The ethnobotany of psychoactive plant use: a phylogenetic perspective

Psychoactive plants evolved chemicals as allelochemicals that also affect human neuronal receptors, altering perception, emotion, and cognition. A phylogenetic analysis of culturally diverse psychoactive plant taxa reveals multiple evolutionary origins of psychoactive families. Families such as Myristicaceae, Papaveraceae, Cactaceae, Convolvulaceae, Solanaceae, Lamiaceae, and Apocynaceae contain a disproportionate number of psychoactive genera, with different indigenous groups using geographically separate members for the same psychoactive effect—an example of cultural convergence. Hallucinogenic and sedative traits are phylogenetically conserved within families, and unrelated families with similar psychoactive effects modulate similar neurotransmitter systems (mechanistic convergence). Stimulant mechanisms are more evolutionarily labile. Chemically similar psychoactive compounds in unrelated lineages suggest convergent evolution or differential gene regulation. These findings motivate pharmacological investigation into psychoactive plants as modern therapeutics for neurological disorders.

Study at a glance

Abstract

Psychoactive plants contain chemicals that presumably evolved as allelochemicals but target certain neuronal receptors when consumed by humans, altering perception, emotion and cognition. These plants have been used since ancient times as medicines and in the context of religious rituals for their various psychoactive effects (e.g., as hallucinogens, stimulants, sedatives). The ubiquity of psychoactive plants in various cultures motivates investigation of the commonalities among these plants, in which a phylogenetic framework may be insightful. A phylogeny of culturally diverse psychoactive plant taxa was constructed with their psychotropic effects and affected neurotransmitter systems mapped on the phylogeny. The phylogenetic distribution shows multiple evolutionary origins of psychoactive families. The plant families Myristicaceae (e.g., nutmeg), Papaveraceae (opium poppy), Cactaceae (peyote), Convolvulaceae (morning glory), Solanaceae (tobacco), Lamiaceae (mints), Apocynaceae (dogbane) have a disproportionate number of psychoactive genera with various indigenous groups using geographically disparate members of these plant families for the same psychoactive effect, an example of cultural convergence. Pharmacological traits related to hallucinogenic and sedative potential are phylogenetically conserved within families. Unrelated families that exert similar psychoactive effects also modulate similar neurotransmitter systems (i.e., mechanistic convergence). However, pharmacological mechanisms for stimulant effects were varied even within families suggesting that stimulant chemicals may be more evolutionarily labile than those associated with hallucinogenic and sedative effects. Chemically similar psychoactive chemicals may also exist in phylogenetically unrelated lineages, suggesting convergent evolution or differential gene regulation of a common metabolic pathway. Our study has shown that phylogenetic analysis of traditionally used psychoactive plants suggests multiple ethnobotanical origins and widespread human dependence on these plants, motivating pharmacological investigation into their potential as modern therapeutics for various neurological disorders.