What a Mushroom Lives For

Matsutake and the Worlds They Make

Michael J. Hathaway

• Publisher: Princeton University Press
• Year: 2022
• ISBN:
  9780691225890
• Topic: Ciencias sociales
• Subtopic: Antropología cultural y social

How the prized matsutake mushroom is remaking human communities in China—and providing new ways to understand human and more-than-human worlds What a Mushroom Lives For pushes today's mushroom renaissance in compelling new directions. For centuries, Western science has promoted a human- and animal-centric framework of what counts as action, agency, movement, and behavior. But, as Michael Hathaway shows, the world-making capacities of mushrooms radically challenge this orthodoxy by revealing the lively dynamism of all forms of life.The book tells the fascinating story of one particularly prized species, the matsutake, and the astonishing ways it is silently yet powerfully shaping worlds, from the Tibetan plateau to the mushrooms' final destination in Japan. Many Tibetan and Yi people have dedicated their lives to picking and selling this mushroom—a delicacy that drives a multibillion-dollar global trade network and that still grows only in the wild, despite scientists' intensive efforts to cultivate it in urban labs. But this is far from a simple story of humans exploiting a passive, edible commodity. Rather, the book reveals the complex, symbiotic ways that mushrooms, plants, humans, and other animals interact. It explores how the world looks to the mushrooms, as well as to the people who have grown rich harvesting them.A surprise-filled journey into science and human culture, this exciting and provocative book shows how fungi shape our planet and our lives in strange, diverse, and often unimaginable ways.

CHAPTER ONE

Fungal Planet

The Little-Known Story of How Fungi Helped Foster Terrestrial Life

In 2017, I spent four months as a visiting professor at the University of Hawai’i. There, I learned about an earth that was far more dynamic and alive than I had previously imagined. I saw new land being made as streams of lava poured into the ocean, starting to harden almost instantaneously as it hissed and roared. Making land in this way was a slow process, as these waters were deep. Yet one could see vast stretches of land that rose from the ocean, where lava had been slowly added, layer by layer, until at last it was exposed to the sun. Then, the land began to erode and fall back to the sea—slowly at first, through pounding rains and powerful winds; sometimes more suddenly by massive landslides that in turn created tsunamis that smashed into neighboring islands leaving boulders perched well over a hundred feet high.

I enrolled in a university class to learn more about this strange and wonderful land. The professor asked how long it would take for life to start transforming this landscape of new lava rock, with its thin, hard skin, and glowing molten insides. “Several years,” answered one student. “Less than a year,” said another. The professor then answered herself: “Almost instantaneously: microorganisms are floating everywhere, and some will soon adhere to this new earth, surviving the heat and making their niche.” We had all been contemplating macroscopic animals like spiders, forgetting about the microscopic beings like bacteria and fungi that make our worlds possible.

Later, hiking on the Big Island, I walked over vast stretches of new lava flows, improbable landscapes of hard rock that grew unbearably hot in the sun. My only referent for these rocky places made by fire were mountaintops made by ice along the high ranges of North America’s west coast. Glaciers traveled over the region ten thousand years ago, bulldozing forests and soils in front of them and, in retreat, leaving behind stretches of bare rock, polished and scratched. On the mainland, forests slowly returned to these soil-scraped lands, but some places remained bare. In Hawai’i, however, I discovered another timescale, where fresh lava became thick forests in just a few centuries or less. I experienced a fluid, rapidly changing earth, where land is created and lost almost instantly, not transformed and polished over millennia. I could imagine the possibilities of ancient Earth at the start of terrestrial life, how organisms landed on hard lava and turned it into soft soil, creating a place for plant and animal life. At the time, I had no idea these first organisms were likely fungi.

—Reflections on Fieldwork

In 2007, Alan Weisman wrote the now-famous book The World without Us, a well-informed, speculative account that began with a simple yet powerful question: What would happen to Earth if humans vanished? Weisman shows there would be all kinds of disasters if humans disappeared, including the destruction of more than four hundred nuclear power plants, yet surprisingly, even with thousands of catastrophes, let alone the breakdown of our oil pipelines and so forth, he suggests that life on Earth would quickly return if humans disappeared. Considering this scenario, I couldn’t help but ask my own version of the question by adding a “fung” to Weisman’s query: What would happen to “the world without fungus”?

