Randomness in Evolution: Valid and Invalid Usage

[Paul C. Anagnostopoulos]

The most common argument against evolution by natural selection's being random is that mutation is random but natural selection isn't. Therefore, one cannot appeal to the randomness of mutation to say that evolution by natural selection is random. You seem to be arguing that mutation is acausal because the things that ultimately cause it are acausal.

I have no idea what you're trying to say here. Why can't I appeal to the randomness of mutation to argue that evolution is a random process?

Isn't your argument regarding acausality and mutation both self-contradictory and inconsistent in light of your argument regarding randomness and evolution?

What do you think my argument about randomness and evolution is? It's nothing more than suggesting that "evolution is random" is a misleading statement. I didn't say "incorrect," just "misleading."

You might want to check this post out for my position on saying "evolution is random, full stop":

I must have had you confused with someone else.

~~ Paul

 

[Paul C. Anagnostopoulos]

Here we go:

http://www.puc-rio.br/marco.ind/stoch-a.html

Following Dixit & Pindyck's textbook (p.60): "Stochastic process is a variable that evolves over time in a way that is at least in part random".

And then the definition of pure random process:

http://stats.oecd.org/glossary/detail.asp?ID=3807

Evolution is a stochastic process, but not a pure random process. I believe that when most people hear "random process" they think "pure random process."


~~ Paul

 

[Meadmaker]

Sweet Jesus. Not again.

This thread will come to a bad end.

If we're lucky. It might not end.

(And of course, after I read more of it, I'll probably comment.)

 

[mijopaalmc]

I'll take koans involving equivocation for $800 Alex.

Perhaps those of you who feel it's worth your time to interact with an intransigent might try getting him to accept that mutations are random, but evolution is not. Would that be verbiage he could agree with, or would we still need to clad it in several layers of defining definitions and explaining explanations plus a nice whipped metaphysical topping?

What about it mijo? Would a simple, cut and dried statement like "mutations are random, but evolution is not" be satisfactory for you to give up all the non-sense you've wasted server space with or will you continue to obfuscate and equivocate?

It's always funny when the people who insist that I am obfuscating and equivocation are the ones what are actually obfuscating and equivocating.

I think Vorticity said it best way back in May of last year:

Here's another thing that's been bugging me:

...
If a series of coins are tossed that have a 50/50 chance of coming up heads or tails, but only those that come up heads are selected to be placed in a piggy bank and the coins that come up tails are thrown into a river, then the results of the selection process are not random.

This idea has been stated in several forms in this thread, i.e. that while the mutation process is certainly random, the process of natural selection by which less-well-adapted variants are culled from the population is deterministic.

This seems to me to be a highly dubious claim. I'm having trouble seeing how the natural selection process could be completely deterministic. Certainly, the more-well-adapted variants will have a higher chance of surviving and reproducing. Perhaps siginificantly higher. Likewise, a poorly-adapted variant will have a much higher chance of becoming lunch. But it's not a certitude. These probabilities are not 1 and 0.

To put it another way, suppose we know the set of gene/allele frequencies of a population in a given generation. Even if we suppose that no mutation events will occur between this generation and the next, we cannot in advance specify the precise gene/allele content of the next generation. There is still significant randomness left over. Who will be eaten, who will reproduce, how much will they reproduce, etc. Now of course this is a sort of 'directed randomness', in the sense that the more adapted variants have a much better chance. But this does not suddenly make it nonrandom.

I repeated this sentiment in my OP in What evidence is there for evolution being non-random?:

The title of the thread says it all. I understand that evolution is a process directed through natural selection, but, as I understand it, natural selection is based on the probability, not certainty, of an organism with a specific "fitness complement" (i.e., the set of genes that contribute to its survival and reproduction relative to others of the same species). An individual whose fitness complement confers a greater chance of survival and reproduction is only more likely to survive and reproduce that one with a fitness complement that a lesser chance, but the survival and reproduction is not determined to such an extent that all the individuals with a specific fitness complement don not survive and reproduce. Thus, it is possible for one individual with a certain fitness complement to survive while another individual with the same fitness complement doesn't.

I only ask this, because I am thoroughly disappointed in the evidence that I have received from the posters in this thread. No-one to my knowledge has either explained how a process that operates on probability is non-random or directed me toward a resource that does. They all seem to be more interested, as is most of the literature on the internet that doesn't specifically deal with non-random genetic processes such as mutation and unequal cross over, in refuting the creationist straw man that holds that organisms in their current state are far too complex to have arisen by chance.

I would appreciate it if someone could point me toward some literature (especially of the peer-reviewed kind)that explain clearly and concisely why evolution is non-random.

Thus far, I have only received responses that explain why evolution is non-random in every other way than the way in which I defined it, which is equivocation on the part of the respodants.

