In 1976, scientists inserted electrodes into red bread mold and discovered something unexpected: the fungus was generating electrical spikes. These weren't random static. The pulses had patterns, rhythms, amplitudes that varied from 0.03 to 2.1 millivolts. For decades, this observation sat quietly in the scientific literature, a curiosity without context. Then researchers started paying closer attention to what was happening beneath our feet.
The Chemical Language of Soil
Fungi don't have neurons, but they've developed their own sophisticated communication system using volatile organic compounds—molecules light enough to drift through soil and air. These compounds, called FVOCs, are small carbon-based molecules weighing less than 300 daltons. Their low boiling points and high vapor pressure mean they can travel significant distances through the spaces between soil particles.
The chemistry involves four main biosynthetic pathways: mevalonate, shikimate, polyketide, and fatty acid-derived oxylipin pathways. Each produces different molecular structures—alcohols, ketones, terpenoids, benzenoids. One particularly interesting compound is pentyl-α-pyrone, synthesized by Trichoderma atroviride through a gene called Lox1. This molecule both promotes plant growth and fights off competing fungi, a dual function that hints at the complexity of underground chemical conversations.
These aren't simple on-off signals. Different FVOCs trigger specific responses in neighboring organisms. Some compounds prime plant immune systems without actually activating them—a kind of advance warning that helps plants respond faster when real threats arrive. Others coordinate fungal growth or reproduction. The specificity suggests a vocabulary, not just noise.
Electric Highways Through the Mycelium
The electrical signals discovered in 1976 turned out to be more than curiosities. In 2022, Andrew Adamatzky at the University of the West of England analyzed electrical patterns in four fungal species: ghost fungi, enoki, split gill, and caterpillar fungi. He found spike trains that appeared to cluster into distinct patterns—up to 50 different configurations that could represent something like words.
This claim sparked immediate controversy. The electrical spikes likely result from calcium waves propagating through fungal cells, coordinating responses across the organism. A 1986 study found that electric fields could alter hyphal growth direction, branching frequency, and spore germination. But whether these signals constitute true communication—intentional information transfer—remains hotly debated.
The spikes vary dramatically: durations from one to 21 hours, different amplitudes, distinct patterns between species. Fungi might use these signals to maintain mycelial integrity across large distances, report discovered food sources, or coordinate responses to damage. The mycelium needs some way to know what its far-flung parts are encountering. Electrical signals travel faster than chemical diffusion, making them ideal for urgent coordination.
The Wood Wide Web Controversy
In 1997, Suzanne Simard published research in Nature that changed how ecologists think about forests. She demonstrated that carbon moved between tree species through shared ectomycorrhizal fungi—trees were trading resources underground. The finding earned the nickname "Wood Wide Web," and subsequent research mapped networks spanning kilometers, linking multiple generations of Douglas fir.
Simard's 2015 work showed something more provocative: when Douglas fir trees were damaged by defoliation, they increased carbon transfer to neighboring ponderosa pines and triggered defense signaling. This suggested forests might function as cooperative networks rather than collections of competing individuals.
But the interpretation remains contentious. Some scientists argue the carbon transfer is simply fungal metabolism—the fungi taking what they need from one tree and excreting it near another—not intentional plant communication. The difference matters. If fungi are just middlemen extracting fees, the network is less cooperative than it appears. If plants can actually signal through fungal connections, it transforms our understanding of plant intelligence.
What Fungi Get From the Exchange
The focus on plant benefits obscures what fungi gain from these relationships. Arbuscules—specialized fungal structures that penetrate plant root cells—exchange soil nutrients and water for complex carbon compounds that plants produce through photosynthesis. This isn't altruism; it's trade.
Fungi are degraders of organic material, breaking down dead matter that plants can't process. They're also carbon sinks, storing carbon in soil that would otherwise return to the atmosphere. The mycorrhizal networks that connect forest trees help ecosystems recover from disturbances: clear-cutting, wildfire, insect outbreaks, drought. Established networks can jump-start recovery by connecting surviving trees to new seedlings.
The chemical signals fungi produce serve their own interests first. When Trichoderma species release FVOCs that prime plant defenses, they're protecting their carbon source from competitors. When electrical signals coordinate spore production, fungi are responding to environmental opportunities. That these signals create network effects doesn't mean they evolved for that purpose.
The Indigenous Knowledge Gap
Western science has spent three decades mapping mycorrhizal networks and analyzing fungal chemistry. Indigenous peoples have managed forests with implicit understanding of these connections for millennia. Indigenous territories contain 80 percent of global biodiversity, and traditional stewardship practices have created the world's most biologically diverse ecosystems.
This knowledge gap matters for practical reasons. Industrial forestry typically treats trees as individual units to be harvested and replanted. If forests actually function as interconnected networks, this approach damages the infrastructure that supports forest health. Simard's Mother Tree Project, established in 2015, tries to integrate network thinking into forestry practice, but adoption remains slow.
Signals We're Only Beginning to Decode
Research published in 2023 emphasized how little we understand about plant perception of fungal signals. Plants clearly respond differently to FVOCs from beneficial versus harmful fungi, but the mechanisms remain unclear. Do plants recognize specific molecular signatures? Do they integrate multiple chemical cues? Can they distinguish between fungal species?
The electrical communication research is even more preliminary. We can measure the signals, but interpreting them requires understanding fungal neurobiology—a field that barely exists. Claiming fungi have language might be premature, but dismissing the patterns as meaningless seems equally hasty.
Underground communication networks predate human language by hundreds of millions of years. They've shaped terrestrial ecosystems since plants first colonized land. We've spent a few decades with electrodes and gas chromatographs, detecting signals we don't yet fully comprehend. The conversation has been happening all along. We're just learning to listen.