When a San Shaman goes into a trance, he harnesses that power, becomes part of the world beyond, becomes invisible to the singers and dancers around … - Richard Leakey

Jerison argues that we should think of brains as creating a species' version of reality. ...As brains enlarged through evolutionary time, more channels of sensory information could be handled more completely, and their input integrated more thoroughly.

It appears that the evolutionary process promotes its own progress: learning about the environment (which demands a certain intelligence) means living in a stable social mileau (which demands at least an equal and possibly a greater intelligence); as social intelligence increases, so too will the ability to learn; this in turn encourages an even longer social apprenticeship; and longer group living leads to more social intelligence.

I'm known for speaking my mind, a trait I probably inherited from my parents, Louis and Mary Leakey—neither of whom was renowned for tact.