Randomness in Evolution: Valid and Invalid Usage

[zosima]

Mijo has a very strong need to see evolution as random He cannot cede that it might not be useful or informative to say otherwise. Your explanations are patient and stellar. But I suggest you read this thread http://www.internationalskeptics.com/forums/showthread.php?t=82155&page=65 or at least pieces of it... because all the people who insist that evolution is "not nonrandom" appear there and have the same non arguments. All biologists, and people who actually teach and explain evolution to others recognize that your explanation is correct and useful and clear... as is Dawkins whom mijo imagines he's more of an expert than (he has no expertise in evolution at all as one can see by any of his posts here, but he appears to imagine himself as having expertise in both evolution and probability.) So it's not you.

Any thread where anyone says "evolution is not random"-- the same people appear saying the same things trying to convince someone or themselves that it really is. Every one tries to explain very carefully thinking that they might make progress, but it never happens. This thread from over a year ago will show you how the same people have identical "non arguments" to support the same garbled way of obfuscating understanding. Interestingly, it's the very same technique used by creationists to obfuscate understanding of natural selection by claiming that scientists think "all this life stuff just came about randomly"

Yes, there is no plan--no designer needed... but it's far from "random"-- it's a progressive accumulation of the best reproducing DNA over time... a long, long time. Darwin's theory was about natural selection... he had no way to know if the variations in pheontype were "random" or not. They don't need to be "random" for evolution to work.

Thanks for the tip, on your advice, unless (s)he presents something substantive, I'm out.

 

[jimbob]

zosima,

a quick "heads up" about articulett: (ETA she ikes using the phhrase "heads up" about people she cionsiders to be her oponents, and doesn't read what they say either..)

She has a strong need to see everything in black and white, and also to denegrate other people who she thinks is on "the other side".

She has consistently accused miojo of being a creationist, when there is no evidnce of that in his posts.

I suggest you read what people are catually saying and ignore articulett's interpretation of what they say.

(I'd also recommend missing out most of the esoteric discussion about who knows what about statistics ...)

Anyway:

There is more consensus than articulett would suggest:

As far as I am concerned there is a slight difference in emphasis;

Here is an example discussion about natural selection on another thread, hidden for brevity...

My expansion on the other thread below:

If identical conditions do not lead to the same outcome every time, then I would consider that to be a working definition of "random".

Agreed.

I would argue that a quantum decay event is the archetypal "random event".

Also agreed.

In the context of evolution, I would argue that because weather is a highly nonlinear system, quantum events can be magnified to have a significant effect on the weather. If this is the case, then there is going to be a random element in natural selection. I would also argue that the relationships between organisms is even more nonlinear than the weather, and a chance mutation happening befoore anonther could alter the selective pressures on other organisms within the ecosystem, and thus alter the "direction" of evolution in the ecosystem.

If we assume weather to be affected at a significant level by quantum events, I would agree with you. I also agree that interorganism interactions are very complex, and specific mutation events are boardering on quantum randomness. Of course, we don't know that for certain, but so far that is how it looks.

This means that should one have the luxury of creating identical universes just before the KT impact, the course of evolution in each of these initially identical universes would diverge.

Agreed.

Given the low chance of any individual organism managing to have reproducing offspring, I would contend that there was noting inevitable about the emergence of hominids, until some time after the last common ancestor with apes.

Agreed.

Evoulution would happen in all the other cases, it is just that the species mix, and indeed occupied niches would probably differ in each case. There is nothing special abut the emergence of humanity, except to us...

Yep, couldn't put it better myself.

Walter Wayne, this is a perfect example of what I asked for.

Do you actually disagree with anything in my post below, or is it made up of "non-arguments"?

Hidden for brevity:

Indeed wowbagger.

I would define an outcome as "random" if identical starting conditions could lead to significantly different outcomes. I think this would mean that any cahotic physical system would be random by this description, as the infinite precision would mean that quantum fluctuations would eventually have a significant difference, in a way that isn't the case for non-chaotic systems. ETA: Sol, is that still the understanding? IIRC it was when I was an undergrad, but I tended to concentrate on solid-state physics...

I agree that there are situations where, despite the inherently random nature of the process, there are aspects that are highly predictable.

Talking about the process, mutation is essentially "undirected" with respect to the direction of evolution. It is needed as a source of variation, but the "clever" part is natural selection.

