Indoles as Molecular Growth Instructions: Psilocybin as Conserved Morphogenetic Signal from Deep Ancestry to Neural Execution

The Psilocybin Corpus — Abstracts A five-paper corpus advancing a single thesis: that psilocybin and the broader family of tryptophan-derived indoles are, primarily, conserved signaling molecules whose ancestral function is the coordination of growth, and that this reading reorganizes the clinical, evolutionary, phenomenological, and ecological questions the field has been asking. The papers are offered as a research program with named, falsifiable predictions — built to be tested, not to be deferred to. Paper 1 — Messiah Drift and the Phenomenology of Psilocybin A Dual-Drift Clinical Model and a Mycelial-Signaling Conjecture This paper offers two companion contributions for a field expanding faster than its frameworks: a clinical model for managing archetypal integration responses, and a mechanistic conjecture about why psilocybin experiences exhibit consistent structure rather than random noise. The clinical model distinguishes Mystification Drift (elevation of the substance or its source to sacred or communicative status) from Messiah Drift (elevation of the self to chosen messenger or uniquely enlightened status), and supplies a five-step anchoring protocol facilitators can apply immediately, independent of any theoretical commitment. This material stands on observation and established neuroplasticity science; it does not depend on the conjecture. The conjecture proposes that psilocybin functions primarily as an intercellular signaling molecule within mycelial networks, and that human phenomenology arises from cross-kingdom receptor compatibility: conserved indole architecture lets a fungal coordination signal activate mammalian 5-HT2A receptors. Experience remains entirely self-generated but unfolds under an altered constraint regime, producing coherent rather than arbitrary content. The paper states the governing principle of the whole corpus — that conserved biological molecules are characteristically multifunctional, so the real question is never “signal or defence” but which role is primary within a repertoire — and argues that signaling is the most parsimonious primary function on present evidence. Testable predictions, including temporal precedence of biosynthesis, distinguish it from defence-only accounts. The clinical material is offered as a framework for facilitation, not as medical advice or a standard of care. Paper 2 — From Indoles to Tryptophan Reclassification of Physarum polycephalum Deepens the Signaling Hypothesis by 1.5 Billion Years This paper corrects a taxonomic point in the earlier work and shows that the correction strengthens rather than weakens the thesis that tryptophan-derived indole signaling is an ancient, conserved mechanism of biological coordination. Physarum polycephalum, long grouped with fungi, is now resolved within Amoebozoa — the sister supergroup to Opisthokonta (fungi and animals), a divergence dated to roughly 1.4–1.6 billion years ago. The reclassification moves Physarum from “a fungus that signals” to “a distant relative that signals the same way,” which is the stronger evidence, since convergence at that phylogenetic distance is far less likely than inheritance. Physarum engages tryptophan directly through chemotaxis, synthesizes it via the conserved shikimate pathway and AROM architecture, carries an extensive GPCR repertoire, and responds to mammalian neurotransmitters despite having no nervous system — pushing tryptophan-based molecular recognition back to the last common ancestor of the two supergroups. The paper assembles the cross-kingdom picture: one precursor, conserved before the supergroups diverged, elaborated independently into auxin in plants, serotonin and melatonin in animals, and the psilocybin family in fungi — with the receptors that read these molecules co-conserved, so that cross-kingdom compatibility is inheritance, not coincidence. The biosynthetic and spatial data are reported in that light: psiD expression peaks ~395-fold in primordia relative to vegetative mycelium, and concentration per unit dry weight is highest in the youngest fruiting structures and declines with maturity — the distribution of a signal concentrating where coordination demand is greatest. Consistent with the companion chemical-ecology paper, the paper argues that the primary function is unlikely to be defence: psilocybin neither kills nor reliably repels its actual consumers, while the same lineage builds lethal deterrents (amatoxins) when selection favours them. Paper 3 — Psilocybin as Conserved Morphogenetic Signal The Growth Instruction, Its Faithful Execution in Neural Tissue, and the Hallucination as Peripheral Render A single conjecture in three movements, ordered by the weight each can bear. First, psilocybin belongs to a family of tryptophan-derived indole signaling molecules conserved across kingdoms — auxin in plants, serotonin and melatonin in animals, the psilocybin family