Uncommon Descent Serving The Intelligent Design Community

Is there a real neutral theory of evolution?

Share
Facebook
Twitter
LinkedIn
Flipboard
Print
Email

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.

Follow UD News at Twitter!

Comments
Piotr, nature isn’t as simple as your model
Of course it isn't. But I'm only trying to tell you what some fundamental notions of population genetics mean. There are more sophisticated models which take into account mutations, lateral gene flow, degree of inbreeding, structure of the population, etc., etc., etc. (whatever is relevant in a given situation) Of course you can always say, "It's a model, not reality". But the same can be said of physics, or any science. Models aren't supposed to represent the real world with 100% fidelity; but they help you to understand what happens in the world by focussing on the most important aspects of real-world phenomena.Piotr
May 6, 2014
May
05
May
6
06
2014
05:57 AM
5
05
57
AM
PDT
jerry: a) My agreement with wd400 was limited to what he says in post #16, and in particular to the following statement: "Natural selection is the non-random survival of alleles (or phenotypes or whatever)." I think that your use of the concept of NS is not correct, or at least does not correspond to what everybody (except maybe MacNeill) means with that name. However, I have a perfect agreement with you, limited to the following statement: "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. It only subtracts as does natural selection. Look at the comment by Allen MacNeill and the only thing that matters is the origin of variation and the survival of this variation." Whatever MacNeill may think, the origin of complex functional variation is one and only one:design. But the product of good design can certainly be expanded and fixed by NS (not drift), because of its high functionality.gpuccio
May 6, 2014
May
05
May
6
06
2014
05:27 AM
5
05
27
AM
PDT
From "What Evolution Is" (Mayr) page 117:
What Darwin called natural selection is actually a process of elimination.
Page 118:
Do selection and elimination differ in their evolutionary consequences? This question never seems to have been raised in the evolutionary literature. A process of selection would have a concrete objective, the determination of the “best” or “fittest” phenotype. Only a relatively few individuals in a given generation would qualify and survive the selection procedure. That small sample would be only to be able to preserve only a small amount of the whole variance of the parent population. Such survival selection would be highly restrained. By contrast, mere elimination of the less fit might permit the survival of a rather large number of individuals because they have no obvious deficienies in fitness. Such a large sample would provide, for instance, the needed material for the excercise of sexual selction. This also explains why survival is so uneven from season to season. The percentage of the less fit would depend on the severity of each year’s environmental conditions.
Joe
May 6, 2014
May
05
May
6
06
2014
05:23 AM
5
05
23
AM
PDT
Piotr, nature isn't as simple as your modelJoe
May 6, 2014
May
05
May
6
06
2014
05:21 AM
5
05
21
AM
PDT
Natural selection is eliminative...
Let's suppose we have two alleles, A and a. Natural selection tends to reduce the reproductive success of the carriers of a in comparison with A, so while carriers of a produce 100 fertile offspring, carriers of A produce 101, on the average. The ratio 101:100 can be expressed as (1+s):1 (here, s=0.01). This s, ranging from -1 to + infinity, but usually rather close to zero, is the selection coefficient favouring A relative to a (the competing allele). It's positive for A despite the "eliminative" character of selection in this case. An alternative way of defining the selection coefficient is 101:100 = 1:(1-s'), where s' is the selection coefficient against a (relative to A). It doesn't matter much which definition you prefer, as long as you use one of those coefficients consistently (they are not quite equivalent but can easily be transformed into each other: s' = s/(1+s)). If you have a large population in which neither A nor a make a statistically significant difference in terms of advantage (or disadvantage) to their carriers, selection can't fix or eliminate either of them. But in a finite population drift alone will eventually fix one of them at the expense of the other, even if complicating factors such as mutation and/or migration can be neglected.Piotr
May 6, 2014
May
05
May
6
06
2014
05:13 AM
5
05
13
AM
PDT
jerry- there is more to evolution than producing adaptations. That genetic drift is more of a factor than natural selection should tell us how impotent evolution really is.Joe
May 6, 2014
May
05
May
6
06
2014
04:57 AM
4
04
57
AM
PDT
jerry: Again, I agree with wd400. It is certainly true that what survives survives, but still drift and NS are two different models of what survives