I have posted many times before why I think natural selection is a random process, in a similar way as a bent game of dice is random. Basically traits modulate the chances of reproducing, but for any individual trait, the odds are still stacked against it surviving the first generation. I don't just believe that there are chaotic systems involved that affect natural selection, e.g. the weather, but that these chaotic systems are also affetced by truly random quantum events.

Furthermore I would say that as organisms affect the selective environment for other organisms in their ecosystem, then there are complex feedback loops in place which depend on random events. To me this implies that if you were able to have universes with identical starting conditions, the course of evolution in each "Earth" would be different. Looking at the diversity in life just tens of millions of years after each large extinction event, and the differences between each one, I would say that not only was humanity just a lucky accident, which only seems special to us, but that it was only pretty recently when it became inevitable that our ecological niche would be filled (Neanderthals being an obvious alternative candidate tjhat could fill "our" niche).


If there is not any inevitibility about what would evolve, and indeed whether some of the less probable* niches are filled, then I would say that it is perfectly valid to talk about the results evolution as being "not-predetermined"**.


I think the random, yet somewhat predictable nature of natural selection is important as I have heard some people (not sure if they were sincere or creatinists) asking whether all animals that "survive" are "fitter" than all that don't. My answer is no, because it is like a loaded dice game, but over time the odds will out.


*Given the timescales, and the length of time that there have been large mammals, it could be argued that our niche (as a, "fire-using social animal") might have been potentially fillable for some time before it was.


**I do agree that describing evolution as "random" is misleading, due to the connotations, unless you try to explain what is meant by this. However, I also think that "nonrandom" is also misleading, and probably even more wrong, but then I am happy talking about random events being highly predictable in certain fashions...

 

[mijopaalmc]

Thanks for the tip, on your advice, unless (s)he presents something substantive, I'm out.

Do you actually have any evidence of individuals of a certain group of phenotypes all surviving while all individuals of the other group of phenotypes don't?

 

[zosima]

zosima,

a quick "heads up" about articulett: (ETA she ikes using the phhrase "heads up" about people she cionsiders to be her oponents, and doesn't read what they say either..)

Thats fair, thats why I wasn't willing to jump thread on her recommendation only.

There is more consensus than articulett would suggest:

Cool cool, I think some people believe evolution is random, rightly, because of a different reading of the evidence. I also think many people believe it is random because they misunderstand evolution. The fact that there is consensus does not surprise me.

Do you actually disagree with anything in my post below, or is it made up of "non-arguments"?

Well I've stated that I believe a somewhat non-standard interpretation of quantum physics that allows the world to be deterministic, but can have some pretty weird other consequences. (ie superdeterminisitic or non-local hidden variable, if you care to read up.)
So I don't agree with the quantum physical claims, but it is purely a matter of opinion, which is why I defined random as unpredictable, but I don't think that disagreement is consequential to the argument at hand.

It seems like what you are claiming is that evolution is a chaotic system. You make an analogy to weather, which I would agree weather is chaotic. It is common for people to look at evolution this sort of way, because they 1. note that the process of evolution is dependent on many random mutations, 2. observe that it is a high level process that we are poor at modeling. 3. Deduce that it is a chaotic system.

First I'm not saying that this is not the case, all I'm saying is that there is some strong evidence that indicates otherwise(punctuated equilibrium), but if you don't buy punctuated equilibrium, then the claim has no premise to stand upon. A chaotic process isn't really an equilibrium process it is violent and arbitrary it swings all over the place. The counter claim to my claim, would be to say that without some pivotal environmental change driving it, a new species spontaneously emerges from an old one. I'm saying the fossil record does not bear out this interpretation. It shows a species staying at a stable equilibrium until an external process applies pressure, then it moves quickly and directly to a new stable form. So I'm saying evolution is only random insofar as history is random.

Since we're on the topic there is a second new claim I would like to make, namely evolutionary convergence. That structures evolve over and over again. Where different unrelated(technically distantly related) species arrive on the same solution to a problem. The canonical example is the lens of the eye. It has evolved independently at least twice and basically the same result is produced.
http://en.wikipedia.org/wiki/Convergent_evolution
This evidence directly refutes your claim of "same situation different results".

