What evidence is there for evolution being non-random?

[Taffer]

Found an interesting paper discussing the original Cairns adaptive mutation experiments. It seems experiments exists that show increased frequency of advantageous mutation that is not due to an overall increase in genomic mutation rate.

http://www.genetics.org/cgi/reprint/126/1/5.pdf

I remember being taught this last year (or was it 2 years ago, I forget). IIRC the increase was due to a switch to a more error prone DNA repair mechanism. I'll have to read the paper again.

 

[Taffer]

Oh, but Djj has a BS in science (sorry Djj, I meant a BSc). He said so himself. Of course he can't tell us what field of study this degree is in or where he earned it because sinister agents are trying to track him down.

I thought he didn't finish university? That's what he said before.

 

[davidsmith73]

I remember being taught this last year (or was it 2 years ago, I forget). IIRC the increase was due to a switch to a more error prone DNA repair mechanism. I'll have to read the paper again.

To be honest, I haven't fully read the last paper I linked yet, and I'm not qualified to fully understand the methods section, but the author says this in the intro about previous experiments:

"The increased frequencies of the advantageous mutations were not accompanied by an increased mutation rate at other loci".

Which would suggest that a simple upregulation of polymerase can't be the full explanation for those experiments.

 

[Meadmaker]

Just because there are many complicated factors does not make it random. Can you show that the snake would not eat the same eggs each time, if the situation were exactly the same?



An asteroid hitting the earth most certainly is not random. This is shown by our ability to predict, with a very high degree of accuracy, where bodies in the solar system will be at any given instance.

The T-Rexes couldn't predict it, that's for certain.

This goes to the nature of randomness and our universe. Is anything truly random? If we knew the initial conditions, could we predict all future activity? Does God play with dice?

The current general belief is that God does play with dice. There are events that occur in our universe that would have occurred differently but for the quantum level randomness that is present. That asteroid was not fated to hit the Earth, and its impact is best understood as a random event. Given a little bit of different dice jiggling during the formation of iron molecules in whatever star produced the particles that became the asteroid, it could have missed.

At least, that's the way an awful lot of scientists see things.

 

[Meadmaker]

Consider two (rather imprecise) descriptions of evolution:

In each generation of organisms, some have traits that make them less fit for their environment, and some have traits that make them more fit. The ones that are more fit pass more of their genes on to the next generation. In each generation, there is also a certain amount of variation introduced, in the form of mutations. Some of these mutations make the organism more fit for its environment, some less. Those that are more fit will pass them on. Over time, those that make the organism more fit become more numerous, while the less fit ones pass out of existence.

Some variations also make an organism able to survive in different environments. This can allow organisms to expand their range or occupy vacant ecological niches. In response to selection pressure, the organisms and their genes become optimized to fill their specific niches in the environment.

Vs.


In each generation, some organisms survive, and some do not. Those that happen to survive pass their genes to the next generation. Since some genes are more likely to survive than others, over time those genes will become more numerous. In each generation, there are also imperfect copies of genes introduced. Some of those may have a survival benefit for an organism, and the imperfect copies may actually eventually become more numerous through having greater survival rates.

Some of those variations on the original genes may make an organism more likely to survive in a slightly different environment. A change in the environment an organism occupies might result in a change in which genes are more likely to survive, thus triggering a change in the population of the gene frequencies. As organisms occupy different environments, the different survival rates can create a higher variation in the range of observed gene frequencies.


The two descriptions say basically the same thing, but I suspect people will be attracted to one or the other. The first one describes “fitness”, “optimization” “selection”. The second emphasizes randomness, through phrases like “happen to survive”, “more likely”, “survival rate”, “higher variation”. The first says that life “expands” to fill niches. The second suggests that environments change, forcing change onto the life within it. I think the second is less misleading than the first. The first seems to suggest a purpose, a goal, a method. The second suggests random variation that happens to work out sometimes. I think that’s a better description of evolution.

 

[Dancing David]

The whole analogy of games is not good.

The individuals with fitter fitness complement are only more likely, but not guaranteed, to pass on that fitness complement.

