Evolution Not Random

[Meadmaker]

The motion of the earth around the sun is almost perfectly predictable, because all those random events add up to something that obeys very simple laws almost all the time. Therefore it shouldn't be called random. Whether or not the atom emits the photon in a given second is totally unpredictable, and should be called random. Evolution is somewhere in the gray area in between.

Exactly. (IMHO)

And any absolute insistence that one describes it as either random or non-random demonstrates either a lack of comprehension, or an ideological bias.

So now let me rewind the clock a bit, back to May of 2007, when I had started a thread that was an in process review of "The God Delusion", by Richard Dawkins. In chapter 3 (or 4? I forget) the subject of evolution and randomness came up. Dawkins was absolutely insistent that evolution was not random. The creationists sometimes say that the world is too complex to have arisen by chance. Dawkins objected vocifirously, because, to quote him, evolution is "the exact opposite of chance".

I disagree, equally vociferously. It has patterns, and certain predictions can be made, but really, there's a whole bunch of randomness involved, and specific predictions cannot be made, because some cosmic ray might come along, cause cancer in an organism, which meant that organism wasn't eaten by a different organism, which changed whether or not some other organism with a beneficial mutation caused by a different cosmic ray reproduced which....etc. etc. etc. There are an awful lot of random events, including some that are truly random in every sense of the word, that end up having dramatic effects on the course of evolution. That hardly seems "the exact opposite of chance" to me.

So why was Dawkins so adamant? I think it was a sort of ideological bias. In the concluding chapter, having demonstrated to his satisfaction that religion was both wrong and dangerous, he waxed eloquently about discovering the true nature of the universe through the means of science. He was particularly impressive talking about the huge and tiny scales of the universe, from vast galaxies to the amazing world inside an atom.

I like that sort of talk, but there's something about it that may not be satisfactory. Suppose we learn everything to know about the universe, as Dawkins encouraged. We know the complete set of the laws of physics that describes the behavior of every particle. Why would we want to do that? Would we know our place in the universe? Would we know our fate?

Ultimately, no. Our place in the universe is some sort of accident. It didn't have to be that way, because it just happened, when the right cosmic rays caused the right mutations. Our fate is also unknown, because one of those photons might cause skin cancer and change (or end) our lives forever. It's all random. Not random with equal probabilities, but it is random. That can be a bitter pill to swallow.

 

[Belz...]

They're produced by quantum mechanical events. For example, take a molecule in an excited state at the surface of the sun. Every second, it has some probability to emit a UV photon.

But it doesn't spontaneously generate one. It needs to get some energy before emitting one, and it's not like it's "random" in the sense that it's chaotic and acausal. Is it ?

The process by which the photon is emitted (and by which it damages the DNA, for that matter) is quantum mechanical.

I said "random", not "quantic".

In the most modern formulations of physics we have, it is a truly random, non-deterministic event. It cannot under any circumstances be predicted with certainty, no matter how much information you have or how precise your measurements are. The only thing we can speak about is the probability per unit time it will occur.

Woah, woah. Wait a minute. I was under the impression that an electron will act in the same way under the same circumstances. Are you telling me that if I throw a photon at an electron and it excites it, it might emit another photon and it might not, and there is no physical law that governs this ?

So everything in the world is affected - actually, determined - by truly random processes, including the orbit of the earth around the sun.

And yet it works the same way, every time. More info is needed.

 

[sol invictus]

Meadmaker - I agree.

But it doesn't spontaneously generate one. It needs to get some energy before emitting one, and it's not like it's "random" in the sense that it's chaotic and acausal. Is it ?

That particular event is not chaotic, and nothing is acausal, but it is random.

Woah, woah. Wait a minute. I was under the impression that an electron will act in the same way under the same circumstances. Are you telling me that if I throw a photon at an electron and it excites it, it might emit another photon and it might not, and there is no physical law that governs this ?

Yes.

There is a physical law that governs the probability the photon will be emitted, but there is no physical law that tells you with certainty what will happen. Furthermore there cannot be such a law, for a deep reason that would take us very far off track.

And yet it works the same way, every time. More info is needed.

It works almost the same way, every time. The uncertainties in the earth's orbit due to quantum mechanics are mind-bogglingly (is that a word?) and undetectably small, but they are real.

 

[Skeptic Ginger]

How is the model that skeptigirl claims I created not representative of evolution?

