For several years people from different places and backgrounds kept recommending the same oddly titled book to me: Paul Stamets’s Mycelium Running: How Mushrooms Can Help Save the World (Ten Speed Press). Everyone told me it was one of the most mind-bending texts they’d ever read. With so many recommendations, I perversely hesitated to pick the book up, and when I finally did, I prepared myself to be disappointed.

I wasn’t. Stamets fundamentally changed my view of nature — in particular, fungi: yeasts, mushrooms, molds, the whole lot of them.

When we think of fungi, most of us picture mushrooms, those slightly mysterious, potentially poisonous denizens of dark, damp places. But a mushroom is just the fruit of the mycelium, which is an underground network of rootlike fibers that can stretch for miles. Stamets calls mycelia the “grand disassemblers of nature” because they break down complex substances into simpler components. For example, some fungi can take apart the hydrogen-carbon bonds that hold petroleum products together. Others have shown the potential to clean up nerve-gas agents, dioxins, and plastics. They may even be skilled enough to undo the ecological damage pollution has wrought.

Since reading Mycelium Running, I’ve begun to consider the possibility that mycelia know something we don’t. Stamets believes they have not just the ability to protect the environment but the intelligence to do so on purpose. His theory stems in part from the fact that mycelia transmit information across their huge networks using the same neurotransmitters that our brains do: the chemicals that allow us to think. In fact, recent discoveries suggest that humans are more closely related to fungi than we are to plants.

Almost since life began on earth, mycelia have performed important ecological roles: nourishing ecosystems, repairing them, and sometimes even helping create them. The fungi’s exquisitely fine filaments absorb nutrients from the soil and then trade them with the roots of plants for some of the energy that the plants produce through photosynthesis. No plant community could exist without mycelia. I’ve long been a resident and defender of forests, but Stamets helped me understand that I’ve been misperceiving my home. I thought a forest was made up entirely of trees, but now I know that the foundation lies below ground, in the fungi.

Stamets became interested in biology in kindergarten, when he planted a sunflower seed in a paper cup and watched it sprout and lift itself toward the light. Somewhere along the way, he developed a fascination with life forms that grow not toward the sun but away from it. In the late seventies he got a Drug Enforcement Administration permit to research hallucinogenic psilocybin mushrooms at Evergreen State College in Washington. Stamets is now fifty-two and has studied mycelia for more than thirty years, naming five new species and authoring or coauthoring six books, including Growing Gourmet and Medicinal Mushrooms (Ten Speed Press) and The Mushroom Cultivator (Agarikon Press). He’s the founder and director of Fungi Perfecti (, a company based outside Olympia, Washington, that provides mushroom research, information, classes, and spawn — the mushroom farmer’s equivalent of seed. Much of the company’s profits go to help protect endangered strains of fungi in the old-growth forests of the Pacific Northwest. I interviewed Stamets in June 2007.


386 - Paul Stamets


Jensen: How many different types of mushrooms are there?

Stamets: There are an estimated one to two million species of fungi, of which about 150,000 form mushrooms. A mushroom is the fruit body — the reproductive structure — of the mycelium, which is the network of thin, cobweblike cells that infuses all soil. The spores in the mushroom are somewhat analogous to seeds. Because mushrooms are fleshy, succulent, fragrant, and rich in nutrients, they attract animals — including humans — who eat them and thereby participate in spreading the spores through their feces.

Our knowledge of fungi is far exceeded by our ignorance. To date, we’ve identified approximately 14,000 of the 150,000 species of mushroom-forming fungi estimated to exist, which means that more than 90 percent have not yet been identified. Fungi are essential for ecological health, and losing any of these species would be like losing rivets in an airplane. Flying squirrels and voles, for example, are dependent upon truffles, and in old-growth forests, the main predator of flying squirrels and voles is the spotted owl. This means that killing off truffles would kill off flying squirrels and voles, which would kill off spotted owls.

That’s just one food chain that we can identify; there are many thousands more we cannot. Biological systems are so complex that they far exceed our cognitive abilities and our linear logic. We are essentially children when it comes to our understanding of the natural world.

Jensen: In your book you say that animals are more closely related to fungi than they are to plants or protozoa or bacteria.