But fitness in evolution means only one thing, "ability to reproduce". It does not mean fitness in any other way. Physical fitness for survival in the enviroment may or may not lead to reproductive sucess so "survival of the fitest" applies only to survival of those able to reproduce effectively.

And the "non-random" aspect that you are talking about, I have tried to find your posts.

Non-random is a creationist proposition.

Randomness in evolution means contrained variability. The choices in the DNA complex are limited to the four choices of amino acids. The variability in morphology is limited by the expression of the genome and the enviroment supporting the critter.

So perhaps the question should be phrased differently, what is it that you are asking?

 

[Dancing David]

It would be pretty groundbreaking stuff if it were found to be so. It makes me wonder if anyone has tried. Perhaps they have, found nothing and retreated in embarrassed silence. Or perhaps the proof lies dormant, supressed by those tyrannous journal editors.

Read The Panda's Thumb it is inherent in evolution that traits may exist that are not selected for until the enviroment changes. SDo there are always hidden traits that may or may not express, when the enviroment changes then there may be a selective process in the expression of traits.

 

[Dancing David]

All biological study shows that evolution is not random but comes from design. Study biology and note that impossibility of one evolving from another. get serious and don't believe the magicians of evolution. Study the specific systems in the bodies of different species and note their differences and instincts as a whole and as separate identities.

Evolution is impossible the more you study and learn.

OOOOK! OOOOK?


That is the boldest peiece of sarcasm ever printed on this forum.

So do you want start with why abiogenesis is impossible?

 

[Dancing David]

Quite. I shouldn't have used that word.



I mean't exactly that! I was being deliberately far out to speculate what such an observation would mean for ID. What if traits were shown to anticipate future environmental conditions that would favour their selection?

For example, the first adaptive mutation experiments (linked previously) showed that lactose intollerant bacteria, exposed to lactose, generate mutations in the genes inhibiting lactose metabolism. But those experiments looked at mutation rates during the evironmental pressure.

What if the number of Lac+ mutants were to rise well above any other type of mutation before the lactose was applied? The ID'ers might take interest, although I do not think such a finding would necessarily mean support for ID.

Post facto reasoninbg, what else would have led to a trait develpoing.

Please read Gould's The Panda's Thumb or The Flamingo's Smile, the development of a trait that later is selected by natural selection for reproductive success is already covered.

 

[jimlintott]

Is there any other term used in the sciences that we are so concerned about the layperson's understanding? Maybe we should ask the layperson to discuss quantum mechanics?



However, be that as it may, there is one sense of the word "random" that is proper English usage and most certainly does not describe evolution. That is the sense in which people think that all outcomes are equally likely. In mathematical terms, they confuse "random" with "uniformly distributed". Some people will insist that if you have a loaded die, the outcome is not random because one side is more likely to come up than the others. Evolution is a bit like a loaded die. Not all forms of a gene are equally likely to survive. Does that make it non-random? If you insist that the outcome of a loaded die is non-random, then evolution is non-random as well.


Even then, your (jimlintott) example of the layperson's understanding isn't quite correct. I think the layperson would say that a fair die was "truly random" (a phrase with no coherent meaning, despite it's common use) even though there was no possibility that it would turn into a parrot and fly away. Even for the layperson, not every conceivable outcome need be possible, such as dogs producing kittens. An uninformed layperson might insist that evolution is not random because not every organism has an equal chance of survival. It's a misunderstanding, but that might be something people think.

Oh, well, maybe all this talk about the meaning of "random" isn't all that important. When describing evolution, why not use the language the way the layperson uses the language, instead of its more precise technical meaning. After all, the whole thing's only a theory.

Thanks that's helpful. I like the loaded die analogy. Also the backgammon analogy.

I would like to comment on the first paragraph. Quantum Mechanics is not a political / religious hot potato. Lay people are really being asked to decide the issue and if they can't understand evolution in easy terms then the anti-evolution (you know the guys with the sloped foreheads and knuckles dragging ) crowd has an easier time convincing them. While it is nice to understand any scientific concept in lay terms it's really important that evolution be easily understood.