Everything that wd400 wrote was nonsense and you agreed with him. For example, I suggest you look at how he used the term "sample" and justify your comment. I didn't respond to his comment because it was fatuous. There is too much response on this site to nonsense comments. ----------------------- Every offspring that arises is subject to the pressures of the environment no matter how the alleles it possesses came about. There will never be a perfect replication of the gene pool due to how reproduction works. So the frequency distribution of alleles is constantly changing in small amounts by natural processes . But if an allele frequency change remains then it was not eliminated by environmental pressures no matter how the frequency distribution of the allele arose and one then says that natural selection allowed this allele frequency to remain. So called selection pressures or environmental pressures are constantly operating. They usually operate to keep the gene pool pretty much the same but nonetheless they are still operating. And the gene pool as I said always changes a little from generation to generation. So when these slight allele frequency changes due to differential heredity (a population frequency distribution different due to random reproductive events), it does not mean that environmental pressures stopped operating. People are confusing the processes of reproduction that led to a slight change in the gene pool with the environmental pressures that affect the survival of particular organisms. Or rather with the survival of a subset of the population of the organism that possess a certain allele or combination of alleles. If an allele becomes fixed it went through a long process of environmental pressures and survived. It was naturally selected at each step of the way. 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. It only subtracts as does natural selection. Look at the comment by Allen MacNeill and the only thing that matters is the origin of variation and the survival of this variation.jerry
May 6, 2014
May
05
May
6
06
2014
04:49 AM
4
04
49
AM
PDT
As for natural selection being non-random, well all that just means is not every organism in a population has the same probability of surviving/ being eliminated. It isn't magical non-randomness.Joe
May 6, 2014
May
05
May
6
06
2014
04:35 AM
4
04
35
AM
PDT
jerry- I understand what you are saying wrt natural selection. However natural selection can be defined as: differential reproduction due to heritable chance mutations. So that would also be or could be considered to be the process. Genetic drift wouldn't be special case of natural selection because it is not eliminative.Joe
May 6, 2014
May
05
May
6
06
2014
04:33 AM
4
04
33
AM
PDT
Piotr- Natural selection is eliminative and "selection coefficients" only exist in computer programs. And no one knows what it takes to get a new allele fixed.Joe
May 6, 2014
May
05
May
6
06
2014
04:29 AM
4
04
29
AM
PDT
It is possible in theory that a gene which confers reproductive advantage be fixed by drift, but as the genes which confer reproductive advantages are a minimal part of the total, that effect is not relevant. The few genes which confer reproductive advantage will be fixed by a NS process, if they are fixed. The probability that they may be fixed by drift is really negligible.
It isn't negligible if the selection coefficient s and the effective population size N_e are both sufficiently small (to wit, if 4×N_e×s is smaller than 1). A "preferred" allele may be lost by drift or fixed more thanks to drift than to positive selection, and a deleterious allele may be fixed by drift despite selection against it, or lost -- again more thanks to drift than to purifying selection. The importance of drift is inversely proportional to the effective population size, which is why fixation by natural selection is more likely in big populations than in small ones (where unpredictable random fluctuations may override the effects of selection).Piotr
May 6, 2014
May
05
May
6
06
2014
03:17 AM
3
03
17
AM
PDT
jerry: Again, I agree with wd400. It is certainly true that what survives survives, but still drift and NS are two different models of what survives (different, but not incompatible). Drift describes how genes can survive by random processes. NS is the classical model of neo darwinism, which describes how genes can preferentially survive because they confer a reproductive advantage. In the NS model, it is important that the gene survives for reasons related to the gene itself, because that is an integral part of how neo darwinism tries to explain the generation of complex functions (without succeeding, but that's another story). Drift is by definition unrelated to the functional activity of the gene, and to any possible reproductive advantage it may confer. It is possible in theory that a gene which confers reproductive advantage be fixed by drift, but as the genes which confer reproductive advantages are a minimal part of the total, that effect is not relevant. The few genes which confer reproductive advantage will be fixed by a NS process, if they are fixed. The probability that they may be fixed by drift is really negligible.gpuccio
May 6, 2014
May
05
May
6
06
2014
02:48 AM
2
02
48
AM
PDT
I really couldn't care less if we called natural selection a 'process' in whatever sense jerry want to use to word. But if you definition ends up saying "when it survives it was selected" then it's just wrong with the way words are used in biology. Natural selection is the non-random survival of alleles (or phenotypes or whatever). Likewise, sampling is indeed a useful way to think about drift. Only some sample of the near-infinite set of possible alleles is realised in each generation. That's why drift is stronger effect in small populations (it's a small sample drawn from a large population).wd400
May 5, 2014
May
05
May
5
05
2014
08:03 PM
8
08
03
PM
PDT
Drift is a phenomenon of sampling. Even alleles under selection are subject to drift.
