I was reading an article in a neurological medical journal a couple days ago about a strange experiment in which a man who was already suffering from dementia agreed to allow specialists to slowly reduce his working intelligence to bare minimum. Basically, the whole purpose was to see how little brainpower is actually needed to sustain life.
So these specialists kept working and working on him, reducing his intelligence incrementally. Finally, they hit the absolute bare minimum, translating to an IQ of around 20. The head of the specialist team asked the patient if he was aware of anything around him, and the patient first drooled all over himself, then started making all sorts of unintelligible sounds, before finishing with "GO BUCKS!"