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What evidence is there for evolution being non-random?

CFLarsen said:
If selection is chaotic - unpredictable - and evolution is random, how can you correctly predict that from a gene pool of exclusively blue eyed people, you will get blue eyed children?
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You left out the random inputs, mutation. They are rare, but making that prediction you could get unlucky and be wrong.

So if you simplfiy down to one generation, you don't involve mutation, heck you even involve selection, the random elements become incosequential. Now, by stating the parents both have blue eyes, you have removed some variability in the offspring. How much does that reduce the 70 trillion genotypes by (considering only two parents., more if you have a larger population)
 
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When we're talking about evolution by natural selection of inherited characteristics, are we talking about a single process? Mutations may be random, but the range of mutations we actually observe in living organisms does not include those mutations that are incompatible with life. Immediately we have a selection process that is non-random. When we look at the frequencies of particular mutations in subsequent generations, again the selection process that leads to those frequencies is not random.

We may be talking about a process that, because part of its input is random, is random by a strict mathematical definition of the term, but we're certainly not talking about a process that is random in the sense of the "747 assembled by a tornado in a junkyard" strawman that creationists use.
 
Walter Wayne said:
Technically, from identical initial conditions, several results are possible. I am using the technical a little more narrowly in that I am suggesting there are significantly different results possible. So I don't include an electronic system where the voltage is 100V +/-10mV because of thermal noise. In the case of evolution I would say that even with the exact same non-biological inputs, they is no guarantee that the end of the age of dinosaurs guarantees a branch as intelligent as humans as one example of a "siginificantly different possibility".

I do that because I think that evolution is random even in many non-technical senses. I would agree that evolution is not random if using the layman's definition of uniform probability, but the sum of two dice is non-uniform, but in most ways I have seen it used in general speech I think it is random.

Edited to add: Sorry for the long answer, but I really think it is random in many senses of the word, trying to be specific about some of the senses that don't apply.
And also so people understand I don't mean it in the almost useless sense that anything made up of quarks and leptons (i.e. everything) is going to be random in a very strict sense.
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Thank you. :)

Now that we have a definition, we can have a discussion. To use my philosophy minor for some use, your argument appears to be the following:

1 - Systems which have identical initial inputs can have different outputs. (In other words, non-determanistic).
2 - Evolution is such a system.
C- Therefore, evolution is random.

Your argument is sound, but I disagree with your premises. Specifically, 2. You are including all of evolutionary history as your "system", but only setting the first set of inputs as the same.

So lets simplify your example into three scenarios:

1) A point mutation occurs. Assuming equal ratios of nucleotide mutation frequiencies, and assuming identical initial conditions, do you think the same mutation would occur a second time?

2) A defined level of variation exists in a population. Selection changes the frequencies of alleles in the population over time (i.e. evolution). Assuming identical initial conditions (i.e. the same defined variation), do you think we would see the same change in allele frequencies occur a second time?

3) A population of E. coli exists in which all the members contain a plasmid which encodes a Kanamycin resistance gene. In this gene is a transposon (transposable element), thus switching this gene off. Growing colonies of this E. coli strain on growth medium which contains Kanamycin leads to the arisal of Kanamycin resistant colonies, as a result of the transposon 'jumping' out of the gene, thus switching it back on. When this happens is unpredicable. Given identical initial conditions, do you think the same ratio of Kanamycin resistant colonies would arise?
 
Walter Wayne said:
And also so people understand I don't mean it in the almost useless sense that anything made up of quarks and leptons (i.e. everything) is going to be random in a very strict sense.
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That clears it up for me. I was hoping you weren't meaning that!

But I think the sense by which Dawkins uses the term is as corollary to rejecting any notion that evolution is driven by "purpose" or "goals". Although theoreticaly problematic and a bit "far out", I don't see why someone couldn't attempt to construct a scientific theory of "goal driven evolution" and test whether such things can actually occur.

For example, we could take population A and B of the same species and plan to subject each population to different selection pressures at some point in the future. What we would be looking for is the emergence of anticipatory, advantageous phenotypes before any selection pressure is present, and at a much greater probability than other disadvantageous phenotypes.

Hey, I know this is probably a little too "woo" for most people here, and would involve major theoretical changes in how we view causation and the arrow of time, but I think it would be the only way to test if evolution could proceed in a way that satifies everyones definition of non-random.
 
Walter Wayne said:
Oh, that's why the little lady and I can't seem to have anymore kids. Well the house was getting crowded anyways.
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:D

As a side note, doing some very bad maths (it's most likely horribly wrong), I get 8,883,608 possible combinations of chromosomes in a spermatozoon.
 
l0rca said:
Read The Extended Phenotype, by Richard Dawkins.

Because I'm the sort, I recommend highly that you use a local library to get the book, and not to buy it.
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An aside: This puzzles me. Why do you recommend not buying this book?
 