What if all fungi disappeared from planet Earth? This world would be profoundly different, and the result would be catastrophic. Fungi play a major role in decomposition, that is, breaking down the dead bodies of plants and animals. Without fungi, masses of dead grass, herbs, and trees would pile up and up, likely blocking the growth of the next generation. Not only would this take up land, but, as importantly, the disappearance of fungi would mean that many of the planet’s nutrient and carbon cycles would either grind to a halt or be so severely slowed that some plants and animals would not have enough nutrients to keep growing. Thus, as death piled up, life could not renew itself. As scientists are increasingly learning, however, fungi not only play a crucial role as “decomposers” or “rotters” that break down life; they also are absolutely essential to many forms of life coming into being, especially plants. As I will later explain in more detail, they do this through connections between plant roots and fungal bodies. Fungi are living within and around the roots of nearly every plant on the planet, and plants have relied on fungi’s assistance for hundreds of millions of years. If fungi disappeared, we would face a plant apocalypse, as plants would no longer get enough water to drink and food to eat. Indeed, for most plants, more nutrients are provided by fungi than by their own roots.¹

It is extremely difficult to imagine our planet without any fungi, especially as they are so diverse and omnipresent. Yet on the flip side, they are often unseen and relatively little studied. Fungi are all around us and also within us, but few of us know much or anything about what they do and how they affect the world. For some time, I tried to imagine the world without the one kind of fungus that I am most interested in, the matsutake, but I could not find enough scientific knowledge about their particular ecological role to envision the effects of its absence. What would happen to forests without matsutake’s presence? It turns out that while matsutake need certain trees to grow, we don’t know of the opposite reliance: there aren’t any known trees that require, in particular, matsutake’s assistance. Many animals eat matsutake, but I couldn’t find any that ate only this mushroom—so its disappearance, I assumed, would likely not cause any known visible species to starve. I later learned that this was not completely true, for there is one plant, the candy cane (Allotropa), that seems to rely completely on matsutake, so if matsutake disappeared overnight, Allotropa likely would too. But again, there was little information about Allotropa’s ecological role, so it was difficult to envision the effects of its absence. This led me back to my original thought experiment about what would happen if all fungi disappeared, but this time I approached it from the opposite direction: not based on a speculative future where they disappeared, but on a possible past where they had never evolved.

Taking this tack, I wondered what might happen if the history of life on planet Earth was looked at, not through the usual focus on animals, but on fungi as the central players. How might this history of life differ?² First, such a shift would reveal some of the critical relationships that make our world possible yet are little known. Second, and perhaps most importantly, a fungi-centric view might reframe some of the dominant underlying frameworks that biologists use to explain life. For instance, accounts of life tend to focus on animal-centered forms of competition between individuals of the same species (competing for mates, scarce food, and habitat for activities like nesting) or different species (in terms of predator-prey relations).³ Such relatively simple and antagonistic relations are stressed in “survival of the fittest” accounts. This notion of life, which builds on a Victorian view of nature as “red in tooth and claw,” was first articulated as a scientific claim around the time of Darwin’s main writings in the 1860s.⁴ More than a century later, such perspectives remain strong; I clearly recall my own indoctrination into such perspectives via TV documentaries in the 1980s, when the announcer, David Attenborough, described, in his authoritative older-male British voice, dramatic scenes as a “ruthless battle for survival.”⁵ These programs encouraged a vision of nature that was overwhelmingly competitive, a vision that is now increasingly being challenged by a few ecologists,⁶ especially those who have worked closely with organisms that have prominent mutualisms with other species, such as bacteria⁷ and truffles,⁸ and are recognizable even in the intimate relations between animals and bacteria writ large.⁹ In my fungi-centric account, I emphasize the importance of complex relationships that are interspecies, and even interkingdom, some of which are antagonistic but many of which are not.

Turning to macroscopic fungi, basic assumptions about the nature of their ways of being are now coming into question (fig. 1.1). For years, it was thought that each fungus fell into one of three categories: saprobic, parasitic, and mutualistic (mycorrhizal). Saprobes eat dead bodies, whereas parasites eat living bodies, and mutualists create mutual benefits with the living. These were thought to be permanent qualities, fixed types of relationships between fungi and plants or animals, yet scientists found that some fungi can dramatically change their own modes of living when circumstances change. As early as 1925, researchers began to notice that some fungi were mutualists in the field, but under laboratory conditions, they became saprobes.¹⁰ And in 1963, Kazuyoshi Hiromoto found the matsutake in the field could change from being a mutualist to a saprobe within a single lifetime.¹¹ Thus, these relations are not always fixed but can be dynamic.