 

[Wowbagger]

Are there any chaotic physical systems that wouldn't be significantly influenced by quantum uncertanites given enough time?

None that I can think of. Which is why it is futile to single Evolution out as random for that reason. Everything would be random in that way, and so the word becomes meaningless, in that context.

Another valid use of "random" is to mean "directionless". I'd prefer a more accurate term like "directionless".

I can agree with that! Perhaps "directionless" would be better than "unconsciously indifferent"?

Wowbagger's favourite term "unconciously indifferent"

For the record, my favorite term happens to be "paredolia", which is followed closely by "The Tyranny of a Discontinuous Mind", "psychological neotny", and then "hoopy frood". I would say "unconsciously indifferent" probably ranks somewhere towards the bottom of the Top 200 list.

The word "indifferent" has the connotation of a person not caring about about something he could care about. Wowbagger needs feels the need to add "unconciously" to it in a futile attempt to remove the connotation, but it only makes the term an oxymoron.

Not necessarily. What I mean is "Not just indifferent, but indifferent in the way only a cold, unconscious thing could be."

The scientific concepts are non-intuitive, and there simply are no everyday words that are commonly understood by non-scientists that accurately describe them.

We can at least try. And, it might be better to experiment with language, here, before using phrases in a more formal manner.

What do you think of "directionless" as a substitute for "indifferent"?

Using the word "random" to describe evolution is fine, but in popular science texts perhaps need to be explained what is meant with it.

I agree with that. Though, that does not mean the readers are going to pick up on it. One look at the word "random", and they will automatically assume they know what it means, and ignore the explanation.

I understand 2 and 4, which are the same thing. What are the other three?

I would say 2 and 4 are related to each other, but not the same thing. Not all variables in a stochastic model are precise enough to reach the quantum level.

In the OP, it should be clear why I separated them out. It is valid to use stochastic models to help us describe Evolution. However, it would be invalid to dismiss it as invalid due to quantum uncertainty, because every other science would then be "invalid" in the same way. And, yet, we all know all the legit sciences work pretty darn well, in spite of that.

The other three are just other uses of the term, that I have seen around.

I think definition #3 could better be summarized as "pure random", incidentally.

Why are you trying to define "random" is such a way that it if precluded from being random by definition?

Correct me if I am wrong, but I do think I am using the word in a similar manner as you, in the second bullet point about stochastic processes.

If I am wrong, then please inform me of how your definition is different. (And, optionally, how that difference is relevant to Evolution, if at all.)

Mutations, that have a selective effect (advantageous or disadvantageous) must affect the selective landscape for other organisms in the ecosystem. Which mutations occur first could affect the "direction" of the selective pressures.

I agree with that, but fail to understand how that is an objection to the bullet point you quoted.

On to the statement about predictions:
(snip)

Exactly! And, of course, all those examples you gave work against the idea of Evolution being purely random. The Creationists don't know what they're missing!

If we're lucky. It might not end.

I think I might be a gluten for punishment.

 

[Taffer]

Have you ever taken a statistics course?

Yes. They were a requirement for my degree.

The null hypothesis is most often assumed to yield a certain distribution, and then the sample statistic is tested against this distribution, which in turn determines probability of the null hypothesis being true given the data collected due purely to variations in the sample.

That is how hypotheses are tested against a null hypothesis. You said that randomness, as you have defined it, was used in the specific statistical tests used for evolutionary biology. I don't dispute this. What I dispute is that your definition is the one used, since it makes no difference to the tests. Further, we test AGAINST a random null hypothesis, to show that the data is not random.

 

[mijopaalmc]

Correct me if I am wrong, but I do think I am using the word in a similar manner as you, in the second bullet point about stochastic processes.

If I am wrong, then please inform me of how your definition is different. (And, optionally, how that difference is relevant to Evolution, if at all.)

Here is your bullet point:

* Describing a model of evolution, where our knowledge is not perfect. Such usage implies that the Evolution is actually deterministic behind the scenes. But, information about its initial conditions are lost to time and thermodynamics; and the number of variables involved in the current conditions are too many for us to handle. Therefore, we resort to simplified models that utilize either stochastic algorithms and/or random variables. As the models improve, the less we rely on these things.

You are quite explicit that your are intent on only describing the models as stochastic and not the actual process of evolution by natural selection. I, on the other hand, think that the way evolutionary biologists describe the process of evolution by natural selection as it occurs in the physical world is inherently stochastic (and not necessarily just because of out lack of knowledge of the details of the process) and that the existing data that we have corroborates this interpretation.

 

[sol invictus]

Thus far, I have only received responses that explain why evolution is non-random in every other way than the way in which I defined it, which is equivocation on the part of the respodants.

That's because your definition is totally useless, as we already established in that other horrible thread.

