I could buy that schizophrenia was more prevalent than today; and that schizophrenics had higher status because they could speak with the gods, so they set up the whole priest-kinghood thing, and people followed.

I remember perfectly well my imaginary friends at 5 years old. I couldn’t actually hear it. fMRI shows activation all over the brain when processing language, can’t reach conclusions from that.

All pre-state farming societies are organized in large tribes of common descent. Which means the ancestors are a big deal. Claiming to be able to hear old dad’s voice carries a lot of weight; so it’s no wonder people said they could. Motivated reasoning goes a long way. Men actually claim to be feminist these days.

Jaynes’ theory is entirely unrelated to genetic changes, Alex. You are correct, though, that one of its weaknesses is that there are no humans left with bicameral minds despite many groups not having undergone the societal and environmental changes that he posits were its undoing.

It's not. He posits that genes played a role in its disappearance.

Also, it could be argued that the bicameral mind is a liability even for hunter-gatherers, so one can imagine it being on retreat for quite some time everywhere.

Also, telling apart a bicameral person from a normal one would involve a lot of questioning in the person's native language. Not sure if this kind of thing's ever been attempted.

There is something weird going on with the human mind. About 50% of people admit to hearing voices at least once, and children have imaginary friends. I thought these were, well, imaginary, but if you stick kids conversing with imaginary friends into an fMRI machine, they show brain activity like people having auditory hallucinations.

(Oh, to study the Sentinelese…)