Evolution Not Random

[Meadmaker]

Mead, are you saying that the mutation IS the selection ?

No. I'm saying that a mutation is an event, and selection is the outcome of a series of events.

Sometimes, we speak of death as a selection event. We could speak of birth or mating as a selection event, but that isn't really accurate. Unlike mutation, there is no specific moment when "selection" happens. After a long time, we can say which mutations were selected, and we can point to events (births, deaths, matings) that contributed to the selection, and we can say to some extent how a particular mutation contributed to its own selection.

 

[sol invictus]

This is one of the most common comments regarding randomness and evolution, and I want to make my own comment. It seems to me that when you compare mutations and selection, you are comparing apples and oranges.

Mutations are very real events. They are concrete, and they occur at a point in time. When the organism has a gene that was not present in a parent (or other gene donor, for simplicity I'm going to say that organisms have parents) a mutation has occurred. It's fairly simple. Now that we know that DNA is the source of genes (mostly) we can even talk about causes of mutations, e.g. radiation that splits DNA in a place it wasn't split before.

I see your point, but I don't completely agree. We can regard mutation as a process too - not the individual mutations themselves, but the collective effects of many mutations on a genome. We can speak about mutation rates.

For example we could imagine a computer model in which the genome is modified randomly at some rate (mutation), and in which some configurations replicate and some don't according to a deterministic rule (selection). The rate of mutation and the strength or number of selection pressures are parameters in the model. Then we can ask what happens when we vary those parameters.

If we turn off mutations, the genome is frozen and no evolution will occur. If we turn off selection, the genome will fluctuate randomly, but no evolution towards greater fitness will occur (or only very very slowly). If both are turned on, there may be an special point or points in the parameter space where evolution happens the fastest, and we can investigate and characterize the model in interesting ways.

Anyway, from this point of view mutation and selection are parameters in a model, and I don't see any real problem in comparing them and their effects.

 

[articulett]

Meadmaker believes he is smarter than and clearer than the article referenced in the OP and Dawkins. Most creationists probably agree. Most biologists would not.

 

[sol invictus]

Meadmaker believes he is smarter than and clearer than the article writers in the OP and Dawkins. Most creationists probably agree. Most biologists would not.

I used to be very frustrated when I read popular books in my field (which is quite technical) - even those written by experts - because they are never really correct. They use language in an imprecise or non-technical way, and I would be irritated by what I felt were the distortions and near falsehoods they contained.

I realize now that it is impossible to communicate with the broader public without such imprecision. Words are used differently by different groups of people, and some important concepts are almost completely lacking to the broader public. So if you say something in a precise way that a specialist would recognize as rigorously correct, it may mean something quite different to a layperson, and it may not be the best way to communicate the facts.

There is a real tension there, and it's very hard to find the best middle ground - particularly when the debate gets politicized, and some people start twisting words for the purposes of obfuscation rather than clarity (I'm not talking about anyone in this thread, just to be clear).

 

[articulett]

Yes, humans learn by getting the big pieces of the puzzle-- through analogies and the like. They tend to first understand in terms of black and white... and then slowly fill in shades of gray and if they are lucky, fill in the details in color. What is important is the overall message (big picture) being conveyed. I just find it amusing that some people truly believe they are being clearer than people who actually communicate the subject to large numbers of people when there is no evidence that they could describe the essence of evolution to anyone. To me, the people who think the OP or Dawkins are unclear are people who haven't really seemed to understand what exactly natural selection is and why it readily leads to the appearance of design (exponential replication of the best replicators in the given environment.)

I don't think anyone can understand the details of a process if they think the process is "random"... no matter what definition they use. The randomness is the easy, non-essential part of understanding the process of evolution... Natural Selection is at the heart of what we observe--and it is not random though unpredictable events can influence the outcome.

I, frankly don't think it's correct to call mutations random, but I'm willing to live with it, because it is random in regards to whether they benefit the organism or not.... however, evolution has made some areas of the genome far more resistant to mutation than others, and this is not random. Plus all mutations have causes... even if we don't know what they are.

 

[Meadmaker]

I see your point, but I don't completely agree. We can regard mutation as a process too - not the individual mutations themselves, but the collective effects of many mutations on a genome. We can speak about mutation rates.

It occurred to me that the phrase "genetic mutation" probably preceded the knowledge of DNA. It probably meant, "genetic variation" or "genetic change". Later, once we learned about DNA as the carrier of genetic information, "mutation" became synonymous with DNA alteration in most minds.

If we spoke of variation and selection, instead of mutation and selection, it would probably be more obvious what is meant by the two components. Neither one is a real, physical, event, but both are correlated with real, physical events. Then, in describing the results of the two components, we would say that the results of variation are random, not favoring any sort of variation, while the results of selection were not random. On the other hand, both variation and selection occur as a consequence of underlying random events.

 

[mijopaalmc]

Meadmaker believes he is smarter than and clearer than the article referenced in the OP and Dawkins. Most creationists probably agree. Most biologists would not.

