Dennis McKenna — The Depths of Ayahuasca: 500+ Sessions, Fundamentals, Advanced Topics, Science, Churches, Learnings, Warnings, and Beyond (#523)

Artist's rendering of Dennis McKenna.Artist's rendering of Dennis McKenna.
Illustration via 99designs

“To my mind, science, properly pursued, only deepens the mystery. It doesn’t take the mystery away. It shows you how mystery exists profoundly at every level.”

— Dennis McKenna

Dennis McKenna (@DennisMcKenna4) has spent more than 40 years researching the interdisciplinary study of Amazonian ethnopharmacology and plant hallucinogens. He has conducted extensive ethnobotanical fieldwork in the Peruvian, Colombian, and Brazilian Amazon.

His doctoral research at the University of British Columbia focused on the ethnopharmacology of ayahuasca and oo-koo-he, two tryptamine-based hallucinogens used by indigenous peoples in the Northwest Amazon.

He is a founding board member of the Heffter Research Institute, and was a key organizer and participant in the Hoasca Project, the first biomedical investigation of ayahuasca used by the UDV, a Brazilian religious group. He is the younger brother of Terence McKenna.

From 2000 to 2017, he taught courses on ethnopharmacology as well as plants in human affairs in the Center for Spirituality and Healing at the University of Minnesota. In 2019, in collaboration with colleagues, he incorporated a new non-profit, the McKenna Academy of Natural Philosophy. He emigrated to Canada in the spring of 2019 together with his wife Sheila, and now resides in Abbotsford, B.C.

Please enjoy!

Listen to the episode on Apple Podcasts, Spotify, Overcast, Stitcher, Castbox, Google Podcasts, or on your favorite podcast platform.

Brought to you by Wealthfront automated investing, Allform premium, modular furniture, Tonal smart home gym. More on all three below.

This episode is brought to you by WealthfrontWealthfront pioneered the automated investing movement, sometimes referred to as ‘robo-advising,’ and they currently oversee $20 billion of assets for their clients. It takes about three minutes to sign up, and then Wealthfront will build you a globally diversified portfolio of ETFs based on your risk appetite and manage it for you at an incredibly low cost. 

Smart investing should not feel like a rollercoaster ride. Let the professionals do the work for you. Go to and open a Wealthfront account today, and you’ll get your first $5,000 managed for free, for lifeWealthfront will automate your investments for the long term. Get started today at

This episode is brought to you by AllformIf you’ve been listening to the podcast for a while, you’ve probably heard me talk about Helix Sleep mattresses, which I’ve been using since 2017. They just launched a new company called Allform, and they’re making premium, customizable sofas and chairs shipped right to your door—at a fraction of the cost of traditional stores. You can pick your fabric (and they’re all spill, stain, and scratch resistant), the sofa color, the color of the legs, and the sofa size and shape to make sure it’s perfect for you and your home.

Allform arrives in just 3–7 days, and you can assemble it yourself in a few minutes—no tools needed. To find your perfect sofa, check out Allform is offering 20% off all orders to you, my dear listeners, at

This episode is brought to you by Tonal! Tonal is the world’s most intelligent home gym and personal trainer. It is precision engineered and designed to be the world’s most advanced strength studio. Tonal uses breakthrough technology—like adaptive digital weights and A.I. learning—together with the best experts in resistance training so you get stronger, faster. Every program is personalized to your body using A.I., and smart features check your form in real time, just like a personal trainer.

Try Tonal, the world’s smartest home gym, for 30 days in your home, and if you don’t love it, you can return it for a full refund. Visit for $100 off their smart accessories when you use promo code TIM100 at checkout.

What was your favorite quote or lesson from this episode? Please let me know in the comments.


Want to hear another episode with someone who’s not afraid to tread Amazonian rainforests in the puddles left by Richard Evans Schultes’ footsteps? Lend your ears to my discussion with ethnobotanist Mark Plotkin about Schultes’ proclivities as a trickster in the shamanic tradition, how a shaman in the northeastern part of the Amazon cured Mark’s foot pain instantly when no one else could, the “holes” in Western medicine’s understanding, hallucinogenic frogs, the risks of ayahuasca and other Amazon-derived hallucinogens, and much more.


