Evolution in action

[downbeatplumb]

You are thinking of theories as though they are the ramblings of someone down the pub who reckons Hitler survived the second world war.
Scientific theories arent like that they have to satisfy certain criteria.

In practice a body of descriptions of knowledge is usually only called a theory once it has a minimum empirical basis, according to certain criteria:

It is consistent with pre-existing theory, to the extent the pre-existing theory was experimentally verified, though it will often show pre-existing theory to be wrong in an exact sense.
It is supported by many strands of evidence, rather than a single foundation, ensuring it is probably a good approximation, if not totally correct

Evolution is a fact.

http://www.talkorigins.org/faqs/evolution-fact.html