
Then you selected number would be random with respect to its value, which makes a pretty poor analog to natural selection.
Nope. No analogy is perfect, of course, but it is a pretty good analogy and well worth considering. The mistake comes in thinking that natural selection is selecting some definitive special "value." It isn't; at least not over time. The "value" that natural selection selects (anthropomorphizing again for a moment) is just as random as my random number -- a temporary blip on the scene of life until the myriad random organismal and environmental factors change, and then something entirely different may be "selected." All anyone has ever been able to articulate to try to explain natural selection's "non-random" selection process is a vague general claim that natural selection selects for more reproductive success. Yet a moment's observation of the natural world will tell us that this doesn't have much substance. What has been "selected" in the real world? Larger organisms, smaller organisms. Faster organisms, slower organisms. More complex organisms, simpler organisms. Organisms with fur, organisms without fur. Eyes, lack of eyes. Legs, lack of legs. Longer gestation periods, shorter gestation periods. More offspring, fewer offspring. And on and on. There isn't anyone who can give us any prediction or assessment about what will happen over time -- precisely because it is essentially a random series of events, there is no directionality. Why does any particular organism exist? Who knows? Stuff Happens. The whole series of events and environmental factors that lead to one organism happening to survive is a crapshoot. And we deceive ourselves if we think we can apply a label of natural selection to the stochastic results of the process and make what was a crapshoot into not a crapshoot.Eric Anderson_{May 7, 2014
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The only thing that is of interest in the evolution debate is the origin of new variation and its integration into the gene pool. And selection is key to understanding that "integration" part: what happens to new variants, from what starting place is variation created in subsequent generations. I really think that if you can concoct a story that makes natural seleciton "meaningless in the evolution debate" then you need to check your premises.wd400_{May 7, 2014
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Selection doesn’t apply a force to a phenotpye. It changes allele frequencies, or the distribution and mean of phenotypic traits in a population. The ‘units’ are the units of the phenotype under selection, and selection will be directional, stabilizing or diversifying depending on the fitness of the variants under consideration.
There is nothing that selects. And selection what ever it is, certainly does not change allele frequencies. There are only environmental pressures affecting the fecundity of individuals of a population in various ways and random reproductive processes that affect the proportion of alleles in the next generation. There are also random forces which affect the environment. The result is frequently a different distribution of alleles in the next generation. Over time this distribution of alleles could be pretty much the same as the current gene pool, slightly different in some alleles or dramatically different. Call this process what you may but nothing selects anything. The outcome of parts of this process has frequently been called natural selection but natural selection is not the process and never selects anything. It is just a result. Some call parts of the process genetic drift but genetic drift when it actually occurs in any population, is happening along with changes of the gene population due to environmental pressures. It will almost be impossible to determine when or if ever genetic drift happens. There will always be changes in the gene population due to random events each generation. All of the outcomes from these processes of environmental pressures or random process affecting allele frequency does not add anything new to the gene pool. They actually subtract alleles especially in the case of genetic drift and make it less likely the gene pool could survive in the future. Thus these processes are meaningless in the evolution debate. They certainly have usefulness in other areas but not in evolution. The only thing that is of interest in the evolution debate is the origin of new variation and its integration into the gene pool. So the discussions on natural selection and genetic drift are pointless for the evolution debate.jerry_{May 7, 2014
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I'm afraid this is just a longer version of one of Joe's catechisms, and hardly worth more time. Suppose I have a random number generator that generates a string of 100 random digits. Then I have a “selector” that always selects the 6th digit in the string. Then you selected number would be random with respect to its value, which makes a pretty poor analog to natural selection.wd400_{May 7, 2014
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wd400:
Whatever point you are trying to make with this quibbling, selection is not random.
If by "quibbling" you mean that I am interested in the details and am not satisfied with descriptions of natural selection that are vague, overly-broad, and (often) self-contradictory, then I plead guilty as charged. If people anthropomorphize natural selection and keep talking about it as though it "selects" (it doesn't) or it "produces" (it can't), then I will continue to quibble. As to the claim that natural selection imparts some non-random directionality to evolution:
No. By definition selection means reproductive sucsess that is not random with respect to some heritable trait.
That sounds great. Until we consider the details. How do you suppose that heritable trait came about? Some random mutation or some random biochemical error occurring in some random organism, which happens to confer a reproductive advantage in a particular environment, based on the predators in the environment, the food supply, other competitive organisms and a hundred other random factors, any of which could change at any time. So sure, we could say that natural selection temporarily "preserves" that trait. That is until some other random factor changes -- new predators, different food supply, different competition, changes in the weather, whatever -- in which case some other trait will come to the forefront. So the trait that we claim was "selected" by natural selection is, at the end of the day, nothing more than a result of all the random factors that existed prior and that happen to exist today. That is all the substance there is to the idea of natural selection: whatever happens to work today, works today. Yesterday was different; tomorrow might be something else as well. We could fix your statement as follows:
By definition selection means reproductive sucsess that is, temporarily, in a given environment not random with respect to some heritable trait, a trait which came about through random processes, and which, at any random time, could change through various random means to no longer provide a reproductive advantage.
