What drwtsn is saying is right, It has been observed in bacteria and animals. It has been observed through the fossils record and DNA. I has been predicted, I can not remember the exact details but there was a fossils of a fish like creature ( not a fish, you must understand the importance of this difference) in northern Canada. The people who found it knew were to look, how deep to dig and what kind of fossil they were going to find. This is a fact and this can only be done if they got it right.
I am happy that I asked this question I have learned a lot. I am realising more and more that a lot of people who do not accept evolution simply do not understand the facts or are afraid of something ( I do not what to sound condescending so sorry). I rejected evolution for a long time until I got the facts straight. I realised what was presented to me as evolution was clearly not the real deal.