 

[Correa Neto]

Well, as many wrote before, depends on how you approach the subject. Five eggs, one with a mutation. Predator eats one egg. Its 1 out of 5 for the mutated bird (sounds like something taken from a B-movie!) hatch. The key point here is which egg will be eaten. This is a random event (OK, one can say it can be predicted if you know the predator's position, predation strategy, etc.). But how many nests there are? Approaching from a broader perspective, chances are mutated birds will eventually hatch, even if only one in five eggs make it. Now, if the mutation does provide some extra benefits, chances are it will be passed ahead. From this point if view, evolution is not random.

On a broader scale, events such as a meteorite impacts a nearby supernova explosion or the rise of a new virus may introduce sudden and random environmental variables with unpredictable results. OK, we can calculate the orbits, etc... The important point here is that a successfull species, regardless of its genetic pool and level of adaptation to a given environment may be extincted by sheer lack of luck while the oddball species might be given an unexepected chance.

Evolution is a group of process whose final outcome is: individuals with the best adaptations to an environment will be more likely to survive and pass their genes to the next generations. Sure, we can not (at least in the foreseeable future) predict if after X million years the top predator will be a giant blue six-legged vertebrate or a paramecium-like microbe. But one thing we can say for sure: it will be an organism shaped with the best possible adaptations for its particular environment. Under this approach, I don't think its exactly random.

 

[Dancing David]

Just because there are many complicated factors does not make it random. Can you show that the snake would not eat the same eggs each time, if the situation were exactly the same?

There would be some variability based upon all the factors in the situation, sensitive dependance upon initial conditions?

An asteroid hitting the earth most certainly is not random. This is shown by our ability to predict, with a very high degree of accuracy, where bodies in the solar system will be at any given instance.

Celestial mechanics is very complex, the three body solution is fairly moderate in complexity, the four body is much more difficult and the five body equations are intense.(At least that is what my math friends have told me.)

The level of accuracy is usualy more like "Within a magin of 300,000" miles in some cases and "within a margin of 60,000" miles for others. The level of accuracy is somehat vauge and fuzzy. You can not take an asteroid and predict to a great accuracy where it will be in fivehundred years. The level of precision is rather low.

Selection most certainly is not random. Selection is the phenomenon where beneficial alleles increase in frequency over time, due to the organisms carrying them, on average, providing more genes to the next generation.

And rainfall is totaly deterministic. as is food source production and growth, as well as parasites and disease. When you right your program that predicts the future let us know will you?

How is this random? We can model it accurately,

Not even close, define accuracy as what, a vauge aprroximation that has no bearing on reality. So farmers can use these models to say where bugs will infest thier crops, or where to preserve the endagered speies to a few acres?

so it would suggest that it is not.

Demonstarte a model with a level of precision, are you sure you have looked at the success of models? can you say where the next outbreal of longhorn beetles will be, can you narrow it down to specific counies, why or why not? You can save the timber industry a fortune.
[/quote]
It is misleading to call evolution random.
[/quote]
And when you demonstrate a model that works I might agree with you. So you can tell me how many tons of soy beans will be in the new crop on October 15 of 2007? That would be really helpful to the comodity market.

It is not misleading to call evolution a combination of non-random selection acting on random variation.

What is the difference between a chaotic system and a random system, what meaning can be assigned to one that can not be assigned to the other. Especialy a chaotic system with twenty or more variables and millions of actors?

And non-random = determanistic. It does not mean there is some "purpose" behind anything.

I think you over estimate the meaning of determined, the cause effect cycle may be known, or speculated upon, but that does not mean that it is deterministic.

Tell me how many head of cattle will be slaughtered on July 15 of 2007?

 

[jimbob]

Is there any other term used in the sciences that we are so concerned about the layperson's understanding? Maybe we should ask the layperson to discuss quantum mechanics?

But evolution is not rocket science, or even quantum mechanics.

It is possible to have an understanding of the basic idea without any maths.

Environmental niches will tend to get filled, and particular advantageous features will tend to evolve more than once (flight or eyes for example).

