Evolution - small to big?

Why would that matter? Oxygen doesn't do that to animals.Here's an experiment you could do. Take some animals and raise them in oxygen tents of various concentration. Try and grow giant animals.If it's oxygen that makes them bigger, then why aren't emphasemics giants? They breathe pure oxygen. Or deep-sea divers? If all you have to do is breathe more oxygen to be a giant, why don't people do that?The evolutionary explanation is simple. In the past, there was a selection pressure on those animals for largeness. Now, there's a pressure for smaller sizes. It works the other way, too. because of artifical selection, our livestock are getting larger and larger. You wouldn't believe how small pigs used to be.

But of course I wasn't challenging the perspective that greater oxygen levels could cause populations to adapt by increasing in size. I was challenging the YEC perspective that exposure to oxygen causes normal individuals to grow to immense size - no adaptation needed.It's ridiculous, of course - oxygen doesn't have that kind of effect on animals. It's not a magic life-gas. It's simply an avaliable reactive gas that animals can take advantage of to metabolize sugars to a greater degree of efficiency.Now, maybe it could be that, in an oxygen-rich world, animals would adapt by becoming large. I don't know why, but maybe they would. However it would be slow, and take geologic time. Hardly a YEC perspective, no?

Yeah. It was message 2 I was replying to.[This message has been edited by crashfrog, 09-06-2003]