What evidence is there for evolution being non-random?

http://www.simonyi.ox.ac.uk/dawkins/FAQs.shtml

I have sought, without success from a number of scientific authorities an answer to the following question, viz. how does the environment influence the gene, e.g. the development of the giraffe's long neck. Random mutations are not fully explanatory.
Perhaps you would be good enough to suggest a hypothesis or perhaps direct me towards further reading.

letter from P. Dawnay


Dawkins response:

You rightly say that random mutation is NOT a good explanation for the evolution of giraffes' necks or, indeed, of anything else! Fortunately, nobody has ever suggested that it IS a good explanation. The correct explanation -- and it is indeed an excellently satisfying one -- is Darwinian natural selection. Darwinian natural selection is emphatically NOT the same thing as random mutation. Although random mutation does play a role in the theory, natural selection itself is the most important ingredient, and natural selection is the exact OPPOSITE of random.

Three of my books, The Blind Watchmaker, River Out of Eden, and Climbing Mount Improbable, are devoted to explaining how Darwinian natural selection works, and why it is such a satisfying explanation.



As mentioned before, my science dictionary defines random as being unrelated to past or future events. It also says that it refers to all possibilities being equally likely. Evolution is wholly dependent on past events--mutations are relatively random--what survives to reproduce is not.

If that does not answer Mijo's question, then I suggest that nothing can.

I would suggest that you are deliberately using a definition of "random" that allows you to ignore the probabilistic processes of evolution. Evolution is by definition a non-trivial stochastic process because it is based on probabilities of individuals' passing on their genes to the next generation in greater proportions to other individuals. Now, I fully admit that if it can be determined all the individuals who pass on their genes to the next generation in greater proportions to other individuals differ in a distinguishable way (i.e., by a specific genetic polymorphism or set thereof) then the process of natural selection is deterministic, because identical individuals are selected in identical ways. If, however, it can be determined some the individuals who pass on their genes to the next generation in greater proportions to other individuals are indistinguishable for others who don't, barring a catastrophe that no individual would survive no matter how fit it was, then the process of natural selection is stochastic, because identical individuals are selected in different ways.

At our current state of knowledge it appears that the latter situation is most likely the case. However, this assessment, as Ichneumowasp has wisely pointed out, could be due to our incomplete knowledge of the genetic compositions of the the individuals who pass on their genes in greater proportions to other individuals and the individuals who don't. I just don't see what the problem is with saying some like I just said above. First, we would acknowledge that the appearance of stochasticity of evolution at the generational level may be because of our incomplete knowledge of just how many genes and polymorphisms thereof effect the fact of whether an individual passes on its genes to the next generation in greater proportions to other individuals and then we would provide for the fact that if identical individuals are selected identically evolution is deterministic whereas if identical individuals are selected non-identically evolution is stochastic.

It may not be the simplest explanation, but it avoids the ambiguities of calling evolution "non-random" or "random".
 
Just out of curiosity...is Mijo's explanation above clear to anybody? I mean, I understand everybody else pretty well...even if I don't agree--I realize it's a semantics issue. I think this is why Biologists prefer not to use the word "random". And it sounds like Walter Wayne understands evolution even if he doesn't agree with Dawkins' definition. But when I read mijo, it sounds like gobbledy gook. Maybe someone can translate. Do you think he understands natural selection?--Do you think he understands the non-random parts of evolution per his OP? Do you think he understands the difference in randomness as it applies to mutation and randomness involved in selection? Do you think he is "more clear" or provides a better description than Dawkins? And if so, for what audience? The hypothetical creationists in the OP?

To me, random is a single event--it is removed from the "random pile" once it is selected. Before a series of dice is thrown all series are equally probable...as each dice is thrown, the probabilities diminish--some series can no longer be in the running. The dice itself has no awareness of what was thrown, so each throw is random. I concede that "random" could also mean unpredictable or without a purpose...hence the ambiguity. But isn't Mijo using stochastic as a synonym for random generating the same ambiguity?
 
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I don't think it is all that complicated. We define 'information content' generally by an increase in protein variability (that is one part of the definition; there are many other parts as well) or significant change in morphology.

So here are two 'mutations' that increase information content. Gene duplication with modification of the second copy to create a useful protein. And mutation in either the regulation of hox genes so that a particular hox gene is active for a longer period of time -- creates longer neck (more vertebrae; or consequently change the genes that increase the size of individual vertebrae so that we see a giraffe's neck).