Gazelles did not evolve in Australia, but other grazing animals did.

If evolution is non-random, does that mean that dinosaurs were inevitable?

A single accident wiping out one of the ancestor animals before it bred would have stopped this. Maybe a metorite hitting in the wrong place and time?

IIRC: there is evidence for a human population bottleneck around 70,000BC, (possibly due to the eruption of Tambora?). A slightly harder fammine then might have really changed the evolutionary prospects for many species (including the Passanger pigeon and the rat). Wolf populations would also look different.​

It isn't *just* survival of the fittest, but being better adapted to an environment means that one has a better chance of surviving to reproduce.

I would say this is random, as the precice outputs aren't knowable: Will the herbivore's offspring evolve to run faster than its predators or develop an armoured shell. In the absense of other carnivores, will some become predators, or will frugality be selected for?

Jim

 

[Dancing David]

double post

 

[T.J.C.]

So here's my first post, with my first two cents: I think people are overthinking this way, way too much.

Can we predict which random mutations will be strongly disfavoured? Of course we can. A mutation that breaks oxygen metabolism in obligate anaerobes will be selected against. A mutation that prevents heart muscle from developing in cheetahs will be selected against.

Given an environment and an organism, we can predict with high certainty mutations or changes that will be disfavoured. Therefore, evolution in that framework is emphatically not random.

 

[Meadmaker]

The really interesting question, to me, is why is it so important? In addition to spawning threads on JREF, Dawkins spends several pages in The God Delusion on the subject. People seem to have strong opinions.

In the sense used in every math textbook in the world, evolution is very clearly random. In almost every sense of the word found in the dictionary, evolution is clearly random. There is one and only one sense found in the dictionary in which evolution is not random. That's the sense of "all outcomes being equal". That clearly is not the case with evolution, but neither evolutionists nor creationists say that it is. We can disregard that sense because the context makes it clear we are not using that sense.

Usually, JREF is pretty sympathetic to using the technical, mathematically precise, definition of a word. Why is this one different?

As usual, I'll offer my opinion. It is partly because the term has occasionally been misused by creationists. Some of them say "evolution claims that animals are assembled at random." Evolution doesn't say that, and some scientists (both professional and amateur, like us) bristle at the comparison. The assembly of organisms follows instructions in the DNA, and the DNA itself, while the result of a random process, is assembled from its predecessor version of DNA, with perhaps a few random errors. No molecule of DNA, except possibly the first, very simple, molecule, has every been assembled randomly.

However, I don't think that's the full explanation. Despite the misuse of the term, the actual term, when used correctly, is very precise, and very accurate in describing evolution. To give my opinion, I'll turn to Dawkins' explanation from "The God Delusion".

Actually, it's from "Climbing Mount Improbable", but I haven't read that book. I've only read the shortened version of the argument in "The God Delusion". In that book, he describes evolution with an analogy of someone staring at a cliff, and saying, "No one could ever go up that cliff!" The "cliff" is the assembly of complex organisms from simple molecules. However, on the other side of the cliff is a gentle slope, that can be walked up easily. The gentle slope is the slow variation of organisms over time. Each step is quite easy, and with time, the "summit", a complex organism, is reached through that series of small steps.

Every analogy has weaknesses, and we can see what Dawkins is getting at here, so the analogy works. However, I think it is not a very good one. I think a better one would be to replace the gentle slope with a pockmarked, canyon strewn wilderness. It is filled with craters, small cliffs, landslides, low summits and deep crevases. Organisms grope blindly in all directions all over the wilderness. Eqrthquakes reshape that wilderness periodically. In the wilderness, though, there is a path leading to the summit. It goes up and down all over the place, but it does get there, and it gets there with no single step that requires a large cliff. Lots of organisms start at the bottom, and their descendants end up in every nook and cranny of the wilderness, including, eventually, one that finds its way to the top, after many, many failures along the way.

