Dennis McKenna

Dennis McKenna is an ethnopharmacologist and research pharmacognosist whose work on Amazonian plant medicines spans more than four decades. He is a founding board member of the Heffter Research Institute, was a key investigator on the Hoasca Project, and is Director & President of the McKenna Academy of Natural Philosophy, which he incorporated in 2019. He is the younger brother of Terence McKenna.

Education

Born in Paonia, Colorado, in 1950, McKenna received his master’s degree in botany from the University of Hawaiʻi at Mānoa in 1979. He completed his doctorate in botanical sciences at the University of British Columbia in 1984, with a dissertation on monoamine oxidase inhibitors in Amazonian hallucinogenic plants — an ethnobotanical, phytochemical and pharmacological investigation of ayahuasca and oo-koo-hé, two tryptamine-based preparations used by Indigenous peoples of the Northwest Amazon.

Postdoctoral and industry research

McKenna held postdoctoral research fellowships at the Helicon Foundation in San Diego (1984–86), in the Laboratory of Clinical Pharmacology at the National Institute of Mental Health (1986–88), and in the Department of Neurology at Stanford University School of Medicine (1988–90).

He then moved into industry, serving as Director of Ethnopharmacology at Shaman Pharmaceuticals from 1990 to 1993, before relocating to Minnesota to join the Aveda Corporation as Senior Research Pharmacognosist. Across both roles his work centered on the same question that has run through his whole career: what traditional plant knowledge can tell us about where to look for pharmacologically active compounds.

The Hoasca Project and Amazonian fieldwork

McKenna was a key organizer and participant in the Hoasca Project, an international biomedical study of ayahuasca as used sacramentally by the União do Vegetal, a syncretic religious community in Brazil. It was the first investigation of its kind, and remains one of the most frequently cited studies in the field.

From 2004 to 2008 he was Principal Investigator on a project funded by the Stanley Medical Research Institute, investigating Amazonian ethnomedicines for the treatment of schizophrenia and cognitive deficits. He has conducted extensive fieldwork in the Peruvian, Colombian and Brazilian Amazon, and serves on the advisory boards of a number of non-profit organizations working in ethnobotany and botanical medicine.

Teaching at the University of Minnesota

From 2001 to 2017, McKenna taught courses in Ethnopharmacology, Botanical Medicines, and Plants in Human Affairs at the Center for Spirituality and Healing at the University of Minnesota.

The Ethnopharmacologic Search for Psychoactive Drugs

In 2017 McKenna organised and presented at a landmark symposium, the Ethnopharmacologic Search for Psychoactive Drugs: 50 Years of Research, marking the fiftieth anniversary of the original 1967 conference in San Francisco. Synergetic Press published the proceedings of both the 1967 and 2017 symposia as a double-volume set in 2018.

The symposium has since become a recurring gathering. McKenna presented at ESPD 55 and is convening ESPD 60. He also opened the Academy’s Wisdom of the Leaf Coca Summit.

The McKenna Academy of Natural Philosophy

In the spring of 2019, working with colleagues in Canada and the United States, McKenna incorporated the McKenna Academy of Natural Philosophy — a non-profit founded in the spirit of the ancient Mystery Schools, and dedicated to the study of plant medicines, consciousness and intelligence in nature, the preservation of Indigenous knowledge, and a re-visioning of humanity’s relationship with the natural world.

Through the Academy he teaches two courses in the Living Library and hosts the Brainforest Café podcast, in conversation with researchers, elders and practitioners from across the field. He emigrated to Canada in the spring of 2019 with his wife Sheila, and lives in Abbotsford, British Columbia.

Books

Ethnopharmacologic Search for Psychoactive Drugs, Vol. III: 55 Years of Research. Editor. Synergetic Press, 2025.
Brotherhood of the Screaming Abyss: My Life with Terence McKenna. Polaris Publications, 2012; Synergetic Press edition, 2023.
Ethnopharmacologic Search for Psychoactive Drugs: 50 Years of Research. Co-editor with Ghillean Prance, Wade Davis and Benjamin De Loenen. Synergetic Press, 2018.
Botanical Medicines: The Desk Reference for Major Herbal Supplements. With Kenneth Jones and Kerry Hughes. Haworth Herbal Press, 2002.
The Invisible Landscape: Mind, Hallucinogens and the I Ching. With Terence McKenna. Seabury Press, 1975; revised edition, HarperOne, 1993.

McKenna is also the author or co-author of more than fifty scientific papers in peer-reviewed journals.

Courses on the Living Library

Plant Chemistry – the molecular logic of how plants build the compounds that act on the human nervous system. Seven modules, 48 lessons, available to members of the Living Library.
Stoned Ape Hypothesis: Psilocybin and the Origins of Consciousness – McKenna revisits his brother Terence’s landmark proposal and tests it against current evidence from primatology, mycology and evolutionary genetics. Seven modules, 23 lessons.
Featured contributor: When the Ceremony Doesn’t End – McKenna reflects on La Chorrera, the nature of delusion, and what set and setting really mean, in a course on psychedelic crisis and integration.