Is this sort of like skeptigirl thinking she's smarter than the engineers is the car industry because she thinks saying that the manufacturing of cars is random is "absurd"?

Seriously this seems to be one of articulett's biggest problems: she seems to think that the people she thinks are smart can't be mistaken. Well, in this case they are because they are using a different definition of "random" and refuse to acknowledge that mathematics offers a perfectly sensible and non-trivial definition that is useful in describing evolution.

 

[cyborg]

Cyborg:

Over the last hundred million years, would you say that random events have affected the environment to such an extent as to significantly affect the "path" of evolution?

I could say events affect the outcome - but then I wouldn't be saying much - it really is quite irrelevant as to how random they "really" are.

But then I have been trying to show you this for some time and you keep resisting.

Now, why isn't Chess a random game when you surely must realise that as soon as you say "there is no random event that can affect the outcome of the result of a game of Chess" that I can introduce one?

Is it because it would look silly?

 

[Meadmaker]

I could say events affect the outcome - but then I wouldn't be saying much - it really is quite irrelevant as to how random they "really" are.

But then I have been trying to show you this for some time and you keep resisting.

Now, why isn't Chess a random game when you surely must realise that as soon as you say "there is no random event that can affect the outcome of the result of a game of Chess" that I can introduce one?

Is it because it would look silly?

By coincidence, my son played in a Chess tournament last night. (3rd place ) After one of his games, we discussed it and said he "got lucky". There was a potential mating attack that an opponent overlooked. Although down considerably in material, he made the move that checkmated the king, and won the game.

We said he was "lucky". Would we say that makes the game "random"? We could debate the question endlessly. It all depends on what aspect of the game you are looking at. We both knew that my son won the game because the opponent made bad moves. It's not like a lucky die roll came about. You could say that my son was "selected" for the trophy.

Except, well, he wasn't selected, because it turns out that there were only 3 trophies, and he tied for 3rd place. The tiebreaker was based on the final finishing position of the opponents. The other guy played tougher opponents, and so got the trophy. The opponents were chosen randomly. If that trophy were a meal, it could be the difference between life and death, and random events would have influenced the selection.

Even when it comes to Chess, it's not always black and white. (Pun intended)

 

[jimbob]

Mead, are you saying that the mutation IS the selection ?

I like to think of it as loading the dice, but still so that there is chance about the outcome... (a deleterious mutation loads the dice heavily agianst survival).

Do you see my point, even if you don't accept it?

Actually I think of it modulating the mean value for the number of reproducing offspring per parent, and thus the chance of the traits being transmitted or surviving for a particular number of generations. (Assuming a poisson distribution, which I would argue is probably adequate.)

Thinking about the actual odds, the stability or otherwise of populations and the brood-sizes, you can conclude that any individual organism at birth is unlikely to breed.

Barn owls, for example, have a clutch-size of about 5, (many sources, for example here), mates at one year old, tends to live for 1-5 years inthe wild, and 15-20 years in a more benign environment, they can have two broods in a year.

A successful pair of barn owls could easily produce 25 chicks over that 5 years. However the population is declining in many parts of the world.

This means that on average, fewer than two chicks per pair will produce breeding offspring. The odds of a barn-owl chick surviving to breed could be *about* 1:12.

It is thus far more likely for a deleterious to be removed than for an advantageous one of a similar effectiveness to be retained.

Suppose a chick had a trait that doubled its chances of successfull reproduction; it would now have a 1:6 chance of successful reproduction. This particular trait, arising in a single individual is 6x more likely to die out in one generation than survive.

Suppose a chick had a trait that halved its chances of reproduction; it would now have a 1:24 chance of successful reproduction. This trait, arising in a single evolution, is 24x more likely to die out within a single generation than to survive.

If the advantageous trait conferred a 11.5x advantage compared to the lack of trait, then the odds of the chances of survival for one generation would be 11.5:12=23/24, and the odds of the trait being removed would be 1:24, the same as the odds of the original deleterious trait surviving.

Given a large enough population, and enough time, of course some beneficial traits will survive, and once established, will spread through the population.

Again, how likely this is for a particular trait, can best be explored with a probabilistic treatment.

 

[H'ethetheth]

You guys seem to be talking past each other here.

Also, this applies to the entire thread.

 

[Fredrik]

I'm sure everyone who has participated in the discussion about randomness in chess understands this, but no one has said it, and I think it should be stated explicitly:

The game of chess doesn't contain any randomness. Every position is ether drawn, won for white, or won for black. What we can describe as "random" are certain physical systems, e.g. a computer which records the moves as they are performed on a chess board by two human players. The humans are effectively random number generators here.

Chess isn't random, but a game of chess is.

 

[cyborg]

We both knew that my son won the game because the opponent made bad moves. It's not like a lucky die roll came about.

Not even the random die being quantum mechanically rolled in the opponent's head?

 

[cyborg]

Chess isn't random, but a game of chess is.

