[fredliu]

That's a great point. Just thinking out loud, if we can time travel back to the cavemen time, and assuming we speak their language, there would still be so much that we couldn't explain or they wont' be able to understand even for the smartest cavemen adults. Unless, of course we spend significant time and effort to "bring them up to speed" with modern education.

[kbelder]

In Jayne's 'The Origin of Consciousness in the Breakdown of the Bicameral Mind', there's some interesting investigation into some of our oldest known tales... Beowulf, The Iliad, etc.

In those texts, emotional and mental states are almost always referred to with analogs to physical sensation. 'Anger' is the heating of your head, 'fear' is the thudding of your heart. He claims that at the time, there wasn't a vocabulary that expressed abstract mental states, and so the distinction between the mind and body was not clear-cut. Then, over time, specialized terms to represent those states were invented, passed into common usage, which enabled an ability to introspect that didn't exist before.

(All examples are made up, I read it more than 20 years ago. But it made an impression.)