How is it you cannot address my comments about why your model doesn't apply? How hard is it to comment on determined selection from a random pool?

 

[Skeptic Ginger]

I noticed a random process that leads to a definite result everytime.

A tire had blown out on the interstate leaving shards of rubber everywhere. Everytime one of the pieces was run over it would randomly move, sometimes left and sometimes right. But eventually all the pieces end up off the roadway. An example of random events leading to a decidedly non-random conclusion.

This is a similar case to taking the random mutations and then presuming all the following actions are directed by the random initiating event. In the case of the tire shreds, you've chosen to look at the seemingly random movement of the shreds as they are hit by the vehicles. But the vehicles are not random. So do you put random tire shred movement into your mathematical model, or do you put non-random vehicle movement into the model?

 

[mijopaalmc]

How hard is it to comment on determined selection from a random pool?

So you're saying that picking a number from a finite or countable infinite subset of a uncountably infinite set* where each number has an equal probability of being picked is "determined" because the subsets are smaller than the set from which they were picked, therefore limiting the choices that can be made?

*e.g., the set {1,2,3,4,5,6} or the natural number, which are a finite subset and a countably infinite subset, respectively, of the real numbers

 

[Skeptic Ginger]

There is an interesting question one could ask. Suppose you went back to the time just after the first life had emerged, and you changed some small thing (the proverbial butterfly flapped its wings, or Homer Simpson sneezed). Three billion years later, what kind of life would be around?

Obviously no one knows the answer, but my intuition is that while complex life would have evolved, it would look quite different from us (at least superficially). That alternate skeptigirl might have ten arms, or none. Maybe we'd be born in pouches, or spread on the wind like dandelion seeds. So in that sense, evolution is random.

But on the other hand I think it's almost certain that complex (and probably intelligent) life of some sort would come to be, given enough time. In that sense evolution is deterministic.

This is what I meant to represent with my pinball analogy - the motion of the ball is unpredictable, and whether it drains down the middle or to the side is too, but it's inevitable that it will drain eventually.

This has been one suggested hypothesis. And, some suggest organisms all have certain features, especially faces, only because we evolved from that initial random event. But another hypothesis is more supportable that we have certain features because that is what will always evolve given the conditions. For example, it is predictable that eyes devolve when organisms become isolated in environments devoid of light, such as caves.

You could argue it is random that fish swim side to side and mammals which went back into water from land such as whales swim up and down. You also could say it is random which means a marine organism will develop to get around.

There are a number of types of locomotion in water, on land, and through air. But when it comes down to counting those types, they can be counted on one hand. If evolution were going to be correctly described by mijo's choice of applying his mathematical model (after all, that's what the model we choose is supposed to do, describe something) then you would expect an infinite number of types of locomotion, and infinite number of eye types, and infinite variety of the locations of mouths and eyes and noses.

No one is denying there is a random component in evolution. Organisms evolve some very clever ways of getting around. Is it useful then to describe evolution as a random process because a swimming organism could evolve its propelling motion from side to side or up and down? Or because an organism can evolve one of two types of eyes? Is it random because eyes can be of different sizes and colors?

What makes mijo's particular choice of his mathematical model a poor choice, is it describes a minor element in evolution, but it does not describe the major elements. It's akin to Shoogar's tire shred example. It describes the movement of the tire shred, but it misses the main element, the fact the vehicle movement isn't random. If you made the tire shred's movement the focus in your model, you would describe the fact that how long it took and exactly where the shreds ended up were random. That is useless when you think about the more important elements you could use to describe the process. The cars hitting the shreds are not random. And even though the timing and exact locations of the shreds are random, you can determine the shreds will always end up off the road. And that is a much more useful model that gives you much more useful information.

 

[Skeptic Ginger]

... In most chaotic systems worth studying there are some states that are highly likely. There are other states that are absolutely impossible. One way, but only one way, to characterize systems might be to talk about the probability distribution of final states based on whatever is known about the initial state.

Evolution is a bit like that. We don't know how species will look in a million years. Furthermore, this is not just a limitation of our ability to measure initial conditions or compute equations of motion. Quantum effects will influence the future development of life. On the other hand, we can say that some developments are highly likely, while others are absolutely impossible.

Does that mean that evolution is random? I think it means that one sentence summaries of such a complex phenomenon are useless.

