Rather than living as aggregations of families in nomadic bands, as modern hunter-gatherers do, the first humans probably lived like savanna baboons. - Richard Leakey

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

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.

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.