The painted, engraved, and carved images of prehistory are threads from past cultures, and we are foreigners trying to interpret their meaning. Perha… - 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.

The neurobiologist Harry Jerison has made a long study of the trajectory of brain evolution since the advent of life on dry land. ...the origin of new faunal groups is usually accompanied by a jump in the relative size of the brain, known as encephalization. ...the first archaic mammals... were equipped with brains four to five times bigger than the average reptilian brain... primates are twice as encephalized as the average mammal. Within primates, the apes... are some twice the average size. And humans are three times as encephalized as the average ape.

Because the art of Africa was on rock shelters, not deep in caves, as in Europe, the ravages of time have eroded most of a rich expression. What we now see is the merest glimpse of what was on the minds of these people.