The beauty of these evidentiary claims, is that I don't really have to worry about the specifics of your model of non-linear evolution or feedback loops. The evidence says that whatever the case, it doesn't end up working out that way. (*If* you believe the evidence. I keep adding these caveats because there is nothing more tedious than arguing over facts.)

Do you actually have any evidence of individuals of a certain group of phenotypes all surviving while all individuals of the other group of phenotypes don't?

Punctuated equilibrium doesn't require all the individuals disappearing in a single generation, just quickly. I claimed that it happens in 1000s or 10000s of years(which in evolutionary terms is very very fast). Unless you know a lot of species that live 1000s of years, you could deduce that it happens over at least several generations.

Actually, as we find more evidence of evolution that isn't just from the fossil record, its suggesting that scales like 100s to 1000s of years are likely in long lived species like humans, and far less than that in short lived species, but that evidence is still very preliminary.

That said, it certainly does happen in single generations, sometimes. We can't see this in the fossil record, because the time resolution of fossil evidence doesn't get that good. But we see it in our world all the time. Here's a very common example. Penicillin is applied to a Staphylococcus Aureus population, and all the bacteria that don't have penicillin resistance die in a single generation. I don't think knowledge of this fact is really all that persuasive one way or the other, Its missing the point.

If you want evidence, read "The Structure of Evolutionary Theory" by Stephen J. Gould, he lays it all out in as much detail as you could possibly want.

 

[jimbob]

zosima, pretty much a correct reading of my POV, some slight clarifications:

I am arguing that because of the chaotic nature of factors affecting selection i.e. survival and reproduction (e.g. weather) these will themseslves be significantly affected by random quantum events, which would make natural selection not predetermined, but probabilistic. In other words traits would "load the dice" but not determine which organism survived.

I think it is fair to Cyborg and articulett that thay are claiming that there is nothing random in the process of natural selection. That is where I am arguing that this is wrong and that it would imply that every beneficial trait would survive at the expense of every deleterious trait. I view selection more as a percentage game, where the odds are against any individual trait surviving more than one generation, just that they are stacked far heavier against deleterious traits, and obviously the odds are in favour of some individuals and their traits surviving.

I seem to have misemphasised the bit about "different solutions to the same problem".

Talking about the convergent evolution of the eye is a good one, because it seems to have evolved many more times, sometimes two different times on the same animal.

I would interpret this as showing that there is a great selective advantage in being able to sense and respond to distant stimulii; thus a selective "pressure" towards sight. Because of the electrochemical nature of reactions, light-sensitive mutations must be not that uncommon. Evolution of the eye is thus a probable event.

Sight is a common solution, but this can take different forms, the retina can have the blood vessels in front of the light-sensing cells (doh, mammals) or the other way round, the "better" solution (e.g. octopodes).

I am thinking about your punctured equilibrium argument:

I believe that river drainage systems patterns are fractal, which, (IIRC) is indicitive of a chotic system. These move about, but do also have some form of stability, because eroding the valleys is a positive feedback loop, making the water more likely to flow in the eroded valley. However significant events can also push the rivers out of these patterns and into a new set of ones.

I am not saying that evolution is like a river system, but that to me this seems that there are "quasi-stable" chaotic systems that can be aslo subject to major sudden change.

I do think the maths does explain or predict punctured equilibrium, and I would say a probabilistic analysis does especially, I'll try to dig up some of my other posts on this should you be interested in that part of the conversation.

 

[jimbob]

ETA:

Cool cool, I think some people believe evolution is random, rightly, because of a different reading of the evidence. I also think many people believe it is random because they misunderstand evolution. The fact that there is consensus does not surprise me.

And semantics as to what "random" means.

To me it means that identical, i.e at the quantum level starting stuations could give significantly different outcomes, in other words, if we could have identical universes each containing an Earth at the time of the KT impact, then there would be no inveitibility that every Earth would have a fire-using social animal 65-million years later. Not just no humanity, but possibly nothing occupying the ecolgical niche occupied by us...

 

[articulett]

Here's a geneticist, Jerry Coyne, discussing Behe's book--the ambiguity of "random"--the need to distinguish--and the fact that what we see in various species did not come about "randomly"...

