The Experiment at the End of the World

“Because I am either an unsung Newton or completely nuts, there is very little room to maneuver between these two positions.”

In February 1971, five young Americans flew to Colombia, took a series of boats up the Putumayo River, and walked into a fog-bound jungle mission station called La Chorrera in search of a rare indigenous hallucinogen. They were looking for oo-koo-he, a DMT preparation used by the Witoto to communicate with 'little men.' They had brought their academic credentials (Terence McKenna was reading Chinese at Berkeley, his brother Dennis was studying botany), their sleeping bags, and an ambitious theory about the relationship between tryptamine chemistry and human consciousness.

What they found instead was a cow pasture full of psilocybin mushrooms.

True Hallucinations (1993) is Terence McKenna's account of what happened next, written twenty years after the fact, in a voice that holds together self-deprecating irony and genuine cosmic astonishment without letting either one win. It is the most honest book McKenna ever wrote, partly because he could not quite decide whether the events at La Chorrera represented a breakthrough or a breakdown, and he left that ambiguity in.

The experiment itself was Dennis's idea. He proposed that it was possible, through a specific vocalization technique during a mushroom session, to bond the DMT in the psilocybin into the body's endogenous harmala compounds, effectively creating a permanent psychedelic state in which the boundary between self and the collective unconscious would dissolve. Whether this theory was pharmacologically coherent is a question Terence left studiously open. He noted that it was either genius or madness and that the margin between the two was not visible from inside the experience.

Dennis underwent the more dramatic episode, a weeks-long altered state that his brother watched with a mixture of terror and fascination, attempting to determine whether what was happening was dissolution or evolution. Dennis was calm, voluble, and apparently in contact with something Terence couldn't access. He spoke in complex patterns. He made predictions. He was eventually fine. He went on to become one of the most rigorous neuropharmacologists working on tryptamines, and he has spent decades being carefully honest about what he does and does not believe happened at La Chorrera.

Terence's experience was different. During a late-night mushroom session in the forest, he began receiving what he described as a sustained monologue, the mushroom speaking, in his internal voice, on the nature of time, consciousness, and the relationship between human beings and the rest of the universe. He wrote it down. He called it 'the mushroom's claims.' He published them.

From this experience came the Timewave Zero theory, an attempt to map the I Ching's sixty-four hexagrams onto a mathematical model of time's qualitative structure, predicting that novelty would reach a maximum singularity on December 21, 2012. The prediction was falsified. McKenna had acknowledged it was falsifiable, which was one of his more intellectually honest positions. The broader intuition, that time has qualitative structure, that some moments are more 'novel' than others, is a philosophical claim independent of the specific mapping and remains interesting on its own terms.

What persists from La Chorrera beyond the failed prediction is the description. McKenna's account of the machine elves, 'merry elfin, self-transforming, machine creatures, looking like self-dribbling Fabergé eggs on the rebound', has become the most reproduced phenomenological report in the DMT literature. In a 2020 Johns Hopkins survey (Davis et al., J. Psychopharmacol. 34(9):1008-1020) of 2,561 people who had already had a DMT entity encounter, many respondents described features similar to McKenna's. It documents the phenomenology in detail but sets no prevalence rate, because every respondent was recruited for having had an encounter; the 97% figure often attached to it appears in no published paper. What he saw at Berkeley in 1965 and at La Chorrera in 1971 has since been reported by many other people, though no study has checked whether they had read his description first. The consistency of the report is a genuine scientific puzzle, regardless of what it means.

True Hallucinations does not answer the question of what happened at La Chorrera. It documents the question precisely. The book's most valuable quality is its epistemological honesty: Terence McKenna, who spent thirty years speaking with enormous confidence about the nature of reality, spent twenty years uncertain about whether the most important experience of his life was revelation or psychosis. He chose to publish the uncertainty. That is the book.

Sources

• McKenna, Terence. True Hallucinations: Being an Account of the Author's Extraordinary Adventures in the Devil's Paradise (1993)
• McKenna, Dennis. The Brotherhood of the Screaming Abyss (2012)
• Wikipedia, Terence McKenna
• Timmermann et al., PNAS 120(13) (2023)
• Sexton et al., J. Psychopharmacol. 33(9) (2019) [Source not found; under review]
• Davis et al., J. Psychopharmacol. 34(9):1008-1020 (2020)