Mycophilia, p.31
Mycophilia, page 31
Symbiosis, first conceived by the 19th-century German mycologist Heinrich Anton de Bary, describes close, long-term relationships between organisms. The lifestyles of fungi: mutualism, commensalism, and parasitism, are examples of symbiotic partnerships—evolutionary relationships between two or more organisms. There are countless examples of symbiotic relationships in nature, because all life-forms are symbiotic to some degree, and there are usually more than two partners in a given symbiotic picture. Understanding the symbiotic relationships in an ecosystem is key to retaining the health of that ecosystem. Because we have a history of underestimating the degree to which symbiosis exists, we rarely anticipate the full effect our interventions have on these partnerships.
This point became clear to me when I attended a lecture by Jack States, a retired mycologist from Northern Arizona University, called “Squirrels, Trees, and Truffles.” Over the course of many years’ study, States proved that the “ancient and highly evolved symbiosis” between tassel-eared squirrels, ponderosa pines, and certain truffles (these truffles are inedible to us: “they stink,” said States, “but the squirrels love them”) in the American Southwest was key to their well-being, indeed their very survival. Other organisms, the hawk that fed on the squirrels and the beetle that is exclusive to the truffles, were studied as well, and illustrated that the number of symbiotic partners may grow exponentially. His work describing the relationship was so conclusive he was able to change regional logging practices despite numerous challenges by the industry. At the conclusion of his lecture, I jumped up and yelled “Bravo!” It was like attending the symphony. I had never imagined science could be so graceful.
Endosymbiotic relationships are even more mysterious, mainly because they happen on a microscopic scale. Endosymbionts are organisms that have evolved to live among the cells of other organisms, and often the endosymbiont or endosymbionts and the host need each other to thrive. For this reason, they’re called obligate endosymbionts, because they are obligated to one another: One cannot live without the other. “When such a mutually agreeable arrangement is in place for a long time,” wrote Terrence McKenna, “it will eventually ‘institutionalize’ itself by progressively blurring the clear genetic distinction between the symbionts. Ultimately, one organism may actually become a part of the other….”
The endosymbiotic theory postulated by the pioneering theoretical biologist Lynn Margulis in the 1960s says that the cells of higher life-forms—animal, fungi, and plants—originated through symbiosis with bacterial cells, and that the ongoing symbiotic relationships between organisms from different kingdoms may even be the driving force of evolution. Today, it is generally agreed that eukaryotic cells, “all of them,” said the microbiologist Elio Schaechter, “arose only once by acquisition of a bacterium or something like it, which then whittled down its genome to become mitochondria,” the membrane-enclosed packet of organelles, or diminutive organs, found in the cells of higher life-forms.
There are endosymbionts throughout all the kingdoms in nature. Endophytic fungi and endomycorrhizal fungi (fungi that live in—versus on—roots) are endosymbionts of plants. There are fungi that are endo-symbionts of other fungi, and bacteria are likely endosymbiotic in all life-forms: Scientists have counted as many as 250,000 live bacteria in a single fungal spore. “If you ask me,” said the mycologist Tom Volk, “I think there’s probably bacteria living in everything.”
When it comes to humans, our microbial partners are ectosymbionts (from the Greek, ecto = outside). They live, and do important chores, on our skin, and all our internal surfaces, like the lining of our intestines and respiratory tract. (Microbes living in our body are technically living on us.) Certain yeasts are fungal ectosymbionts of animals. “But we don’t really know if they are mutualistic or simply in competition with the bacteria,” said Volk. “But if you don’t have yeasts in and on your body, you get more bacterial infections.”* Yeasts and bacteria help animals digest food. In some cases, they are obligatory, as in the case of ruminants like cows that cannot digest their food independent of their bacterial flora.
And then there is our gut.
“When I went to school, plants were considered competitors, not symbionts,” said Gary Lincoff. “That’s like calling them communists! After the fall of the Soviets, symbiosis stopped being a dirty word. We think of ourselves as rugged individualists, but where would we be without our E. coli? We are conglomerates. It’s not a bad thing to be. It means you never have to eat alone.” Some scientists are calling the human body a superorganism, that each of us is a colony of organisms, and all our parts—the animal parasites, the fungi and impermanent bacteria in our guts, and the permanently incorporated bacterial descendants in our cells (mitochondria, the membrane-enclosed organelles that give us chemical energy)—have evolved to work in agreement (or maybe it’s a kind of deterrence) to compose the organism known as you, and they continue to evolve.
“People assume evolution is done,” said Tom Volk. “It’s not.”