On the basis of much evidence, scientists have concluded that mutations occur randomly. The term "random" here has a specific meaning that is often misunderstood, even by biologists. What we mean is that mutations occur irrespective of whether they would be useful to the organism. Mutations are simply errors in DNA replication. Most of them are harmful or neutral, but a few of them can turn out to be useful. And there is no known biological mechanism for jacking up the probability that a mutation will meet the current adaptive needs of the organism. Bears adapting to snowy terrain will not enjoy a higher probability of getting mutations producing lighter coats than will bears inhabiting non-snowy terrain.

What we do not mean by "random" is that all genes are equally likely to mutate (some are more mutable than others) or that all mutations are equally likely (some types of DNA change are more common than others). It is more accurate, then, to call mutations "indifferent" rather than "random": the chance of a mutation happening is indifferent to whether it would be helpful or harmful. Evolution by selection, then, is a combination of two steps: a "random" (or indifferent) step--mutation--that generates a panoply of genetic variants, both good and bad (in our example, a variety of new coat colors); and then a deterministic step--natural selection--that orders this variation, keeping the good and winnowing the bad (the retention of light-color genes at the expense of dark-color ones).

It is important to clarify these two steps because of the widespread misconception, promoted by creationists, that in evolution "everything happens by chance." Creationists equate the chance that evolution could produce a complex organism to the infinitesimal chance that a hurricane could sweep through a junkyard and randomly assemble the junk into a Boeing 747. But this analogy is specious. Evolution is manifestly not a chance process because of the order produced by natural selection--order that can, over vast periods of time, result in complex organisms looking as if they were designed to fit their environment. Humans, the product of non-random natural selection, are the biological equivalent of a 747, and in some ways they are even more complex. The explanation of seeming design by solely materialistic processes was Darwin's greatest achievement, and a major source of discomfort for those holding the view that nature was designed by God.

http://richarddawkins.net/article,12...e-New-Republic

 

[articulett]

Per a peer review papered as requested and ignored by Mijo and Jim-Bob in the prior thread: http://www.pnas.org/cgi/content/full/104/suppl_1/8567

Natural selection accounts for the "design" of organisms because adaptive variations tend to increase the probability of survival and reproduction of their carriers at the expense of maladaptive, or less adaptive, variations. The arguments of intelligent design proponents that state the incredible improbability of chance events, such as mutation, to account for the adaptations of organisms are irrelevant because evolution is not governed by random mutations. Rather, there is a natural process (namely, natural selection) that is not random but oriented and able to generate order or "create." The traits that organisms acquire in their evolutionary histories are not fortuitous but rather determined by their functional utility to the organisms, designed, as it were, to serve their life needs.


But why, of course, would anyone look to the experts for the best way to convey understanding?

 

[articulett]

And Dawkins review of Behe's book... posted multiple times.

http://www.mukto-mona.com/Articles/dawkins/inferior_design140707.htm

Darwin set no store by randomness. New variants might arise at random, or they might be acquired characteristics induced by food, for all Darwin knew. Far more important for Darwin was the nonrandom process whereby some survived but others perished. Natural selection is arguably the most momentous idea ever to occur to a human mind, because it — alone as far as we know — explains the elegant illusion of design that pervades the living kingdoms and explains, in passing, us. Whatever else it is, natural selection is not a "modest" idea, nor is descent with modification.

I don't know why some people think that all these folks are wrong and that they (with whatever limited training they have)--know a "better" way of explaining evolution when no one but themselves seems to think so. Why don't they hear anyone tell them that they are sounding garbled and confused in their explanations? Why do they keep insisting every time this subject comes up that their garbled definitions are better or more right than the experts who actually teach the subject to others? What makes them need to believe that "evolution is random"-- whatever the hell that means.

Having random components, does not a random process make. (Except to some people who need evolution to be random for some unspoken reason.)

If you are describing evolution as random, you either don't understand natural selection, cannot convey natural selection, or are missing the most important component of evolution in your in your bizarre persistence in describing evolution as "random".

 

[articulett]

Dawkins again:

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.

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

This has all been explained patiently and many times to these same people... the reward they return for these detailed and patient explanations is attack upon the messenger, as they realize the messenger won't confirm their delusion that they are conveying evolution with some degree of clarity. You have to cede that, per their definition (whatever the hell it is), evolution is, indeed, "random" (whatever the hell that means.) I can tell you each and every one their "sticking points"-- exactly how much they'll cede in regard to the above explanations and where they will stop. None will concede that any of the above are clear as they imagine themselves to be much more so.

