What evidence is there for evolution being non-random?

[Dancing David]

Absolutely. That is definately a process that happens. But my thought experiment was looking at something fundamentally different. When the environment changes and selection pressures exist, what if it were found that a substantially greater frequency of favourable traits compared to other unfavourable or irrelavent traits were consistently observed to exist before the selection pressure exists. As if the adaptations were anticipating their selection in a fundamentally non-random way. Practically very difficult to observe in "nature" but much easier to devise an experiment to test if one were so inclined. The way I see it, such a hypothetical observation would really set the ID cat amongst the neo-darwinian pigeons!

Uh huh, and you would win the Nobel Prize for chaos theory. The problem is this, how many factors effect an organism? Thousands? How do you rule out that a particular trati that is later beneficial is not already being selected for from thousands of candidates?

 

[Dancing David]

But the state variables are not random numbers in the same way that a random number is described:

yes, but I would argue for contrained variability. The breaks in the copy of the genetic code are likely to be randomly distributed, the insertions into the genetic ode are also likely to be random as well. I don't think you can predict without probability where a break in correct replication will occur in the DnA complex.

 

[Vorticity]

...Having taken a year of physical chemistry during my undergraduate tenure, I understand the power of what one poster somewhere in one of the threads devoted specifically to the stochastic characteristics of evolution called the "ensemble mean"...

Are you refering to this? :

It is known that you can rewrite Fick's Second Law using probability densitites.

But this response doesn't cut to the crux of the matter:

While a single process may be stochastic, the evolution of the mean of an ensemble of such processes is necessarily deterministic by definition (although perhaps not Markov). Ficks law is fundamentally a relation describing the mean evolution of the concentration field of some material, and as such must be deterministic.

Any given real-world instance of a system nominally governed by Fick's law will display deviations from it, to a degree that depends on the size of the system, the temperature, and other factors. However, an ensemble average of many such instances will indeed obey Fick's law.

 

[Dancing David]

So?



Erm, no. I'm fairly certain that cosmologists and astronomers would disagree with you. Once the properties of the asteroid were know, it could be accurately predicted. Ditto, once the properties (read: variation) of a population is known, the direction selection will take it can be accurately predicted. This is why there is a field known as 'population and evolutionary genetics'.

Uh huh, care to cite where these predictions occur. Please tell us where the Asian Longhorn beetle will have it's next outbreal, or even better the Emerald Ash Borer, please tell us where the American Chestnut with resistance to disease will arise.

Show your work, where are these amazing predictions, what level of accuracy.


Please tell me where the rain will fall next week, that way I will know if the flea population will rise due to lack of moisture. It will also help in firefighting forest fires.

What model and what accuracy, bold claims Lone Star.

 

[Dancing David]

To post this before we fire off endless rebuttles to each other before coming to the point: I am more comfortable with this. A random process need not include entirely random elements. I maintain that selection is non-random. This is because we can both model it, and because it is necessary for evolution to occur. Just random mutation is not enough to drive evolution. This is the key misunderstanding with most creationists.

As I said earlier, I would always describe evolution as: "Evolution is the result of non-random selection acting upon randomly generated variation within a population."

But while the selection may or may not be non-random, predicting which enviroment an organism will be in five years is very random.

 

[Meadmaker]

Can anyone describe to me what it means when someone says "Selection is non-random."


A fascinating aspect of this and related threads is how many people have been accused of supporting ID and/or creationism based on what they say here. I haven't noticed anyone actually supporting one or both of those ideas, but there have been accusations that they have. Why?

 

[Cuddles]

Erm, no. I'm fairly certain that cosmologists and astronomers would disagree with you. Once the properties of the asteroid were know, it could be accurately predicted.

I think you'll find these cosmologists and astronomers would disagree with you.
http://www.newscientist.com/article/mg18124365.100-chaotic-heavens.html
http://www.newscientist.com/article/dn6796-moon-behaving-badly.html
http://www.newscientist.com/article...mean-for-the-future-of-the-solar-system-.html

 

[Paul C. Anagnostopoulos]

Can anyone describe to me what it means when someone says "Selection is non-random."

It means that the process of natural selection, although a stochastic process, has highly skewed probabilities. An organism fit for its environment is much more likely to be selected than one that is not so fit. The process is "nonrandom with respect to the environment," because the environment is the source of the probabilities.

If someone wants to call evolution "random" because it is a stochastic process, that's fine (if misleading), but then that person has to describe how the intelligent designer's finger-poking is not, by the same token, also random. If there is an IDer, he is simply part of the environment, too.

~~ Paul

 

[Meadmaker]

It means that the process of natural selection, although a stochastic process, has highly skewed probabilities.

Is there a word that describes "random (or stochastic, which is a synonym) with skewed probabilities". It sounds random to me, with an additional qualifier.

Has anyone, ever, in any setting, suggested that natural selection operates with uniform probabilities? That includes any straw man presentation of anything.

If someone wants to call evolution "random" because it is a stochastic process, that's fine (if misleading), but then that person has to describe how the intelligent designer's finger-poking is not, by the same token, also random.

What if he wants to ignore ID altogether? Someone calling evolution "random" may not wish to discuss ID at all. I don't see why he should have to.

 

[mijopaalmc]

Are you refering to this? :

It is known that you can rewrite Fick's Second Law using probability densitites.

But this response doesn't cut to the crux of the matter:

While a single process may be stochastic, the evolution of the mean of an ensemble of such processes is necessarily deterministic by definition (although perhaps not Markov). Ficks law is fundamentally a relation describing the mean evolution of the concentration field of some material, and as such must be deterministic.

