"Jaynes asserts that consciousness did not arise far back in human evolution but is a learned process based on metaphorical language. Prior to the development of consciousness, Jaynes argues humans operated under a previous mentality he called the bicameral (‘two-chambered’) mind. In the place of an internal dialogue, bicameral people experienced auditory hallucinations directing their actions, similar to the command hallucinations experienced by many people who hear voices today. These hallucinations were interpreted as the voices of chiefs, rulers, or the gods" [1].

Basically, the hypothesis that humans as late as the ancient Greeks were sort of schizophrenic [2]. (To be clear, it's a hypothesis, not science.) But it's neat to think of drugs like DMT reverting (converting?) us to that bicameral state.

[1] https://www.julianjaynes.org/about/about-jaynes-theory/overv...

[2] https://en.wikipedia.org/wiki/Bicameral_mentality