Julian Jaynes, primarily in his book "The Origin of Consciousness in the Breakdown of the Bicameral Mind", proposed that religion (and some other psychological phenomena such as hypnosis and schizophrenia) is a remnant of a relatively recent time in human development, prior to the advent of consciousness. Jaynes hypothesized that hallucinated verbal commands helped non-conscious early man to perform tasks promoting human survival. Starting about 10,000 BCE, selective pressures favored the hallucinated verbal commands for social control, and they came to be perceived as an external, rather than internal, voice commanding the person to take some action. These were hence often explained as originating from invisible gods, spirits, ancestors, etc.