"Information content" and "complexity" are very touchy issues when talking about genetic diversity. I've always thought "variation" was the best descriptor to use.
 
I would suggest that you are deliberately using a definition of "random" that allows you to ignore the probabilistic processes of evolution. Evolution is by definition a non-trivial stochastic process because it is based on probabilities of individuals' passing on their genes to the next generation in greater proportions to other individuals. Now, I fully admit that if it can be determined all the individuals who pass on their genes to the next generation in greater proportions to other individuals differ in a distinguishable way (i.e., by a specific genetic polymorphism or set thereof) then the process of natural selection is deterministic, because identical individuals are selected in identical ways. If, however, it can be determined some the individuals who pass on their genes to the next generation in greater proportions to other individuals are indistinguishable for others who don't, barring a catastrophe that no individual would survive no matter how fit it was, then the process of natural selection is stochastic, because identical individuals are selected in different ways.

At our current state of knowledge it appears that the latter situation is most likely the case. However, this assessment, as Ichneumowasp has wisely pointed out, could be due to our incomplete knowledge of the genetic compositions of the the individuals who pass on their genes in greater proportions to other individuals and the individuals who don't. I just don't see what the problem is with saying some like I just said above. First, we would acknowledge that the appearance of stochasticity of evolution at the generational level may be because of our incomplete knowledge of just how many genes and polymorphisms thereof effect the fact of whether an individual passes on its genes to the next generation in greater proportions to other individuals and then we would provide for the fact that if identical individuals are selected identically evolution is deterministic whereas if identical individuals are selected non-identically evolution is stochastic.

It may not be the simplest explanation, but it avoids the ambiguities of calling evolution "non-random" or "random".

Seriously. Define "Random", ok?
 
The problem I have with using random as mijo is doing is that it means that all culling or honing or selective breeding can be called random just because there are random elements involved. And that is misleading, isn't it? Culling, whether done by humans or nature, is based on what came before...it is not random--rather, it connects the random steps to build complexity or prune complexity--creating change through time.
 
The point is that there are two possibilities for an individual of a specific phenotype with respect to the perpetuation of the phenotype. The individual can either succeed in passing its genes on to the next generation are thereby succeed in perpetuating its phenotype (or possibility of its phenotype being reformed through recombination) or it can fail to pass on its genes to the next generation and thereby fail to perpetuate its phenotype. If, on the one hand, all individuals of a given phenotype fail to pass on (or succeed in passing on) their genes to the next generation, then natural selection is a deterministic process because there are identical results (i.e., either all failures or all successes) for identical inputs (i.e., the given phenotype). If, on the other hand, some individuals of a given phenotype fail where other succeed, the natural selection is a stochastic process because there are differnt results (i.e., both failures and successes) for identical inputs (i.e., the given phenotype).

If you don't understand what I am saying, could you please point out where you stop understanding instead of calling what I am saying "gobbledy gook"?
 
The problem I have with using random as mijo is doing is that it means that all culling or honing or selective breeding can be called random just because there are random elements involved. And that is misleading, isn't it? Culling, whether done by humans or nature, is based on what came before...it is not random--rather, it connects the random steps to build complexity or prune complexity--creating change through time.

By definition, selection is the opposite of random. That's why we need to see the defintion he's using for "random" et al.
 
Seriously. Define "Random", ok?

I have, and it has been ignored. In fact, I collected my various statements about randomness in to one post:

I specifically cited Split from: I'm reading "The God Delusion" - a review in progress because there are several posts that give dictionary definitions of "random" (#47, #49) and discuss why all but the mathematical and statistical definition do not describe evolution (#65, #69, #71, #73,
#75). I also made it quite clear that I favored "stochastic" or "probabilistic" over "random" because they have very specific definitions that avoid the common associations and therefore misinterpretations of "random" (#103, #189, #234, #252). Furthermore, I explained in great detail several times in this thread exactly why evolution is probabilistic or stochastic (#158, #230).

If you want definitions of "random" and explanations how it applies to evolution I suggest you start with those posts. I will try to dig up more recent ones too.
 
