Randomness in Evolution: Valid and Invalid Usage

[Southwind17]

I would argue, as marios does four posts down, that it is still wrong and the usual scientific definition of a random event fulfills neither of the options Richard Dawkins stated, but that a random event is an event that is not predetermined, where where identical inputs do not produce identical outcomes. (This is what marios refers to as "meaning #3").

In other words the "opposite of random" is "predetermined", or "predestined", or "preordained"; thus using the incorrect definition of random so that claiming that natural selection is the opposite of random is claiming that natural selection is predetermined, so it doesn't matter what else happens, but that the evolution of particular collections of traits were inevitable as they were driven by an already predetermined natural selection, a bit like dropping marbles onto a slope with a track running along the bottom, where the marbles will all end up running downhill along the track, wherever they started.

Talking about natural selection as though it is preordained is (a) wrong, and (b) playing into the hands of ID proponents.

I'm a little confused as to what you mean by "usual scientific definition", "neither of the options Richard Dawkins stated" and "inputs"? See, you've already managed to obscure matters beyond the pre-existing confusion mentioned by Dawkins!

 

[sol invictus]

I would argue, as marios does four posts down, that it is still wrong and the usual scientific definition of a random event fulfills neither of the options Richard Dawkins stated

There is no "usual scientific definition" of random. It's used in different ways in different fields, and even in different contexts within the same field. That's what makes this debate so utterly pointless.

"Random" simply isn't a precise term, and scientists don't use it as one. When there is the possibility of confusion, they either use a different term or qualify it.

In other words the "opposite of random" is "predetermined", or "predestined", or "preordained";

No, because again - "random" doesn't have a single definition, and therefore it doesn't have a definite opposite. FYI "predetermined", "predestined" etc. are not really technical terms. The term you're presumably looking for is "deterministic" (or "determined by initial conditions"). Its opposite is "non-deterministic". Those are specific terms with unambiguous meanings, unlike "random".

 

[Dancing David]

Eeeeek!

Super zombie thread!

posted by JimBob
In other words the "opposite of random" is "predetermined", or "predestined", or "preordained"; thus using the incorrect definition of random so that claiming that natural selection is the opposite of random is claiming that natural selection is predetermined,

Major fallacy, fallacy of construction, the defintion of the opposite of random is inderterminate, then this is an overgeneralization.

 

[aggle-rithm]

And variation doesn't need to be random at all for evolution to work. Sexual recombination is a great way for making new varieties--no "random mutation" is needed... the genes are just shuffled.

This also, neatly, allows evolvability, a key requirement for evolution to work. Sexual recombination covers a multitude of genetic "sins", which arise inevitably as mutation takes place. These sins might later become assets, but in the meantime they are kept hidden so as not to do any damage.

 

[jimbob]

Eeeeek!

Super zombie thread!


Major fallacy, fallacy of construction, the defintion of the opposite of random is inderterminate, then this is an overgeneralization.

Why?

The overgenralisation is in the statment "opposite of random". I would accept "Opposite of the frequently used definition of random as 'directionless' "... even though it is ugly. "Natural Selection has direction, but no intelligent guidence".

I believe you are an engineer, so what problem do you the statement that a random system can have different outcomes for identical inputs, whilst a nonrandom system can't. In other words a nonrandom output is predetermined, whilst a nonrandom output isn't.

It is the statement "Opposite of random" that I object to.

That is equivalent to a boolean NOT function, and implies (to me) that natural selection has no important features of randomness. Furthermore, I would argue, and there are evolutionary biologists on that thread who agree that the definition as used by me, is a workable definition in their field of evolutionary biology. A statistician on this forum has also agreed that my definition of random is how statisticians define "random".

I would say that it fits the definition of randomness in physics, so that definition is pretty common in many disparate scientific disciplines.

As I have said several times before, the problem I have is that it is perfectly reasonable, and indeed in many respects technically more correct to describe Natural Selection as a random process, or probabilistic, whilst it is only nonrandom i a particular colloquial definition. Attacking people for technical accuracy is itself misleading and confusing.


I would argue that sometimes in complex systems nonrandom variables are treated as random to help analysis, but these are actually pseudorandom rather than actually random.

 

[Paul C. Anagnostopoulos]

The term you're presumably looking for is "deterministic" (or "determined by initial conditions"). Its opposite is "non-deterministic". Those are specific terms with unambiguous meanings, unlike "random".

