Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures

Nonfiction | Book | Adult | Published in 2020

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Summary

Background

Chapter Summaries & Analyses

Prologue-Introduction

Chapters 1-2

Chapters 3-4

Chapters 5-6

Chapters 7-Epilogue

Key Figures

Themes

Index of Terms

Important Quotes

Essay Topics

Chapters 1-2Chapter Summaries & Analyses

Chapter 1 Summary: “A Lure”

Truffles are one of the most famous mushrooms in the world and are many people’s introduction to the intricate world of fungus. Many species of truffles exist and not all are prized by humans, but some, especially the Piedmont white truffle, are such culinary delicacies that they’ve become the most valuable natural things on earth. “A Lure” begins with Sheldrake visiting a truffle farm in Italy, although the term “farm” is used loosely, as people have never managed to domesticate truffles. He first visits the farm’s shop, where he describes the overwhelming scent of the piles of mushrooms. Afterward, he goes for a walk in search of the fungus with two truffle hunters and their specially trained dogs. Since truffles are so valuable, hunting them is incredibly secretive and competitive and can easily end in violence.

Sheldrake explains that the truffle’s irresistible smell is an evolutionary mechanism. Since they grow underground and are not visually appealing, they have become incredibly pungent to lure animals to dig them up, eat them, and spread their spores through their poop. These spores sprout into hyphae filaments, which connect with a vast array of bacteria, plants, and other fungi. This allows the truffle mycelium to develop the complex array of enzymes that will ultimately make the fruiting body’s unique smell. When two truffle hyphae encounter each other, they may or may not be sexually compatible. If they are, they connect and produce a fruiting body. Both mycelia provide genetic material, but only one “felts” its hyphae together into a truffle mushroom. Sheldrake uses this example to introduce the concept of chemical attraction, the poorly understood methods that fungi use to lure and locate other fungi, plants, and even animals.

Chemical attraction features in many relationships between fungi, animals, and plants. A notable example is worm-eating fungi, which use chemical signals to lure nematode worms. Unlike truffles that have a constant, strong smell as soon as they mature, worm-eating fungi are able to dampen or increase the amount of nematode-attracting chemicals that they produce. When there is plenty of other food available, they don’t appear to seek out worms, but if resources are scarce, they alter both their chemistry and their physical attributes. Some develop sticky membranes to trap nematodes, while others release poison onto worms that crawl onto them.

Chapter 2 Summary: “Living Labyrinths”

While mushrooms are the most visible part of most fungal species, they are only a small portion of the organism. The vast majority of fungal cells exist as mycelium, a branching network of thin filaments known as hyphae. These networks can grow to enormous sizes; some mycelia extend for several square miles. Like the slime molds discussed in the introduction, fungi have exhibited the ability to grow their mycelial networks in specific, beneficial ways. Several experiments have shown that fungi can solve mazes or even “choose” to grow toward the best food sources.

Professor Lynne Boddy is a major contributor to the research into mycelial behavior. Sheldrake describes an experiment in which she placed a block of wood laced with fungal spores on a tray. At first, the mycelium grew outward in all directions. When a few of the hyphae touched a second block of wood, the fungus quickly shifted and grew exclusively in the direction of the new food source. The exact way that the fungus communicates within its own structure is not yet understood, but this type of behavior can be seen in many instances. In addition to having complex communication abilities, mycelial networks are remarkably efficient, finding the shortest route to a food source even through complex mazes. Sheldrake likens the behavior to that of large bird flocks or swarms of termites.

Relatively few scientists have explored the question of how mycelial networks are able to communicate within themselves so efficiently. The work that has been done shows that hyphae are incredibly sensitive. Most can respond to small changes in light, moisture, chemical input, and electrical impulses. For this reason, fungal networks are often compared to animal brains. Stefan Olsson, a mycologist who specializes in bioluminescent fungi and electrical impulses in mycelial networks, disagrees with this view. Unlike brains, which have specific areas dedicated to specific tasks, fungi are decentralized; a mycelium can continue to function even if a large portion is removed, and a new mycelium can grow from just a single spore. To add to this, the presence of a brain in any organism suggests that that organism is sentient. Biologists are not universally opposed to the idea that fungi are capable of cognition, but this is far from a widely accepted view. Olsson and others have conducted a number of experiments that compare the electric impulses found in mycelium to that of brains and computers. Research in this field is still in its infancy, and Sheldrake speculates that it is still wildly misunderstood.

Chapters 1-2 Analysis

Chapter 1 of Entangled Life gives an introductory glimpse into the world of fungus through the kingdom’s simpler members, those that produce truffle mushrooms. This is an effective choice, as truffles are a clear example of fungi’s ability to use complex chemistry for a specific evolutionary purpose. They are also one of the mushrooms that humans most admire, with some truffle species selling for thousands of pounds per ounce, and specialized transportation networks existing exclusively to fly fresh truffles across the world to upscale restaurants. Truffles also serve as a good example of the intense emotions that fungi evoke. They have long been associated with sex, and Sheldrake writes that after long exposure to truffle scent, the unique smell can be evoked simply by thinking about the mushrooms. Although humans love truffles, Sheldrake makes it clear that they in no way evolved for the human appetite. Many truffle species are disgusting to the human palate, but all are pungently appealing to at least one kind of animal.

Just as it is a mistake to believe that fungi like truffles have evolved for humans, Sheldrake believes that people should avoid applying human attributes and human assumptions about the world to fungi. This includes the idea that fungi have a brain. Mycelial networks occasionally act in ways that seem similar to organisms with brains, and their structure has led biologists to realize that fungi are biologically more similar to animals than to plants. Sheldrake introduces the idea of the fungal “brain” in Chapter 1, when discussing the nematode-eating fungus appearing to make conscious decisions. He expands on the concept in Chapter 2 with examples of fungi solving mazes and appearing to have memories of where to find food. Although he disagrees with biologists who believe that all fungal behavior is automatic and “brainless,” he posits that “[i]n some sense, the word brain is a distraction” (59). When fungal behavior is shoehorned into being an alternative brain, much of the important context is lost, and the researcher may overlook the important differences that set fungi and animals apart.

Nevertheless, Sheldrake does see the value in comparing fungi to animals, and he does so often throughout Entangled Life to convey just how complex fungi are. In Chapter 1, he compares the chemical signals that fungi evolved to produce and receive to the human olfactory system. In Chapter 2, he writes that certain types of fungi have light-sensing abilities in line with that of the human eye. This helps readers understand the specifics of these fungal attributes more precisely but should not be assumed to mean that fungi behave like eyes or noses.