ThatSoundAgain said:
An aside: This puzzles me. Why do you recommend not buying this book?
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Libraries need attention. If you like what an author stands for, I'd instead suggest giving towards their cause. Richard Dawkins is wealthy enough to subsist. Now, his charity, that could use the money.

I'm also motivated by the hacker ethos. Knowledge should be free domain.
 
CFLarsen said:
If selection is chaotic - unpredictable - and evolution is random, how can you correctly predict that from a gene pool of exclusively blue eyed people, you will get blue eyed children?
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In much the same way as you can predict you won't get 'fish' when you throw a normal die.
 
Taffer said:
It is this reason why I buy the books of those authors who give their novels up to free domain.
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Yes, that's certainly a good reason to buy books.

Myself, I buy them because I can not read them any other way, living in Spain. However I do donate them to libraries, or circulate them to my friends, and people I meet over the internet.
 
Mijo said:
Organisms adapting to their environment in no way proves that evolution is non-random; the mean fitness of a population increasing over time only tells us that the frequency of less fit individuals is increasing and that can occur randomly.
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Are you asking whether evolution is random with respect to the universe or random with respect to the Earth? It's clearly not random with respect to the Earth, because, as you say, organisms evolve to be more fit in their environments. You might argue that evolution is random with respect to some larger environment, such as the universe, because there is much less interaction between Earth's organisms and the universe as a whole.

I'm not sure what you mean by increasing the fitness of individuals, but randomly.

~~ Paul
 
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l0rca said:
Libraries need attention. If you like what an author stands for, I'd instead suggest giving towards their cause. Richard Dawkins is wealthy enough to subsist. Now, his charity, that could use the money.

I'm also motivated by the hacker ethos. Knowledge should be free domain.
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All right, thanks for the clarification. Those are good reasons. I thought it might be on general principle, since it didn't seem plausible (from what I've read of your posts here) that you would have a grudge towards Dawkins specifically.

The original remark just sounded vaguely like being being related to the sentiment of donating Sylvia Browne books to RSLancaster so she doesn't sell extra copies.
 
l0rca said:
Yes, that's certainly a good reason to buy books.

Myself, I buy them because I can not read them any other way, living in Spain. However I do donate them to libraries, or circulate them to my friends, and people I meet over the internet.
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I applaud you, sir.

This is a good site, if you like "hard" sci-fi.
 
Walter Wayne said:
You left out the random inputs, mutation.

They are rare, but making that prediction you could get unlucky and be wrong.

So if you simplfiy down to one generation, you don't involve mutation, heck you even involve selection, the random elements become incosequential. Now, by stating the parents both have blue eyes, you have removed some variability in the offspring. How much does that reduce the 70 trillion genotypes by (considering only two parents., more if you have a larger population)
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No, I didn't leave it out. I was responding to your post about selection - not mutation.

Mutations are rare? How do you know that? Compared to what?

Jekyll said:
In much the same way as you can predict you won't get 'fish' when you throw a normal die.
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Oh, no, it's much more non-random than that. We know it because of the way genetics works.
 
CFLarsen said:
Oh, no, it's much more non-random than that. We know it because of the way genetics works.
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You get a bunch of blue eyed people to breed they all have blue eye kids (but there is variation in the other features). You throw a bunch of normal dice, they always return 1-6.

No brown eyes, no 7s (assuming no mutations or dice being spit in half). What's the difference?
 
Jekyll said:
You get a bunch of blue eyed people to breed they all have blue eye kids (but there is variation in the other features). You throw a bunch of normal dice, they always return 1-6.

No brown eyes, no 7s (assuming no mutations or dice being spit in half). What's the difference?
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That's exactly it: Once in a while, you do get a mutation with humans.
 
Walter, the overall progress of evolution, over long time scales, is unpredictable. Although the natural selection itself is not a random process, its effect depends on the environment which in turn depends on hardly predictable events, including the tectonic and volcanic activity, weather, space collisions (apparently a very important factor determining the progress of evolution on Earth), etc.

Over short time scales, the non-random nature of selection makes the results more predictable; the more you can control (or know) the conditions, the better you can predict the expected results, but never down to the tiniest elements. In this regard, it's not unlike weather.

It seems to me that your question has nothing to do with evolution. It's all about your understanding of randomness. You could have asked the very same question about stock prices or actual coin tossing in the real world, and the debate could have been the same.
 
I think the focus on mutations is obfuscating a key factor- the influence of environmental events such as volcanic eruptions, asteroid/comet impacts, ice ages, etc. Not to mention introduction of new species (example: new pathogens) on an ecosystem.

These events may be random and will introduce factors whose impacts may be nearly impredictable. Species A, for example, may be extincted just by being at the wrong place at the wrong time.

whoops... Thabiguy already said that...
 
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