In one of my favorite David Attenborough clips, his soothing narration goes on as a tropical ant, in a close-up, repetitively wipes its antennae and clacks its mandibles. Then it climbs a plant stem to a particular height, clamps down its jaws and dies. In a time-lapse sequence that follows, a grayish horn grows up from the base of the ant’s armored head. This horn is an Ophiocordyceps fungus, the fibers of which his body has hosted, and which took up reins running as fibrils through all his muscles and drove him up here. After he died, his body was at just the right height for the fungal spores to drift down onto the columns of living ants passing below and infect them, too. When you search for examples of other cordyceps genus online, the twin questions that define our relationship with fungi pop up first: “Can they infect humans?” and “What are the benefits?”
I trained as a veterinarian, and what we learned about fungi was largely adversarial and typical of the Western system of medicine. Fungal infections are rare, at least in otherwise healthy individuals. Still, we were warned and found examples in unusual instances. For example, there was the dog with the chronically bloody, infected nose who turned out to enjoy rooting in the moldy compost pile and now had a festering granuloma up her snout. Or the seabird, kept in a confined space, immunosuppressed and breathing the close, terrestrial air, found on postmortem to have his insides blanketed in blue-green bread mold.
We learned how hard it is to treat fungal infections. Limited as we may be in our fight against bacterial infections, fungi are a different thing altogether, in a literal sense. Most of our medicine is about differential killing. We try to exploit the vulnerabilities in the bacterium or the parasite that human cells do not share. We try to avoid collateral damage. But fungi are often too like us to find a wedge that will drive us apart. Their cellular structure and function is more like ours than we might wish to believe.
Fungi have a plant-like stoicism, but, it turns out, with something more like an animal body. We were taught to see them as invaders to be fended off, slow- and quiet-growing infections that were often untreatable by the time we noticed them. Still, fungi have also given us much of our arsenal against other attackers. When Alexander Fleming discovered the antibiotic properties of a common mold, there was Penicillium he saw in the petri dish, wearing its clear halo of vanquished bacteria.
Fungi in many forms had been good medicine long before Fleming knew anything about them. Across the world from Attenborough’s ant, on the Tibetan plateau, a fungus in the same Ophiocordyceps genus (this one commandeers a caterpillar’s body) has been prized as medicine for kidney and bowel disease, high cholesterol and sexual dysfunction. This last is probably the reason for its wild popularity in global markets, and the subsequent over-harvesting of the fungus for profit.
Many traditional medicines derived from fungi have drawn the attention of scientists who can point to the many bioactive chemical constituents and speak of the intracellular and extracellular polypeptides and nucleosides present in the organisms. As yet, however, no one has ever succeeded in replicating in a lab the complete process of the fungus infecting a caterpillar and directing it, zombie-like, to the right location for launching a crop of spores. It seems nature will keep her own counsel on that.
Thinking about these far-flung species far from home, I picked up the quirky and beautifully illustrated field guide “Fascinating Fungi of New England” for the view closer to home. Written by Lawrence Millman, a mycologist who lives in Cambridge, Mass., it is a marvelous little volume, approachable for the beginner mushroom hunter. As you leaf through the contents, the species list alone speaks to the multiplicity and poetry of fungal nature. Here are the familiar chanterelle and oyster mushrooms, but also the train wrecker, stinky squid, alcohol inky and destroying angel. Scanning the pages I’d looked through countless times before, I noticed for the first time that here also was chaga, a fungus I know from a mushroom coffee my husband likes to buy. Chaga is medicinal, and I searched the book for others, finding that the ubiquitous turkey tail fungus can be an adjunct in cancer therapy, and that maitake, which sits like a fluffed hen at the base of old trees, aids the immune system. A walk in my own backyard, it turns out, reveals a whole pharmacopeia.
Recently, I was listening to mycologist Paul Stamets on the radio. He was trying to define why mushrooms unnerve so many people. Mushrooms are only the temporary reproductive organ of a vastly larger fungus that runs its filaments, called mycelia, underground or into the corpus of a tree, or whatever its food source is, sometimes for acres. We don’t usually notice these mycelia, but they are the true body of the fungus. The mushrooms pop up, often overnight, deploy their spores and quickly melt away again.
Stamets thinks it’s this ephemeral quality that unsettles us, but I was struck by something else he said about how we see these organisms. He talked about how extreme a spectrum they run in terms of their effects on the human body. Some are good food, some are good medicine, some have hallucinogenic properties, and some will kill you in even the smallest amount. There they are, side by side in your backyard, striking in how quickly they appear and are gone — another intimation of their eerily animal-like nature. So we ask the same questions of them that we ask of our fellow humans: “Which can harm me, which can nourish, which can heal?” As with humans, fungi, with their complex natures, can do all three.