Mycorrhizal Networks and the Myth of Individual Organisms

The Romantic Version

You've probably heard the story: trees communicate through underground fungal networks, sharing nutrients with their neighbors, warning each other of pests, even feeding their dying elders. The forest as superorganism, the trees as neurons in a planetary brain.

It's a beautiful story. Suzanne Simard's book Finding the Mother Tree (2021) brought it to mainstream attention, and the documentary Fantastic Fungi (2019, dir. Louie Schwartzberg) made it visually stunning. But the popular version is significantly oversimplified — and the reality is more interesting.

What the Networks Actually Do

Mycorrhizal networks are real. Roughly 90% of land plants form symbiotic relationships with mycorrhizal fungi — the fungi colonize plant roots, extending their reach into the soil in exchange for sugars produced by photosynthesis. This has been known since the 1880s, when the German botanist Albert Bernhard Frank first described the relationship.

What's less clear is the "communication" and "altruism" framing. The carbon transfers that have been documented are real, but their direction and purpose are contested. A 2022 meta-analysis in Nature Ecology & Evolution found that while carbon does flow between trees via fungal networks, the evidence for directed sharing — mother trees deliberately subsidizing seedlings — is much weaker than the popular narrative suggests.

More interestingly, the networks are competitive as well as cooperative. Fungi compete with each other for root colonization. Plants compete for fungal partners. The network is less a commune and more a market — with all the complexity that implies.

The Individuality Problem

What this research really destabilizes is our concept of the individual organism. Is a tree an individual, or is it a node in a network that includes its fungal partners, its bacterial symbionts, its gut-microbiome equivalent in the rhizosphere?

The philosopher of biology Peter Godfrey-Smith explores this question in Other Minds (2016) and Metazoa (2020) — tracing the evolution of individuality itself as a biological achievement, not a given. What counts as "one organism" turns out to be deeply contingent.

This is the problem that haunts discussions of human enhancement. When we enhance an individual human — with drugs, implants, genetic modification — we're not just changing one node. We're changing their relationships, their dependencies, their place in a network. The individual is always already a collective.

Current Debates

In 2023, a study in PNAS challenged some of Simard's specific claims about mother trees, triggering a public debate about the line between scientific communication and scientific storytelling. The controversy is worth reading — not because Simard is wrong, but because it illustrates how much we project our social values onto ecological research. We want forests to be cooperative because we want cooperation to be natural. That desire shapes what we look for and what we find.