This sounds a lot like the theory that humans used to have more separate brain hemispheres (pre- corpus colossum), and thus had a higher prevalence of schizophr

This sounds a lot like the theory that humans used to have more separate brain hemispheres (pre- corpus colossum), and thus had a higher prevalence of schizophrenia (messages from the right side of the brain to the left, perceived as coming from "outside the self") which was interpreted as a voice of God.