Stamets: Yes. For example, we inhale oxygen and exhale carbon dioxide; so do fungi. One of the big differences between animals and fungi is that animals have their stomachs on the inside. About 600 million years ago, the branch of fungi leading to animals evolved to capture nutrients by surrounding their food with cellular sacs — essentially primitive stomachs. As these organisms evolved, they developed outer layers of cells — skins, basically — to prevent moisture loss and as a barrier against infection. Their stomachs were confined within the skin. These were the earliest animals.

Mycelia took a different evolutionary path, going underground and forming a network of interwoven chains of cells, a vast food web upon which life flourished. These fungi paved the way for plants and animals. They munched rocks, producing enzymes and acids that could pull out calcium, magnesium, iron, and other minerals. In the process they converted rocks into usable foods for other species. And they still do this, of course.

Fungi are fundamental to life on earth. They are ancient, they are widespread, and they have formed partnerships with many other species. We know from the fossil record that evolution on this planet has largely been steered by two cataclysmic asteroid impacts. The first was 250 million years ago. The earth became shrouded in dust. Sunlight was cut off, and in the darkness, massive plant communities died. More than 90 percent of species disappeared. And fungi inherited the earth. Organisms that paired with fungi through natural selection were rewarded. Then the skies cleared, and light came back, and evolution continued on its course until 65 million years ago, bam! It happened again. We were hit by another asteroid, and there were more massive extinctions. That’s when the dinosaurs died out. Again, organisms that paired with fungi were rewarded. So these asteroid impacts steered life toward symbiosis with fungi: not just plants and animals, but bacteria and viruses, as well.

Jensen: Can you give some examples of these partnerships?

Stamets: A familiar one is lichens, which are actually a fungus and an alga growing symbiotically together. Another is “sleepy grass”: Mesoamerican ranchers realized that when their horses ate a certain type of grass, the horses basically got stoned. When scientists studied sleepy grass, they found that it wasn’t the grass at all that was causing the horses to get stoned, but an endophytic fungus, meaning one that grows within a plant, in the stems and leaves.

Here’s another example: At Yellowstone’s hot springs and Lassen Volcanic Park, people noticed that some grasses could survive contact with scalding hot water — up to 160 degrees. Scientists cultured these grasses in a laboratory and saw a fungus growing on them. They thought it was a contaminant, so they separated the fungus from the grass cells and tried to regrow the grass. But without the fungus the grass died at around 110 degrees. So they reintroduced this fungus and regrew the grass, and once again it survived to 160 degrees. That particular fungus, of the genus Curvularia, conveyed heat tolerance to the grass. Scientists are now looking at the possibility of getting this Curvularia to convey heat tolerance to corn, rice, and wheat, so that these grasses could be grown under drought conditions or in extremely arid environments, expanding the grain-growing regions of the world.

Other researchers took a Curvularia fungus from cold storage at a culture bank and joined it with tomatoes, expecting that it would confer heat tolerance. But the tomatoes all died at 105 degrees. They discovered that the cold storage had killed a virus that wild Curvularia fungus carries within it — which was odd, since you’d think cold storage would keep the virus alive. When they reintroduced the virus back into the Curvularia cultures and then reassociated the fungus with tomato plants, the plants survived the heat. So this is a symbiosis of three organisms: a plant, a fungus, and a virus. Only together could they survive extreme conditions.

These examples are just the tip of the iceberg. They show the intelligence of nature, how these different entities form partnerships to the benefit of all.

A mycelial “mat,” which scientists think of as one entity, can be thousands of acres in size. The largest organism in the world is a mycelial mat in eastern Oregon that covers 2,200 acres and is more than two thousand years old.

Jensen: Of course this raises the question of boundaries: Is that tomato-fungus-virus one entity or three? Where does one organism stop and the other begin?

Stamets: Well, humans aren’t just one organism. We are composites. Scientists label species as separate so we can communicate easily about the variety we see in nature. We need to be able to look at a tree and say it’s a Douglas fir and look at a mammal and say it’s a harbor seal. But, indeed, I speak to you as a unified composite of microbes. I guess you could say I am the “elected voice” of a microbial community. This is the way of life on our planet. It is all based on complex symbiotic relationships.