There are 10 trillion or so microbial cells living on us, exceeding human cells by 10 to 1 (but only constituting a pound or two), and they harbor millions of genes (the human genome has 20,000 genes). There are so many bacteria, fungi, and viruses living on us, particularly in our guts, known as gut flora, that this microbial colony functions like a shadow digestive organ, “a collective metabolic activity equal to a virtual organ within an organ,” according to Ann M. O’Hara in her article “The Gut Flora as a Forgotten Organ” (and analogous to the role of endophytic fungi functioning as a virtual immune system for plants, or mycorrhizal fungi functioning as a virtual digestive organ for trees). As a result, massive projects like the Human Microbiome Project are under way in order to actually figure out where the body ends and the microbes begin, and to determine if there is a core microbiome common to all people.* When I refer to my body, I am usually talking about the whole shebang. But the truth is, we have private spaces in our body and public spaces. The microbiologist Terry Hazen likes to say we are “bacteria living on a person.”
“I am me, and my symbionts,” said Elio Schaechter.
Or, as Tom Volk, who has had a heart transplant, told me, “I am a bunch of organisms, plus one other person.”
There are microbes living in all the public spaces in our bodies—our sinuses, mouths, and ears; our throats, esophagus, intestines, colon, vagina, and anus, even our lungs. Scientists at Imperial College in London found there are 6,000 microbes in every square inch of lung tissue. There may be a little or a lot of microbial diversity from person to person and place to place on any individual: Our personal microbial recipe defines us. The community that lives in my gut may be very, very different than the one that lives in yours. The microbes on my tongue and on my hands are different from yours, and not only composed of different species but different quantities of species. There are even different microbial populations on my left hand versus my right. These populations may be different based on all kinds of factors: climatic zone, lifestyle, and genetics. “Although we fall into groups, no two of us are alike,” pointed out Elio Schaechter. “Suum quique—to each his own—is the way of the microbial world.”
Our fear of microbes is based on misunderstanding. I have a friend who would never dip herself into the Breitenbush Hot Springs, or sit on the rude wood benches to cool off without laying a towel down first, or suck in the steam in the mossy freestanding sauna that resembled a gypsy wagon. But she shouldn’t worry. She is filled with microbes that help her stay healthy by keeping invaders out.
Microbes protect their habitats, just as endophytic fungi protect their host plant. You can get sick when the microbial colonies that live in your public spaces become out of whack and certain species overgrow, or when a fungus or bacteria or virus penetrates your private spaces where it doesn’t belong (or when you get infected with something neither your immune system nor your microbes can handle). And the makeup of that microbial population could matter. The flora in your lungs may determine whether you are asthmatic or not, or microbe-deficient patients may have under-regulated immune systems, leading to autoimmune disease. From this kind of revelation comes therapy. Someday chronic GI problems may be managed by ingesting a dose of the right microbes. That’s what probiotic yogurts are: live microorganisms.
Microbes live in our public spaces (darkened portions of torso).
If friendly microbes weren’t occupying and defending and modifying the public spaces—their habitats—in our bodies, maybe unfriendly microbes would. Our microbial partners are synonymous with our immune System. They have other roles, too, like helping us absorb nutrients in our lower intestine, but there is much about the roles played by our microbial colonies that we don’t know, and human fungal ectosymbionts—mainly in the form of yeasts—are less studied than bacteria. Our gut flora is composed of far more bacteria, but that doesn’t deny fungi’s potential importance. The science simply hasn’t been done.
The concept of symbiosis has led scientists to utilize the idea of the superorganism in place of the organism. In the past, superorganisms referred to eusocial animals, like ants and bees; colonies composed of multiple individuals acting in concert to produce a collective result. “If humans are thought of as a composite of microbial and human cells,” wrote the microbiologist Peter J. Turnbaugh, “the human genetic landscape as an aggregate of the genes in the human genome and the microbiome, and human metabolic features as a blend of human and microbial traits, then the picture that emerges is one of a human ‘superorganism.’”
At the end of the weekend, Daniel Winkler, who was one of the speakers at the foray, and Thom O’Dell took off on their own. I tagged along. This was the pros’ foray. No identifying mushrooms, just gathering for the table. I was happy to hunt without inhibition. When I search with a group or with people who are new to mushroom hunting, I rein in my impulses. I try to be polite and carry on conversation while walking, but I really prefer to be silent. I try to have eye contact when they talk to me, but it is hard to keep from glancing to the forest floor. I try to stick with the group, but I am restless to move on. Hunting mushrooms seems like a solo sport, but it is not. It is deeply participatory, just not with other people. Instead, the hunter experiences the company of trees and mushrooms and birds. It’s a communion with the woods and the grand mosaic of nature.
In the evening, I returned to the spring that overlooked the meadow. Breitenbush is indeed the sexy foray, but I realized it was not because of the company, although one of my roommates did meet a man who had tempted her earlier in the day with a private hunt for matsutake, and she had carefully agreed, and was now tasting the hot waters with him and letting him whisper in her ear. No, for me the Breitenbush foray became sexy when I stepped out of the hot spring and realized the thick green grass under my bare feet was warm, not from the day’s sunshine, not from the balmy temperature, but from the primeval hot water that ran through the soil. From the soil, to the grass, to me.
