Ahhh...you are a true Darwinist. Now I know this statement is no longer theory...
The reason the theory of evolution cannot be proven false is because when a discovery is made that disproves the theory of evolution; the theory of evolution is simply modified to incorporate the new discovery.
I don't suppose we could trouble you for an example.
I mean theories have to account for all kinds of unexpected stuff.
Gravity, for example, has to account for the fact that the moon is falling up, or receding away from the earth.