The Central Sahara is considered the greatest museum of rock art in the world, containing several thousand prehistoric and recent images. The oldest paintings, called Round Heads, originated during a humid phase in the 10th millennium before present and they were created by dark-skinned hunter-gatherers living in the Algerian and Libyan mountains. Rock shelters show mainly anthropomorphic figures with body paintings and other embellishments testifying ancient rituals and ceremonies. Only two animal species - antelope and mouflon - appear to be as important as men and women; mixed with them on...