Humans invented the plow in 4,500 BC, the wheel in 4,000 BC, and writing in 3,400 BC. But long before that, by 6,000 BC, they had learned how to brew beer and make psychoactive drugs from plants. Psychopharmacologist Ronald Siegel points to this evidence to support his hypothesis that the yearning to transform our normal waking consciousness is a basic drive akin to our need to eat and drink. Of course, there are many ways to accomplish this shift besides alcohol and drugs. They include dancing, singing, praying, drumming, meditating, and having sex.