I agree that random is a slippery term that's best avoided. However, it seems to me that as far as processes are concerned, there is no logical room left after we include deterministic and random factors. That makes random a synonym for nondeterministic. Am I missing something?

I presume we agree that a stochastic process is one that has some random generators. Here is the definition from the Penguin Dictionary of Mathematics:

stochastic process. A random process. Common usage excludes essentially deterministic processes that are subject only to random errors.

~~ Paul

 

[Dancing David]

Why?

The overgenralisation is in the statment "opposite of random". I would accept "Opposite of the frequently used definition of random as 'directionless' "... even though it is ugly. "Natural Selection has direction, but no intelligent guidence".

I believe you are an engineer, so what problem do you the statement that a random system can have different outcomes for identical inputs, whilst a nonrandom system can't.

Hardly, I am a computer aide, with a psych degree and social work as a former profession.

In other words a nonrandom output is predetermined, whilst a nonrandom output isn't.

Now that is also a statement I don't agree with, you mean a closed system with known inputs and responses to inputs?

It is the statement "Opposite of random" that I object to.

Now that i can understand.

That is equivalent to a boolean NOT function, and implies (to me) that natural selection has no important features of randomness. Furthermore, I would argue, and there are evolutionary biologists on that thread who agree that the definition as used by me, is a workable definition in their field of evolutionary biology. A statistician on this forum has also agreed that my definition of random is how statisticians define "random".

I would say that it fits the definition of randomness in physics, so that definition is pretty common in many disparate scientific disciplines.

As I have said several times before, the problem I have is that it is perfectly reasonable, and indeed in many respects technically more correct to describe Natural Selection as a random process, or probabilistic, whilst it is only nonrandom i a particular colloquial definition. Attacking people for technical accuracy is itself misleading and confusing.


I would argue that sometimes in complex systems nonrandom variables are treated as random to help analysis, but these are actually pseudorandom rather than actually random.

 

[lenny]

I agree that random is a slippery term that's best avoided.

in fact it is used regularly and with little confusion in statistics, physics, and (slightly less so, like all concepts) philosophy.

why it causes such recurrent gnashing of teeth in discussions of evolution ... there must be several psychology dissertations in there...

However, it seems to me that as far as processes are concerned, there is no logical room left after we include deterministic and random factors. That makes random a synonym for nondeterministic. Am I missing something?

I presume we agree that a stochastic process is one that has some random generators. Here is the definition from the Penguin Dictionary of Mathematics:

stochastic process. A random process. Common usage excludes essentially deterministic processes that are subject only to random errors.

~~ Paul

i do not think you are missing anything.

perhaps a note that "subject only to random errors." is intended to refer to observational noise, not dynamic noise.

and the idea of including "deterministic and random factors" is tricky in nonlinear systems (where we cannot invoke linear superposition). not a problem in defining dynamical systems, but fundamental in terms of identifying a dynamical system.

 

[sol invictus]

I agree that random is a slippery term that's best avoided. However, it seems to me that as far as processes are concerned, there is no logical room left after we include deterministic and random factors. That makes random a synonym for nondeterministic. Am I missing something?

Yes - the way the term "random" is used, it is not synonymous with "non-deterministic". "Random" often implies "flat distribution", "directionless", or "equiprobable". As one example, consider the lottery where the numbers are drawn from bouncing balls. Is that process "random"? Certainly most people would agree that it generates random numbers, and yet the process itself might be deterministic.

Another example is suggested by your dictionary definition. Consider a measurement in a physics experiment, say of the length of some object. The length is not precisely defined due to quantum fluctuations, and therefore the result of the measurement is, strictly speaking, non-deterministic. And of course in addition there are the usual types of measurement errors, which may or may not be deterministic.

And yet, no one in their right mind would say that the results of measuring something with a tape measure are "random". They might say the errors are random (even though they may be deterministic), but they would never say the result is. Why not? Because the result has a non-zero mean and small fluctuations around that mean. We don't usually characterize distributions like that, distributions that are fairly sharply peaked around some non-zero value, as "random".

I presume we agree that a stochastic process is one that has some random generators.