I think that's a better analogy, but it isn't very appealing. It makes it seem like the achievement of the summit isn't an "achievement" at all. Eventually, by sheer dumb luck, someone will make it to the top. That isn't as exciting as saying that the complex organisms, i.e. us and our pets, are part of a magnificent adventure that makes clear the amazing power of nature. Nevertheless, it is accurate. We have achieved a temporary summit on the evolutionary hill, and we did it by chance.

 

[davidsmith73]

Read The Panda's Thumb it is inherent in evolution that traits may exist that are not selected for until the enviroment changes. SDo there are always hidden traits that may or may not express, when the enviroment changes then there may be a selective process in the expression of traits.

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!

 

[mijopaalmc]

In the same way you could ask for proof that gravity isn't random "... and things falling only proves that their altitude is decreasing over time and that can occur randomly."

But they all fall in the same direction, don't they?

---

I see that most of this thread has degenerated into a bickering about the meaning of the word "random". Well, it is clear that if you told someone that "evolution is random", you'd be giving them an entirely false impression.

The line of reasoning leading to the claim that "evolution is random" would seem susceptible to a reductio ad absurdum. If evolution is "random" because the mutations on which selection acts are "random", then we must regard evolution by artificial selection as being "random" too, on the same basis. What's sauce for the goose is sauce for the fundie propaganda.

If the collisions of gas molecules against the walls of their container is random, then air pressure must be random too. So how can air pressure in your tires hold your car up off the road?

If the outcome of a pull on a slot machine is random, then the money the casino makes (or pays out) must be random too. So how can casinos predict their profit margins?

If the directions that neutrons are emitted by a nucleus undergoing radioactive decay are random, then a fission chain reaction must be random too. So how is it possible to control a nuclear reactor?

If passive diffusion of a molecule across a membrane is random, then osmosis must be random too. So how can the net flow through a membrane be precisely repeatable for a given salt concentration?

If individual variation is random, and some accidents of birth and death unrealated to genotype are random, then evolution must be random too. So how can complex inderdependent genes arise?

The answer is the same in all cases: The statistical characteristics of a large number of individually random events are not random.

Respectfully,
Myriad

Let's try this again.

First, fitness landscapes are at minimum pseudo-random; they are determined by exigent circumstances. For example, what does the path of a comet have to do with the shape of the fitness landscape? Not much- unless it hits the Earth. Then it has a great deal to do with it. So again, what do you mean by "random?"

Now, genes. The production of novel genes occurs by several means, all of which are again, at minimum, pseudo-random, and some of which are truly random- for example, the fastest spermatozoan happens to be the one that had a chromosome altered by a passing cosmic ray. The speed of the spermatozoan doesn't depend on this alteration. So an egg is fertilized, and the altered chromosome happens to be expressed. That leads to a novel phenotypical characteristic that leads to the organism surviving the above-mentioned comet strike.

And yet again, what do you mean, "random?" It looks pretty random to me.

Did you read the reference thread? It listed several definitions of "random" and discussed at reasonable length the problems with the various "layman's" definitions offered. I think the best one cited is a definition from Eric Weisstein's MathWorld listed under "stochastic":

Stochastic is synonymous with "random." The word is of Greek origin and means "pertaining to chance" (Parzen 1962, p. 7). It is used to indicate that a particular subject is seen from point of view of randomness. Stochastic is often used as counterpart of the word "deterministic," which means that random phenomena are not involved. Therefore, stochastic models are based on random trials, while deterministic models always produce the same output for a given starting condition.

The narrowness (or at least the clarity) of the definition allows a clear and concise explanation of why evolution is random. Quite simply, not every individual with the same fitness compliment will survive; therefore, the outputs given identical inputs are different, or, said another way, the input does not determine the output, making evolution a stochastic process.

