It seems like you regard scientific theories as a "best guess." Maybe you don't but in case you do I just want to say that scientific theories, especially old, heavily peer reviewed and tested ones are on essentially the same level as fact. They are an attempt to unify known facts and through this make predictions. In the case of the theory of evolution many many predictions have been made and have been proven correct. A good theory is not strong because of the evidence it has supporting it, it is strong because of the lack of evidence against it. Sorry if I misunderstood what you were saying