Maybe it is no accident that I became obsessed with mushrooms. I think we all search for a way to connect with something bigger than ourselves, and mycology opened that window for me. I may have started out interested in mushrooms because I liked to eat them, but I ended up with a more profound understanding not only of the natural world but of myself as a symbiotic organism living within it. I came to understand that the traditional idea of an ecosystem, which had been locked in a scale relative to our experience of the world, has both contracted into microecosystems and expanded into macroecosystems. Instead of referring to an area within the natural environment and its interdependent organisms, organisms themselves can be described as ecosystems. Pull back the lens and I could see how organisms are symbionts in an ecosystem, and ecosystems are symbionts in a biome, and biomes are symbionts on the globe. Just as I am a collection of organisms functioning together as a whole, life on the planet—the entire living community—may be considered an organism, one where all life-forms work together to move energy around.
And there’s more. The Gaia hypothesis, which was crafted by James Lovelock, a chemist and inventor who turned 90 in 2009, imagines the entire planet as an ecosystem, one that includes the Earth’s atmosphere, surface rocks, and water functioning in conjunction with the life cycles of living organisms.* Lovelock proposed that the living and nonliving aspects of Earth, the planet’s biologic, climatic, geologic, and chemical aspects, compose an integrated symbiotic system, too.
The degree of complexity that symbiosis suggests is so awesome that creationists consider it evidence of God. “It seems nothing less than a supernatural, super-intelligent Creator can explain all the intricate designs required in advance of launching symbiotic relationships,” wrote Hugh Ross, PhD, a Canadian-born former astronomer and current Old Earth creationist. Lynn Margulis suggests that humans—indeed, all higher life-forms—are the work of “thousands of millions of years of interaction among highly responsive microbes.” Like the bumper sticker on Paul Stamets’s car says: “Evolution is God’s intelligent design.”
“So what are the implications?” the microbiologist Elio Schaechter asked me in his heavy mosh pit of a European accent, his voice musical with intelligence and sass. “It’s this. An understanding of what the human being is today is based on an understanding of all our direct and indirect relationships with other creatures.”
Indeed, the eternal question is no longer Who am I? but Who are we?
It rained heavier and longer every day I was at Breitenbush. It always rained at night, and all the trails were puddled by the time I packed my bags and dragged my muddy roller bag through the dark, damp pine trees. Somehow I lost a small box containing three Jurassic-size orange chanterelles, two of which I had received in trade for four matsutake. (I think I left it springside after my rather discombobulating nude interview with Thom O’Dell.) I was exceedingly bummed about those chanterelles, and as I drove the winding highway out of the mountains, I had to keep talking myself out of turning around and trying to locate them. As I got farther and farther away from Breitenbush and the dark forests receded in my rearview mirror, I began to scan spots beside the road where I could pull over and maybe find a few mushrooms to compensate, and then I did see a spot and parked.
I stepped a few feet into the ferny damp woods, eyes sweeping the terrain for the telltale orange chanterelle color, but it was clear other hunters had been there before. There were mushroom stumps everywhere, mixed in with tossed Pampers and beer cans. It was an ugly place, a bit of a dumping ground, and it was stupid to have stopped and I knew it. But as I headed back to the car I noticed, clinging to the side of a fallen log, a Pseudohydnum gelatinosum, a strange, clear little fungus that looks like water muscled into the shape of a mushroom. It struck me as basically sex plus water. For all my efforts to understand mushrooms, that simplistic metaphor gave me a sense of completion and an understanding and appreciation of the nature of things that I never intended or expected to understand or appreciate when I first joined the New York Mycological Society. I pocketed the fungus, because I am a mushroom hunter, got back in the car, and headed home.
Pseudohydnum gelatinosum
* * *
*The molecular estimates suggest the first terrestrial fungi fell into three groups—Basidiomycota, the club fungi, Ascomycota, the cup fungi, and Glomermycota, soil-based mycorrhizal fungi—with particular spore features, and originated about 600 million years ago.
†Since 1859, scientists have tried to figure out a bizarre fossil named prototaxites, a 20-foot-tall tree-trunk-like organism that lived 420 to 350 million years ago and was the largest land organism at the time. The latest findings conclude that the fossil was most likely a giant fungus, although some scientists have suggested it was actually a giant liverwort. Liverwort is technically a plant but is often lumped together with lichen, slime molds, and algae.
*A study conducted in 2011 found that a large cluster of ancient fungal genes jumped from one species to another, a phenomenon called horizontal transfer. It suggests that the tree of life might not be the only model that describes evolution.
*To wit: There is a fungus, Pneumocystis, that lives in human lungs—and cannot survive outside your lungs. Maybe it has a function, maybe it is simply biding its time, because when the host becomes immunocompromised, it becomes pathogenic.
*The National Institutes of Health’s Human Microbiome Project was launched in 2008 and should be complete by 2013. Previously, the study of the human biota was limited to culturing, or growing out the bacteria in a sample to see what’s there, but scientists could only culture about 1 percent of all different bacteria present (lots die when exiled from their habitat—you). The beauty of the Human Microbiome Project is its utilization of genomics: With DNA analysis, scientists can bypass culturing altogether to determine what species are present.
