One of the best crackpot theories that I ever heard was that intelligence can be eaten, and man devolved from a species of apes that ate the brains of fellow apes. These cannibalistic apes acquired intelligence, but also insanity, eventually becoming modern humans. These theories are presented in a book called The Beginning Was the End, written by Oscar Kiss Maerth, who claimed to have eaten raw ape-brain in restaurants in Southeast Asia. If you're really stoned, and able to accept something with little evidence, as I was at one time, the book can be convincing. Maerth was an influence on the New Wave band DEVO. I still have the original book in a box under my bed, lol.