In the Sonoran Desert, the toad Incilius alvarius secretes a potent cocktail from its skin—including 5-MeO-DMT, bufotenine, and compounds that can profoundly alter human consciousness. For decades, scientists have studied these substances for their effects on the human brain. But a bold new question has emerged from a laboratory in northeastern China: What if these molecules were never meant for us at all?
Researchers led by Prof. Wang Xiaohui at the Changchun Institute of Applied Chemistry have published a perspective in PNAS proposing that natural hallucinogens like psilocybin, mescaline, and DMT may have evolved as ecological tools—molecules shaped by millions of years of survival pressures, not accidental quirks of chemistry. The work draws on chemical ecology, comparative genomics, and evolutionary biology to construct what the team calls a new framework for understanding why unrelated organisms across plants, fungi, and animals keep producing the same kinds of mind-altering compounds.
"Natural hallucinogens should be viewed as products of chemical ecology," the researchers argue, "and of convergent evolution, in which similar traits evolve independently in unrelated organisms because they face similar environmental challenges." The key insight is that animals across the tree of life share ancient, highly conserved neurotransmitter systems—particularly the serotonin signaling pathway. By producing small amounts of compounds that tap into these shared pathways, organisms may be able to influence the behavior of other species: deterring predators, regulating symbiotic relationships, or shaping ecological interactions in ways that boost survival.
The evidence spans the biological kingdoms. Peyote (Lophophora williamsii) accumulates mescaline, which tastes bitter and produces physiological effects that likely discourage herbivores. Psilocybin-producing fungi carry a biosynthetic module encoding four enzymes—PsiD, PsiH, PsiM, and PsiK—that together convert the amino acid tryptophan into psilocybin. Comparative genomics suggests these gene clusters spread through genomic rearrangement and horizontal gene transfer. The Sonoran Desert toad's skin secretions form a multicomponent chemical defense system that promotes predator avoidance. Across all these examples, the repeated emergence of hallucinogenic chemistry points to convergent evolution driven by shared ecological pressures and the same conserved neural targets.
The 5-HT2A serotonin receptor, which mediates the classic psychedelic experience in humans, emerged early in animal evolution and is found in both invertebrates and vertebrates. By modulating this signaling pathway, the researchers suggest, producer organisms may influence feeding, movement, learning, and orientation in other creatures—essentially using chemistry as a language across species boundaries.
The team is careful to note that many ecological hypotheses remain untested, requiring field studies, genetics, and behavioral biology. But they also point toward a hopeful practical application: advances in synthetic biology, microbial fermentation, and pathway engineering could allow these compounds to be produced sustainably in laboratories, reducing the need to harvest wild organisms and supporting conservation efforts.
Ultimately, the researchers propose that reframing natural hallucinogens through an ecological and evolutionary lens could open new doors—not only for finding related compounds in nature, but for producing and applying them responsibly.