in fungi — whose recurring ancestral role is the coordination of growth, and whose common root traces to the selection of tryptophan as a signaling precursor before the major eukaryotic lineages diverged. In plants this is not conjecture but textbook fact: auxin is the proven growth-direction member of the family. Second, when a mammal ingests psilocybin — or any of several members of this indole family — the conserved growth instruction is read by neural tissue fluent in the ancient signal and executed as dendritic and synaptic growth. That this growth is a class effect — driven by LSD, DMT, and psilocin alike through the conserved 5-HT2A receptor and abolished by 5-HT2A antagonism — is the strongest confirmation that what the tissue reads is the conserved root, not the specific molecule. This raises the question of why the endogenous indole, serotonin itself, does not drive the same growth through the same receptor — and the answer is established, and is about location rather than quantity: the growth-relevant 5-HT2A population is largely intracellular, reached by the lipophilic psychedelic indoles but not by polar serotonin, which cannot cross the membrane without a transporter to carry it in (Vargas et al., 2023). Access to the interior receptor, not potency or amount, is the gate — which is why an exogenous indole drives a growth program the endogenous neurotransmitter does not. This converges with developmental neuroscience, which independently describes serotonin as a morphogenetic factor during the critical period of dendritic growth. Third, the visual cortex bears the receptor but was never the intended addressee of a growth signal, and in the signal’s kingdom of origin has no counterpart at all. It renders its best approximation of an instruction it cannot parse, producing the ordered, recursive, space-filling geometry of the experience. The molecule was never made to be rendered visually; the mammalian cortex is the first rendering surface it has ever met. The render comes out growth-shaped because the growth-shape is in the signal whether or not the cortex understands it — and so the nature of the render is itself circumstantial evidence of what the molecule is for. A within-subject receptor contrast supports this: serotonergic 5-HT2A compounds (psilocybin, LSD, DMT, mescaline) produce recursive-branching geometry regardless of molecular class or duration, while the kappa-opioid agonist Salvia divinorum produces a categorically different laminar, planar geometry — the form tracks the receptor, not the molecule. The cortical form-constant model is conceded in full as the account of how a destabilized cortex renders geometry; the conjecture concerns the provenance and content of what it renders. Four falsifiable predictions are stated; the conjecture stands or falls on them. Paper 4 — A Deterrent That Does Not Deter Reconsidering Chemical Defence as the Function of Psilocybin, and Why the Deterrence Question Is Malformed This paper examines the long-standing default that psilocybin evolved as a chemical defence against fungivores and argues that both the hypothesis and the experiments used to test it are structurally flawed. Defence is a coevolutionary claim: it can be tested only against an organism with which the producer shares an evolutionary history, and its signature is differential harm between naïve generalists and coevolved specialists. Recent work feeding Psilocybe material to Drosophila larvae — a naïve frugivore with no such history — cannot adjudicate it. The study’s own controls undercut the defensive reading: non-psychedelic mushroom tissue reproduces much of the harm; the receptor-knockdown line was not protected but if anything more affected; and in the field, specialist mycophages thrive on and develop within the very tissue the compound is said to defend. The investigators named these limitations themselves, and the paper treats their candour as an opening, not a target. More fundamentally, the question “is psilocybin a deterrent?” is malformed. A genuine evolved chemical defence carries a fixed valence — it harms every receiver, as the amatoxins of this same lineage do. Psilocybin’s effect is receiver-dependent and reversible: aversive to one consumer, attractive to another, to the point of being cultivated worldwide for the very effect a defence would use to repel. That reversibility is positive evidence that deterrence is not the primary function. The paper sharpens the contrast with the toad: where a tryptamine genuinely is a primary defence (Incilius alvarius secreting a modified variant, 5-MeO-DMT, sequestered in dedicated glands), selection leaves unmistakable marks — a derived molecule in a purpose-built apparatus — that psilocybin entirely lacks, concentrating instead where the organism grows. Deterrence is at most peripheral; the primary function is signaling and the coordination of growth. The temporal-precedence test is named as the observation that would discriminate the accounts. Paper 5 — Growth on Demand