Randomness in Evolution: Valid and Invalid Usage

[jimbob]

How about

The role of historical contingency in evolution has been much debated, but rarely tested. Twelve initially identical populations of Escherichia coli were founded in 1988 to investigate this issue.

The long-delayed and unique evolution of this function might indicate the involvement of some extremely rare mutation. Alternately, it may involve an ordinary mutation, but one whose physical occurrence or phenotypic expression is contingent on prior mutations in that population.[/COLOR]

Thus, the evolution of this phenotype was contingent on the particular history of that population. More generally, we suggest that historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection.

 

[cyborg]

As ever you seem to think the people disagreeing with you have reading comprehension difficulties. As I said many months ago you are simply emotionally responding to words you don't like; such as "affect" is okay, but "determines" is not despite the semantic equivalence because of your intense need to argue against anything in evolution being associated with the word. You've had this all explained to you before. You finding new examples of basically the same stuff you've gone over before is not going to change anything.

Is this too difficult a concept for you to grasp? It's not going to work no matter how many quotes you make because our point in response to it isn't going to change.

 

[jimbob]

So it is a semantic discussion.

"Determines" in this situation usually implies "determies in its entirety". "Affects" implies that other factors are important.

There is a semantic difference.

• [1]"The winner of a game of poker is determined by both the dealing of the cards and the strategies of the players"
  
  [2]"The winner of a game of poker is affected by both the dealing of the cards and the strategies of the players"
  
  [3]"The winner of a game of poker is affected by the dealing of the cards"
  
  [4]"The winner of a game of poker is determined by the dealing of the cards "

#1,# 2, and #3 could be consistent with each other, but #1, and #4 are contradictory, as are #2 and #4.

 

[jimbob]

Are you saying that you are using the "determines" and "affects" interchangably?

This is a red herring as far as the question of randomness is concerned.

In the expermient, significantly similar starting conditions produced significantly dissimilar outcomes. The starting conditions could have been identical and they still could have producesd significantly different outcomes.

Why is that not a significant a significant affect* due to chance?



*Note that I did not calim that chance "determined" the outcome, as there are non-chance factors affecting the outcome too.

 

[articulett]

No. You are the one making it a semantics argument. Yes, evolution and papers can be twisted so that some in some sense you can describe it as random or probabilistic... However nobody who actually conveys understanding of evolution to others describes it as you do.

Yes, you can twist any article so that it might seem to support your point-- just as Mijo and Behe do.--that people can call evolution random. That doesn't mean that actual people who want people to convey information to other actual people regarding how evolution comes about use language in the muddled way you do, Jim-bob. Nor do Mijo and Behe actually convey information about evolution in a way that others find useful and coherent.

Having random components does does not a random process make.

"contingent upon history" means "determined by the environment over time"

DETERMINED. Opposite of RANDOM.

 

[cyborg]

So it is a semantic discussion.

That's the game you like to play:

"Determines" in this situation usually implies "determies in its entirety". "Affects" implies that other factors are important.

Are you saying that you are using the "determines" and "affects" interchangably?

Nope.

Why is that not a significant a significant affect* due to chance?

Significance is irrelevant. An insignificant difference is still a difference and should make no difference to your argument.

I explained this months ago: there is no difference in outcome if the event was purposely induced or not. This is staggeringly simple to grasp.

 

[articulett]

you could use "determined by" and "contingent on" interchangeably.

 

[jimbob]

The original 12 were clones. Of course there were the usual errors in DNA replication so they were not completely identical, however the differences were only one generation. The environmental conditions were as close to identical as the experimenters could make.

What differences there were, were insgnificant with respect to the outcome. This was proved because there was no increased propensity to evolve citrate metabolism in samples taken from "early" generations of the "interesting" population. Samples taken from "later" generations did show an increased likelyhood of evolving citrate metabolism.

In other words something changed between generation 15,000 and generation 20,000 that made citrate metabolism more likely. This was when the significant difference occured. This significant difference was the occurance of an "enabling" mutation. It took until generation 31,500 (another 11, 500 to 16,500 generations) for citrate matabolism to actually evolve.

In other words the initial conditions could have been completely identical, and the outcomes could still have been significantly different.

That is an example of the sort of randomness that I have been talking about as important in evolution. It also is more important over longer timescales than shorter timescales.

Do you disagree with the following statement?

The evolution was not haphazard, but technically whether the bactreia evolved citrate metabolism was heavily influenced by chance.

 

[articulett]

No. I think there are much clearer ways to say things. I opt for the words used by the scientists who actually do describe the evolution of ecoli rather than the way you and those who need to see evolution as "random" describe the process.