The point is that there are two possibilities for an individual of a specific phenotype with respect to the perpetuation of the phenotype. The individual can either succeed in passing its genes on to the next generation are thereby succeed in perpetuating its phenotype (or possibility of its phenotype being reformed through recombination) or it can fail to pass on its genes to the next generation and thereby fail to perpetuate its phenotype. If, on the one hand, all individuals of a given phenotype fail to pass on (or succeed in passing on) their genes to the next generation, then natural selection is a deterministic process because there are identical results (i.e., either all failures or all successes) for identical inputs (i.e., the given phenotype). If, on the other hand, some individuals of a given phenotype fail where other succeed, the natural selection is a stochastic process because there are differnt results (i.e., both failures and successes) for identical inputs (i.e., the given phenotype).

If you don't understand what I am saying, could you please point out where you stop understanding instead of calling what I am saying "gobbledy gook"?

Instead of thinking in terms of Phenotypes, I find it easier to think of it in terms of alleles. This is also more accurate, because it reflects our models for evolution within a population. It is also more realistic, because not everything which affects an individual's fitness is phenotypically expressed. Changes in synonymous DNA, for example, have no over all effect in the amino acid sequence of the resulting protein.
 
I have, and it has been ignored. In fact, I collected my various statements about randomness in to one post:



If you want definitions of "random" and explanations how it applies to evolution I suggest you start with those posts. I will try to dig up more recent ones too.

That's ok, all I'm really asking is you cut/paste any definition you've given, either here or elsewhere. Call me lazy, but if you've posted it in this thread I've missed it. :o
 
The point is that there are two possibilities for an individual of a specific phenotype with respect to the perpetuation of the phenotype. The individual can either succeed in passing its genes on to the next generation are thereby succeed in perpetuating its phenotype (or possibility of its phenotype being reformed through recombination) or it can fail to pass on its genes to the next generation and thereby fail to perpetuate its phenotype. If, on the one hand, all individuals of a given phenotype fail to pass on (or succeed in passing on) their genes to the next generation, then natural selection is a deterministic process because there are identical results (i.e., either all failures or all successes) for identical inputs (i.e., the given phenotype). If, on the other hand, some individuals of a given phenotype fail where other succeed, the natural selection is a stochastic process because there are differnt results (i.e., both failures and successes) for identical inputs (i.e., the given phenotype).

If you don't understand what I am saying, could you please point out where you stop understanding instead of calling what I am saying "gobbledy gook"?

I just think it's a very unclear way to describe natural selection. And why don't you define random and/or stochastic as others have asked.

In my hand right now is a QPB Scientific Encyclopedia. It has no listing for random by itself--although it has a listing for random event described thusly:
"in statistics, an event that is not affected by either previous or future events. For example, if a new book is opened at random, all page numbers are equally likely". I think that is a pretty good definition from a biological stand point. It has no listing for "stochastic", and I have not seen that term in biology--though I gave an online definition of the term. You have provided no definitions of any of the terms you use and they seem to have different meanings accordingly. In actuality, book opening is not random due to the way books are built and the way people interpret "open a page at random"--I suspect you are much more likely to get a page in the middle...and one that has been opened frequently before. But that is irrelevant...as are your examples of fit things dying or lesser fit things living. Mutations are random in a similar way. Recombination is more stochastic because genes sort together along chromosomes--a fixed entity.

Science does know enough to know enough to say evolution is not "random" unless, by random, you mean purposeless-- unplanned. Dawkins' gives a much clearer explanation and your explanation sounds as convoluted as the question asked of Dawkins. It doesn't clarify anything. You pretend it's a more precise definition, but it isn't. Especially since you've never really defined the words you use. Yes there are differing probabilities as to what will survive. But just as it would be misleading to call culling of any sort a "random process", so too would it be misleading to call evolution "random" or to emphasize the word "random" (or stochastic or probabalistic) in describing it. It doesn't clarify anything. Random is the easy part. Selection through time is where creationists get stuck. Your explanation does nothing but encourage the wallowing in the mire. I maintain that no answer will work for you, because you have a need to see evolution as "random" (whatever definition you give it.) I think that you also have a need to see the fossil record as "discontinuous". I think you are playing word games to hear what you want just like all "intelligent design proponents" quoted here. You are unable to convey "natural selection" and how it builds complexity. You have a desire to conclude that science thinks that "chance alone" produced the complexity around us. That is simply a gross oversimplification of the facts.

However, if someone here thinks you've described anything particularly well or in a useful way, then I'm sure they'll speak out. Perhaps it is only I who see your words as pedantic gobbledy gook...useless...uninformative...more confusing than the question it was supposed to address.