Any given real-world instance of a system nominally governed by Fick's law will display deviations from it, to a degree that depends on the size of the system, the temperature, and other factors. However, an ensemble average of many such instances will indeed obey Fick's law.

Yes, that is the post to which I was referring. I thought the exact phrase "ensemble mean" and not "mean of the ensemble" (emphasis in the original) was used. I apologize for not giving credit where credit was due.

 

[sphenisc]

Are you saying that gravity is random? What?

Why would the "big funnel" be a better analogy for artificial selection than for natural selection?

No, I'm saying that Post-It notes fall chaotically, they don't follow a geodesic on their way to the ground. A note's instanteous behaviour will be the result of its current orientation, momentum and the local forces from its surrounding microenvironment. The only practical way of describing the final outcomes is with a probability distribution.

If, however, I add some 'foresight' to the system, such as a funnel, then I guide a note towards a particular outcome, collapsing my pdf down to a single location with p=1.

My point is that in the analogy between 'the movement of Post-It notes' and evolution, gravitation is not an exact match for natural selection.
Gravitation matches those aspects of natural selection which are universal across living organisms, the 'fundamental' selective pressures, things like 'don't die before you reproduce*', 'try and optimize net energy uptake',' adjust your investment in offspring based on your assessment of current and future limiting resources'.

The are other aspects of natural selection which more closely resemble the microenvironment influence on notefall. "The environment is fluctuating dramatically, try producing more, lower-quality offspring.", "Seed size is going up, produce a bigger, stronger beak." In each case local conditions may alter and the selection pressure start to act in the opposite direction, the fitness landscape has an "earthquake" so to speak. And, for some populations/traits, the changes in landscape may make it more strongly resemble a seascape with bobbing corks, never quite finding the crest of their wave before it rolls on and they're deposited in a trough.

Such as Darwin's Finches
http://www.pbs.org/wgbh/evolution/library/01/6/l_016_01.html


* Adactylidium comes pretty close to being an exception.

 

[sphenisc]

Eyes.

Never heard of "randomize"?

 

[Darat]

Never heard of "randomize"?

Yep.

 

[sphenisc]

Is there a word that describes "random (or stochastic, which is a synonym) with skewed probabilities".

"biased", though if you think "random" is open to misinterpretation...

 

[jimbob]

A percentage game. "There is an x% chance of flight evolving from this population within a certain timeframe"

"There is a 90% chance that this bacterial population will be dominated by an antibiotic resistant strain within a defined number of generations given these environmantal conditions".

This would fit with my defintion of random, people accept gambling as (pseudo)random, with different odds, so they can understand non-uniform probability distributions.

 

[Paul C. Anagnostopoulos]

Is there a word that describes "random (or stochastic, which is a synonym) with skewed probabilities". It sounds random to me, with an additional qualifier.

Yes, "biased," for example. That'll help, for sure! Perhaps "nonuniform" or "skewed" would be better.

Has anyone, ever, in any setting, suggested that natural selection operates with uniform probabilities? That includes any straw man presentation of anything.

No one has suggested it in a scientific setting. I'm simply saying that the average guy does not understand the nuances of a "random process."

What if he wants to ignore ID altogether? Someone calling evolution "random" may not wish to discuss ID at all. I don't see why he should have to.

He doesn't have to. But who rants and raves about the randomness of evolution except IDers? Certainly someone who understands the nuances of random processes wouldn't make too fine a point of calling evolution simply "random."

~~ Paul

 

[Soapy Sam]

What evidence is there for evolution being non-random?

None whatever. The internet just happened by itself and by an amazing coincidence there were people there to use it.

 

[Meadmaker]

He doesn't have to. But who rants and raves about the randomness of evolution except IDers? Certainly someone who understands the nuances of random processes wouldn't make too fine a point of calling evolution simply "random."

I think there are several counterexamples in these threads.

I think your post illustrates why these threads exist. Someone says, "Evolution is random" or some variant thereof, and someone else assumes that there must be a pro-ID argument in there somewhere, and then feels compelled to argue against it.

I haven't seen a pro-ID argument anywhere in this thread, in the "split from God delusion" thread, or the original "I'm reading the God Delusion" thread.

My original interest was from that thread, where I noted that Dawkins had ranted and raved (though I didn't use those words) against the phrase "by chance" as applied to evolution. That didn't make any sense to me. Saying we are here "by chance" doesn't support any sort of ID argument, but it seems like there's a knee-jerk, "I heard an ID guy say it once, so I have to disagree" reaction. I'll restate my own position, along with a question that, so far, everyone seems to have avoided.

We are here by chance. What's the problem?

 

[mijopaalmc]

What evidence is there for evolution being non-random?

None whatever. The internet just happened by itself and by an amazing coincidence there were people there to use it.

Nice straw man. The internet is a created non-biological entity and therefore not at all an analog to an evolved (and evolving) biological entity. It is interesting that this thread seems mainly to be motivated by the desire to combat the creationist straw man that order cannot arise from disorder, or as they put it, "evolution cannot happen because, as evolutionists say, it is random" yet the "non-randomites", who, I might add, have not presented a cogent argument in support of their position, resort to straw men such as the above to trivialize the argument that "probabilistic", "random", and "stochastic" are proper descriptors of evolution.

 

[Paul C. Anagnostopoulos]

We are here by chance. What's the problem?

There is no problem; I agree with you. But what does the definition of "by chance" have to do with "random"?

Nice straw man.

I'm not sure you understand what Soapy meant.

~~ Paul