I believe drift is a phenomenon of random heredity. it is not a sampling issue since nothing is being sampled. The population is reproducing and certain alleles may appear more frequently than expected due to random events. All alleles are theoretically under environmental pressures and all alleles are subject to random heredity.jerry
May 5, 2014
May
05
May
5
05
2014
06:49 PM
6
06
49
PM
PDT
I will say it again, natural selection is not a process or mechanism. It is a name given to an outcome of a complicated process of reproduction in different environments. NS does not do anything. It does nothing more than describe a result. The environment affects outcomes, random events affect outcomes, internal genomic processes affect outcomes. NS just describes the outcomes that are due to these processes. Certain alleles are left after numerous reproductive cycles. The ones that are left are the result of differential fecundity of the offspring as well as differential heredity of alleles. The differential fecundity and heredity may be due to a lot of things and the actual cause is almost impossible to determine. The actual result could be due to random events or to environmental pressures or something else. In all cases the ones that exist after each reproductive round are said to have survived and these alleles will form the new gene pool. Sometimes this differential fecundity and heredity will end up with one allele and we will probably never know the reason why this happened. In nearly all cases more than one allele will survive, sometimes there will be several alleles at the same loci. Sometimes the differential heredity will be due to strictly random events and we could end up with several or just one allele at a loci. But all must face survival so every allele that persists in a gene pool is said to have survived. Natural selection just describes the alleles that survived. It is the output of fecundity, heredity and the environment and in some cases random processes. From Allen MacNeill who teaches evolutionary biology at Cornell. https://uncommondescent.com/intelligent-design/microbe-evolution-virtually-finished-25by-ago/#comment-306698
This quote demonstrates a basic misunderstanding of the process of natural selection. According to Darwin (and virtually all evolutionary biologists), natural selection has three prerequisites: 1) Variety (generated by the “engines of variation” 2) Heredity (mediated by the transfer of genetic material, either vertically – from parents to offspring – or horizontally – via viral transduction, retrotranscription, etc.) 3) Fecundity (reproduction, usually at a rate that exceeds replacement). Given these three prerequisites, the following outcome obtains: 4) Demography: some individuals survive and reproduce more often than others. Ergo, the heritable variations of such individuals become more common over time in populations of those organisms. Natural selection is synonymous with #4; it is an outcome of the three processes listed first, not a “mechanism” in and of itself. Ergo, the real dispute here is not over natural selection per se, but rather the properties and capabilities of the “engines of variation”. I have written extensively about these here: http://evolutionlist.blogspot.com/2007/06/what-is-engine-of-evolution.html and here: http://evolutionlist.blogspot.com/2007/10/rm-ns-creationist-and-id-strawman.html Yes, natural selection (i.e. #4, above) is conservative not creative. It produces no new genetic nor phenotypic information, which is why Darwin eventually came to prefer the term “natural preservation” rather than “natural selection”. However, it is also abundantly clear that the “engines of variation” – that is, the processes the produce phenotypic variation among the members of populations of living organisms – are both extraordinarily creative and extraordinarily fecund. The real problem in biology is not producing new variation, but rather limiting the production of new variation to the point that the “engines of variation” do not cause the rapid disintegration of living systems. As just one example of this problem, the genetic elements known as transposons generate a huge amount of new genetic variation, much of which is either phenotypically neutral or deleterious to the organism. There are biochemical mechanisms by which cells can monitor the incidence