You can play all you want, Zosima, I'm just warning you so that you don't set your expectations too high or get frustrated. I have become their enemy for giving them the very information they pretended to want. Don't take my word-- we have the words of multiple experts-- but some people envision themselves as having more expertise than those who actually convey understanding to many. We have many experts including yourself on this very thread. Just not the ones who imagine themselves "the experts".

Try and find out why they think any of the above explanations are wrong and why they think theirs is better. Go ahead... learn what I'm talking about. We have some very predictable forum members here.

 

[cyborg]

I think it is fair to Cyborg and articulett that thay are claiming that there is nothing random in the process of natural selection.

Then you haven't understood a single word of what I've said.

 

[UnrepentantSinner]

zosima, {snip}

You're just saying all this because you're an apologist!

 

[zosima]

ETA:

And semantics as to what "random" means.

To me it means that identical, i.e at the quantum level starting stuations could give significantly different outcomes, in other words, if we could have identical universes each containing an Earth at the time of the KT impact, then there would be no inveitibility that every Earth would have a fire-using social animal 65-million years later. Not just no humanity, but possibly nothing occupying the ecolgical niche occupied by us...

If you use that definition and believe the standard interpretation of quantum physics then everything is random so it renders the statement that evolution is random trivial. Also, if you believe that it is random because it is dependent on unpredictable events things like asteroid impacts and all the other crazy stuff that happens in history, the idea that evolution is random becomes pretty trivial, because it is reducing to saying history is random.
Or at least it breaks down to saying things like "evolution is random because if the dinosaurs hadn't been killed in a highly improbably asteroid impact humans wouldn't exists". I would agree with that, but it is the asteroid that is random not the evolution.

I submit this definition, which I think could bear out either claim. If two situations are experimentally identical and a different result obtains, then the processes observed were random. By experimentally identical, I mean all the variables that your model deems important are the same within some decided degree of experimental error. We can debate which variables are important, and indeed this reduces the entire argument to something empirically testable. We simply ask how close must the relevant variables be to produce identical results.

I think this is a good definition, no matter how you feel about quantum physics, because realistically, even by the time you get up to the scale of atoms and molecules quantum effects have pretty much been averaged out and the world starts acting more like billiard balls. Then on top of that most stochastic processes(like chemical processes) remove any remaining "quantum randomness". The chemical processes in organisms are non-random enough that a cell can be reproduced identically many of times more than it is not. A universe with quantum mechanical roots doesn't automatically turn chaotic. We can talk about that randomness, while completely ignoring quantum effects. We can frame the argument, scientifically in terms of rates of mutation, and distribution of genes and therein come to an agreement on the validity of a scientific statement, rather than stray into philosophy(which I consider to be quite boring).

I hope we can agree on that, so now lets talk about the neat stuff.

That is where I am arguing that this is wrong and that it would imply that every beneficial trait would survive at the expense of every deleterious trait.

I totally agree. Evolution is often suboptimal because it can only take small steps and because sometimes a deleterious trait is either fundamentally or structurally linked to a beneficial trait. I would differ in that If a deleterious trait survived, this would be because it was necessarily so. An example of a fundamentally linked deleterious and beneficial trait is sickle cell anemia. It confers a resistance to malaria but also significantly shortens life. You just can't get one without the other.

If we examine the "its in the dice" example you make. Lets say we have a deleterious trait that is not linked to a beneficial one. Lets say it kills you before you procreate 50% of the time. Then sure you might make it one generation, but your children will die, or theirs will die, The probability that a gene survives in a single indiviual situation like this is (1/2)^n where n is the number of generations. 5 generations, which in humans is about 100 years, is only 3%. Or 3 in 100, thats not even close to geological time. You might argue that they may have more than one child, but they need to live even long than that, so more often than not they won't make it that far. Also, we need to remember that sexual selection plays a huge factor, the fact that they breed children that may die before reproduction makes them less desirable as mates....further driving down their likelihood of surviving. In other words the algorithm produces deterministic results at the temporal limit.

Talking about the convergent evolution of the eye is a good one, because it seems to have evolved many more times, sometimes two different times on the same animal.

First, the eye only evolved twice and was passed down to future generations. One of the properties of evolution is that it saves previous solutions, for the most part, and I am unaware of it ever evolving twice in one organism. It probably was developed on both sides of the organism simultaneously due to bilateral symmetry. To use the term like you are using it above is either very imprecise or incorrect.

