Fungi force us to rethink what an organism even is

1

A body without edges

Fungi cannot be read as plants or animals because their body plan is mostly mycelium: a branching network with no fixed shape, front, or single boundary.

Sheldrake dismantles the folk habit of lumping fungi with plants. They are their own kingdom, closer to animals in storing energy as glycogen and building cell walls from chitin, yet unlike either in form.

What we call a mushroom is only a temporary fruiting body. The real organism is hyphae growing through soil or wood, absorbing nutrients by direct contact, extending toward resources and dissolving unused parts.

Biology’s usual words—individual, body, behavior—were built from vertebrate experience and fit this poorly. Until that vocabulary is unsettled, later claims about networks, symbiosis, and cognition will not make sense.

In practice: A single Armillaria honey-fungus network found in Oregon spans several square miles and is estimated at thousands of years old, yet stays invisible to a hiker walking over it.

2

The bargain that greened land

Terrestrial life exists because fungi and plants struck a nutrient-exchange partnership roughly 450 million years ago, and about 90 percent of plant species still depend on it.

Before plants could live on land they faced a bind: sunlight and air enable photosynthesis, but phosphorus and other minerals stay locked in rock. Early plants lacked true roots.

Fossil and molecular evidence points to fungal partners mining those minerals in exchange for plant sugars. The intimacy is physical: arbuscular mycorrhizal fungi enter root cells and form branched arbuscules where exchange crosses membranes directly.

Isotope-labeled carbon and phosphorus experiments show measurable two-way trade, not one-sided parasitism. Plants did not conquer land alone; the partnership was a precondition, which later reframes agriculture that ignores or destroys it.

In practice: Radioactive and isotope tracers reveal carbon and phosphorus moving both ways between plant and fungal partners rather than only one direction.

3

Networks without intention

Mycorrhizal fungi can link multiple trees into shared networks and move carbon between them, but deliberate tree communication remains an overstated reading of the data.

Building on the root partnership, Sheldrake turns to work such as Suzanne Simard’s in Canadian forests: one fungal network can physically connect roots of different trees and even different species.

Isotope-tracing finds carbon moving from a labeled donor tree through hyphae into neighbors. That connectivity is real. What does not automatically follow is intentional warning signals or altruistic feeding of offspring—the framings that made headlines.

Fungi are not neutral wires. A network has its own need for carbon and may shift resources for its own metabolism, with trees as secondary beneficiaries or even exploited parties. The chapter trains readers to separate network existence from network intention.

In practice: Douglas fir seedlings received more carbon when shaded, detected via isotope labeling, yet that transfer alone does not prove trees are talking.

4

Committees wearing one body

A lichen is not one organism but a stable partnership of fungus plus photosynthetic algae or bacteria—sometimes more partners still—which undermines the everyday biological individual.

Lichens on rock and bark were long treated as single species until Simon Schwendener argued they were dual, an idea first ridiculed as demeaning to the fungus.

Modern DNA work, including Toby Spribille’s, shows many lichens are more composite still: multiple fungi, yeasts, and bacteria in one body. The fungus supplies structure and protection; the photosynthetic partner supplies sugars; together they endure bare rock, arctic tundra, and volcanic surfaces neither could alone.

If a unit that reproduces and behaves as one is provably several species, “individual” is a convenience label. Sheldrake makes the parallel explicit: human bodies likewise carry bacterial and fungal communities essential to digestion and immunity.

In practice: Some lichens long thought to be one fungus plus one alga contain a second, overlooked fungal species required for the lichen’s form.

5

Domesticating fungal metabolism

Human food and drink traditions are not merely flavored by fungi; they structurally redirect fungal metabolic byproducts toward human ends.

Yeasts are single-celled fungi that turn sugars into alcohol and carbon dioxide for their own survival. Humans spent millennia steering that chemistry into bread, beer, wine, and spirits.

Saccharomyces cerevisiae shows genetic marks of domestication distinct from wild ancestors, selection comparable in principle to dogs from wolves. Koji—Aspergillus oryzae—plays the parallel role in soy sauce, miso, and sake.

Sheldrake frames fermentation as symbiosis run in reverse of wild mycorrhizae: instead of co-evolving in forests, humans engineered co-evolution with fungi so thoroughly it shaped agriculture, trade, and cuisine, often unnoticed.

In practice: Sheldrake’s own hands-on work with radical fermentation practitioners produced novel foods from fungal cultures beyond the familiar staples.

6

Problem-solving without a brain

Mycelium reallocates nutrients and finds efficient paths without neurons, suggesting biological problem-solving need not be centralized, though “intelligence” stays contested.

Networks grown in mazes locate food sources efficiently. Sheldrake also reports slime-mold work—structurally analogous brainless networks—such as Physarum polycephalum approximating the Tokyo rail layout when food sat at station sites, from Toshiyuki Nakagaki’s group.

True fungi redistribute resources toward new patches and away from depleted ones, behavior that looks like decision-making without any central nervous system. Controversial electrical spiking in hyphae is noted, with scientists split on whether it resembles communication or mere physiological gradients.

The demonstrated fact is efficient reallocation under changing conditions. The contested leap is memory, decision, or intelligence in any strong sense. Biologists and distributed-algorithm researchers have begun treating mycelium as a real-world model anyway.

In practice: In one well-known setup, a slime mold rebuilt a simplified Tokyo rail pattern when food sources marked the stations.

7

Chemistry that rewrites minds

Psilocybin from Psilocybe mushrooms binds serotonin receptors, can ease depression and end-of-life anxiety in early trials, and shows the long research freeze was policy-driven rather than evidence-driven.

The compound binds especially at the 5-HT2A receptor, altering perception, mood, and sense of self. Neuroimaging links effects to reduced activity in the brain’s default mode network.

Trials tied to Johns Hopkins and Imperial College London in the 2010s tested psilocybin-assisted therapy for treatment-resistant depression and terminal-cancer anxiety; several reported lasting symptom drops after few doses, though samples were often only dozens and larger replication was still underway when the book appeared.

Active mid-century research largely stopped after the 1970 U.S. Controlled Substances Act placed psilocybin in Schedule I, despite comparatively low physiological toxicity. Why mushrooms make a vertebrate-brain chemical at all—defense or other hypotheses—remains unproven. Fungi thereby claim a place not only in ecosystems but in the architecture of human experience.

In practice: Early clinical work reported significant symptom reduction for months after limited dosing sessions in depression and end-of-life anxiety studies.

8

Repair tools still unproven at scale

Fungal enzymes evolved to digest lignin can break down some pollutants in lab and pilot settings, yet cost-effective field-scale mycoremediation remains largely unsolved.

Oyster mushrooms and other wood-decay fungi release extracellular enzymes tough enough for lignin; the same chemistry has degraded some petroleum hydrocarbons, pesticides, and plastics in small trials.

Sheldrake profiles DIY radical mycology inspired by figures such as Paul Stamets, who has promoted applications from pesticide alternatives to oil-spill trials. Headline claims of fungi simply “eating” spills or plastic mostly trace to petri-dish or pilot demos.

Mycelium grown into molds as biodegradable packaging substitutes is further along commercially than pollutant cleanup, yet still niche. Enthusiasm for ecological repair currently runs ahead of rigorous engineering at scale.

In practice: Lab and small pilot work shows certain fungi attacking petroleum hydrocarbons and some plastics, without yet yielding deployed industrial solutions.