 Abandoning the assumption that consciousness is innate, Jaynes explains it instead as a learned behavior that “arises ... from language, and specifically from metaphor.” With this understanding, Jaynes then demonstrated that ancient texts and archeology can reveal a history of human mentality alongside the histories of other cultural products.His analysis of the evidence led him not only to place the origin of consciousness during the 2nd millennium BCE but also to hypothesize the existence of an older non-conscious “mentality that he called the bicameral mind, referring to the brain’s two hemispheres”.Jaynes wrote an extensive afterword for the 1990 edition of his book, in which he addressed criticisms and clarified that his theory has four separate hypotheses