Evolutionary theory is a theory, nothing more. We cannot prove Darwin's theory as amended, and we never will - it is not falsifiable. Same with global climate change, I think. Both theories are supported by data from the records we can access by core drilling, analysis of fossils and so on.
Incidentally, Robert Hooke stated in one of his lectures (in 1696 I think) that fossils were the petrified remains of creatures which had died out. It took a couple of years for the idea to catch on and there are some people even now who assert with immense confidence that man and dinosaur roamed the earth together: - sadly currently unavoidably closed due to some footling disagreement between the owner, Kent Hovind, and the IRS. Hovind is very fond of pointing out that evolution is "just a theory", and he's absolutely right. It is, however, a rather more plausible theory than his. Guy