"Stochastic" is close to synonymous with non-deterministic, but carries a slightly different connotation. In physics it's often used for systems in which the non-deterministic element is some kind of noise, thermal or otherwise. More generally it usually implies the presence of some kind of direction, force, or tendency, one that is perturbed but not destroyed by the noise. I'd say it's the best term to describe evolution.

 

[Wowbagger]

More generally it usually implies the presence of some kind of direction, force, or tendency, one that is perturbed but not destroyed by the noise. I'd say it's the best term to describe evolution.

That does sound like a nice, succinct summary of evolution, to me.

 

[jimbob]

Why?

The overgenralisation is in the statment "opposite of random". I would accept "Opposite of the frequently used definition of random as 'directionless' "... even though it is ugly. "Natural Selection has direction, but no intelligent guidence".

I believe you are an engineer, so what problem do you the statement that a random system can have different outcomes for identical inputs, whilst a nonrandom system can't.

Hardly, I am a computer aide, with a psych degree and social work as a former profession.

Sorry, I must have been confusing you for someone with a similar name/location or posting style

In other words a nonrandom output is predetermined, whilst a nonrandom output isn't.

Now that is also a statement I don't agree with, you mean a closed system with known inputs and responses to inputs?

Schrödinger's Cat could be a closed system that is random (if the radioactive source is placed in the box next to the cat.

If you don't like cruelty to imaginary cats, you could change the response of the detector to maybe multiply an input by a factor that depended on the number of radiation counts in the preceding five seconds, or something akin to that. The external inputs will be known , and even how it responds to particular random events, but it will still produce a random output, because it has its own modification of the inputs according to some random number.


Many statistical techniques are often based on assuming not that something is *actually* random, on other confounding factors that are too complex to model.

In such cases "randomness" might be illusory, but that is not the situation in evolution.

For example, a collection of random mutations in a flu virus suddenly can make it far more lethal, so these few mutations can exert a large evolutionary pressure on birds.

A different set of mutations, and you get a different set of evolutionary pressures exerted on the host population. Just because we can't *see* proteins generated by the immune system doesn't make this evolution any less important than running ability for gazelles, for example.

It is the statement "Opposite of random" that I object to.

Now that i can understand.

Furthermore, it means that if you learn that Natural Selection is nonrandom, then if you want to study population genetics and its interaction with evolution, you will have to unlearn this "fact".

Evolution can be simply approximated as nonrandom if you are considering sufficiently large populations in a stable environment and the environment remains stable for sufficient time. This is the easiest situation to understand, and is probably what is often implicitly assumed in discussions about how evolution works in theory. This is not what happens in real environments though. Not even in simple environments like flasks of e-coli with no other bacteria present.

 

[Southwind17]

Sorry, I must have been confusing you for someone with a similar name/location or posting style

Ivor the Engineer comes to mind!

 

[sphenisc]

Stochasticity and speciation events

http://www.nature.com/nature/journal/v463/n7279/full/nature08630.html

 

[jimbob]

Stochasticity and speciation events

http://www.nature.com/nature/journal/v463/n7279/full/nature08630.html

And new scientist's article and interview about this:

http://www.newscientist.com/article/mg20527511.400-accidental-origins-where-species-come-from.html?full=true

(I don't know about the blocking for registering in that site now)

anyway, form my viewpoint here are the key paragraphs:

The key point emerging from the statistical evidence, Pagel stresses, is that the trigger for speciation must be some single, sharp kick of fate that is, in an evolutionary sense, unpredictable. "We're not saying that natural selection is wrong, that Darwin got it wrong," Pagel adds. Once one species has split into two, natural selection will presumably adapt each to the particular conditions it experiences. The point is that this adaptation follows as a consequence of speciation, rather than contributing as a cause. "I think what our paper points to - and it would be disingenuous for very many other people to say they had ever written about it - is what could be, quite frequently, the utter arbitrariness of speciation. It removes speciation from the gradual tug of natural selection drawing you into a new niche," he says.

This has implications for one of the most contentious aspects of evolution: whether it is predictable or not. If Pagel is correct, natural selection shapes existing species in a gradual and somewhat predictable way, but the accidental nature of speciation means that the grand sweep of evolutionary change is unpredictable. In that sense his findings seem to fit with the famous metaphor of the late Stephen Jay Gould, who argued that if you were able to rewind history and replay the evolution of life on Earth, it would turn out differently every time.

That is why I dislike descriptions of evolution as "nonrandom".

