I am in the middle of an oldish, but still fascinating book, "The Origin of Consciousness in the Breakdown of the Bicameral Mind" by RIP Julian Jaynes.
In the first two chapters, Jaynes, who was a professor of psychology, does away with the need for human consciousness in most mental acts: learning, concentrating, thinking, remembering, problem solving, etc." He then postulates, using then available studies from neurology, that consiousness is dependent on language, and that it is the act of 1) creating a mental space, 2) creating a mental time 3) creating an analog "I" to move in the mental (also analog) space and time while the real I narratizes in my head.
Having shown how consciousness is dependent on language, Jaynes then postulates that we were unconscious prior to having developed language, and that after that and for a long time (almost all the BC time and for South America well into the AD) we were bicameral. Lacking full consciousness (yet having language), prehistoric man's actions were often governed by voices, which are in many ways similar to certain forms of schizophrenia. These voices were perceived as the gods, and originated in the right hemisphere of the brain.
The book itself is powerfully written and although I fully know that the theory cannot be proven, yet it links in with a number of other books I read.
For example, Jaynes talks about the breakdown of the bicamerality and the growth of consciousness as creating chaos and upheavals among the pre-historic peoples. It seems that once man lost the "voices of God" he also lost the ability to coexist peacefully with other people.
Now, according to Jaynes, consciousness is based on language and language is a left-hemisphere function. Last year, I read a book by a British cardiologist, Leonard Shlein, in which he postulates that the act of learning written language exercises the human brain's left hemisphere--the half that handles linear, abstract thought--and enforces its dominance over the right hemisphere, which thinks holistically and visually. This has, apparently, some collateral damage: abstraction is a masculine trait, and that holistic visualization is feminine. The switch to left-brain thinking upset the balance between men and women. The rise of male dominance led to a corresponding decline in goddess veneration and the status of women. Ok, so the more lingusitically oriented, the more analytical, the more chuvanistic.
The other book that I think links with Jaynes theory is Friedman's "The Disappearance of God". He probes what he calls three mysteries: the gradual disappearance of God in the Hebrew scriptures, Nietzsche's dictum, "God is dead," relating it admirably to the works of Dostoyevsky and the problem of ethics without God; and the mysticism of the Kabbalah and the Big Bang theory. It is the first part of the book that links with Jaynes, as Firedman (Doctor of Hebrew) points out that throughout the Torah, Yehwa seems to become more and more remote - from walking with Adam in the garden, to being one of the angels in the "Sarah laughed" story, to being an angel in Sodom, to becoming a voice in the burning bush, to becoming a voice per se. Hmmm... right side of the brain being taken over?