Woodruff wrote:Koesen wrote:
Eyes don't need a guiding hand to be explained. Essentially, what you start with is a simple light sensitive cell that may have a completely different function than vision. There are, for example, very simple deep sea organisms that use them to feed. Since it's a useful mechanism for survival, evolution wil make it stronger, increasing the photosensitivity a little bit each generation. Eventually, you get an eye.
A computer model described in Proceedings of the Royal Society of London, volume 256, shows you can go from a single photosensitive cell to something as complex as an eye in about 100,000 generations, and every new generation will be better than the one before.
100,000 generations may sound like a lot, but humans can reach that in two to three million years and organisms that reproduce faster don't even need that. Given the age of the earth, there has been time to redevelop the eye many times over, and there is no need for any guiding hand other than the principle of survival of the fittest.
I understand all of that, though I would heartily disagree with the presumption that "every new generation will be better than the one before", because that's simply not going to hold true. My basic point is that the eye is complex enough that it does cause me to pause on the subject and consider the possibility of a guiding hand.
Why disagree? Most people who use the complexity of the eye as proof or at least an indication of a guiding hand, tend to think along the lines of "take an eye, remove the retina and you've got nothing." (I am aware that you did not say this with so many words, so if you're thinking along different lines, let me know)
But that's not how it went. What you have, is a light sensitive organ that gets more light sensitive as it evolves, and all of the interim steps to improve its light sensitivity are improvements.
I will concede that it's quite possible that the eye has stopped evolving at some point, because with today's easy ways to correct most eyesight problems, it probably isn't anything like the survival factor it used to be anymore. In that case, new generations no longer improve it. Note that each individual improvement is likely to be very subtle.
But I do maintain that all evolutionary changes to the eye as it developped were improvements at the time (though it's true that what worked really well a million years ago may be useless today. But in their own environment, they were improvements.
The key conclusion to be drawn from models like the one I described, is that they show that even if you start with something as simple as a cell and you add no more than the possibility of very gradual change over time, in the long run huge complexity can occur. The guiding hand simply is not necessary. Granted, you can't prove it was never there, but it adds nothing to the explanation.
