Randomness in Evolution: Valid and Invalid Usage

[Almo]

Though, "harness" sounds like there is conscious intention involved. As long as it is understood not to be the case, the verbiage is otherwise fine, in my opinion.

Yes, you're absoulutely right.

 

[Ichneumonwasp]

It's not a minor point when people get seemingly incensed at me for engaging in a "semantic argument" when I argue that evolution is mathematically random but then they insist they didn't say "random means acausal" based on a sematic argument.

Actually it is a minor point. And it is semantics.

This is precisely what happens when you take terminology from one area of discourse and introduce it into another area for which it wasn't devised. It will stick if it is useful. Right now, it doesn't seem useful for anything beyond derailing existing threads and generating new threads to rehash the same old arguments.

 

[Wowbagger]

The only problem I have with the word random is that when it comes to use it with the general public, it tends to trigger the typical negative reaction:

"Oh so you're just saying that everything that is, is nothing but the consequence of a bunch of random events?? I can't believe you want me to swallow that"

And then they throw the one about the airplane parts and the tornado that can't randomly build a plane and blablabla.

Exactly!

All those examples fall into the "happy accident" category, in the opening post.

Yes, you're absoulutely right.

Sometimes you can't help it. I've read about how birds "calculate the most effective ratio of egg-count to yolk-content", for example. It doesn't mean the birds are really consciously calculating anything. It just means that, over time, genes that were more prone to result in effective ratios have emerged through selection pressures.

We still use the terms "sunrise" and "sunset" even though we know better.

 

[jimbob]

Just out of interest:

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

Yes, but what I want from Mijo is a random process that is causally based, using the actual definition of random, not a folk definition.

Would the drunkard's walk count? (or at least the mathematical concept of the drunkard's walk)

ETA: Thinking about it, probably no...

 

[mijopaalmc]

Actually it is a minor point. And it is semantics.

This is precisely what happens when you take terminology from one area of discourse and introduce it into another area for which it wasn't devised. It will stick if it is useful. Right now, it doesn't seem useful for anything beyond derailing existing threads and generating new threads to rehash the same old arguments.

Actually, scientists (including evolutionary biologists) use the definition of "random" that I use every time the perform a statistical test, so I don't see what the problem is with applying it to yet another object of study.

 

[mijopaalmc]

So the word random needs to be either dismantled and re-defined or replaced by a different word, such as " chaotic" (already mentioned here).

But "chaotic" does not mean "random". A chaotic system is by definition deterministic but sensitively dependent of initial conditions. A random system is by definition not deterministic.

 

[JoeTheJuggler]

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

Evolution does not have any goal or end point. Knowing any given "starting" point will not enable you to predict future forms. (Remember the Twilight Zone episode with the machine that let you "fast forward" or "rewind" evolution? Yeah--that's not right in the least.)

The story of the evolution of the modern horse, for example, is not accurately portrayed as starting with a smaller animal with more toes and somehow trying to perfect that form as the modern horse by selecting larger animals with fewer toes.

 

[Taffer]

Actually, scientists (including evolutionary biologists) use the definition of "random" that I use every time the perform a statistical test, so I don't see what the problem is with applying it to yet another object of study.

Can you elaborate on this? How exactly are these random elements included in said statistical tests?

 

[Earthborn]

So the word random needs to be either dismantled and re-defined or replaced by a different word, such as " chaotic" (already mentioned here).

The average person is not likely to know the scientific definition of "chaotic" either. I don't think it will make much difference to say "chaotic" instead of "random". Perhaps it is even worse; when you say "random" you can explain how many random events sometimes lead to predictable outcomes, such as casino owners getting richer. The term "chaotic" conjures up associations that pretty much anything can happen, no matter how wild and unlikely.

Wowbagger's favourite term "unconciously indifferent" will evoke a "Huh? What?" to most people. 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.

Let's not forget that many people have a bit of a problem understanding what is mean with the word "theory" in "Theory of Evolution". Replacing words for complex scientific concepts with other words is not going to give the general public a better understanding of the science. The scientific concepts are non-intuitive, and there simply are no everyday words that are commonly understood by non-scientists that accurately describe them.

Using the word "random" to describe evolution is fine, but in popular science texts perhaps need to be explained what is meant with it. It doesn't mean that in a given environment all organisms have an equal chance of survival; some are more likely to 'win' than others. But because random events play a role in shaping organisms and their environments, organisms play a role in shaping their environments and environments play a role in shaping organisms, if evolution had taken a slightly different route early on, things would have looked very differently today. We really are the result of many rolls of God's* dice.

* 'God' in the metaphorical and not necessarily in the metaphysical sense...

 

[mijopaalmc]

Can you elaborate on this? How exactly are these random elements included in said statistical tests?

Have you ever taken a statistics course?

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.

 

[Paul C. Anagnostopoulos]

Mitchell's definitions of Random (summarizing the bullet points in the OP):
1. Analagous to "indifferent"
2. A stochastic model
3. A "happy accident"
4. Quantum uncertainty
5. Arthur Dent's daughter

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

~~ Paul

 

[Paul C. Anagnostopoulos]

Mutations: they don't "just happen". For instance, ionizing radiation causes two pyrimidine dimers to dimerize which causes a transcription error.

But the ionizing radiation is random with respect to which base is affected. So a random event triggers a deterministic chemical process.

This is exactly why it is confusing to say "evolution is random, full stop."