Once again, whether we call the system "random", or not, depends on exactly what aspect of the system we are considering.

There are a couple of important points here. One of the reasons we can't predict what life will be like in another million years is mostly because we can't predict the conditions that life will exist in.

And as I said, which you echoed in your second post, it matters which part of the system you are looking at. Can we predict which color a flower will evolve? No, I don't think so but we can predict the flower's color will evolve because it will serve particular purpose. Which is more important in understanding or describing evolutionary processes, the color or the purpose of the color? Well does knowing the flower's color will be random help you understand evolutionary processes, or does knowing the purpose of the color will not be random give you a better model to focus on?

 

[Skeptic Ginger]

If you by "species" do not limit yourself to arthropods, then sea stars and many kinds of flatworms have more than 2 eyes. I believe there are nematodes that have more as well, and maybe gnathostomulids, but I can't remember at the moment.

ETA:
Having read skeptigirl's post again, I can point out that there are also numerous groups of organisms which develop no eyes. For instance sponges, cnidarians and many of the smaller phyla.

I also assume that mijo is not interested in being given an example which, so far, complies with all his criteria, but is more interested in semantics and squabbling. I keep my examples to myself, then.

Eyes evolved from a series of steps. I was referring to the end results not the steps. Eyes begin with simple light sensing cells and for that matter, plants sense and react to light.

With that said, it's interesting that the spider eye turned out to be something that evolved from compound eyes. There may be a future evolution which gives us a completely different eye and maybe then 8 eyes will prove to be one of the options. It may also prove to be dysfunctional and two or more of the spider eyes will cease to function. There still will be a limit or a point where the number of eyes is limited by the usefulness of those eyes. In other words, there are not random numbers of eyes on any organism. There is a point of diminishing return. Also, eyes that are not needed evolve away. There is a great degree of determinism along with a small degree of randomness.

But I shall also look into the organisms you mention to see where those eyes fit into the evolutionary pattern.

 

[Skeptic Ginger]

Gnathostomulids appear to have primitive eyes which sense light. I only found descriptions of binary eyes.

Starfish^WP

The tube feet, spines, and pedicellariae found on starfish are sensitive to touch, while eyespots on the ends of the rays are light-sensitive.

So these are light sensing cells, not actual eyes.

Eye evolution

LIGHT SENSITIVE EYE PATCHES...

SIMPLE EYE-CUP WITHOUT LENS...

COMPOUND EYE VS. SIMPLE EYE...

HUMAN EYES vs. CAMERA...

 

[Skeptic Ginger]

Exactly. (IMHO)

And any absolute insistence that one describes it as either random or non-random demonstrates either a lack of comprehension, or an ideological bias.

So now let me rewind the clock a bit, back to May of 2007, when I had started a thread that was an in process review of "The God Delusion", by Richard Dawkins. In chapter 3 (or 4? I forget) the subject of evolution and randomness came up. Dawkins was absolutely insistent that evolution was not random. The creationists sometimes say that the world is too complex to have arisen by chance. Dawkins objected vocifirously, because, to quote him, evolution is "the exact opposite of chance".

I disagree, equally vociferously. It has patterns, and certain predictions can be made, but really, there's a whole bunch of randomness involved, and specific predictions cannot be made, because some cosmic ray might come along, cause cancer in an organism, which meant that organism wasn't eaten by a different organism, which changed whether or not some other organism with a beneficial mutation caused by a different cosmic ray reproduced which....etc. etc. etc. There are an awful lot of random events, including some that are truly random in every sense of the word, that end up having dramatic effects on the course of evolution. That hardly seems "the exact opposite of chance" to me.

So why was Dawkins so adamant? I think it was a sort of ideological bias. ....

...Ultimately, no. Our place in the universe is some sort of accident. It didn't have to be that way, because it just happened, when the right cosmic rays caused the right mutations. Our fate is also unknown, because one of those photons might cause skin cancer and change (or end) our lives forever. It's all random. Not random with equal probabilities, but it is random. That can be a bitter pill to swallow.

Your last comment here is a good place to present an alternate scenario. Would you consider us the result of accidental random events if life always arose among common circumstances found in the Universe?

Is it random that intelligence always increasingly evolves?

Is it random that life evolves microorganisms, plants, insects, and animals?