of transposition in themselves, and limit its consequences (up to and including the active self-destruction of the cell via apoptosis). At the same time, there is very good evidence in the genomes of many organisms that retrotransposition events mediated by transposons have produced genetic changes that have resulted in increased survival and reproduction of the organisms in which such events have taken place. There is a large and growing literature on this phenomenon, all of which points to the inference that retrotransposition via transposons both creates new genetic and phenotypic variation, and that in some cases such variation can provide the raw material for evolutionary adaptations, which are preserved via natural selection. So, if you really want to find out where the “intelligent designer” might create new variations, you should follow the lead of Darwin’s good friend, Asa Gray, and look for the telltale evidence for such intervention in the “engines of variation”. Of course, you will have to show pretty conclusively, using empirical investigations and statistical analysis, that such “creation events” are not the result of purely natural, unguided processes. If you can do this, you will undoubtedly win a Nobel Prize and a Crafoord Prize (plus a MacArthur or two). Notice that this will involve looking carefully into the mechanisms by which new variations are produced, rather than pointing to the outcomes of such processes (i.e. natural selection) and simply asserting that “you can’t get here from there”. Simply asserting (without empirical evidence) that something can’t happen isn’t “doing science” at all. In fact, it’s doing just the opposite…
So genetic drift which is really just a change in the gene pool due to random heredity events does not change the fact that any allele must face survival. When it survives it is said to have been naturally selected.jerry
May 5, 2014
May
05
May
5
05
2014
06:40 PM
6
06
40
PM
PDT
jerry, perhaps it would help if you could explain what you mean when you say that natural selection and drift are part of the same process. Drift is a phenomenon of sampling. Even alleles under selection are subject to drift. wd400, any issues with the bolded text?Mung
May 5, 2014
May
05
May
5
05
2014
05:18 PM
5
05
18
PM
PDT
Wikipedia had a front page story today about Huntsman (Daddy Long Legs) non-spiders. They have had EXACTLY the same body plan for 400 MILLION years, and the details of the earliest fossils agree remarkably well with Daddy Long Legs living today. So, does the new Evolution explain Stasis? How can a species have been PERFECTED 400 million years ago and NOT "evolved" since. There are many, many different Huntsman species alive today. The guess is 10,000 separate SPECIES. But none of them are radically different from each other, and Huntsman are different enough from real spiders to have NOT formed the basis for real spiders. So a Theory of Evolution must not only provide an Origin of Life from chemicals. It must also explain Stasis from the same mechanisms with which it describes "descent with modification". And how can Competition explain Stasis? No change after 400 MILLION years would seem to indicate that Competition is NOT a factor.mahuna
May 5, 2014
May
05
May
5
05
2014
04:43 PM
4
04
43
PM
PDT
wd400: You are right. Thank you for helping to clarify that.gpuccio
May 5, 2014
May
05
May
5
05
2014
03:04 PM
3
03
04
PM
PDT
. At every step of the process that leads to a fixation the allele that survives is subject to elimination but survives. That is called natural selection. No. In natural selection the odds are stacked such that some alleles are more likely to survive. Selection is the process when the odds are skewed in some way, drift for the process with uniform odds.wd400
May 5, 2014
May
05
May
5
05
2014
12:26 PM
12
12
26
PM
PDT
First, we’ve been hearing about the neutral (or mutationist) theory for years, but explanations vary with the explainer. Since the neutral theory, and mutationist theories of evolution are entirely separate things, are we left to conclude that you've learned nothing in all those years of hearing about them? Your further confusion between drift and mutation in comments here suggest so. They think genetic drift (mutation) iwd400
May 5, 2014
May
05
May
5
05
2014
12:21 PM
12
12
21
PM
PDT