At least that is closer. ----- Suppose I have a random number generator that generates a string of 100 random digits. Then I have a "selector" that always selects the 6th digit in the string. Then I go out and claim to people that because my selector always selects for the same thing (perhaps I can even prove to their satisfaction that it always perfectly, without fail selects the 6th digit) that the result of my process is not random. I claim that my selector is a "non-random" factor I have introduced into the process. People would rightly raise an eyebrow and point out that the selection of the digit does not change the underlying substantive randomness of the process. Claiming that natural selection somehow imparts directionality or somehow makes evolution non-random commits the same error.Eric Anderson_{May 7, 2014
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wd400:
By definition selection means reproductive sucsess that is not random with respect to some heritable trait.
Contigent upon the environment, of course.
Whatever point you are trying to make with this quibbling, selection is not random.
Yes some organisms may have a higher probability of surviving than others depending upon the enivironment. Big whoop. Whatever is good enough to survive gets the chance to try to reproduce. It's as non-random as the spread pattern of a sawed-off shotgun shooting bird shot.Joe_{May 7, 2014
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Mung:
So what does random survival mean, Joe?
By what Mayr said it would mean that all organisms have the same probability of surving/ being eliminated.
Does it also mean that contingency rules?
You guessed it. Give Mung a bisquit.Joe_{May 7, 2014
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Well, that is the assertion, isn’t it. People keep wanting to claim that natural selection imparts some “non-random” direction to the process of evolution. (Makes the whole story seem more believable that way, of course.) But in fact when we pin down what actually happened with the population, it is very much random. No. By definition selection means reproductive sucsess that is not random with respect to some heritable trait. Whatever point you are trying to make with this quibbling, selection is not random.wd400_{May 6, 2014
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wd400:
You sound suspiciously like someone that wants to play a round of amateur philosophy.
Nope. Not philosophy. Just interested in scientific clarity.
Natural selection is a pretty well understood phenomenon, it arised from non-random survival of heritable characters.
Well, that is the assertion, isn't it. People keep wanting to claim that natural selection imparts some "non-random" direction to the process of evolution. (Makes the whole story seem more believable that way, of course.) But in fact when we pin down what actually happened with the population, it is very much random. Unless, of course, one wants to point back to mere 'survivability' as the "non-random direction" natural selection imparts to the process. In which case we are dealing with a useless tautology.
As i said to start, if you want to spend energy arguing about “processes outcomes and forces” your welcome to, but it will do nothing to help us understand biology, so i’ll skip that one.
Yes, better to stick to vague assertions about natural selection's power than to actually delve into the details. That's fine. Look, I have no problem with someone using the term "natural selection" -- as long as they realize it is an after-the-fact label and as long as the acknowledge that natural selection doesn't actually produce anything, doesn't cause anything.Eric Anderson_{May 6, 2014
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Joe:
Non-random survival just means that some organisms have a higher probability of surviving than others. ... contingency rules.
So what does random survival mean, Joe? Does it also mean that contingency rules?Mung_{May 6, 2014
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Non-random survival just means that some organisms have a higher probability of surviving than others. Big deal. That could be anything- better sight, better hearing, better taste, faster, slower, bigger, smaller, taller, shorter, eyes or no eyes, legs or no legs- contingency rules.Joe_{May 6, 2014
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Alleles under selection will tend to be represented in greater numbers in each succeeding generation. If you take a random sample from that population, alleles which exist with greater frequency are more likely to appear in the random sample.Mung_{May 6, 2014
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vjtorley:
Gert Korthof recognizes that Darwin was wrong about a number of things, but still regards neo-Darwinism as an adequate theory of evolution.
Given that neo-darwinism cannot explain the things that Gert Korthof thinks ought to be explained by a theory of evolution (complex life and adaptations), why doesn't he likewise hold that neo-darwinism is not a theory of evolution? At least that would be consistent.Mung_{May 6, 2014
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jerry:
I believe drift is a phenomenon of random heredity. it is not a sampling issue since nothing is being sampled.
