"Julian Jaynes (February 27, 1920 – November 21, 1997) was an American
psychologist, best known for his book The Origin of Consciousness in
the Breakdown of the Bicameral Mind (1976), in which he argued that
ancient peoples were not conscious (did not possess an introspective
mind-space), but instead had their behavior directed by auditory
hallucinations, which they interpreted as the voice of their chief,
king, or the gods. Jaynes argued that the change from this mode of
thinking (which he called the bicameral mind) to consciousness
occurred over a period of centuries about three thousand years ago and
was based on the development of metaphorical language and the
emergence of writing."

"At one time, human nature was split in two, an executive part called
a god, and a follower part called a man. Neither part was Consciously
aware.”

According to Jaynes, ancient people in the bicameral state would
function in a manner similar to that of a modern-day schizophrenic.
Rather than making conscious evaluations in novel or unexpected
situations, the person would hallucinate a voice or "god" giving
admonitory advice or commands, and obey these voices without question.
Others have argued that this state of mind is recreated in members of
cults.

In his 1976 work The Origin of Consciousness in the Breakdown of the
Bicameral Mind, Julian Jaynes proposed that human brains existed in a
bicameral state until as recently as 3000 years ago. Jaynes builds a
case for this hypothesis by citing evidence from many diverse sources
including historical literature. He took an interdisciplinary
approach, drawing data from many different fields.

Jaynes asserts that until roughly the times written about in Homer's
Iliad, humans did not generally have the self-awareness characteristic
of consciousness as most people experience it today. Rather, Jaynes
argued that the bicameral individual was guided by mental commands
believed to be issued by external "gods"—the commands which were so
often recorded in ancient myths, legends and historical accounts;
these commands were however emanating from individuals' own minds.
This is exemplified not only in the commands given to characters in
ancient epics but also the very muses of Greek mythology which "sang"
the poems: Jaynes argues that while later interpretations see the
muses as a simple personification of creative inspiration, the
ancients literally heard muses as the direct source of their music and
poetry.

Jaynes inferred that these "voices" came from the right brain
counterparts of the left brain language centres—specifically, the
counterparts to Wernicke's area and Broca's area. These regions are
somewhat dormant in the right brains of most modern humans, but Jaynes
noted that some studies show that auditory hallucinations correspond
to increased activity in these areas of the brain.[4]

For example, he asserts that, in The Iliad and sections of the Old
Testament in The Bible, no mention is made of any kind of cognitive
processes such as introspection, and he argues that there is no
apparent indication that the writers were self-aware. According to
Jaynes, the older portions of the Old Testament (such as the Book of
Amos) have little or none of the features of some later books of the
Old Testament (such as Ecclesiastes) as well as later works such as
The Odyssey, which show indications of a profoundly different kind of
mentality—an early form of consciousness.[4]

Jaynes noted that in ancient societies, the corpses of the dead were
often treated as though they were still alive (being seated on chairs,
dressed in clothing, and even fed food) and he argued that the dead
bodies were presumed to be still living and the source of auditory
hallucinations (see ancestor worship).[4] This adaptation to the
village communities of 100 individuals or more formed the core of
religion. Unlike today's hallucinations, the voices of ancient times
were structured by cultural norms to produce a seamlessly functioning
society. In Ancient Greek culture there is often mention of the Logos,
which is a very similar concept. It was a type of guiding voice that
was heard as from a seemingly external source.

In ancient times, Jaynes noted, gods were generally much more numerous
and much more anthropomorphic than in modern times, and speculates
that this was because each bicameral person had their own "god" who
reflected their own desires and experiences.[5]

Even in modern times, Jaynes notes that there is no consensus as to
the cause or origins of schizophrenia (the subject is still hotly
debated). According to Jaynes, schizophrenia is simply a vestige of
humanity's earlier state.[4] Recent evidence shows that many
schizophrenics don't just hear random voices but experience "command
hallucinations" instructing their behavior or urging them to commit
certain acts. As support for Jaynes's argument, these command
hallucinations are little different from the commands from gods which
feature so prominently in ancient stories.[4] Indirect evidence
supporting Jaynes's theory that hallucinations once played an
important role in human mentality can be found in the recent book
Muses, Madmen, and Prophets: Rethinking the History, Science, and
Meaning of Auditory Hallucination by Daniel Smith"

http://en.wikipedia.org/wiki/The_Origin_of_Consciousness_in_the_Breakdown_of_the...