The Los Angeles Times recently had a story about a 6-year-old child with florid schizophrenia [url]http://www.latimes.com/features/health/la-he-schizophrenia29-2009jun29%2C0%2C5289139%2Cfull.story[/url]
(follow-up [url]http://www.latimes.com/features/health/la-hew-jani-update9-2009jul09,0,7752925.story[/url]) .
Obviously such a child would not survive even to the age of 6 in any society but our own. She would wander off and fall over a cliff, or befriend a dangerous animal, if she were not killed by other people for misbehaving.
1. Florid schizophrenia is and always has been maladapative. Voices on demand was adaptive. We have to be careful when describing in shorthand the bicameral world. Not "everyone was schizophrenic" but "everyone was capable of hearing voices, but did not hear them constantly."
2. To the extent schizophrenia has a genetic basis, maladaptive florid schizoprenia would be weeded out of the gene pool early in human history, leaving partial or on-demand schizophrenics.
3. It's interesting that the article says, "Born Aug. 8, 2002, Jani was different from the start, sleeping fitfully for only about four hours a day. Most infants sleep 14 to 16 hours a day. Only constant, high-energy stimulation kept Jani from screaming." In tribal societies and in the more complex but regimented bicameral societies this behavior would not be tolerated. Probably they would try to determine if the child was hearing culturally approved voices - it it was, they'd try to train it, if not, exposure.
4. The child hears the voices of cats and rats. One wonders if at a critical moment at a younger age she was told a story, or saw a tv show or film, with speaking cats and rats, whom she (mis)percieved as cultural authorities.