I would interpret this as showing that there is a great selective advantage in being able to sense and respond to distant stimulii; thus a selective "pressure" towards sight. Because of the electrochemical nature of reactions, light-sensitive mutations must be not that uncommon. Evolution of the eye is thus a probable event.

I would certainly agree that it is advantageous, but a trait being advantageous does not imply a trait is probable.
It seems to me that there are numerous different ways you could build a light sensing organ; multiple lenses, non-spherical shapes, retinal reformation rather than lens deformation. To examine the probability of it just showing up randomly, lets assume an eye is just a beneficial trait that any organism would want and that the probability of any part of the full eye showing up in an organism randomly is 1% every year(which I think is incredibly generous) and that the eye we're talking about has 5 parts(also very generous, say... cornea,retina,light sensitive neurons,brain capable of processing image, and its spherical compartment.). Then the probability of it showing up twice is: (.01^5)^2=.01^10= 10^-20 = 10^18% change every year. Or in other words we wouldn't expect it to happen twice for over 100 billion billion years. Earth has only been around for 4.5 billion years, which isn't even close.
The bottom line is that the math does not support this belief that evolution could not produce complex forms like this in a way that is similar twice, even with very generous estimates, if the model is that evolution is just plodding along accumulating desirous traits. It must be highly directed by the needs of its environment.

Sight is a common solution, but this can take different forms, the retina can have the blood vessels in front of the light-sensing cells (doh, mammals) or the other way round, the "better" solution (e.g. octopodes).

Well I could just answer this by modifying the equation above. IE they only share 4 components. Giving us a result of (.01^4)^2 = 10^-16 or it would develop twice once in 10 million billion years, still far too low a probability.

But there is a more important point here. While the solutions are different, and the mammalian solution has a blind spot, which poses a small disadvantage in sensation. Cephalopods like the octopus are invertebrates and the other branches of creatures with the type of eye we're discussing are all vertebrates. Being a vertebrate means that we have a very different developmental process. If vertebrates were to develop the everted retina of cephalopods rather than their traditional inverted retina, it would come at a huge expense in terms of the complexity of the developmental process, the amount of energy required to develop, and the time required. Which would mean if vertebrates were to get an everted eye, they would either have to give up the stuff that makes them vertebrates or have more miscarriages, need more food during pregnancy, and have to carry the baby much longer. Better to have unnoticeably worse vision than likelihood of being tiger food. In other words these traits are linked and they couldn't be built efficiently in any other way.

I am thinking about your punctured equilibrium argument:

Its called PUNCTUATED EQUILIBRIUM not PUNCTURED EQUILIBRIUM.
The name explains the phenomenon, long periods of equilibrium where the species is unchanging, punctuated by quick bursts of change. It is not my argument it is Stephen J Gould's argument. I'm just trying to do my best to explain it. You should really read the primary source.

I believe that river drainage systems patterns are fractal, which, (IIRC) is indicitive of a chotic system. These move about, but do also have some form of stability, because eroding the valleys is a positive feedback loop, making the water more likely to flow in the eroded valley. However significant events can also push the rivers out of these patterns and into a new set of ones.

I am not saying that evolution is like a river system, but that to me this seems that there are "quasi-stable" chaotic systems that can be aslo subject to major sudden change.

I'm not clear where the feedback loop shows up in evolution, maybe in ecology but ecology!=evolution.

Without getting into the details, I don't think this analogy is very good. It's not very precise, what events? The patterns are apparently fractal, but not necessarily. Is the flow constant or inconstant in this river? What variables do we care about? What sort of external events? These questions are intended to show you the analogy is poor, I'd prefer you find something clearer rather than try to pack this one up, so don't feel obligated to answer those.

But let me say it one more time. The inability to model evolution is terms of species does not imply the system is chaotic. Why do you think that evolution is chaotic?

But here are some general points.
1. As far as the fossil record shows us new species don't just pop up without cause. Its not like things like the eye just appeared one calm sunny sunday, new species show up during periods when external stress is applied.

2. The rate of speciation is very inconstant, sometimes new species are generated very very slowly, then conditions change to necessitate the development of new traits and those traits are developed.

