Terence McKenna

Terence McKenna (Paonia, Colorado, 1946 – San Rafael, California, 2000) was an American writer, lecturer and ethnobotanist who became one of the best-known voices of the psychedelic counterculture in the late twentieth century. He argued for the responsible use of naturally occurring psychedelic plants and mushrooms, and his thinking combined shamanism, alchemy, the philosophy of language and a speculative view of human evolution.

Raised in Paonia, he showed an early interest in fossil hunting and psychology. After studying in California, he enrolled at the University of California, Berkeley, in 1965, where he developed a growing fascination with shamanism. He travelled through Asia, and in 1969 went to Nepal to seek out practitioners of the Bön tradition. In 1971, after his mother's death, he and his brother Dennis set out for the Colombian Amazon in search of a visionary plant, but found instead fields of Psilocybe mushrooms, which became the focus of their expedition. Together they later wrote a cultivation guide that sold widely.

His best-known hypothesis, the "stoned ape" theory, proposed that psilocybin mushrooms may have played a decisive role in the early evolution of human consciousness. He also developed "novelty theory", a view of time based on fractal patterns he claimed to find in the I Ching. The theory has no scientific standing, and its link to the Maya calendar fed popular beliefs about 2012.

From the early 1980s he lectured widely, and in 1985 he co-founded with his wife, Kathleen Harrison, the nonprofit ethnobotanical garden Botanical Dimensions. He held public debates with the mathematician Ralph Abraham and the biologist Rupert Sheldrake, and his ideas reached the rave scene of the early 1990s. His legacy lives on mainly in countercultural circles and in debates about psychedelics, though his claims have been received very divisively.