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**Hypothesis Two: Bicameral Mentality**
The second hypothesis proposes that preceding the cultural invention of consciousness people possessed a different mentality—bicameral or “two-chambered”—that generated hallucinations; these functioned as a type of social control (the details of this earlier mentality are presented later in Hypothesis Four—bicameral neurology—which deals with the finer points of the neurology subserving bicameral psychobehavior).
Jaynes concluded that hallucinations must have an innate structure in the nervous system. He pointed out how the historical record is replete with examples of individuals claiming visitations from divine beings. Moreover, presently, many people diagnosed with schizophrenia and other mental health disorders report hearing voices. What’s more, not a small number of people still experience benign audiovisual hallucinations.
Hallucinations as a Side Effect of Language Comprehension
Since the nature of language is key to consciousness, Jaynes proposed an origin-of-language account that traces humankind’s linguistic evolution through “calls,” “modifiers,” “commands,” etc. But his main point was to emphasize how language makes dramatic changes in humankind’s attention to things and persons: Each new stage of word development literally created new perceptions that resulted in significant, revolutionary cultural changes that are reflected in the archaeological record. This point is relevant when we consider Jaynes’s views of how metaphors undergird conscious cognition. Another key point is that “verbal hallucinations were a side effect of language comprehension which evolved by natural selection as a method of behavioral control” (Jaynes, 1976, p. 134).
The Origins of Bicamerality Are in the Internalization of Communicative Acts
By definition communication requires two parties. But we cannot assume that the sender and receiver are always two individuals. Communication transpires not just among people (inter-individually) but also intra-individually between dual hemispheres.
Very early on, among small groups of hunter and gatherers, speech was used for stabilizing dominance hierarchies and exchanging information. But as group size scaled up and complex solitary behavior became increasingly necessary with advances in technology, “internal speech” had to evolve. Imagine individuals who could not narratize what they were doing. Such preconscious individuals would simply forget to stay on task. Unless their leaders constantly reminded them of what to do, they would neglect their chores. Behaviors based on aptic structures (Jaynes’s version of “instincts”) require no temporal priming. But learned activities lacking consummatory closure—such as tool-making—do need to be maintained by something external to themselves. This is what verbal hallucinations provided.
Language-capable humans either have others to remind them what to do, or they can repeat to themselves behavioral sequelae. However, preconscious people could not as easily remind themselves of what to do. So the hypothesis is that “internal” verbal hallucinations told people how to stay on track.
Having to carry out enduring, complicated tasks established selective pressures that made speech hemispherically unilateral. This freed up the right side to generate hallucinated verbalizations that could maintain complex behavior. The earliest inner speech acts may have been hallucinated repetitions of simple externally-attributed commands, requests, instructions, and admonishments; such recordings may have evolved into a particular person’s own hallucinated voice. For example, in crafting a tool the hallucinated verbal command of “sharper” enables preconscious individuals to keep on task.
Hallucinated voices arose in the first hunter-gather groups as simple nonvoluntary reminders of one’s current endeavors, such as stone-chipping. However, in the initial stages of the Neolithic revolution, auditory experiences were recruited not as short-term individual task prompts but as organizing instructions for entire communities.
Names Recreate a Person’s Presence
The invention of names, which according to Jaynes can be dated to around 12,000 to 10,000 BCE, allowed an individual to be recreated even though absent—a powerful but taken-for-granted linguistic capacity. And when a person dies, he or she can still exists as an ancestor or some other spiritualized being.
Also, up to this time hallucinations had been probably “casually anonymous” and lacked significance from the perspective of social dynamics. But when specific hallucinations were linked to a name, as a voice originating from a particular person, something revolutionary occurred. Hallucinations started to play a much more salient role in social interaction as well as individual behavior.
Kings, Tombs, and Voices from the Grave
Now that people had names that lived on even after they “died,” their voices could be heard from the grave—this was the beginning of ancestor worship. Beginning in the Neolithic period, an evolution from elementary internal hallucinations (self-looping communication) to the grandeur and sophistication of the first literate bicameral civilizations governed by rulers who acted as stewards for the gods and sat atop hierarchies of priests. Burying the deceased in ceremonial graves became a regular practice. The tombs of kings and important rulers became “houses of gods” (temples). After the king died, his voice did not vanish immediately but continued to be heard, until the new ruler was enthroned. In the bicameral period the gods were in no sense figments of one’s imagination. Divine voices were volition. The corpses of god‒kings were eventually replaced with statues and the tombs grew into mortuary monumental complexes. Such edifices dominated small towns, next city-states, and then entire civilizations.
Personal Gods
As societies became larger and more complex, the theocracies could not handle all the communication demands of expanding populations. Hallucinatory diversity began to weaken the divine order. The ordinary citizens heard less and less directly the voices of the great gods. Increasingly the supreme deities communicated with individuals through intermediaries. What can be called “personal gods” would be asked to convey a request to divine powers higher up the hierarchy. Or the transmission could work in the opposite direction: A high god might inform an individual’s personal god of an order or admonishment first, and then the personal god would relay the information to the individual. What we have, as strange as it is to the modern, conscious mind, is a neurologically layered command-and-control organization reflected in the hierarchies of social behavior.