A mycelial “mat,” which scientists think of as one entity, can be thousands of acres in size. The largest organism in the world is a mycelial mat in eastern Oregon that covers 2,200 acres and is more than two thousand years old. Its survival strategy is somewhat mysterious. We have five or six layers of skin to protect us from infection; the mycelium has one cell wall. How is it that this vast mycelial network, which is surrounded by hundreds of millions of microbes all trying to eat it, is protected by one cell wall? I believe it’s because the mycelium is in constant biochemical communication with its ecosystem.

I think these mycelial mats are neurological networks. They’re sentient, they’re aware, and they’re highly evolved. They have external stomachs, which produce enzymes and acids to digest nutrients outside the mycelium, and then bring in those compounds that it needs for nutrition. As you walk through a forest, you break twigs underneath your feet, and the mycelium surges upward to capture those newly available nutrients as quickly as possible. I say they have “lungs,” because they are inhaling oxygen and exhaling carbon dioxide, just like we are. I say they are sentient, because they produce pharmacological compounds — which can activate receptor sites in our neurons — and also serotonin-like compounds, including psilocybin, the hallucinogen found in some mushrooms. This speaks to the fact that there is an evolutionary common denominator between fungi and humans. We evolved from fungi. We took an overground route. The fungi took the route of producing these underground networks that are highly resilient and extremely adaptive: if you disturb a mycelial network, it just regrows. It might even benefit from the disturbance.

I have long proposed that mycelia are the earth’s “natural Internet.” I’ve gotten some flak for this, but recently scientists in Great Britain have published papers about the “architecture” of a mycelium — how it’s organized. They focused on the nodes of crossing, which are the branchings that allow the mycelium, when there is a breakage or an infection, to choose an alternate route and regrow. There’s no one specific point on the network that can shut the whole operation down. These nodes of crossing, those scientists found, conform to the same mathematical optimization curves that computer scientists have developed to optimize the Internet. Or, rather, I should say that the Internet conforms to the same optimization curves as the mycelium, since the mycelium came first.

Jensen: In your new book you describe the intelligent behavior of a fungus-like organism called a “slime mold.”

Stamets: A group of Japanese researchers put a slime mold in a maze with five exits. Two of the exits had rewards: oats the slime mold could eat. The slime mold first navigated the maze by growing equally in all directions until it found the oats. Now, here’s where it gets interesting. When the same slime mold was later reintroduced to the same maze, rather than exploring every possible route, it navigated directly to the two end points that had the oats — showing, according to the scientists conducting the experiment, cellular intelligence.

Furthermore, fungi are exceptionally able to adapt to their surrounding environment; they send out “messenger molecules” — which we know little about — that seem to allow them to anticipate, in advance of actual contact, what nutrients they’re going to encounter.

Over the years I’ve had a lot of debates about the existence of intelligence in nature, especially with my brother Bill. I’ve tried various arguments on him, but it nearly always comes down to how we define “intelligence.” In a way, any cross-species measure of intelligence is unfair. Won’t the intelligence of the mycelium be different — and therefore be measured differently — from our own? And wouldn’t the same be true for every species?

I did finally succeed in convincing my brother of the intelligence of nature by arguing that he and I are born of nature, so it would be hypocritical to think — with our brains that nature has given us — that nature’s not intelligent. That much he conceded.

We are developing the language with which to talk about the deep intelligence of nature, but we’re moving very slowly. I think our descendants will look back on us as people who had the power to devastate ecosystems but not the wisdom to avoid doing so. We are unraveling the very networks that gave rise to life. As we undermine those networks, we are harming our descendants’ future and maybe imperiling our own survival. It’s estimated that 50 percent of the known species on this planet will become extinct in the next hundred years. That means we are at the start of the planet’s sixth great extinction, and the first one caused by humans.

Jensen: Perhaps this would be a good time to talk about the subtitle of your latest book: How Mushrooms Can Help Save the World.