~~ Paul

 

[jimbob]

Evolution is a stochastic process, because at least some of the mechanisms involved are stochastic (that is, random). However, it is misleading to call evolution a "random process, full stop" because selection is not random with respect to the local environment.

I would argue that selection is probabilistic ("random" gust of wind etc affecting survival). However, we can still see how different traits affect the odds of producing reproducing offspring. I think a valid analogy might be between weather and climate. The individual slection event might be "random" but the efffect over a large enough population means that some beneficial traits will propagate.

Doing the sums, I would conclude that most "beneficial" traits that arise probably don't survive more than one generation.

This is because the odds are against any individual organism reproducing, for virtually any species (possibly except our own currently). For example, the Barn Owl population is roughly stable, but it tends to have a clutch sizes of about 3-7 and sometimes breed twice a year, and live for 1-5 years in the wild (25 years in captivity). Of the total brood size over the lifetime of the pair, on average only two offspring will breed if the population is stable.

Say this equates to 5 clutches, of 4 birds. Then there is 90% chance of any individual not breeding, and a 10% chance of it breeding. To get an evens chance of a particular trait making it past the first individual, it would need to confer a 500% advantage compared to its peers...

However we are dealing with big numbers, and some (enough) advantageous traits will survive and get passed on...

Disadvantageous traits are almost certain to vanish very quickly. In the barn owl example, a neutral trait already has a 90% chance of not getting passed on.

 

[mijopaalmc]

But the ionizing radiation is random with respect to which base is affected. So a random event triggers a deterministic chemical process.

But you have to follow a chain of causality backward to get to the actual acausal event. If it is in appropriate to call evolution by natural selection because mutations are random, why is it appropriate to call mutation acausal because the production of ionizing radiation (or base tautomerization) is acausal?

This is exactly why it is confusing to say "evolution is random, full stop."

Where have I ever said that it was not confusing to say "evolution is random, full stop"?

 

[Paul C. Anagnostopoulos]

So the word random needs to be either dismantled and re-defined or replaced by a different word, such as " chaotic" (already mentioned here).

But a chaotic process is not a random process.

~~ Paul

 

[mijopaalmc]

Wowbagger-

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

 

[Paul C. Anagnostopoulos]

But you have to follow a chain of causality backward to get to the actual
acausal event. If it is in appropriate to call evolution by natural
selection because mutations are random, why is it appropriate to call
mutation acausal because the production of ionizing radiation (or base
tautomerization) is acausal?

I can't quite parse this. Could you reword it?

Where have I ever said that it was not confusing to say "evolution is
random, full stop"?

Way back when all this started. Or was it someone else? As I've said before, I have no idea where you're going with this.

~~ Paul

 

[jimbob]

Wowbagger, I would partially take issue with this "invalid description" in your OP:

* Appeals to quantum uncertainty. While quantum uncertainty might have some small impact on the course of evolution, it would be unfair to "out" Evolution as a theory of randomness because of this, simply because quantum uncertainty makes an impact on all of the other sciences, as well. Also, most quantum fluctuations are averaged out (or "smeared out") in large scales, anyway.

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.

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.

I can think of one (convoluted) mechanism where quantum events should affect the weather. A radioactive decay event causs a cancer that kills an animal prematurely. This is no longer wandering around, so that is definitly of a size to affect weather patterns. Of course it actually looks as if weather patterns should be directly affected by quantum events too. But, I believe it is not confirmed yet.



On to the statement about predictions:

I'd say that we can make certain predictions with a high level of confidence.

If there are steady selective pressures, then there will be a steady "direction" to the evolution. A classic case being the experiments with heat tolerance of e-coli colonies.

However the mechanism ofr this adaptaiton is not predetermined. A classic case being the experiments with heat tolerance of e-coli colonies, when moved to cool environments: most of the heat-adapted strains did worse than the parental strains, but some did better, they had evolve different mechanisms that gave improved heat-tolerence.

We can make predictions about drug resistance too.

In the wider world we can make predictions about particular niches that are likely to be filled. (Large herbivore, predator of large herbivore, parisites of these animals for example).

We can also state that sight and flight are traits that are advantageous enough to have evolved independently many times, so these are likely to occur in suitable ecosystems.

Conversely, should the need for flight vanish (for example in an isolated island) the energy costs would make flight a disadvantageous trait, and so you would expect to see flightless animals that had flying ancestors.

What you can't predict is how future evolved organisms will interact, and how these will modulate the selective pressures.

Catastrophic events, e.g. the KT impact also have the effect of clearing out many niches, sometimes removing them completely and creating others, essentially Year-Zero. Large carnivores and large herbivores, but a triceritops isn't a rhino...

 

[mijopaalmc]

I can't quite parse this. Could you reword it?

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.

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

Way back when all this started. Or was it someone else?

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

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

 

[Ichneumonwasp]

Actually, scientists (including evolutionary biologists) use the definition of "random" that I use every time the perform a statistical test, so I don't see what the problem is with applying it to yet another object of study.

I didn't say there was anything wrong with it, just that this is what happens. When words are used across disciplines they create some controversy. Useful words continue to be used and words that don't work well die.

We don't know about this word yet. The only problem that anyone has with it is that it is used as a strawman argument by creationists, as you know, so it has created a maelstrom here.

I think we all have a pretty good idea about the underlying processes, so the only real controversy is whether or not to use this particular word. I guess part of the issue comes from folks worried that ideas that don't fit are being jammed into the 'random' carton, but really, it's just a word.