What about shamanism. Is it when they use these certain kinds of hallucinating drugs, that they actually enter a different "spiritual" world, maybe a parallel universe?
All over the world you can find ancient paintings in caves, which describes beings that are half man half animal. Look at the ancient Egypt's, with their Gods, also often half man half animal, or the myth of the Minotaur who was described as a man with the head of a bull. There are all over the world lot's of examples to find in the history of civilisation.
It all didn't came out of the blue. About 200.000 years ago men where just like the "modern" men, with the same brain capacity, nerve system and all. But about 40.000 years ago they developed a sense of awareness, that made them believe in a spiritual world.
Don't have much time now, but hopefully this will bring an interesting discussion.
(Sorry for my English, it's very basic)