Stamets: One way they can help is by a process called “mycoremediation.” The enzymes that forest fungi produce are designed to break the hydrogen-carbon bonds that hold wood and other plant material together. These same bonds also hold oil together, because oil comes from plant matter that decomposed millions of years ago. Most petroleum products — including petroleum-based pesticides and many other toxic compounds that are destroying the natural world — contain hydrogen-carbon bonds. If we can break those bonds, we can reduce those substances to their nontoxic elemental components.

Here’s an example: For more than thirty years the Washington State Department of Transportation operated a maintenance yard for trucks. The soil at the site was contaminated with diesel fuel and oil at levels approaching twenty thousand parts per million — about the same concentration as the beaches of Prince William Sound after the Exxon Valdez oil spill. In 1998 I helped conduct an experiment: The Department of Transportation set aside four large piles of contaminated soil. One pile was left untreated; one pile was inoculated with bacteria; one was treated with chemical enzymes; and the fourth was planted with oyster-mushroom spawn. The piles were covered, and four weeks later we removed the covers. The first three were black, lifeless, and stank like diesel fuel and oil. The fourth, the one inoculated with mushroom spawn, had hundreds of mushrooms growing from it, some up to a foot across. The pile no longer stank. Five weeks later, plants began to grow on the mushroom-inoculated pile: The mushrooms had attracted insects, who had laid their eggs in the fruits. When those eggs had hatched, the larvae had attracted birds, whose feces had brought plant seeds. Our mushroom-treated pile was the only one to flourish and rebound as an oasis of life.

In less than eight weeks the total petroleum hydrocarbons had dropped from twenty thousand parts per million down to two hundred parts per million. Among the pollutants that remained, the mushrooms had converted the larger, more-toxic molecules into smaller, less-toxic molecules. A state employee who loved mushrooms wanted to take the oysters home and eat them. We discouraged that, since we didn’t know what contaminants they might not have metabolized and broken down, but subsequent analysis revealed that the mushrooms contained no detectable amount of petroleum residue. (We didn’t check for heavy metals.) The primary byproducts were carbon dioxide and water.

The fungi connect different parts of the forest to each other like a natural Internet, transferring nutrients from a species that has enough to spare to another species that needs more to survive.

Jensen: It sounds, as you say, like a “mycomiracle.”

Stamets: Yes. Life was flowering on what had been a dead landscape.

In another experiment, I provided Battelle Laboratories with twenty-six strains of my fungi for testing. One day I received a confidential, classified report on the destruction of chemical-warfare components. I was named as a coauthor. I called up my associates, and they said they had tested my strain library against some potent neurotoxins, including sarin, soman, and VX, which Saddam Hussein had used against the Kurds in Iraq. Two of my strains did a good job of breaking down VX.

The interesting part is how adaptive these fungi proved to be. The researchers transferred these two strains from one culture plate to another, and every time they transferred them, they increased the amount of dimethyl methylphosphonate, or DMMP — which is the core toxin of VX nerve gas — and decreased the amount of other nutrients in the culture, such as malt sugar, yeast, peptone, and the like. At the end of the experiment, the sole nutrient source was this nerve-gas agent, DMMP; there were no other nutrients in the dish. And the fungi cultures grew luxuriantly. So the fungi were able to adapt to live on the available nutrition.

Jensen: Can mushrooms break down plastics?

Stamets: Some researchers have been able to train fungi to break down plastics. My understanding is that bacteria do a better job. But there are 2 million species of fungi; so there are plenty of candidates that we haven’t tried. Perhaps one of them can adapt and break down plastic. I would never underestimate the power of fungi; they are the grand molecular disassemblers in nature. This is what they do: unravel complex, sometimes toxic compounds into smaller, edible compounds. They’ve been doing this since the beginning of life on the planet. So if we have enough mycodiversity in the ecosphere, the right candidate will eventually come forward and break down a wide array of most, if not all, pollutants. It may not happen in our lifetimes, but it will happen. In geologic time, I think these fungi will make quick work of returning nutrients to the carbon bank.

Jensen: Why don’t we have emergency-response fungi teams that can rush out and drop fungi onto oil spills or other contaminated sites?