*sigh* Let me try to help. Alleles are being sampled. How many alleles make it into the next generation (or not). How many alleles make it into the next generation is not solely determined by their "selective" value. A particular allele may be very beneficial to the carriers of that allele, but if only one individual in a large population carries that allele, tough cookies. Random heredity. Taking samples. jerry:
The environment affects outcomes, random events affect outcomes, internal genomic processes affect outcomes. NS just describes the outcomes that are due to these processes.
Random events would include what? Genetic drift? If not, why not? So your position is that natural selection is an amalgamation of of all processes, both random and non-random? jerry:
Genetic drift is a red herring that never adds anything to a gene pool. To say that it is a major factor in evolution is ludicrous.
The claim that genetic drift is a red herring that never adds anything to a gene pool is a red herring. To say that random events are not a major factor in evolution is ludicrous.Mung_{May 6, 2014
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You sound suspiciously like someone that wants to play a round of amateur philosophy. Natural selection is a pretty well understood phenomenon, it arised from non-random survival of heritable characters. As i said to start, if you want to spend energy arguing about "processes outcomes and forces" your welcome to, but it will do nothing to help us understand biology, so i'll skip that one.wd400_{May 6, 2014
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wd400:
Selection doesn’t apply a force to a phenotpye. It changes allele frequencies, or the distribution and mean of phenotypic traits in a population.
Now, come on. Let's consider whether natural selection can "change allele frequencies" (or do anything for that matter) if it doesn't apply some kind of force. Or perhaps what you really meant to say was:
Something in the environment causes a change in allele frequencies. After the fact, we then attach the label "natural selection" to the results.
That's more like it.Eric Anderson_{May 6, 2014
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Selection doesn't apply a force to a phenotpye. It changes allele frequencies, or the distribution and mean of phenotypic traits in a population. The 'units' are the units of the phenotype under selection, and selection will be directional, stabilizing or diversifying depending on the fitness of the variants under consideration.wd400_{May 6, 2014
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Hi News, Thanks for your question. Gert Korthof recognizes that Darwin was wrong about a number of things, but still regards neo-Darwinism as an adequate theory of evolution. You can find out more about his current views here: http://wasdarwinwrong.com/kortho13.htm . PZ Myers and Larry Moran, on the other hand, regard the neutral theory of evolution as adequate at the genetic level, although they acknowledge a limited role for natural selection as well. I'm still trying to ascertain which aspects of evolution they think require an explanation in terms of natural selection.vjtorley_{May 6, 2014
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wd400:
Natural selection is the non-random survival of alleles (or phenotypes or whatever).
What kind of non-random force does natural selection apply to a phenotype? How is it measured? What is the unit of measurement? In what direction will the force be applied in a given situation?Eric Anderson_{May 6, 2014
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(I should say, following Mung's comment: indeed drift is still in operation on very large populations and with large selection coefficients. It's just the relative strengths of the random effects is dwarfed by the directional ones in such cases)wd400_{May 6, 2014
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So tell me when you say there is NS? When can measure its effect, and see a pattern (in survival or reproductives, heterozygosity, types of substitutions occuring) that is best explained by selection and not drift. You are really all at see on this, I'm afraid. Also the changes in the gene pool could be random or due to environmental pressures or a combination of both. Yes, of course. And we have names for the process when it's largely due to the random processes (drift) and when it's largely due to differential success of variants (selection).wd400_{May 6, 2014
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Population genetics has nothing to do with the evolution debate. It only deals with what is already there. What the debate is about is the origin of novel variation. After the variation appears, natural processes will affect how widespread the variation becomes. So natural selection and genetic drift are real but meaningless concepts in terms of the debate. People tend to want to use the term "natural selection" as a special case of the natural environmental pressures that are always working on populations. Eventually there will be a different skew of allele frequencies. When does one say in this process that NS has taken place? The answer is that NS takes place at every step. It is just that no one sees anything of interest in nearly all the steps in this process. Most of the times there is no essential difference in the gene pool. So tell me when you say there is NS? Also the changes in the gene pool could be random or due to environmental pressures or a combination of both.jerry_{May 6, 2014
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Piotr, pop gen is not based on reality and no one has ever verified its equations. And no one has ever observed a new allele reach fixation in the wild. OTOH we have a very good understanding of gravity and why the earth orbits the sun. I doubt any physicist would ever say that gravity is as well established as pop gen.Joe_{May 6, 2014
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I understand pop gen.
+
And no one knows what it takes to get a new allele fixed.
is like saying, "I understand gravity... and no-one knows what makes the Earth orbit the Sun."Piotr_{May 6, 2014
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Piotr:
But I’m only trying to tell you what some fundamental notions of population genetics mean.
I understand pop gen. I also understand that it is useless wrt reality and it doesn't help us understand reality. That said, no one can model unguided evolution doing what it is claimed it has done.Joe_{May 6, 2014
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