Psilocybin and the Evolutionary Significance of Altered Neural States: Interaction-Based Perspectives Beyond Deterrence Models

Philip Rebensburg

Psilocybin is a psychoactive tryptamine produced by a phylogenetically discontinuous yet ecologically diverse subset of fungi. Despite decades of chemical, pharmacological, and ethnobiological research, the evolutionary forces driving the emergence and persistence of this compound remain insufficiently explained. Recent hypotheses proposing that psilocybin evolved primarily as a deterrent against insect fungivory account for certain laboratory observations but struggle to reconcile key features of the molecule, including its substantial biosynthetic investment, its highly specific and conserved neuromodulatory effects across taxa, and its patchy phylogenetic distribution.
Here, I present a hypothesis-driven conceptual synthesis that reassesses the evolutionary significance of psilocybin by integrating evidence from fungal genomics, chemical ecology, evolutionary biology, and systems neuroscience. To test the limits of deterrence-based explanations, psilocybin is situated within a broader comparative framework that includes other naturally occurring tryptamines, most notably N,N-dimethyltryptamine (DMT) and related derivatives such as baeocystin and bufotenin. These compounds occur across fungi, plants, animals, and microbial symbioses, act on conserved serotonergic systems, and reliably induce transient but structured alterations of perception, behavior, and cognition.
I argue that psilocybin is more parsimoniously understood as an interaction-modulating secondary metabolite that alters neural and behavioral states in ways that can influence ecological interactions, rather than as a narrowly targeted defensive toxin. Comparative analysis reveals convergent evolutionary patterns that are difficult to reconcile with deterrence-only models but are consistent with a broader evolutionary solution space in which altered neural states represent biologically accessible and functionally meaningful regimes.
By reframing psilocybin as part of a class of secondary metabolites that modulate organism–environment interactions through transient alterations of neural state, this synthesis advances an interaction-based evolutionary framework and outlines testable predictions for future empirical work.