We don't know the answers to those questions and won't until we have more than one example, (Earth), from which to gather data. But as we discover more and more about evolutionary processes, there is evidence accumulating that there is a lot more determinism in the system than there is randomness.

So is it ideological bias or is it evidentiary bias?

 

[Skeptic Ginger]

So you're saying that picking a number from a finite or countable infinite subset of a uncountably infinite set* where each number has an equal probability of being picked is "determined" because the subsets are smaller than the set from which they were picked, therefore limiting the choices that can be made?

*e.g., the set {1,2,3,4,5,6} or the natural number, which are a finite subset and a countably infinite subset, respectively, of the real numbers

The subsets are not just smaller, they are specific. Useless sets are never selected. By that I don't mean they never occur in the genetic code, I mean they are not propagated.

No one is denying there are 6 billion different human genomes give or take. What I'm saying is those 6 billion different people may all look slightly different. But it's a lot more important that they are all humans than the fact they have minor differences.

 

[mijopaalmc]

The subsets are not just smaller, they are specific.

Again, this doesn't make selection for those sets non-random.

 

[Kotatsu]

Eyes evolved from a series of steps. I was referring to the end results not the steps. Eyes begin with simple light sensing cells and for that matter, plants sense and react to light.

I am familiar with the evolutionary history of these things.

But I shall also look into the organisms you mention to see where those eyes fit into the evolutionary pattern.

I think flatworms may be the poster children for pigment cup ocelli.

Gnathostomulids appear to have primitive eyes which sense light. I only found descriptions of binary eyes.

Hmmm. I may misremember. One of the groups of animals we studied at a meiofauna PhD course last autumn had members which possessed more than one pair of eyes, but when you get to look at 5-6 phyla a day for almost two weeks, they all sort of become jumbled together after a while... I'll look in Brusca and Brusca and see what I can come up with.

 

[Skeptic Ginger]

http://www.thefreedictionary.com/specific

spe·cif·ic (sp-sfk)
adj.
1. Explicitly set forth; definite. See Synonyms at explicit.
2. Relating to, characterizing, or distinguishing a species.
3. Special, distinctive, or unique
n.
1.
a. Something particularly fitted to a use or purpose.
b. A remedy intended for a particular ailment or disorder.
2.
a. A distinguishing quality or attribute.
b. specifics Distinct items or details; particulars.

http://www.thefreedictionary.com/nonrandom

Adj. 1. nonrandom - not random
random - lacking any definite plan or order or purpose; governed by or depending on chance; "a random choice"; "bombs fell at random"; "random movements"

No mijo, it doesn't make it nonrandom, it just makes the nonrandom component irrelevant.

 

[Skeptic Ginger]

....
Hmmm. I may misremember. One of the groups of animals we studied at a meiofauna PhD course last autumn had members which possessed more than one pair of eyes, but when you get to look at 5-6 phyla a day for almost two weeks, they all sort of become jumbled together after a while... I'll look in Brusca and Brusca and see what I can come up with.

Considering the light sensing cells in plants and starfish, it wouldn't surprise me to see multiple light sensing cells in other primitive organisms.

 

[mijopaalmc]

No mijo, it doesn't make it nonrandom, it just makes the nonrandom component irrelevant.

Huh?

You seem to arguing the exact opposite of what you were arguing before: that the selection from a specific set is "determined"* if the set is some how limited.

*which I read as a synonym for "deterministic" based on what you have said before

 

[jimbob]

Which is exactly why I asked Mijo and Jimbob to explain what they mean by random:

1) Deterministic and entirely causal, but impossible to predict by us.
2) Random in the sense that they are acausal i.e. like quantum fluctuations.

I would say that it depends on the timescales involved:

Was it inevitable that a tool-using social biped would have evolved 65 millioon years after the KT impact? No. (See the discussion about quantum events causing macroscopic effects in nonlinear systems). A slight alteration in the weather could have wiped out a common ancestor of the hominids (for example). Something similar might have evolved, but there was no inevitability.

It was inevitable that something would have evolved, and that evolutionary niches would have been made/filled, but quite possibly ones that are not filled today. The commoner niches would have been filled, grazing herbivores and carnivores that prey on them, for example.