And, as far as I'm concerned, Dawkins' explanation is much, much clearer, and addresses your supposed question much better than you have...or anyone here has. It's important to understand the general concept before getting into word games, specifics, probabilities, etc. Scientific explanation can usually be boiled down pretty simply--

I don't think there is a biologists in the world that misunderstands Dawkins' explanation, and I think his explanation explains evolution a lot better than you do. I can't tell if you understand "natural selection" or not. You seem so fixated on the probabilistic semantics that the overall idea seems to elude you. In fact, to me, you seem to be having an entirely different conversation than people with a scientific background...just like Kleinman. You hear what you want to hear and ignore anything that allows you to understand how natural selection is not random...unless you are playing fast and loose with your terms.
 
Just out of curiosity...is Mijo's explanation above clear to anybody?

Yes.

Suppose you have two individuals with no obvious differences. One of them lives, and passes on its genes. One of them dies, and doesn't. If that ever happens, then the outcome is not deterministic. Hence, it's random.
 
Yes.

Suppose you have two individuals with no obvious differences. One of them lives, and passes on its genes. One of them dies, and doesn't. If that ever happens, then the outcome is not deterministic. Hence, it's random.

Whether reality follows a strict selection method is beside the point, IMHO. Selected, in and of itself, is non-random, by its very definition.
 
By definition, selection is the opposite of random. That's why we need to see the defintion he's using for "random" et al.


I agree...but in the crazy world of semantics, others here do not. I see their point. If randomness is a scale--mutations are more random and selection is much less random--but I think the word random and probabilities are being used to obfuscate. The sky is blue; the grass is green--that's good enough for general understanding...sure, the sky isn't always blue, and it's really a reflection and the grass isn't always green...it can be dead grass, and so forth...but fixating on the exceptions doesn't clarify anything if you are just trying to get someone to learn the basics.

By way of analogy, mutations are random; natural selection is not. Though a case could be made that mutations are not really random and that since selection has "random" components, it could be called "random"...such bickering isn't useful for helping people understand how evolution builds complexity.
 
Instead of thinking in terms of Phenotypes, I find it easier to think of it in terms of alleles. This is also more accurate, because it reflects our models for evolution within a population. It is also more realistic, because not everything which affects an individual's fitness is phenotypically expressed. Changes in synonymous DNA, for example, have no over all effect in the amino acid sequence of the resulting protein.

I've told him this as well...it is important in understanding things like the sickle cell mutation. It isn't random--it confers a benefit against malaria and so it was selected multiple times in regions where Malaria did a lot of "culling'. Plus, I'd want to make sure that someone understood the basics before detailing the difference between phenotype and genotype (and the places where there is overlap...blood groups for example--we don't look at genes to see the difference, but they are hardly visible to the naked eye.)

The Selfish Gene helps clear up the confusion, because people always think of "fittest" as what humans find "desirable" or "good" or visibly evident. In biology the ones that live to reproduce are the fittest by definition--and the ones that don't, are the least fit by definition. This is true whether they live to reproduce through trickery, luck, strength, health, swiftness, phenotypic advantages, genotypic advantages, intelligence, or a combination thereof.
 
I've told him this as well...it is important in understanding things like the sickle cell mutation. It isn't random--it confers a benefit against malaria and so it was selected multiple times in regions where Malaria did a lot of "culling'. Plus, I'd want to make sure that someone understood the basics before detailing the difference between phenotype and genotype (and the places where there is overlap...blood groups for example--we don't look at genes to see the difference, but they are hardly visible to the naked eye.)

The Selfish Gene helps clear up the confusion, because people always think of "fittest" as what humans find "desirable" or "good" or visibly evident. In biology the ones that live to reproduce are the fittest by definition--and the ones that don't, are the least fit by definition. This is true whether they live to reproduce through trickery, luck, strength, health, swiftness, phenotypic advantages, genotypic advantages, intelligence, or a combination thereof.

Agreed. Although it might be more correct to say that those that the alleles which are most fit are the alleles which are passed on more often.