But maybe someone somewhere will think you sound less muddled then the experts and teachers and science writers who convey this understanding to others.

 

[jimbob]

Firstly I made a mistake in my previous post:

The original 12 were clones. Of course there were the usual errors in DNA replication so they were not completely identical, however the differences were only one generation. The environmental conditions were as close to identical as the experimenters could make.

They obviously were seperated by more than one generation. However they were very close in generations (the closest possible would be four generations).


Are you sure it is me that is "twsting this paper" and not you?

No. You are the one making it a semantics argument. Yes, evolution and papers can be twisted so that some in some sense you can describe it as random or probabilistic... However nobody who actually conveys understanding of evolution to others describes it as you do.

Yes, you can twist any article so that it might seem to support your point-- just as Mijo and Behe do.--that people can call evolution random. That doesn't mean that actual people who want people to convey information to other actual people regarding how evolution comes about use language in the muddled way you do, Jim-bob. Nor do Mijo and Behe actually convey information about evolution in a way that others find useful and coherent.

Having random components does does not a random process make.

"contingent upon history" means "determined by the environment over time"

DETERMINED. Opposite of RANDOM.

OK from later on in Lenski's paper:

Gould argued that contingency renders evolution fundamentally quirky and unpredictable, and he famously suggested that replaying the ‘‘tape of life’’ from some point in the distant past would yield a living world far different from the one we see today. Simon Conway Morris countered that natural selection constrains organisms to a relatively few highly adaptive options, so that ‘‘the evolutionary routes are many, but the destinations are limited’’ (16). He and others point to numerous examples of convergent evolution as evidence that selection finds the same adaptations despite the vagaries of history. Evolution may thus be broadly repeatable, and multiple replays would reveal striking similarities in important features, with contingency mostly confined to minor details (16–19).

Of course, replaying life’s tape on the planetary scale is impossible, but careful experiments can examine the role of contingency in evolution on a more modest scale (15, 20, 21). To address the repeatability of evolutionary trajectories and outcomes, the long-term evolution experiment (LTEE) with Escherichia coli was started in 1988 with the founding of 12 populations from the same clone (2). These populations were initially identical except for a neutral marker that distinguished six lines from six others.

The discussion is about whether "replaying the tape" of evolution would produce significantly different results.

This is what is meant by historical contingency in this case. The answer is that replaying the tape needn't always produce the same result.

The experiment did replay the tape many times and sometimes got different results. These differences are due to chance, as the other factors were taken account of, and were shown to be unimportant.

It is misguided, and confusing, to deny the role of chance (or historical contingency) in the evolution of citrate metabolism in these populations.

 

[jimbob]

Significance is irrelevant. An insignificant difference is still a difference and should make no difference to your argument.

There are differences, I was conceeding that, however they were shown to be insignificant, so do make no difference to my argument.

Rerunning the tape of evolution would (given time) produce significantly different results, even if all initial situations were identical.

 

[mijopaalmc]

Why don't those who are arguing that evolution is non-random see identical clonal populations developing in the same environment and evolving differently (in Lenski's most recent publication, evolving the cit+ phenotype) as contradicting the premise of their argument?

 

[sol invictus]

Rerunning the tape of evolution would (given time) produce significantly different results, even if all initial situations were identical.

I actually don't see how this experiment shows that. In fact if anything I think it indicates the opposite. It took a long time for citrate-metabolizing bacteria to evolve in one of the colonies. I would expect that if the experiment goes on for another decade that trait will evolve independently in another colony, and then another, until all the colonies have evolved to more or less the same final state. That would be a good example of one of the non-random aspects of evolution.

In fact, that even one colony evolved in that specific way is a good example of how predictive evolution is. Those bacteria evolved the ability to eat citrate because that's what they were given to eat. That's highly predictable. Precisely when they evolved that way, and through precisely which pathway, is impossible to predict. But the end result it more or less the same. Of course this was a highly controlled and artificial situation, which proves nothing about the actual evolution of life on earth, which took place in a complex and variable environment.

The truth is not so black and white as the posters in this thread seem to want. Evolution is not random, full stop, and it is not non-random or deterministic, full stop. It is a complex and fascinating phenomenon which cannot be described in such simple - and simplistic - terms.

 

[sol invictus]

Why don't those who are arguing that evolution is non-random see identical clonal populations developing in the same environment and evolving differently (in Lenski's most recent publication, evolving the cit+ phenotype) as contradicting the premise of their argument?

You put some bacteria in a citrate-rich environment, and they evolve the ability to metabolize citrate. That's what you call "random", mijo?

A bit like the smoke detector, isn't it?