It was highly predictable that something would have evolved. Having said this, given a stable environment, it is predictable that evoutionary adapations to that environment will occur. It is also predictable that the rate of change in evolutionary adaptations will be fastest when the environment is changing or has changed, as deviations from the norm are less likely to be deleterious than when an organism is well-adapted to its niche.

For an individual orgainism, selection is a game of chance, with the odds modified by its traits. Over a longer time and for a population, one can work out how traits will spread (and in principle put a number on the likelyhood of this happening).

Roulette is (for arguments sake) random, you can't say with certainty who will will a particular roll. Over time, the slightly better odds for the house "ensure" profit for the casino owners. Similarly over time, and with a large enough population, traits with a selective advantage as low as a few percent will spread.

I wasn't aware chaos theory dealt with quantum physics, but then I don't know much about it. And again, it depends what you mean by "random".

That is why, I like to think of selection as probabilistic, not just because events like weather are unpredictible, but because quantum events and chaotic sstems would mean that these quantum effects could have macroscopic effects. If the wind blows form a slightly different direction, a hunter misses the scent of its prey etc.

I would say that (because of nonlinear amplification of quantum uncertanties, that truly are random, it is in principle impossible to predict the weather, far enough ahead. However it is still possible to predict climate.

Organisms haven't haven't evolved adaptations to weather, they have evolved adaptations to climate.


In answer to your question:

Selection is probabilistic, but this still leads to optimisation to environments (although the nature of the optiimisations will depend on mutations, and might be surprising, or indeed diferent if it were posible to rreun the situation, to identical conditions, as the quantum events would still be different).

That optimisation to environmental stimuli will occur is inevitible, what optimisation isn't.

Over geological timescales, I would argue that the environment itself is random. Some orbits are chaotic, should that include a potential "dionosaur killer" asteroid, then quantum events could influence asteroid strikes on earth. As organisms fill empty niches, they prevent other organisms filling slightly differnet niches; whilst lions exist, no leopard descendant will evolve into something that competes completely with lions.

Some niches must be easier to fill than others: flight, for example keeps on evolving independently. Sight, does too, sometimes simple and compund eyes on the same organism (AFIK- they are sold as aquasaurs in toyshops, I don't know their proper name).

Atrophy of flight for birds and dwarfism on small islands away from large predators, are other examples.

Some niches seem less easy to fill. Large mammals have been around for at least 35 million years, but only very recently have humans evolved. There must have been a "potentially available" niche for tool-using social animals for a long time befor the various hominids and great apes began filling it. I would tentitively suggest that this could be because such a niche had a lower proabability of being filled in any particular length of time (but that is just thinking aloud at this time).

Does that make my position a little clearer?

That adaptations would evolve to particular environments is inevitable (or highly likely), what form these take is not.

 

[Skeptic Ginger]

Huh?

You seem to arguing the exact opposite of what you were arguing before: that the selection from a specific set is "determined"* if the set is some how limited.

*which I read as a synonym for "deterministic" based on what you have said before

It sure seems like you really haven't read much of what I have been saying at all. So I'll repeat myself,

No one is denying there is a random component in evolution. Organisms evolve some very clever ways of getting around. Is it useful then to describe evolution as a random process because a swimming organism could evolve its propelling motion from side to side or up and down? Or because an organism can evolve one of two types of eyes? Is it random because eyes can be of different sizes and colors?

What makes mijo's particular choice of his mathematical model a poor choice, is it describes a minor element in evolution, but it does not describe the major elements. It's akin to Shoogar's tire shred example. It describes the movement of the tire shred, but it misses the main element, the fact the vehicle movement isn't random. If you made the tire shred's movement the focus in your model, you would describe the fact that how long it took and exactly where the shreds ended up were random. That is useless when you think about the more important elements you could use to describe the process. The cars hitting the shreds are not random. And even though the timing and exact locations of the shreds are random, you can determine the shreds will always end up off the road. And that is a much more useful model that gives you much more useful information.

 

[mijopaalmc]

skeptigirl-

The thing that you are adamantly refusing to acknowledge is that an overall orderly outcome can arise from a random process. For instance, in a Galton-Watson process, an individual produces a random number of offspring. If the mean number of offspring is less than 1, the individuals of this type will go extinct with probability 1. If the mean number of offspring is equal to 1, the individuals of this type go extinct with non-zero probability. If the mean number of offspring is greater than 1, the individuals of this type grow exponentially with probability 1.