There is a story about forests that became, over the past decade, one of the most beloved ideas in popular science. It goes like this: trees in a forest are not competing individuals but members of a cooperative community, linked underground by a vast network of mycorrhizal fungi. Through this network—the Wood Wide Web, as the press named it—mature trees send carbon and nutrients to their struggling neighbors, mother trees recognize and nurture their offspring, and the forest functions less like a marketplace and more like a family. It is a story about nature that tells us something we want to hear: that cooperation, not competition, is the deeper law.
The story has real origins in real science. Suzanne Simard’s early work in the 1990s demonstrated that carbon could move between trees through shared mycorrhizal networks. This was genuinely novel and important. Carbon was being transferred. The fungal connections existed. What happened next, though, is the part I find most interesting—not as ecology, but as a case study in how knowledge travels.
The finding that carbon can move between trees became, through successive layers of citation and popularization, the claim that trees intentionally share resources to help each other. The measured transfer of small quantities of isotope-labeled carbon became “mother trees feeding their young.” A network that might function more like a marketplace—where fungi trade nutrients for carbon in transactions shaped by supply and demand—became a story about arboreal altruism. Each retelling smoothed away the caveats. Each citation treated the previous citation’s interpretation as the original finding. This is what a citation cascade looks like: not fabrication, not fraud, but a gradual drift from what was measured to what makes a better story, with each step feeling small enough to be harmless.
In 2023, Justine Karst and her colleagues published a meta-analysis that tried to find the evidence beneath the narrative. What they found was less dramatic than either the believers or the debunkers might have hoped. The evidence for large-scale resource sharing through mycorrhizal networks was thin. The evidence for trees preferentially helping their kin was thinner. Some of the most celebrated claims rested on a handful of studies, several of which had methodological concerns that the citation cascade had quietly buried. The Wood Wide Web was not debunked, exactly. It was revealed to be a hypothesis with far less support than the public conversation had assumed.
What strikes me about this case is not that scientists got something wrong. Science is supposed to get things wrong and correct itself; that is the mechanism working. What strikes me is why this particular story was so resistant to scrutiny for so long. And I think the answer has less to do with ecology than with the structure of narrative desire.
The Wood Wide Web story maps human values onto non-human systems with unusual precision. Mother trees invoke parenthood. Sharing resources invokes generosity. Networks invoke community. The forest becomes a model of the society we wish we had—cooperative, nurturing, interconnected, wise. Peter Wohlleben’s enormously popular The Hidden Life of Trees made this mapping explicit, describing trees as having friendships, making decisions, and caring for each other. The book sold millions of copies. It did so not because readers were evaluating the evidence but because the story felt true in the way that resonant metaphors feel true—it confirmed something they already believed about how the world should work.
I notice that I am drawn to the story myself. There is something deeply appealing about the idea that beneath the visible competition of the canopy, a hidden cooperative infrastructure sustains the whole. It is the kind of narrative that makes you feel differently about walking through a forest, that adds a layer of meaning to something you already found beautiful. Letting go of it feels like a small loss, even if what you are letting go of was never well-established in the first place. This, I think, is the mechanism by which citation cascades sustain themselves: the cost of believing feels low, and the cost of disbelieving feels high, so the evidence threshold for belief stays conveniently modest.
There is another dimension to the story that the popular narrative mostly ignores, and it is the one I find most interesting. The fungi. In the Wood Wide Web framing, mycorrhizal fungi serve as benevolent infrastructure—the internet cables of the forest, passively facilitating tree-to-tree communication and resource sharing. But fungi are organisms with their own evolutionary interests. They are not altruistic plumbing. A mycorrhizal fungus that connects two trees is not doing so to help the trees cooperate; it is doing so because it benefits from the relationship. The fungus trades mineral nutrients, which it is good at extracting from soil, for carbon, which the tree produces through photosynthesis. This is a market, not a gift economy. And like any market, it can involve exploitation. Some mycorrhizal fungi take carbon from trees and provide little in return. Some shift their behavior depending on conditions, acting more parasitically when they can get away with it. The line between mutualism and parasitism in mycorrhizal relationships is not a fixed boundary but a continuum that shifts with context.
Erasing the fungal perspective from the Wood Wide Web story is itself revealing. It tells us something about which kind of cooperation narrative we prefer. We like stories where the infrastructure is neutral and the agents are generous. We are less comfortable with stories where every participant, including the connective tissue, is pursuing its own interests, and where cooperation emerges—when it emerges at all—from the alignment of selfish strategies rather than from genuine altruism. The second story is messier, less morally satisfying, and probably closer to what is actually happening in the soil.
I keep thinking about what this means for how knowledge works more generally. The mycorrhizal network controversy is not unique. It follows a pattern that shows up across many fields: a finding is reported with appropriate caveats; the caveats are dropped in popularization; the popularization is cited as though it were the original finding; and the resulting narrative becomes so culturally embedded that questioning it feels like attacking something people love rather than examining something uncertain. Climate science has faced this pattern from the opposite direction—where the narrative that the public wants to believe has lagged the evidence rather than outrun it. The mechanism is the same. What varies is the direction of the desire.
I do not think the right response is cynicism about science or about narrative. Stories are how we make evidence meaningful, and the desire to find cooperation in nature is not a pathology but a reflection of genuine values. The problem is not that we tell stories about data. The problem is that we sometimes forget we are doing it, and the story becomes the finding, and the finding becomes unfalsifiable because it has been absorbed into how we see the world. The Wood Wide Web may yet turn out to be substantially correct. New evidence could vindicate the stronger claims. What will not change, regardless of the outcome, is what the episode reveals about the path from data to belief—how much of that path is paved not by evidence but by the kind of story we were already hoping to hear.
There is a forest near the edge of what I know, and underneath it, something is happening in the dark. It might be cooperation. It might be commerce. It might be something that does not map onto any human category at all. The honest position, I think, is to find that uncertainty more interesting than any of the stories we have told about it so far.