It also doesn't correspond to any of the 10 or so definitions from various sources which were posted there, including the one from a standard text on probability and statistics.

 

[mijopaalmc]

That is how hypotheses are tested against a null hypothesis. You said that randomness, as you have defined it, was used in the specific statistical tests used for evolutionary biology. I don't dispute this. What I dispute is that your definition is the one used, since it makes no difference to the tests. Further, we test AGAINST a random null hypothesis, to show that the data is not random.

I'm sorry but that is how hypotheses are tested. For a parametric test, the statistic defines a tail on the distribution for which the null hypothesis true just by the variation in the sample. The p-value is then the area in the tail, which translates to the probability that the null hypothesis is true by the variation in the sample. If p-value is greater than the confidence level, the null hypothesis cannot be rejected. If p-value is less than the confidence level, the null hypothesis is rejected.

 

[mijopaalmc]

That's because your definition is totally useless, as we already established in that other horrible thread.

It also doesn't correspond to any of the 10 or so definitions from various sources, including the one from a standard text on probability and statistics.

And where did you provide these examples?

For instance the definition you provided from the Oxford English Dictionary does in fact back up my definition from the American Heritage Dictionary:

random, n., a., and adv.

<snip noun definitions>

B. adj. (from phr. at random: see A. 3).

1. a. Not sent or guided in a special direction; having no definite aim or purpose; made, done, occurring, etc., at haphazard.

b. Statistics. Governed by or involving equal chances for each of the actual or hypothetical members of a population; also, produced or obtained by a random process (and therefore completely unpredictable in detail); random distribution, a probability distribution, esp. the Poisson distribution; random error: see ERROR 4d; random noise (see quot. 1954); random number, a number selected from a given set of numbers in such a way that all the numbers in the set have the same chance of selection; also, a pseudorandom number; random process, (a process characterized by) a sequence of random variables (see also quot. 1937); random sample, a sample drawn at random from a population, each member of it having an equal or other specified chance of inclusion (sometimes contrasted with quota sample s.v. QUOTA n. 4); so random sampling; random selection, a random sample; random sampling; random variable, variate, a variable whose values are distributed in accordance with a probability distribution; random walk, the movement of something in successive steps, the direction, length, or other property of each step being governed by chance independently of preceding steps.

The Poisson distribution is not in anyway uniform, so can't be properly described by the first sense in 4, so it must be random by some other metric.

 

[sol invictus]

Dear god.

Really? So why not name one?

Every single example you gave was a mathematical model. Should I remind you (again) of what they were? One particularly entertaining one was "orbital dynamics", by which you meant the ideal N body problem with only classical Newtonian gravity acting.



Nowhere in there is a definition of random, let alone one like yours. I just checked two books on probability on amazon using booksearch. Neither appears to define "random" (although both use the word quite a lot).

Here are a long list of web definitions, not a single one of which comes even close to yours:

http://www.google.com/search?q=define:+random

 

[mijopaalmc]

Dear god.

Really? So why not name one?

Every single example you gave was a mathematical model. Should I remind you (again) of what they were? One particularly entertaining one was "orbital dynamics", by which you meant the ideal N body problem with only classical Newtonian gravity acting.



Nowhere in there is a definition of random, let alone one like yours. I just checked two books on probability on amazon using booksearch. Neither appears to define "random" (although both use the word quite a lot).

Here are a long list of web definitions, not a single one of which comes even close to yours:

http://www.google.com/search?q=define:+random

Congratulations, you managed to find merely the most commonly used definition of "random" (and probably the only definition of "random" used on those sites) and are now trying to pass it off as only definition in use in the English language.

 

[UnrepentantSinner]

I think I might be a gluten for punishment.

I'll strand by you.

 

[mijopaalmc]

Does anyone else recognize that "evolution by natural selection is random (stochastic)" and "evolution by natural selection is a random (stochastic) process" could mean different things?

 

[Paul C. Anagnostopoulos]

Does anyone else recognize that "evolution by natural selection is random (stochastic)" and "evolution by natural selection is a random (stochastic) process" could mean different things?

Since evolution is a process, I don't see how they could mean different things. But I'm willing to learn.

~~ Paul

 

[cyborg]

I said it before and I'll say it again:

Variation is non-deterministic with respect to form.
Selection is deterministic with respect to form.

It does not matter ONE BIT whether or not that variation is caused by quantum mechanics, a die roll, a list of numbers, or even, horrors, a deterministic process, etc.. the important part is the deterministic relationships.

If variation is based on form then mutation is not the mechanism of change in form - previous forms are.

If selection is not based on form then what variations arise are inconsequential to what forms persist.

These are the basic and fundamental conditions that must be satisfied for any system that would be considered "evolutionary" - be it biological or a abstract model.