FIGURE 1.1. The three main categories of macroscopic fungi as a continuum. From Arevalo 2019. Image courtesy of the artist, Carmen Olson, and New Society Publishers.

Fungi are powerful world-makers. Here, I describe how the world was in large part made possible by fungi and how fungi continue to shape it. In crafting a history of the fungi-generated world, I focus on four important ways fungi shaped the world as well as hint at relationships that are only recently being explored. First, starting about a billion years ago, fungi were critical in chemically breaking down rock and creating the beginnings of soil. Second, fungi, through their underground hyphae, formed intimate relationships with almost every single plant species, hence enabling plants to survive and flourish. Third, fungi invented ways to digest wood and turn dead plant bodies back into food for others, rather than having these former plants be locked away in an underground tomb of nutrients (becoming what we call “oil” and “coal”). Fourth, fungi were powerful parasites and predators: their ability to harm and kill bacteria, plants, and animals made them major players in shaping the diversity of life.

The ubiquity of fungi in every known terrestrial ecosystem is, in fact, a legacy of the ancient history of these organisms and a powerful testament to their ability to adapt. In addition, many scientists were surprised to discover recently that fungi are also plentiful in the oceans; scientists had imagined that fungi were terrestrial and that the ocean’s salinity was hostile to fungal life.¹² As I will soon explain, however, a long time ago, fungi were found only in the sea, and they allowed the first movement of life from sea to land. As plants and animals diversified, so did fungi, and it is hard to imagine any plant or animal without relations to fungi. Such fungal relations with plants and animals are far more diverse and complex than many realize. These relationships, in fact, are largely unknown or ignored, hidden from virtually everyone except for a handful of some of the world’s most dedicated mycophiles. I bring you into this world of fungal life and into the worlds that mushrooms are making.

Before doing so, however, allow me to introduce a brief caveat, which is that for the next few pages I will be knowingly mycocentric. I recognize that the world is shaped by a diverse set of mainly microscopic organisms (often referred to as “microbes”), not only fungi but also bacteria, viruses, and others, a whole slew that makes and keeps our planet vibrant. Unfortunately, much of the scientific and lay orientation toward microbes has focused on them as pathogens, as “germs.” This pathogenic bias toward microbes, however, is changing, in part through stories like those told in this book, which reveal how thriving life on Earth depends on microbial organisms and their complex interrelationships. Yet, as the global Covid-19 pandemic makes clear, some fear of microbes is reasonable as humans remain deeply vulnerable to viruses and other microbes. The pandemic has done a great deal to undermine a sense of human mastery and shows a virus’s power not only to attack and kill humans, but to compel people to reconfigure the global economy and nearly all aspects of social life to a degree unprecedented for a century (since the so-called Spanish flu epidemic of 1919).¹³

Fungal World-Making: How Fungi Made the Planet Green

In terms of our present-day planetary ecology, fungi have been and remain key world-makers. Fungi, in fact, were critical to developing the complex ecology enjoyed today. Fungi have, for hundreds of millions of years, been changing the planet into one that supports more than just oceanic life, one where plants and animals could live on land. Although fungi did not directly enable animal life, as far as we know they enabled land plants, which, in turn, allowed land animals to flourish. In terms of the history of Earth, the importance of fungi goes back in deep time to when fungi were significant forms of ocean life. Indeed, for billions of years life existed only in the ocean, but finally some species started to explore the land.

Turning Rocks into Minerals

For more than half a billion years, terrestrial fungi helped make the rocky earth inhabitable for plants, in part by helping them to weather rock and break it down into assimilable pieces.¹⁴ Fungi, along with many other organisms, were key to creating soil. For a long time, soil scientists thought that fungi played only an insignificant role in “rock weathering” (the process by which solid rock breaks into smaller pieces and eventually into minerals available as plant nutrients), less than 1 percent of the effect compared to water and wind.¹⁵ However, researchers now suggest that fungi, along with other microorganisms, play a significant role in breaking up rocks, creating mineral nutrients for plants’ nutrition as well as for their own.¹⁶ Fungi’s exploratory t...