PDF Summary:Entangled Life, by Merlin Sheldrake

After publishing Entangled Life in 2020, biologist Merlin Sheldrake made a meal out of two copies of the book. He dampened the pages of the first copy, inoculated it with fungal spores, and feasted on the mushrooms that burst from its pages. He then macerated the pages of the second copy and fermented them into a beer he drank.

Sheldrake’s process of transforming these copies of his book embodies the themes he explores throughout its chapters. He examines what we know and don’t yet know about fungi, these mysterious organisms that transform their surroundings—and us. He argues that fungi are an understudied group of organisms that expand our imaginations and offer promising solutions to modern-day problems such as mental illness and environmental destruction. In our guide, we’ll present Sheldrake’s insights into fungal biology and why fungi matter. Throughout our guide, we’ll supplement Sheldrake’s insights with recent research on fungi and offer steps you can take to contribute to our scientific understanding of fungi.

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Throughout his book, Sheldrake highlights the variety of strategies fungi employ to access or ensnare food. In this section, we’ll explore two of these strategies: predation and symbiosis. Afterward, we’ll explore what mysteries still remain.

Strategy 1: Predation

According to Sheldrake, some fungi prey on other living organisms by trapping and then digesting them. For example, one type of predatory fungi ensnares nematode worms (also known as roundworms). Some of these fungi secrete a toxin that paralyzes nearby worms; then, the fungi enter the worms’ mouths and digest them from the inside. Other predatory fungi trap worms in sticky webs or grab them with hyphal protrusions.

(Shortform note: Researchers are exploring whether predatory fungi can help treat parasitic roundworms in animals’ digestive tracts. Several preliminary studies suggest that this treatment may be effective. These studies’ researchers claim that these treatments may be better than current, drug-based treatments for two reasons: 1) some roundworms have developed resistance to existing drug treatments, and 2) some of these drugs are toxic to animals.)

Strategy 2: Symbiosis

According to Sheldrake, other fungi acquire energy through symbiosis: close partnerships with other organisms called symbionts. While people use the term symbiosis colloquially to refer to mutually beneficial partnerships, Sheldrake and other scientists use this term to refer to any close partnership between organisms.

(Shortform note: While scientists typically use the word “symbiosis” to describe close partnerships between organisms, biologist Richard Dawkins contends that there’s also a symbiotic partnership within every organism. In The Selfish Gene, he argues that genes are in a symbiotic relationship with their organisms. This is because genes first arose, and continue existing, because they self-replicate. Replication typically happens through reproduction, so genes that code for traits that support reproduction continue to replicate. Dawkins calls this a symbiotic relationship because organisms wouldn’t exist without their genes, and their genes wouldn’t continue existing without the organisms that ensure their replication.)

Let’s examine the role fungi play in two types of symbiosis: parasitism and mutualism.

Parasitism: Some symbiotic relationships involving fungi are parasitic: one symbiont benefits from the partnership at the expense of another. For instance, the aforementioned Ophiocordyceps forms a parasitic relationship with the ants it invades and eventually kills.

(Shortform note: Both predation and parasitism involve one organism harming another—so what’s the difference? With predation, the predatory and prey don’t share a physical body until the steps of ensnarement and digestion (such as when a predatory fungus captures and digests a nematode worm). By contrast, parasitic organisms live most of their life cycle within or on their victim’s body. For instance, the life cycle of Ophiocordyceps begins when an ant steps on a fungal spore, continues as the fungus feeds on the ant’s innards, and ends after the fungus explodes from the ant’s body and releases new spores.)

Mutualism: Other symbiotic relationships involving fungi are mutualistic, meaning all symbionts benefit. Lichen—those pale green, scaly coatings on trees and rocks—embody a mutualistic relationship. What we refer to as lichen is actually more than one organism: It’s a fungus, plus one or more photosynthetic partners (such as algae). In this mutualistic relationship, the fungal tissue provides physical protection for the smaller, photosynthetic organisms it houses. In return, the fungi absorb the complex sugars that its symbionts produce through photosynthesis.

