“The Origins of Consiousness in the Bicameral Mind”...one of the deepest books I’ve ever read. Sagan’s “The Dragons of Eden” is right there also.
He came to the (wrong) conclusion that human societies had evolved into a state of being guided by systems of what he called "auditory hallucinations" and I assume this was because he was limiting his view to an age from around the Exodus to about the time just prior to Alexander.
What he DIDN'T consider was the true antediluvian age as described in Genesis and by Plato and other classical authors, and whether the scheme he had discovered might in fact have been the normal basis of workable human communications prior to the event associated with the tower of Babel. In other words, there is reason to think that human "language" pror to the flood and the tower of Babel was basically telepathic.