But hey, I'm into population genetics. :o
 
Dawkins response:

You rightly say that random mutation is NOT a good explanation for the evolution of giraffes' necks or, indeed, of anything else! Fortunately, nobody has ever suggested that it IS a good explanation. The correct explanation -- and it is indeed an excellently satisfying one -- is Darwinian natural selection. Darwinian natural selection is emphatically NOT the same thing as random mutation. Although random mutation does play a role in the theory, natural selection itself is the most important ingredient, and natural selection is the exact OPPOSITE of random.


In addition to the objections Walter Wayne brought up, I'll add another. The reason it has been said that "random" is such an awful word is that some people might misunderstand it, and creationists might misuse it. The same thing could happen with Dawkins' argument, and indeed it has.

Their complaints take the form of "If natural selection favors long necks, then why aren't their more long necks around? Why does only the giraffe have a long neck?" Here's a variation on that theme: "Why did the Okapi stop evolving? Why didn't its neck keep growing, like the giraffe?"

One of the most extreme variants was posted by Paul some time ago, quoting a creationist. "If fish turn into lizards, why are there still fish?" It's worth remembering that this creationist did in fact quote Mr. Dawkins, proving that Dawkins' argument could be twisted around just as easily as any other argument.

Dawkins' explanation suggests determinism and inevitability, and that's wrong. It was not inevitable that an eighteen foot tall ruminant would develop on the African plain.

So, each explanation has shortcomings. Each can be misunderstood and/or exploited by people who don't believe evolution. So, the question that interests me is why Dawkins et. al. are so insistent about using one or the other in all circumstances.
 
Yes.

Suppose you have two individuals with no obvious differences. One of them lives, and passes on its genes. One of them dies, and doesn't. If that ever happens, then the outcome is not deterministic. Hence, it's random.

Yes, I understand. But how does that help anyone understand the question in the OP? How does that explain natural selection?

Two guys of equal fitness are walking across the street. One gets hit by a car before having a chance to reproduce. The other reproduces. Once the random event occurs. The choice as to who can reproduce is no longer random. It is only random from the point of view before the accident...and only if you knew one was not going to be passing on their genes. Once the random event occurs, there is only one option left. The survivor is the only one with the chance to pass on genes--and as such, he is by definition the "fitter" because he's alive. Dead organisms, by definition, are the least fit. The outcome is deterministic once the random event has occurred. The same is true of evolution.

In the same way, all series of coin tosses are equally likely (random) before the first toss...but each toss eliminates the possible outcomes, and therefore acts as a "de-randomizer". At the end of the series of coin tosses, there are only 2 series left--all the coins that have been tossed + heads or all the coins that have been tossed + tails. That particular coin toss may be random--but the probable outcome for the series has been limited to only two possibilities, whereas, before the tosses--the probability of any given series is one-half times the number of coin tosses in the series...with the possibilities decreasing by one half with each throw (akin to selection) of the dice.

And by the way, I wouldn't use deterministic to describe evolution either. I wouldn't use random unless I defined it beforehand. Random as it applies to mutation means that all possible mutations are equally likely to occur. This isn't exactly true, in that mutations are not completely random--but it's close enough that it doesn't confuse the concept.
 
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So, each explanation has shortcomings. Each can be misunderstood and/or exploited by people who don't believe evolution. So, the question that interests me is why Dawkins et. al. are so insistent about using one or the other in all circumstances.

The way Dawkins explains it works better at helping younger people develop an intuitive understanding of evolution. Understanding evolution is more important than understanding how to address creationist claims.

And the question that interests me, is why are some people so intent on saying "evolution is random" (or driven by "chance alone" or stochastic or based on probabilities). Especially when it's so misleading and unclear for conveying meaning. I don't think Dawkins' explanation sounds determinist at all. I think it's the best way to describe evolution. I doubt you or Mijo or Walter Wayne could convey an understanding of evolution very well to anyone who was shaky on the subject--and wondering how all the complexity we see could have come about by chance.

Dawkins can, has, and does.
I can, have, and do.

Regarding giraffe necks, we know that those with longer necks preferentially survived over those with shorter necks. At one time, it was hypothesized that this gave them a feeding advantage in their environment (they could eat leaves others could not reach)--the current thinking is that there was a selective advantage to males with longer necks--they had a better weapon for fighting other males and were preferentially chosen by females as mating partners. I don't know of anyone who would define "sexual selection" as "random". I don't really understand how you think your explanation clears up the giraffe neck question better than Dawkins'...or any question like it. How exactly are the creationist canards you mentioned exacerbated by Dawkins' explanation?
 
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