NOTA BENE deterministic with respect to is not the same as wholly determined by - yes mijo, I am thinking of you and your twins. Their form does not wholly dictate their selection but to argue that their selection is not deterministic with respect to it would be WRONG.

 

[sol invictus]

Congratulations, you managed to find merely the most commonly used definition of "random" (and probably the only definition of "random" used on those sites) and are now trying to pass it off as only definition in use in the English language.

So mijo, you really don't remember that long and excruciatingly annoying discussion we had in the "Evolution Not Random" thread about how your definition is useless, since according to it every single process in the world is random?

Strange, because here you are in a different thread more recently parroting almost verbatim what I was telling you there all along:

Except, to the best our knowledge, quantum mechanical events are random no matter how you try to constrain the variables. While it is mathematically true that a function of a random variable is itself a random variable*, it is not very useful in describing real world physical processes, because every actual physical process is based on quantum mechanics. However, it still important to make a distinction between non-chaotic deterministic systems (i.e., roughly systems in which small variations in initial conditions lead to small variations in final conditions) and chaotic deterministic systems (i.e., roughly systems in which small variations in initial conditions lead to large variations in final conditions). Evolution is most likely the latter because it takes place in a in an environment that is dependent on other chaotic systems (e.g., climate and weather). This means that exact predictions cannot be made about specific elements of adaptation, whereas predictions about the general course of adaptation can be made and are best handled in a probabilistic/statistical framework.

*meaning that random mutation based on probability leads to random evolution by natural selection regardless of whether natural selection itself is random or deterministic

 

[Taffer]

I said it before and I'll say it again:

Variation is non-deterministic with respect to form.
Selection is deterministic with respect to form.

It does not matter ONE BIT whether or not that variation is caused by quantum mechanics, a die roll, a list of numbers, or even, horrors, a deterministic process, etc.. the important part is the deterministic relationships.

If variation is based on form then mutation is not the mechanism of change in form - previous forms are.

If selection is not based on form then what variations arise are inconsequential to what forms persist.

These are the basic and fundamental conditions that must be satisfied for any system that would be considered "evolutionary" - be it biological or a abstract model.

NOTA BENE deterministic with respect to is not the same as wholly determined by - yes mijo, I am thinking of you and your twins. Their form does not wholly dictate their selection but to argue that their selection is not deterministic with respect to it would be WRONG.

There was a farmer, had a dog, and...

 

[Taffer]

I'm sorry but that is how hypotheses are tested. For a parametric test, the statistic defines a tail on the distribution for which the null hypothesis true just by the variation in the sample. The p-value is then the area in the tail, which translates to the probability that the null hypothesis is true by the variation in the sample. If p-value is greater than the confidence level, the null hypothesis cannot be rejected. If p-value is less than the confidence level, the null hypothesis is rejected.

I'm sorry, but that's not what I'm arguing about. I'm arguing about whether your definition of random is important in statistics.

 

[jimbob]

Are there any chaotic physical systems that wouldn't be significantly influenced by quantum uncertanites given enough time?

None that I can think of. Which is why it is futile to single Evolution out as random for that reason. Everything would be random in that way, and so the word becomes meaningless, in that context.

There are non-chaotic physical systems where this isn't the case. The key word is "significantly".

I design and develop power transistors; these rely on the law of large numbers to average out quantum uncertainties, which make them work with very large numbers of electrons. Because they are power devices, they have to be large enough to manage high electric fields, so "normal" semiconductor physics (dealing with conduction bands and Fermi-Dirac statistics is valid, in a way that is getting less so for very small devices.)

Mutations, that have a selective effect (advantageous or disadvantageous) must affect the selective landscape for other organisms in the ecosystem. Which mutations occur first could affect the "direction" of the selective pressures.

I agree with that, but fail to understand how that is an objection to the bullet point you quoted.

I would argue that this means that the selection pressures, and thus the "direction" of evolution is subject to change due to random events.

If the direction is subjected to random change, then surely this is "random".

On to the statement about predictions:
(snip)

Exactly! And, of course, all those examples you gave work against the idea of Evolution being purely random. The Creationists don't know what they're missing!

I think this is mostly an issue of semantics. I think that the interesting aspect is that the actual mechanism and implications. I would agree that evolution isn't "completely random", but I would argue that nor is it determined either.

I would argue that, in stable environments, the random mechanisms would tend to produce repeatable results (i.e. the stability of the environment provides a constant enough selective pressure). For these conditions I would argee that describing evolution as random, is unhelpful.

Over long timescales, with unstable environments, I would argue that the random element is important, as it will alter the direction of the selection pressures. This is important if one is discussing the evoultion of humanity, as the KT impact, the ice-ages, the cambrian extinction, Toba, etc could have altered the course of evolution so that intelligent hominids wouldn't evolve, maybe so that nothing occupied the ecological niche of complex-tool and fire using social animals.