[citizenpaul]

Its been a while since I read about it but there is some theorizing on the split halves of the brain and the corpus callosum that connects the two halves.

One theory is that the connection between the two halves is a recent evolution and that people used to and some still do perceive the other half of their brain as a separate entity that communicates with them. Possibly being due to the corpus callosum not being the same in everyone. The greater theory being that this is basically the root of all religion.