Stamets: One obstacle is blocking patents. A patent holder has a seventeen-year exclusive license to commercially produce products based on his or her patent. Even if the patent holder doesn’t produce a product, he or she can still block everyone else from producing anything based on the same design. Battelle and I were working on industrializing a nerve-gas decontamination technology when Battelle received a nasty letter from a lawyer representing a patent holder who had such a blocking patent on the technology.

Some of these blocking patents expire this year, and as a result there’s a huge surge in interest in mycoremediation. I’m being peppered almost daily with requests. In Mason County, Washington, where I live, a lot of estuary shellfish habitats are threatened by contamination from upland development, so we are involved in several projects to ameliorate the impact of pollutants on saltwater estuary environments. That’s really what Mycelium Running is all about: it’s a manual for the mycological rescue of the planet.

Jensen: Is this largely a new area of scientific exploration?

Stamets: Not exactly. Science has known the benefits of fungi for decades. In 1941 a housewife in Peoria, Illinois, found a moldy cantaloupe at a market and sent it in to a government lab in response to an official request for moldy fruit. From her moldy cantaloupe came a strain of Penicillium chrysogenum that allowed for the industrialization of penicillin. Even though Alexander Fleming had received the Nobel Prize in 1927 for the discovery of penicillin, there had been no strains that would allow the antibiotic to be mass-produced. The strain from that moldy cantaloupe produced two hundred times more penicillin than any previous strain. The Germans and the Japanese did not have penicillin during World War II; the Americans and the British did. The fungus strain from that cantaloupe saved millions of lives and played a major role in winning the war.

Today old-growth forests are habitat for a mushroom called Fomitopsis officinalis, otherwise known as “agarikon.” It’s thought to be largely extinct in Europe because it’s unique to old-growth environments, such as we still have in Washington State, Oregon, British Columbia, and northern California. About five years ago I signed a contract with the BioShield program of the U.S. Defense Department, which is searching for fungi that will help in the fight against bioterrorism. Bioterrorism is hard to prevent: you can track nuclear weapons because of their radioactive signature, but you can’t track viruses. I sent the BioShield program a few hundred fungal extracts, and they began testing them. We now have extremely credible evidence that the agarikon mushroom produces anti-smallpox compounds.

That’s crucial, because people born after 1980 have not been immunized against smallpox, and al-Qaeda is believed to have bought smallpox virus from the disintegrating republics of the Soviet Union. A smallpox epidemic today would cause mass devastation. Smallpox knows no borders and doesn’t care whether you are a Republican or a Democrat. We have no antidotes to smallpox, and if it did run rampant, 30 percent of us would be dead within two weeks; many more would be horribly scarred, maimed, or blinded. Only around 10 percent of us would survive with no physical scars. This mushroom — if indeed it proves to be effective against smallpox — could literally save millions of lives. So we can make the argument that we should save old-growth forests as a matter of national defense.

Biodiversity holds many treasures that we will need over time. The loss of these niche environments, of which we have been such poor custodians, would be extremely detrimental.

Whether nature and God are the same — which is my bet — may be open to debate, but I think there is more common ground between creationists and evolutionists than we think, so long as we recognize that the complexity of the universe exceeds our ability to understand it.

Jensen: You’ve said that mushrooms might help clean up nuclear contamination as well.

Stamets: Yes, Gomphidius glutinosus, a slimy mushroom that grows in conifer forests all over the world, is also a hyper-accumulator of the radioactive isotope cesium-137. In 1986 a reactor melted down at the Chernobyl nuclear power plant in the Ukraine and spewed cesium-137 into the atmosphere. The Ukrainians later discovered that this one type of mushroom contained concentrations of cesium-137 more than ten thousand times greater than the background level of contamination. The surrounding ecosystem had lost much of its radioactivity because the isotope was concentrated in this one fungus, which had become highly radioactive. This is why I think fungi play a governing, mothering role in the ecosystem: they can detoxify the environment for the benefit of other species.

Jensen: Are you saying that fungi do this consciously?

Stamets: I’m saying that mushrooms are good at surveying a landscape and taking a long-term view of the health of the entire population — which includes the organisms that give rise to forests, which create the deadwood that feeds the fungi and helps the fungi’s own progeny to survive. Fungi play an advanced role in ecosystem health and management; they increase soil depth and the richness of the soil, which in turn increases the carrying capacity of the ecosystem. Higher carrying capacity leads to more biodiversity, more sustainability, more resiliency.