They are not processes. They are outcomes of the same process. At every step of the process that leads to a fixation the allele that survives is subject to elimination but survives. That is called natural selection. In most cases more than one allele survives the process.. So the case where one survives is a special case.jerry
May 5, 2014
May
05
May
5
05
2014
02:55 AM
2
02
55
AM
PDT
jerry: I would say that you are right that drift is similar to NS in one aspect, because it is a form of natural fixation, a process whose results are the same as those of natural selection: the expansion and fixation of a gene in a population. But it is also different, because in drift there is no "selection", in the sense that NS acts on a subset of new genes that are different from others for a definite property (they confer reproductive advantage), while drift acts randomly, in the same way (IOWs, with uniform probability distribution) on all the genes which are there. So, NS is a selective natural fixation where the fixation is based on a specific functional advantage, while drift is a random natural fixation, which introduces random variation in the scenario of random variation, and nothing else. That's a big difference, even if both are certainly processes which do not "do" anything.gpuccio
May 4, 2014
May
05
May
4
04
2014
11:47 PM
11
11
47
PM
PDT
Could someone please tell me why isn't genetic drift just a special case of natural selection/ In other words genetic drift is a subset of natural selection. Remember natural selection is not a process and does not do anything. NS is just an outcome of another process. Genetic drift is just another outcome of the same process. Isn't this biology 101?jerry
May 4, 2014
May
05
May
4
04
2014
11:22 PM
11
11
22
PM
PDT
So Korthof thinks (thought) that Darwinism is an adequate theory, but Myers and Moran don't? They think genetic drift (mutation) is an adequate theory and natural selection isn't? Is this where we are now?News
May 4, 2014
May
05
May
4
04
2014
09:59 PM
9
09
59
PM
PDT
Hi Mung, Just to be clear: Korthof himself believes that Darwinism is an adequate theory of evolution, although I would say otherwise, as an Intelligent Design advocate. What Korthof believes is that the neutral theory is not an adequate theory of evolution. As he puts it (see his review at http://wasdarwinwrong.com/kortho37.htm ):
Please note that ‘the neutral theory of evolution’ is not sufficient to explain complex life and adaptations. In that sense it is not a theory of evolution.
vjtorley
May 4, 2014
May
05
May
4
04
2014
04:45 PM
4
04
45
PM
PDT
Hi Mung, Thank you for your comments. Regarding the first passage you quoted, I think the point that News was making was that on the neutral theory, natural selection is no longer the main mechanism of evolutionary change. Regarding my second question, which you quoted from: first, I was simply quoting an argument put forward by Gert Korthof, a Dutch biologist; and second, I happen to think Korthof was right. Darwinism purports to be an all-inclusive biological theory. If there is some central aspect of our biological make-up which Darwinism cannot explain (e.g. complexity) then it fails as a theory, and can no longer be considered an adequate theory of evolution, but at best, a mere hypothesis, or outline of a theory.vjtorley
May 4, 2014
May
05
May
4
04
2014
04:39 PM
4
04
39
PM
PDT
Hi News, Thanks for re-posting my five questions. By the way, I think one of the hyper-links in your post needs to be fixed: the one about the New York Times reporter should be directed here: https://uncommondescent.com/intelligent-design/prominent-science-writer-insists-darwinian-evolution-is-ongoing-want-to-revive-conversation-about-race/ Thanks again.vjtorley
May 4, 2014
May
05
May
4
04
2014
04:30 PM
4
04
30
PM
PDT
Okay, but if natural selection is not a mechanism of change (because it simply cannot create the level of new information needed), what is?
Neutral theory does not claim that natural selection is not a mechanism of change.
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?
Most or perhaps even all intelligent design advocates deny that Darwinian theory is sufficient to explain complex life and adaptations. It's not therefore a theory of evolution? VJT is a philosopher and should know better than to make such a specious argument.Mung
May 4, 2014
May
05
May
4
04
2014
04:04 PM
4
04
04
PM
PDT
1 2

Leave a Reply