Then (1993), True Hallucinations
Psilocybin and Human Evolution: McKenna's Core Claim
The McKenna brothers proposed at La Chorrera that tryptamine compounds, specifically psilocybin, had been co-evolutionary partners with human cognition for hundreds of thousands of years, and that the 'experiment' at La Chorrera was an attempt to access this ancient relationship.
partially-confirmed
Archaeological evidence now confirms psychoactive plant use going back at least 9,000 years (Peruvian shamanic cactus burial, 2014) and possibly much longer. DNA studies have identified 5-HT2A receptor variants in humans that differ from other primates in ways consistent with selective pressure related to serotonergic experience. The specific claim about psilocybin and human evolution remains untested and unfalsifiable. Dennis McKenna became one of the leading neuropharmacologists studying tryptamines and has consistently supported the broader hypothesis while qualifying the specific claims of La Chorrera.
Sources
- McKenna, True Hallucinations (1993)
- Mayer et al., Jour. Ethnopharmacol. (2015) [Source not found; under review]
- D. McKenna, The Brotherhood of the Screaming Abyss (2012)