Less than 50,000 years ago, humans had no art, no religion, no sophisticated symbolism, no innovative thinking. Then, in a dramatic change, described by scientists as 'the greatest riddle in human history', all the skills and qualities that we value most highly in ourselves appeared already fully formed, as though bestowed on us by hidden powers.

In Supernatural, Hancock sets out to investigate this mysterious before-and-after moment and to discover the truth about the influences that gave birth to the modern mind. His quest takes him on a detective journey from the beautiful painted caves of prehistoric France, Spain, and Italy to rock shelters in the mountains of South Africa, where he finds extraordinary Stone Age art.

He uncovers clues that lead him to the Amazon rainforest to drink the hallucinogen Ayahuasca with shamans, whose paintings contain images of 'super-natural beings' identical to the animal-human hybrids depicted in prehistoric caves. Hallucinogens such as mescaline also produce visionary encounters with exactly the same beings.

Scientists at the cutting edge of consciousness research have begun to consider the possibility that such hallucinations may be real perceptions of other dimensions. Could the supernaturals first depicted in the painted caves be the ancient teachers of humankind? Could it be that human evolution isn't just the meaningless process Darwin identified, but something more purposive and intelligent that we've barely begun to understand?