For example, in a subpopulation of 100 with a fitness compliment that confers on the individual a probability of passing on their genetic information* of .1, the probability that no individuals with that fitness compliment will not "survive" is 2.65614×10^-5. In other words, it is approximately 37647 time more likely for at least one individual to "survive" than for all of them to not "survive". When the probability of "survival" is .2, the probability that all 100 individuals will not "survive" is 2.03704×10^-10, which means that on average none of a group of 100 will "survive" information every 4.90908×10⁹ generations, which is considerably longer than most species have been around and assuming a generation length of a year is longer than the age of the Earth. Because I used a simple binomial probability model one of the assumptions of which was that I could reduce all the complex interactions that an individual has with other individuals and its environment to one probability (which I freely admit is open to criticism), the probabilities I listed are also the probabilities that all the individuals with probabilities "survival" of .9 and .8, respectively, will "survive". The point is that, as I have stated many times before, natural does not require that all individuals that have a beneficial fitness complement "survive" or that no individuals with detrimental fitness compliments not "survive". In fact, when the idea of probability of "survival" is introduced, it becomes clear that, in subpopulations on the order of 100 individuals or larger, the probability of the elimination of a detrimental fitness complement or the fixation of a favorable one in one generation is vanishingly small. Moreover, it is most likely that individuals with a fitness complement that confers a given probability of "survival" will "survive" with a frequency proportional the given probability (e.g., 10% of a subpopulation with a probability of "survival" of .1 will most likely "survive"). Because of this reliance on probability, evolution is most accurately called "probabilistic" or "stochastic", which in the common parlance is "random".

*"survival"; this terminology can be extended to any other form of the word which is why I put all forms in quotes

 

[Dr Adequate]

In the sense used in every math textbook in the world, evolution is very clearly random ... Usually, JREF is pretty sympathetic to using the technical, mathematically precise, definition of a word. Why is this one different?

Because there isn't a technical, mathematically precise definition of the word "random".

Look here for example. "Random number", "random matrix", "random walk", et cetera, are all defined. "Random" is not.

Saying "evolution is random" is about as precise as a Rorschach inkblot test.

 

[EugeneAxeman]

Just because there are many complicated factors does not make it random. Can you show that the snake would not eat the same eggs each time, if the situation were exactly the same?



An asteroid hitting the earth most certainly is not random. This is shown by our ability to predict, with a very high degree of accuracy, where bodies in the solar system will be at any given instance.



Selection most certainly is not random. Selection is the phenomenon where beneficial alleles increase in frequency over time, due to the organisms carrying them, on average, providing more genes to the next generation. How is this random? We can model it accurately, so it would suggest that it is not. It is misleading to call evolution random. It is not misleading to call evolution a combination of non-random selection acting on random variation.

And non-random = determanistic. It does not mean there is some "purpose" behind anything.

This seems to be an argument with an expected outcome on your part.

You wish to argue some divine plan into an observed random situation.

Asteroid paths can be predicted, but not to the degree where their impact (pardon the unintended pun (yes, it really was unintended)) can be predicted on the evolutionary cycle of the planet. Gravitational forces, solar winds, and collisions from other spatial bodies contribute to the trajectories of these objects and cannot be predicted far beyond a few years at best.

The orbits of many comets have been plotted with considerable accuracy, but even then, the exact path cannot be determined with enough precision to determine if it will impact with a solar body beyond one orbital period.

So to say that evolutionary changes can be predeterminantly linked to solar system events is quite the stretch and leads to a deitistic belief system. But then, this is probably the conclusion to which you are trying to force the debate to arrive at.

Good luck.

Evolutionary changes are based on a number of related and unrelated factors. The process of evolution will introduce environmental changes which cannot be predicted and whose effects will often require millions of years to assert themselves.

The ecosystem is a dynamic entity and can take sudden turns when confronted with major geologic activity, such as caldera eruptions.

The resulting dust clouds can kill off species of algae and plants, causing a ripple effect throughout the life structure. The volcanic eruptions cannot be predicted, and therefore the effects they have on the evolutionary process cannot be predicted and, ipso facto, the resultant ecosystem cannot be predicted.

Mutations are random, and their effect on other existing lifeforms cannot be predicted.

At best, life is a fractal pattern. There are some possibilities which are excluded from the matrix. The part-monkey-part-crocodile-part-penguin creature will never evolve, but there will be a variety of new finches, probably including a few species with bright orange, red, green and blue feathers at some time.

You are entirely welcome to your belief in intelligent design.

Just realize that you can't prove the intelligence that exists behind it.