Entangled Life: The Illustrated Edition

Introduction

What Is It Like to Be a Fungus?

Fungi are everywhere but they are easy to miss. They are inside you and around you. They sustain you and all that you depend on. As you read these words, fungi are changing the way that life happens, as they have done for more than a billion years. They are eating rock, making soil, digesting pollutants, nourishing and killing plants, surviving in space, inducing visions, producing food, making medicines, manipulating animal behaviour, and influencing the composition of the Earth’s atmosphere. Fungi provide a key to understanding the planet on which we live, and the ways that we think, feel and behave. Yet they live their lives largely hidden from view, and more than 90 per cent of their species remain undocumented.

Fungi make up one of life’s kingdoms—as broad and busy a category as ‘animals’ or ‘plants’. Microscopic yeasts are fungi, as are the sprawling networks of honey fungi, or Armillaria, which are among the largest organisms in the world. The current record holder, in Oregon, weighs hundreds of tons, spills across 10 square kilometres, and is somewhere between 2,000 and 8,000 years old. There are probably many larger, older specimens that remain undiscovered. 

Many of the most dramatic events on Earth have been—and continue to be—a result of fungal activity. Plants only made it out of the water around 500 million years ago because of their collaboration with fungi, which served as their root systems for tens of million years until plants could evolve their own. Today, more than 90 per cent of plants depend on these ‘mycorrhizal’ fungi. This ancient association gave rise to all recognisable life on land, the future of which depends on the continued ability of plants and fungi to form healthy relationships.

There are few pockets of the globe where fungi can’t be found; from deep sediments on the sea floor to the surface of deserts, to frozen valleys in Antarctica, to our guts and orifices. The capacity of fungi to prosper in such a variety of habitats depends on their diverse metabolic abilities. Metabolism is the art of chemical transformation. Fungi are metabolic wizards and can explore, scavenge and salvage ingeniously, their abilities rivalled only by bacteria. Using cocktails of potent enzymes and acids, fungi can break down some of the most stubborn substances on the planet, from lignin, wood’s toughest component, to rock, crude oil, polyurethane plastics and the explosive TNT. Few environments are too extreme. A species isolated from mining waste is one of the most radiation-resistant organisms ever discovered. The blasted nuclear reactor at Chernobyl is home to a large population of such fungi. A number of these radio-tolerant species even grow towards radioactive ‘hot’ particles, and appear to be able to harness radiation as a source of energy, as plants use the energy in sunlight. 

Mushrooms dominate the popular fungal imagination, but mushrooms are only the reproductive structures of fungi, the place where spores are produced. Fungi use spores like plants use seeds: to disperse themselves. Reproductive structures like mushrooms are a fungus’s way to entreat the more-than-fungal world, from wind to squirrel, to assist with the dispersal of spores, or to prevent it from interfering with this process. They are the parts of fungi made visible, pungent, covetable, delicious, poisonous. Some, like truffles, produce aromas that have made them among the most expensive foods in the world. Others, like shaggy ink cap mushrooms (Coprinus comatus), can push their way through asphalt and lift heavy paving stones, although they are not themselves a tough material. Pick an ink cap and you can fry it up and eat it. Leave it in a jar, and its bright white flesh will deliquesce into a pitch-black ink over the course of a few days.

We all live and breathe fungi, thanks to the prolific abilities of fungal fruiting bodies to disperse spores. Some species discharge spores explosively, which accelerate 10,000 times faster than a space shuttle directly after launch, reaching speeds of up to 100 kilometres per hour—some of the quickest movements achieved by any living organism. Other species of fungi create their own microclimates: spores are carried upwards by a current of wind generated by mushrooms as water evaporates from their gills. Fungi produce around 50 megatons of spores each year—
equivalent to the weight of 500,000 blue whales—making them the largest source of living particles in the air. Spores are found in clouds and influence the weather by triggering the formation of the water droplets that make rain and the ice crystals that make snow, sleet and hail. 

Some fungi, like the yeasts that ferment sugar into alcohol and cause bread to rise, consist of single cells that multiply by budding into two. However, most fungi live most of their lives as tubular cells known as hyphae (HY-fee), which branch and fuse to form networks, known as mycelium. Mycelial networks have no fixed shape. By ceaselessly remodelling themselves they can navigate mazes, solve complex routing problems and expertly explore their surroundings. If you teased apart the mycelium found in a teaspoon of healthy soil and laid it end to end it could stretch anywhere from 100 metres to 10 kilometres.

Human life has forever been shaped by fungi. Diseases caused by fungi cause billions of dollars of losses—the rice blast fungus ruins a quantity of rice large enough to feed more than sixty million people every year. Fungal diseases of trees, from Dutch elm disease to chestnut blight, transform forests and landscapes. Romans prayed to the god of mildew, Robigus, to avert fungal diseases but weren’t able to stop the famines that contributed to the decline of the Roman Empire.

However, we have also worked out how to use fungi to solve a range of pressing problems. In fact, we have probably deployed fungal solutions for longer than we have been Homo sapiens. In 2017, researchers reconstructed the diets of Neanderthals, cousins of modern humans who went extinct approximately 50,000 years ago. They found that an individual with a dental abscess had been eating a type of fungus—a penicillin-producing mould—implying knowledge of its antibiotic properties. There are other less ancient examples, including the Iceman, an exquisitely well-preserved Neolithic corpse found in glacial ice, dating from around 5,000 years ago. On the day he died, the Iceman was carrying a pouch stuffed with wads of the tinder fungus (Fomes fomentarius) that he almost certainly used to make fire, and carefully prepared fragments of the birch polypore mushroom (Fomitopsis betulina) most probably used as a medicine.

The indigenous peoples of Australia treated wounds with moulds harvested from the shaded side of eucalyptus trees. Ancient Egyptian papyruses from 1500 bce refer to the curative properties of mould, and in 1640, the King’s herbalist in London, John Parkinson, described the use of moulds to treat wounds. But it was only in 1928 that Alexander Fleming discovered that a mould produced a bacteria-killing chemical called penicillin.

Penicillin became the first modern antibiotic and has since saved countless lives. Penicillin, a compound that could defend fungi from bacterial infection, turned out to defend humans as well. This is not unusual: although fungi have long been lumped together with plants, they are actually more closely related to animals—an example of the kind of category mistake that researchers regularly make in their struggle to understand fungal lives. At a molecular level, fungi and humans are similar enough to benefit from many of the same biochemical innovations.