3. Species at equilibrium have a broad gene pool, most of the diversity between generations in sexual species is from sexual mixing and chromosomal rearrangement, a very small portion of it is provided by traditional mutation, although this will accumulate and stay latent in the gene pool

4. During the brief periods of stress and evolution. The diversity of the gene pool drops down due to die offs, a new species(es) is formed by recombining genes available from the gene pool(it happens too quickly for mutation at that moment to even be significant). When the stress decreases and equilibrium is reestablished the breadth of the gene pool increases again.

p.s. The retinal of the eye is ironically one of the few biological structures in which quantum effects may play a significant part. The excited state in retinal that occurs post interaction with a photon may be a quantum mechanical effect.

 

[zosima]

You can play all you want, Zosima, I'm just warning you so that you don't set your expectations too high or get frustrated. I have become their enemy for giving them the very information they pretended to want. Don't take my word-- we have the words of multiple experts-- but some people envision themselves as having more expertise than those who actually convey understanding to many. We have many experts including yourself on this very thread. Just not the ones who imagine themselves "the experts".

I think I'm about tapped out after this last post.

Although the arguments between Dawkins and Gould are pretty interesting as well, and actually both scientifically valid. So I don't really mind writing out the theory as I understand it. This forces me to think the theory through and really make sure I get all the details. I don't think I would call myself an expert by any means, maybe enthusiastic amateur. Which means to me that I've read quite a few texts in the field and have a decent enough grasp of math.

 

[jimbob]

zosima, what about compound eyes?

several types

Lobster eye...

ETA:

Here is the organism that I was thinking about (one of the "eyes", is more of a light sensor...)

The head bears a pair of dorsal compound eyes that lie close to each other, and are nearly fused together. The compound eyes are generally sessile (not stalked). In addition, there is a naupliar ocellus in between. The compound eyes are on the surface of the head, but the ocellus is deep within the head. All the eyes, however, are easily visible through the shell covering of the head.

 

[jimbob]

I have just realised that you have completely misunderstrood me.

Random, but not haphazard.

Originally Posted by jimbob
ETA:

And semantics as to what "random" means.

To me it means that identical, i.e at the quantum level starting stuations could give significantly different outcomes, in other words, if we could have identical universes each containing an Earth at the time of the KT impact, then there would be no inveitibility that every Earth would have a fire-using social animal 65-million years later. Not just no humanity, but possibly nothing occupying the ecolgical niche occupied by us...

If you use that definition and believe the standard interpretation of quantum physics then everything is random so it renders the statement that evolution is random trivial. Also, if you believe that it is random because it is dependent on unpredictable events things like asteroid impacts and all the other crazy stuff that happens in history, the idea that evolution is random becomes pretty trivial, because it is reducing to saying history is random.
Or at least it breaks down to saying things like "evolution is random because if the dinosaurs hadn't been killed in a highly improbably asteroid impact humans wouldn't exists". I would agree with that, but it is the asteroid that is random not the evolution.

Not everything.

Quantum events might conceivably affect the Earth's orbit, but not significantly (or even measurably). A slight change in the wind direction due to a difference at the quantum level several weeks earlier could very easily affect the survival or otherwise of a particular trait.

The feedback loops I am talking about is because an organism alters the fitness landscape for other organisms in its ecosystem. Which mutation occurs first in which organism would help define the fitness lancdscape for the other organisms.

I dispute that it is trivial. When discussing with other people, most would consider it to be a significant difference whether anything was filling our ecological niche. In fac, given our effect on the evolution of other organisms, this is probably true.

Mamoths, passenger pigeons, dodos, moas, rats, TB, would all have had different evolutionary histories without mankind.

If this depended on random events, as well as nonrandom but unpredictable events, then I can see it is valid to talk about randomness in evolution. It is also valid to talk about inevitibility in evolution too, for example the loss of flight in birds on isolated islands with no predators.

 

[sol invictus]

I would define an outcome as "random" if identical starting conditions could lead to significantly different outcomes. I think this would mean that any cahotic physical system would be random by this description, as the infinite precision would mean that quantum fluctuations would eventually have a significant difference, in a way that isn't the case for non-chaotic systems. ETA: Sol, is that still the understanding? IIRC it was when I was an undergrad, but I tended to concentrate on solid-state physics...

Yes, that is still the understanding, and that alone makes your definition (and mijo's) not very useful.

