Everything you're talking about here is in the context of physically modern humans, right?
If that's the case, then it's more likely that these are cultural events and not biological evolution. That is, taking a little peyote may have been an advantage to early hunters, so it became a cultural advantage to use peyote before a hunt. That cultural group would have had an 'evolutionary' advantage over other physically identical groups of humans, because it made them more successful in the hunt and they survived in hard times when the game was scarce. But it didn't cause any physical changes that could be passed to future generations. It was all just in their learned behavior (culture). So, in effect it was cultural versus biological evolution.
Eventually the practice 'evolved' into something religious. Is this the idea you're getting at? It's interesting.
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