  • Connect with Dennis McKenna:

Blog | Twitter | Facebook | Instagram

  • Connect with McKenna Academy:

Website | Donate | Twitter | Facebook | Instagram | YouTube


  • Dennis describes his first meeting with legendary ethnobotanist Richard Evans Schultes, the ensuing correspondence, and how it began a journey he wasn’t quite expecting. [06:53]
  • After spending 15 years in the sweltering Amazon, can Richard Evans Schultes be blamed for the disarming state in which Dennis first encountered him at Harvard? [20:15]
  • What made Sanford Siegel such a unique, creative scientist, and why is science such a crucial framework for serious explorers of the psychedelic ecosystem? [22:51]
  • What is Dennis’ “tortured” definition of ethnopharmacology? How many of the medicinal compounds we take for granted today have a cultural back story? [27:52]
  • On the government-subsidized 1967 Ethnopharmacologic Search for Psychoactive Drugs gathering, its 50th anniversary (and corresponding volumes edited by Dennis), the intervening Controlled Substances Act, and recent, surprising findings related to ayahuasca. [30:58]
  • What is the UDV? [37:19]
  • Does the UDV differentiate between different types of brews for different purposes? What is the organization’s view of ayahuasca as a medicine, and why have its adherents allowed outsiders to investigate its mysteries with scientific curiosity? [39:47]
  • There’s not just one type of ayahuasca. What has been Dennis’ experience with some of its other varieties, and what practical purposes might be served by learning more about them? Why has further study been elusive thus far? [44:01]
  • What is Brugmansia, and what makes it so scary? How is it used, and what should you do if you discover that some has ended up in your ayahuasca? [48:09]
  • Reasons to be cautious with sight-unseen mercenary “shamans” offering to guide you on psychedelic journeys in strange lands from which you might not return. [51:17]
  • The pros and cons of how ayahuasca tourism has altered its traditional use in recent years. [54:24]
  • If ayahuasca is something that can change your life after just one use, how does Dennis justify taking it over 500 times in his life, and what has it taught him? [58:14]
  • What circumstances might dictate Dennis’ decision to partake of ayahuasca, and why does he believe microdosing ayahuasca might actually be of benefit — even if he’s skeptical of the efficacy of microdosing other compounds? [1:02:54]
  • That time when things went terribly askew: the experiment at La Chorrera (as chronicled in Terence McKenna’s True Hallucinations), and why anyone undertaking such an exploration needs to be prepared for this possibility. [1:08:13]
  • Was it just an unusually bountiful and constantly consumed supply of psilocybin mushrooms over a long period of time to blame for sending the experiment at La Chorrera off the rails? [1:14:24]
  • When is it appropriate to let things play out — as they eventually did for Dennis at La Chorrera — or commit someone having this kind of experience to a professional psychiatric intervention? [1:17:16]
  • What is The McKenna Academy of Natural Philosophy, why was this nonprofit started, and what projects is it currently facilitating? [1:24:22]
  • Is The McKenna Academy a 501(c)(3) tax-exempt organization? [1:29:36]
  • Who else is involved in The McKenna Academy? [1:30:03]
  • What projects would be on Dennis’ shortlist with the proper resources, and what’s on the plate? [1:31:09]
  • New thoughts on the Stoned Ape Theory as Terence McKenna’s Food of the Gods is about to be reprinted. [1:32:38]
  • How much financial support will The McKenna Academy need to accomplish its current roster of goals, and what’s its highest priority? [1:36:15]
  • What is a voucher specimen? [1:38:50]
  • How many plant species are estimated to exist in the Amazon today, and how many have been thoroughly investigated? What are we doing to increase this percentage, what might we hope for from forthcoming discoveries, and what can we do to safeguard the bounty from these discoveries for the people who have been their stewards for millennia? [1:41:33]
  • How quickly can our tax-deductible donations fill The McKenna Academy of Natural Philosophy’s coffers to $600,000? Let’s find out together! I’ll start. [1:45:25]
  • Dennis’ billboard and parting thoughts. [1:49:54]


The Tim Ferriss Show is one of the most popular podcasts in the world with more than 600 million downloads. It has been selected for “Best of Apple Podcasts” three times, it is often the #1 interview podcast across all of Apple Podcasts, and it’s been ranked #1 out of 400,000+ podcasts on many occasions. To listen to any of the past episodes for free, check out this page.