[general_re]

Sorry to disagree, but your math is wrong. Imagine a twenty-page document into which random alphabetic strings are typed. Imagine the memory in which the document resides is bombarded with X-rays, causing bit flips. The odds are astronomical that any particular limerick would turn up somewhere in the document. But, you say, there are many good limericks, and even more bad ones. The odds are still astronomical that a limerick will turn up in our "evolving" document.

But again you're artificially restricting the possible outcomes. If we consider the chances of producing anything cogent - a limerick, a haiku, a sonnet, a knock-knock joke, a single grammatical sentence - then the odds are better than just producing a limerick. And who's to say which of those is more useful?

Moreover, "useful" has to be defined in terms of what might be useful to the current state of the life form's DNA, so the oddsa re even smaller.

No, I think you're still shortchanging the situation. I can, with a little bit of thought, come up with dozens and dozens of ways to improve the human body, for example - it's not a perfect machine. And there are surely hundreds or thousands more that I just can't imagine. The fact that there are so many possible improvements ups the odds significantly. For example, here's a really short list, right off the top of my head:

Imagine that your optic nerve was placed slightly differently, so that you didn't have the blind spot that you do now. Imagine that the tendons and ligaments of your knees were slightly rearranged, such that a sharp blow to the outside of your knee was much less likely to cripple you. Imagine a slight modification to your cellular membranes that rendered you immune to a particular virus. Imagine a small change in the density of the cilia of your inner ear, such that you were able to hear sounds across a greater range, and of a higher pitch than you are now able to. Imagine one small new protein that confers a greater resistance to certain types of cancers. Imagine a slightly more efficient digestive process, such that you could survive with a caloric intake 10% lower than you can now. Imagine a slight change in the chemistry of the junctions of nerve cells such that the nerve conduction velocity was increased, and hence your reflexes were faster than before.

And on, and on, and on....give me some time, and I'll come up with lots and lots more. And there will be potential improvements that simply exceed my ability to imagine them, either because they are improvements that exist in other organisms, but that I am not familiar with, or because they'd be completely new and unique. There's really more than just limericks possible, I think. ;)

As for what the existence of DNA has proved--I would say DNA only shows the common descent, not why life forms changed. Natural selection explains small incremental changes, but not macro-changes. Some OTHER force explains macro-changes.

Actually, I agree with your first sentence there. DNA shows common lineages, and gives us a picture of a family tree. But as for why life forms change over time, for that you have to look at the environments in which they lived and died.

As for the second part, what is a large change but the accumulation of many small changes? Remember the steps in the development of the human brain? If you take only the "beginning" and "end" brains - Australopithecus and us - then the change looks like a huge quantum leap. But when you see all the intermediate steps, it becomes a rather orderly progression, and the end product no longer looks like something that just sprang forth, sui generis. It wasn't an accident that I picked that example ;)

[maro]

First--"quantum leap" literally means very short hops, and shouldn't be used in the way you used it. Second, you are stuck with the photomorph concept, and that's why you don't get it. Let me try a third metaphor. Say you and your son are asked to compete in a soapbox derby, but are given only 48 hours to come up with an entry. Fortunately, your garage is well stocked with all the necessary tools and hardware. Moreover, you and your son are mechanical geniuses. It is certainly plausible, based on these assumptions, that the result of the 48 hours of work will be a derby winner. Now add another constraint. Every hour, or half hour, or minute, your vehicle in its state at that time will be taken out on the track. If it doesn't make a circuit, you are disqualified. You protest against the new rule: most of my engineering ideas will take a while to implement, and it's not fair to test the vehicle while I'm in the middle of one of my ideas--the idea may be great, but the vehicle may be temporarily inoperable. I think that's how it is with all these nifty improvements you suggest to the human body. If you could actually code these changes (without harming some other useful process), more than a few bit flips would be needed. So the path to the improvement probably will pass through (and necessarily pass through) intermediates that don't run, or are hopelessly defective in some significant way. According to evolutionary theory, genetic change is entirely the product of chance bit flips, so changes to the DNA happen piecemeal, and every slightly modified life form is required to survive in its environment, just as the referees hauled out the unfinished soapbox racer every hour, half hour, or minute against your protests, onto the track.