I see we're getting a class/instance distinction.

Progress! - perhaps.

 

[jimbob]

Originally Posted by jimbob
Cyborg:

Over the last hundred million years, would you say that random events have affected the environment to such an extent as to significantly affect the "path" of evolution?

I could say events affect the outcome - but then I wouldn't be saying much - it really is quite irrelevant as to how random they "really" are.

But then I have been trying to show you this for some time and you keep resisting.

Now, why isn't Chess a random game when you surely must realise that as soon as you say "there is no random event that can affect the outcome of the result of a game of Chess" that I can introduce one?

Is it because it would look silly?
Is it because it would look silly?

Chess need not be random. Two computer programs playing each other at chess, might or might not use pseudorandom numbers in their calculations, however the outcome would deterimned.

Monopoly involves chance and simple strategy, Snakes and ladders is pure chance. (Assuming dice rolls are random).

Now, in discussing the evolutionof humanity, one can say either that as soon as there was life, it was inevitable that humanity would eventually evolve; or you can say it was not inevitable.

I would say that it was not inevitable, because truly random events had a significant influence, not only on the evolution of humanity, but on every species curently alive. Do you disagree?

I am talking about the evolution of humanity, because to many religious people, both creationists and not, humanity is considered to be special. I have come across what I call the "light blue touchpaper and retire" deist. Their viewpoint is that the creator created the universe in such a way that it was inevitable that worshipers would evolve without any more interference.

 

[Fredrik]

I, frankly don't think it's correct to call mutations random, but I'm willing to live with it, because it is random in regards to whether they benefit the organism or not.... however, evolution has made some areas of the genome far more resistant to mutation than others, and this is not random. Plus all mutations have causes... even if we don't know what they are.

You're saying mutations aren't random?! Wow...that's...wow. I don't even know where to begin. Those "causes" are interactions that can only be described by quantum mechanics. Nothing is more random that that. Nothing.

 

[cyborg]

Chess need not be random. Two computer programs playing each other at chess, might or might not use pseudorandom numbers in their calculations, however the outcome would deterimned.

Computers may or may not be random - they could use a hardware dongle to convert quantum mechanical events into numbers for use in internal calculations.

Snakes and ladders is pure chance. (Assuming dice rolls are random).

Pure chance of what?

Now, in discussing the evolutionof humanity, one can say either that as soon as there was life, it was inevitable that humanity would eventually evolve; or you can say it was not inevitable.

I can - and neither view in incompatable with saying evolution is a deterministic process.

I would say that it was not inevitable, because truly random events had a significant influence, not only on the evolution of humanity, but on every species curently alive. Do you disagree?

jimbob - you're clearly not getting it at all.

I am talking about the evolution of humanity, because to many religious people, both creationists and not, humanity is considered to be special. I have come across what I call the "light blue touchpaper and retire" deist. Their viewpoint is that the creator created the universe in such a way that it was inevitable that worshipers would evolve without any more interference.

So? I am not talking to these people - stop invoking them as if I give a crap.

 

[cyborg]

You're saying mutations aren't random?! Wow...that's...wow. I don't even know where to begin. Those "causes" are interactions that can only be described by quantum mechanics. Nothing is more random that that. Nothing.

And so we're back to "everything is random."

 

[jimbob]

Originally Posted by jimbob
Chess need not be random. Two computer programs playing each other at chess, might or might not use pseudorandom numbers in their calculations, however the outcome would deterimned.

Computers may or may not be random - they could use a hardware dongle to convert quantum mechanical events into numbers for use in internal calculations.

Cyborg, I said "need not be be random". That does not preclude occasions where something is random.

I always understood that in deterministic systems, identical inputs always gave identical outputs. ETA: when people talked about deterministic systems, they meant systems where identical inputs always produced identical outputs

Are you saying that "evolution is a deterministic process where identical inputs would not always produce identical outputs"?

Quote:
I would say that it was not inevitable, because truly random events had a significant influence, not only on the evolution of humanity, but on every species curently alive. Do you disagree?

jimbob - you're clearly not getting it at all.

So do you think that random events have significantly influenced the course of evolution of life on Earth?

 

[cyborg]

Cyborg, I said "need not be be random". That does not preclude occasions where something is random.

*Sigh*.

Are you saying that "evolution is a deterministic process where identical inputs would not always produce identical outputs"?

No jimbob - that is your contention. It is your contention that it is random when a member of species A is eaten by a member of species B yet another member is not.

It is my contention that the action of a predator is not a die roll.

You are free to introduce QM - I am then free to say, "everything is random," and note your observation of evolution as random as uninteresting.

So do you think that random events have significantly influenced the course of evolution of life on Earth?

I answered that question and you didn't like the answer.

Events affect the course of evolution of life on Earth. Whether or not they are "random" is really quite irrelevant.

Events affect the course of a game of Snakes and Ladders. Whether or not the dice are "random" is really quite irrelevant.