But actually (as I keep trying to explain) quantum randomness is pretty much a red herring in this discussion. Even if it didn't exist and the system was classically deterministic at the level of microscopic interactions, the presence of chaos makes it totally unpredictable. You can never measure the initial conditions with perfect accuracy even in a world without QM, and if the system is chaotic the uncertainty will grow exponentially (that's the definition of chaos), meaning - as in my example of the red gas molecule - you have no information at all after a relatively short time.

 

[sol invictus]

I'm amazed this thread is still going. As far as I can tell, (nearly?) everyone agrees on the following facts:

1) the fine details of evolution - like precisely which species will evolve - are extremely unpredictable.

2) some macroscopic features are extremely predictable. For example, if you expose a population of bacteria to an antibiotic, it will either become extinct or evolve resistance. You can repeat that experiment 100 times with 100 different petri dishes of bacteria and get the same results each time.

If you agree with that, the only argument is over the definition of the word "random". But many different definitions are in use, both among scientists and laypeople, so there is no answer to that. Furthermore finding a definition which encompasses both 1) and 2) will mean the definition is so broad it includes everything, making it not very useful.

 

[kjkent1]

I'm amazed this thread is still going. As far as I can tell, (nearly?) everyone agrees on the following facts:

1) the fine details of evolution - like precisely which species will evolve - are extremely unpredictable.

2) some macroscopic features are extremely predictable. For example, if you expose a population of bacteria to an antibiotic, it will either become extinct or evolve resistance. You can repeat that experiment 100 times with 100 different petri dishes of bacteria and get the same results each time.

If you agree with that, the only argument is over the definition of the word "random". But many different definitions are in use, both among scientists and laypeople, so there is no answer to that. Furthermore finding a definition which encompasses both 1) and 2) will mean the definition is so broad it includes everything, making it not very useful.

You shouldn't be "amazed." True randomness is ultimately unprovable, just as is intelligent design.

Can it be proved that some piece of basalt lying on the sea shore owes its present state as the product of random chance? Can it be prove that the rock was placed in said state by an intelligent guiding force?

Nope. No way -- no how. This makes arguments about the ultimate cause of evolution a perfect vehicle for argument -- especially on the internet, where no one need maintain a personal stake in his/her viewpoint.

Thus, the argument rages on forever without abatement or resolution. It will never end -- so you may as well enjoy the ride.

 

[jimbob]

I would define an outcome as "random" if identical starting conditions could lead to significantly different outcomes. I think this would mean that any cahotic physical system would be random by this description, as the infinite precision would mean that quantum fluctuations would eventually have a significant difference, in a way that isn't the case for non-chaotic systems. ETA: Sol, is that still the understanding? IIRC it was when I was an undergrad, but I tended to concentrate on solid-state physics...

Yes, that is still the understanding, and that alone makes your definition (and mijo's) not very useful.

But actually (as I keep trying to explain) quantum randomness is pretty much a red herring in this discussion. Even if it didn't exist and the system was classically deterministic at the level of microscopic interactions, the presence of chaos makes it totally unpredictable. You can never measure the initial conditions with perfect accuracy even in a world without QM, and if the system is chaotic the uncertainty will grow exponentially (that's the definition of chaos), meaning - as in my example of the red gas molecule - you have no information at all after a relatively short time.

True: some people seemed to present a laplacian viewpoint at one time that it was uncertain but predetermined, and there wasn't any randomness at all, i.e. sufficient knowledge of the initial conditions could allow prediction to an arbitary distance into the future. This was what I was arguing against.

I am slightly puzzled by your statement:

Yes, that is still the understanding, and that alone makes your definition (and mijo's) not very useful.

If this defintion made everything "random", then I would agree with you, but it doesn't: the Earth's orbit, for example isn't significantly affected even by cometry impacts . (I would be interested to know if there is any assessment on the potential effect of the Mars-sized body that helped create the moon...)

This ultimately random aspect of chaotic systems would mean that a probabilistic treatment for natural selection isn't just a good model, but does fundamentally reflect what happens... Belz, for example had been arguing agianst that (IIRC). And Articulett refuses to acknowledge that natural selection can be anything other than "nonrandom". I suggested, "probabilistic but not haphazard", and was accused of being wishy-washy and unclear.

As has been said before, creationists like to pretend that evolution is haphazard, and that this is what scientists mean by random.