And, of course, soil is a great carbon bank. Plants sequester carbon dioxide from the atmosphere by embedding it in soil, which helps prevent global warming.

Jensen: So the mushrooms are tending to the health of the planet.

Stamets: Exactly. Here’s an even better example. Suzanne W. Simard, an excellent research author, was curious about how young trees survived in the shade of thick forests. If you’ve been in an old-growth forest, you’ve probably seen hemlock saplings growing on rotting “nurse logs.” Hemlocks are usually the first trees to come up in these environments where there’s very little sunlight. When these small saplings were dug up and brought to a greenhouse and given a similarly low amount of light, they all died. The question was: Where were these young trees getting their nutrients? So the researchers radioactively tagged carbon to watch the translocation of carbon in the forest. They found that birch and alder trees growing along rivers, where there is more sunlight, were contributing nutrients to the hemlocks via the mycelia running through the forest soil. The fungi connect different parts of the forest to each other like a natural Internet, transferring nutrients from a species that has enough to spare to another species that needs more to survive. I think mycelia do this because they know that the health of the ecosystem aids the survival of fungal populations.

Jensen: My favorite sentence from your new book is “Nature loves a community.” If every person in our culture understood this, I think we wouldn’t be killing the planet.

Stamets: I agree, and I’m hopeful that many people will come to understand it.

My mother gives me hope. She is a charismatic Christian, and I love her deeply. She’s raised five children, all of whom, despite having grown up in a highly religious environment, are scientifically oriented. This makes for some interesting discussions. No, my mother doesn’t believe that the earth is only six thousand years old, but sometimes she feels a little nervous listening to me talk about my work, because most of her friends have an antiscientific bias. I’ve tried to bridge the gap for her between creationism and evolution by telling her that evolution is God’s intelligent design. She likes this idea, and we agree that, whether it’s God or nature, our minds are inadequate to the task of comprehending it. No one can claim to truly know God, just as no one can claim to truly understand nature. (Well, someone might claim to understand it, but he or she would be a deluded egomaniac.)

Whether nature and God are the same — which is my bet — may be open to debate, but I think there is more common ground between creationists and evolutionists than we think, so long as we recognize that the complexity of the universe exceeds our ability to understand it.

Jensen: Author Terence McKenna is known for, among other things, his work with psilocybin — the hallucinogenic compound found in some mushrooms. He writes, speaking from the point of view of the mushrooms, “I am old, older than thought in your species, which is itself fifty times older than your history.”

Stamets: Psilocybin is a neurotransmitter that can temporarily block the release of serotonin from certain neurons in our brain, causing hallucinations. We find such a mind-altering chemical in certain mushrooms because the mycelium utilizes these same compounds — dimethyl tryptamines — that are utilized by our neurological networks. In other words, these fungi produce the same classes of neurotransmitters that enable us to think.

Jensen: And you’ve worked with psilocybin.

Stamets: My work with psilocybin goes back a long way. I was covered for more than twenty years by a Drug Enforcement Administration permit. I’ve named five new species, four of which are psilocybin-active mushrooms, and I’ve published articles about them in scientific journals.

Ingesting these mushrooms has definitely been an important spiritual experience for me. Every time I take these sacraments, I hear voices from nature screaming out to me, “Don’t you see? Don’t you know? The earth is in peril. We need your help. You’re harming the earth. Please wake up!” These experiences were my call to mycological arms, so to speak; my signal to pick up the mycelial torch and march forward with it.

I like to see things get done. Anyone who’s met me knows I’m a workaholic. My motto is “Walk and talk if you want to talk to me, because I’m busy.” The inspiration to work this hard came from my psilocybin experiences. My life’s goal is to make people aware that we can support nature by protecting mycelial networks. They’re everywhere. Just go outside and turn over any piece of wood on the ground. You’ll find a mycelium. It’s the foundation of the food web and infuses all habitats, creating spongy cavities that hold water. Where you have water, life tends to thrive. These mycelial networks are powerful allies. They’re an untapped resource that’s literally underfoot.