 

[Wowbagger]

That is why I dislike descriptions of evolution as "nonrandom".

Almost the same reason the climate shouldn't be called "nonrandom".

 

[mijopaalmc]

As I recall, two of the most commonly advanced arguments about how evolution is non-random that:

1. Evolution is predictable in the long term.
   
2. Natural selection makes evolution non-random.

Doesn't this study cast doubt on both?

 

[recursive prophet]

"Stochastic" is close to synonymous with non-deterministic, but carries a slightly different connotation. In physics it's often used for systems in which the non-deterministic element is some kind of noise, thermal or otherwise. More generally it usually implies the presence of some kind of direction, force, or tendency, one that is perturbed but not destroyed by the noise. I'd say it's the best term to describe evolution.

And I'd say this is one of the more succinct deconstructions of the semantics involved that I've seen, sol. Remember when we discussed an applicable definition for stochastic back on that other thread? It began with a question I asked in the evo-facts stickey? Is evolution stochastic? That thread went on for 10 pages after it was split, and I'm having a deja vous moment. Did I already tell you about this?

Anyway, hail, hail, the gangs all here! Hi mijo, jimbob. I don't think Articulett or Dr. Adequate will be joining us; indisposed, what? Here's a link to that other quite similar thread-http://www.internationalskeptics.com/forums/showthread.php?t=131514 Perhaps some of the replies from there can be recycled.

 

[Wowbagger]

As I recall, two of the most commonly advanced arguments about how evolution is non-random that:

1. Evolution is predictable in the long term.
   
2. Natural selection makes evolution non-random.

Doesn't this study cast doubt on both?

To address the first one: It is a little like the difference between weather and climate. Climate is predictable in the long run. The more specifics of weather conditions are not.
The general directions of evolution are predictable, in the long run. The specific details are usually not.

I believe this applies to what the study is saying, also. Since specific occurrences of speciation are dependent on the little details, we would expect to have difficulty knowing in advance when they will occur, and which features it will involve. But, we can figure out many of the general directions they would take, to survive in their niches, when they do.


The study says nothing about the second one. The influence that is Natural Selection is still nonrandom.

 

[mijopaalmc]

To address the first one: It is a little like the difference between weather and climate. Climate is predictable in the long run. The more specifics of weather conditions are not.
The general directions of evolution are predictable, in the long run. The specific details are usually not.

I believe this applies to what the study is saying, also. Since specific occurrences of speciation are dependent on the little details, we would expect to have difficulty knowing in advance when they will occur, and which features it will involve. But, we can figure out many of the general directions they would take, to survive in their niches, when they do.


The study says nothing about the second one. The influence that is Natural Selection is still nonrandom.

Did you read the abstract of the article?

Phylogenies reveal new interpretation of speciation and the Red Queen

The Red Queen1 describes a view of nature in which species continually evolve but do not become better adapted. It is one of the more distinctive metaphors of evolutionary biology, but no test of its claim that speciation occurs at a constant rate2 has ever been made against competing models that can predict virtually identical outcomes, nor has any mechanism been proposed that could cause the constant-rate phenomenon. Here we use 101 phylogenies of animal, plant and fungal taxa to test the constant-rate claim against four competing models. Phylogenetic branch lengths record the amount of time or evolutionary change between successive events of speciation. The models predict the distribution of these lengths by specifying how factors combine to bring about speciation, or by describing how rates of speciation vary throughout a tree. We find that the hypotheses that speciation follows the accumulation of many small events that act either multiplicatively or additively found support in 8% and none of the trees, respectively. A further 8% of trees hinted that the probability of speciation changes according to the amount of divergence from the ancestral species, and 6% suggested speciation rates vary among taxa. By comparison, 78% of the trees fit the simplest model in which new species emerge from single events, each rare but individually sufficient to cause speciation. This model predicts a constant rate of speciation, and provides a new interpretation of the Red Queen: the metaphor of species losing a race against a deteriorating environment is replaced by a view linking speciation to rare stochastic events that cause reproductive isolation. Attempts to understand species-radiations3 or why some groups have more or fewer species should look to the size of the catalogue of potential causes of speciation shared by a group of closely related organisms rather than to how those causes combine.

(emphasis added)

 

[Wowbagger]

Did you read the abstract of the article?

Yes. Do you think anything I said contradicts anything it said?