Dennis McKenna (b. 1950)
American ethnopharmacologist, and the scientist half of a partnership that began in the Colombian Amazon in 1971 and never really ended — the younger brother of Terence McKenna, and the one who turned what the two of them found there into an actual scientific career.
Born December 17, 1950, in Paonia, Colorado, Dennis followed his older brother into a life built around plants and consciousness, but along a far more conventional academic route. He earned a master’s degree in botany from the University of Hawaiʻi at Mānoa (1979) and a Ph.D. in botanical sciences from the University of British Columbia (1984), with a dissertation on monoamine oxidase inhibitors in Amazonian hallucinogenic plants — the exact enzyme-inhibiting chemistry that makes ayahuasca’s DMT orally active in the first place, and a subject he was, by then, already unusually well positioned to study.
La Chorrera and the cultivation guide
In 1971, following the death of their mother, Dennis and Terence traveled with three companions into the Colombian Amazon in search of oo-koo-hé, a DMT-containing plant preparation, and instead found fields of Psilocybe cubensis. At the settlement of La Chorrera, the brothers conducted an experiment attempting to bond harmine chemistry with their own neural processes through vocalization — the experience that would define the rest of Terence’s public life, and that Dennis, in his own later account, treated with considerably more scientific caution and self-scrutiny. The two co-wrote The Invisible Landscape: Mind, Hallucinogens and the I Ching (1975) about it.
Out of that same Amazon fieldwork came something with a far more practical afterlife: in 1976, writing under the pseudonyms O.T. Oss and O.N. Oeric, the brothers published Psilocybin: Magic Mushroom Grower’s Guide — the first reliable home cultivation technique for psilocybin mushrooms, still in print and still influential nearly fifty years later.
A research career built on ayahuasca
Where Terence became a lecturer and public philosopher, Dennis built an actual laboratory career studying the same plants. He held postdoctoral fellowships at the National Institute of Mental Health’s Laboratory of Clinical Pharmacology and at Stanford University’s Department of Neurology, worked in natural product research for Shaman Pharmaceuticals and Aveda Corporation, and taught ethnopharmacology at the University of Minnesota’s Center for Spirituality and Healing from 2001 to 2017. His research, much of it built on extensive fieldwork in the Peruvian, Colombian, and Brazilian Amazon, has focused on the pharmacology, botany, and chemistry of ayahuasca and related plant preparations.
He has served since its founding as a board member and Director of Ethnopharmacology at the Heffter Research Institute, the nonprofit most responsible for funding modern clinical research into psilocybin and other classical psychedelics — putting him, decades on from La Chorrera, at the institutional center of exactly the kind of rigorous psychedelic science his brother’s lectures could only gesture toward.
Author and current work
His books include Botanical Medicines: The Desk Reference for Major Herbal Supplements (2008), the memoir The Brotherhood of the Screaming Abyss (2012) — his own detailed, more skeptical retelling of the La Chorrera experience and his relationship with Terence — and Return to the Brain of Eden (2014). In spring 2019 he founded the McKenna Academy of Natural Philosophy, a nonprofit he describes as built in the spirit of the ancient Mystery Schools and dedicated to the study of plant medicines, consciousness, and intelligence in nature; he serves as its Director and President, teaches through its Living Library platform, hosts the Brainforest Café podcast, and organizes the recurring Ethnopharmacologic Search for Psychoactive Drugs symposium series. He lives in Abbotsford, British Columbia, with his wife Sheila.
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