Can random mutations cause an increase in information in the genome?

Since Garrett opened this thread in which he puts forward the argument he more or less already made in this message, I've taken the liberty to move my reply to it to this thread. That's not true. If you look at the bare mechanism of evolution, you'll see that a requirement of information gain does not follow from it. Evolution, simply put, is the effect of selective pressure on imperfect replication. The effect becomes manifest in the changes we see in populations over time."Imperfect replication" simply means that something is copied, but the copies aren't always exactly the same. It's important to realise that it doesn't matter whether the copies are somehow "richer" in information, or "poorer". All that matters is that there are differences in the gene pool, because that's what selective pressure can act on."Selective pressure" only means that the environment makes certain demands on the members of a gene pool. In principle, these demands are equal for all of them. But since the members of the gene pool themselves are not equal, some of them are better suited to meet those demand than others. This means that some of the more ill-suited members may succumb to the pressure the environment puts on them, and may not survive long enough to reach the stage where they copy themselves. The well-suited members stand a better chance of reaching that stage.For example, let's suppose a population of moths exists which is predominantly pink. There are some teal creatures, but they are rare. Further suppose something changes in the environment which poses a threat to pink moths, leaving teal ones unharmed. The above description of the mechanism of evolution should tell you that the population will change over time from predominantly pink to predominantly teal. Now suppose the environment changes again, once more giving pink moths an advantage over teal ones. Duly, the population changes back to predominantly pink.The point of this example is that it's hard to tell whether a change from one colour to the other constitutes a gain or a loss in information. It's a change, that's all you can say. But if you really want to maintain that a change from one color to another constitutes an increase in information, then the change the other way must be a loss of information. However, both changes are the result of the process of evolution, and both changes happen. Apart from what I wrote above, I'd like to point out that this statement is refuting the point of your post: if even beneficial mutations result in loss of information, then apparently loss of information isn't much of a problem. After all, the mutation is beneficial, as stated. Evolution - on whatever scale - does not require a direction of information change. If you define information as "organized complexity", then it is information change that requires evolution, not vice versa. Information change, be it gain or loss, is the result of evolution, not the prerequisite.This message has been edited by Parasomnium, 13-Feb-2006 10:33 PM

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Exactly. Belfry is saying what I said in this post (to which I have received no reply, to my great dissapointment), namely that it doesn't matter whether information is gained or lost. The only thing that matters is that the information changes, in whatever direction. If your information changes and mine doesn't, or vice versa, or yours changes this way and mine that way, then the result is that we have different information. If the environment is such that my information gives me an advantage over you, then I'll succeed where you won't, even if I have lost information you kept.Of course, what we see in nature is a steady increase in the complexity of genomes, which is the - for some confounding - characteristic of evolution that this thread is all about. But this phenomenon can easily be explained by considering two metaphors that show two different aspects of evolution.One metaphor is the one-way street. Since random mutations are just that - random, there's no turning back from a certain evolutionary development, because it is extremely unlikely that a particular chain of random mutations is followed by another chain of the same mutations in reverse order. In other words, evolutionary development is a one-way street.The other metaphor is that of a ratchet. Although a ratchet too is a one-way thing, that's not the characteristic I'm thinking of. Apart from being a one-way device, a ratchet is also something that produces an increase of sorts. A mechanical ratchet may for example increase the height of something pulled up with it. The increments are usually small but in the end add up to something large.In a like manner, evolution acts as a complexity ratchet. With many small steps, each having a reasonable probability, the complexity of an evolving genome is ratcheted up to a level that would be very unlikely to be achieved in far fewer steps.Since genomic complexity tends to tranlate as phenotypical versatility, the more complex a genome, the more chances it has to survive a diversity of circumstances. This in turn leads to ever more complex genomes. In other words, evolutionary development works like a ratchet.Feedback/criticism anyone?This message has been edited by Parasomnium, 15-Feb-2006 08:04 PM

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Thank you for pointing that out. Like everything, evolutionary explanations are usually a bit more *complex* than you'd think at first glance.How about this? "Evolutionary development can work like a ratchet, but not necessarily so."