Read my previous comment if you want a more nuanced and less annoyed view, but your comment deserves derision, frankly.

 

[Earthborn]

Articulett, you have repeatedly stated that you think using the word "random" to describe evolution causes misunderstanding of evolution. Okay, fine, I understand your point and I don't really disagree with it. I think we can all agree that we don't want to encourage muddled thinking about evolution.

What I still don't understand is... What makes the word "random" so special? If we should avoid it because it causes confusion, shouldn't we by the same logic also avoid words and phrases like "theory", "Darwinism", "survival of the fittest", "selfish gene" or for that matter teleological phrases like "For some life forms, they evolved to try something new or different when the old stuff isn't working..." ?

Is "random" uniquely confusing?

 

[cyborg]

Rerunning the tape of evolution would (given time) produce significantly different results, even if all initial situations were identical.

And here we go again missing the point. The only way to go from here is me saying, "if the tape rewinds and it plays the same thing, it plays the same thing," and you saying, "QUANTUM MECHANICS FTW!"

 

[mijopaalmc]

You put some bacteria in a citrate-rich environment, and they evolve the ability to metabolize citrate. That's what you call "random", mijo?

A bit like the smoke detector, isn't it?

Read my previous comment if you want a more nuanced and less annoyed view, but your comment deserves derision, frankly.

No, it is not at all like the smoke detector. What I call "random" is that only one out of the twelve populations evolved the ability to metabolize citrate despite the fact that the populations were identical at the beginning of the experiment and the fact that they evolved in the same evirnoment. Even if all the populations eventually evolved the ability to metabolize citrate, the evolution of that trait would still be random in so far as the populations evolved that trait at different times. I've said it before, and I'll say it again: convergence does not imply non-randomness.

 

[sol invictus]

No, it is not at all like the smoke detector.

Really?

What I call "random" is that only one out of the twelve populations evolved the ability to metabolize citrate despite the fact that the populations were identical at the beginning of the experiment and the fact that they evolved in the same evirnoment.

Yes, evolution takes time.

Even if all the populations eventually evolved the ability to metabolize citrate, the evolution of that trait would still be random in so far as the populations evolved that trait at different times. I've said it before, and I'll say it again: convergence does not imply non-randomness.

So you think the fact that these bacteria evolved the ability to metabolize citrate when put in a citrate rich environment is random.

That is just as ridiculous as your earlier contention that a smoke detector is random because it relies on the (truly random) radioactive decay of unstable atoms. You are using the word in a way no one else does - including mathematicians. You were unable to supply a single reference that defines the word your way, and you never responded when I checked several references - including a standard text on prob. and stats. - none of which define it your way.

The statement that "evolution is random", full stop, is (to be blunt) stupid.

 

[mijopaalmc]

sol invictus-

I really don't understand what is preventing you from comprehending that fact that orderly large-scale behavior does not imply non-random small-scale behavior. By the way, I have never claimed that the smoke detector is random because radioactive decay is random; that is you putting words in my mouth. I have, however, maintained that the orderly operation of the smoke detector does in fact arise from the underlying randomness of radioactive decay.

My main objection to the assertions of articulett and others is that all the mechnisms of evolution (i.e., mutation, natural selection, developmental constraints, etc.) can be random, but evolution can still display the orderly behavior that they insist is random.

Does it make sense to call a process all the component of which are random nonrandom simply because it has orderly large-scale bahavior?

 

[blutoski]

sol invictus-

I really don't understand what is preventing you from comprehending that fact that orderly large-scale behavior does not imply non-random small-scale behavior. By the way, I have never claimed that the smoke detector is random because radioactive decay is random; that is you putting words in my mouth. I have, however, maintained that the orderly operation of the smoke detector does in fact arise from the underlying randomness of radioactive decay.

My main objection to the assertions of articulett and others is that all the mechnisms of evolution (i.e., mutation, natural selection, developmental constraints, etc.) can be random, but evolution can still display the orderly behavior that they insist is random.

Does it make sense to call a process all the component of which are random nonrandom simply because it has orderly large-scale bahavior?

I spent some time reading the entries, and I think this is the key question. Is gas expansion random? It's pretty consistent and predictable, to the point where it obeys laws. But the particle behavior that underlies it is entirely random. Smoke dissipates throughout a room due to random brownian motion, but I can guarantee it will dissipate to fill the room. Entropy is so predictable in many environments that it can be considered a force, but its components are random elements.

Evolution has a similar trend: toward increasing diversity. But the details of how it gets there are unpredictable. The process is neither truly random nor truly directed, but parts of the process are random and the net effect can be argued to be directional, if not actually directed.