The quality that accompanies the emergence of learning in the evolution of higher animals, namely intelligence, is surprisingly difficult to define. - Richard Leakey

People who pass from stage two hallucination to stage three often experience a sensation of a vortex or rotating tunnel around them, and soon have hallucinations filled with iconic images, not just signs. ...It is here that "monsters" appear, part human, part beast, known as therianthropes.

When our ancestors discovered the trick of consistently producing sharp stone flakes, it constituted a major breakthrough in human prehistory. ...The modest flake... is a highly effective implement for cutting through all but the toughest of hides... the humans who made and used these simple stone flakes thereby availed themselves of a new energy source—animal protein.

It is impossible to imagine existence in the absence of subjective sensation we call reflective consciousness.