Does Darwin's Theory of Evolution refute Terence McKenna theory "Stoned Ape" theory of human evolution?
Briefly the "Stoned Ape theory" posits that psychoactive Psilocybin mushrooms in the diet of pre-Homo sapiens primates catalyzed the change Homo sapiens.  It suggests that the mushrooms conveyed selective benefits to consumers of the mushrooms, dissolving the 'egos' of our ancestors and allowing them to form communities.  It may also be sexual stimulant, goes the theory and so may have conveyed an advantage there. 

I think this theory is not terribly popular now, but it is difficult to refute or to prove.  The only real proof would be to take a hominid or any other species and give them the fungus and see if they become intelligent.   Just because this has not happened does not disprove the theory.  the only other way to prove this really would be to have a time scope and look back and see what happened.  Its a similar question as to how life emerged on Earth.  We have some interesting evidence but conclusive proof is going to be hard to get. 

I found a large collection of supporting evidence.  Even the definition of human intelligence and whether it is so unique is subject to debate.  Certainly there are other primates who appear to be as or more social than we.  I think other theories seem as or more likely.  

Darwin's theory of evolution doesn't refute many theories of how something happens in evolutionary history.  The Panspermia hypothesis is taken quite seriously at this point - could it be that life originated elsewhere then was introduced here by meteorites.  The origin of Species doesn't have a lot to say about that.  I think the same is true for the emergence of human intelligence, which at this point we believe is unique on Earth.  Hard to make an irrefutable theory based upon a single example.