(Shortform note: Some authors use lichen and other mutualistic relationships as models of human behavior. For instance, in Braiding Sweetgrass, indigenous biologist Robin Wall Kimmerer argues that lichen can inspire you to practice mutual care with fellow humans as well as other living things. Kimmerer defines mutual care as behaving in a way that simultaneously supports you, other people, and other organisms. She claims that lichens represent a harmonious union characterized by reciprocal care—a union we can strive to replicate in our marriages and other relationships.)

What We Still Don’t Know

According to Sheldrake, there’s a lot we don’t yet know about symbiotic partnerships involving fungi.

For example, we’re only beginning to understand how mycorrhizal fungi—fungi that live within the roots of plants—negotiate their partnership with their symbionts. Mycorrhizal fungi feed on the carbon that plants produce through photosynthesis. In return, these fungi increase plants’ access to underground minerals and water and defend them against disease.

Citing research from ecologist Suzanne Simard, Sheldrake explains that plants supply the most carbon to the mycorrhizal fungi that provide the most nutrients and water. It’s as if these two symbionts are part of a bartering economy in which one symbiont says, “If you give me more of this, I’ll give you more of that.” Exactly how plants and mycorrhizal fungi communicate and adjust the quantities of “goods” they trade remains a mystery.

Simard’s research on fungal symbionts also raises questions about how mycorrhizal fungi support trees, specifically. Her research demonstrates that trees communicate “warning signals" and share resources with other trees using mycorrhizal networks. According to Sheldrake, there’s still much to discover about how trees send each other messages via mycorrhizal networks and how it might benefit fungi to connect trees to each other.

The Value of Long-Term Research on Fungal Symbionts

In Finding the Mother Tree, Simard argues that the more we know about the symbiotic relationship between trees and mycorrhizal fungi, the better we can support the long-term health of forests.

According to Simard, we need to transition from traditional forest management—which overlooks the role fungi play in sustaining long-term forest health—to sustainable forest management that takes these relationships into account.

In traditional forest management, loggers cut down large swaths of forest, then they plant fast-growing trees that are ideal for quickly producing salable timber. This approach may not do significant damage in the short term, but it can disrupt complex underground relationships in the long term, harming the health of forested areas even beyond those cleared for logging.

By contrast, in sustainable forest management, foresters base their logging and replanting decisions on long-term research about mycorrhizal fungi and tree health. Under this type of forest management, loggers may be able to both turn a profit and preserve the underground symbiotic relationships in which mycorrhizal fungi provide trees with nutrients, water, and disease resistance and enable trees to communicate with each other.

Property 6: Homeostasis

Finally, all living things have strategies for maintaining homeostasis—a stable internal state—amidst changing environmental conditions (such as drops in temperature). Otherwise, organisms wouldn’t be able to maintain their structures, grow, respond to stimuli, reproduce, and process energy.

Sheldrake argues that fungi are uniquely well-adapted to maintaining homeostasis in extreme environments. Fungi have survived Earth’s five biggest extinction events and continue to thrive in extreme climates. Their hardiness is likely due to their ability to form symbiotic partnerships that enable them to survive conditions that would otherwise kill them.

According to Sheldrake, lichens exemplify fungi’s ability to survive inhospitable conditions. A fungus that is capable of lichenizing may exist on its own through stable environments, then it will form a lichen with photosynthetic algae and/or cyanobacteria when those environments become more extreme. For instance, lichens can endure long periods of dehydration and they can survive deadly doses of radiation in outer space.

How Symbiosis Protects Lichen in Extreme Conditions

Sheldrake doesn’t specify exactly how fungi’s partnership with their symbionts allows them to survive such extreme conditions. Let’s explore other scientists’ research on lichen’s survival mechanisms.

Surviving dehydration: Some lichens survive inhospitable conditions by preparing to become dormant. Research reveals that some lichen can sense when humidity levels are dropping, and they prepare for dehydration. Both partners in the symbiotic relationship contribute compounds that 1) keep cells intact during dehydration, and 2) allow the photosynthetic symbiont to quickly resume photosynthesis after rehydration.

Surviving high radiation in outer space: Lichens have also evolved to offer protection to their symbionts in extreme environments. Researchers theorize that the flesh of the fungus in lichen protects the photosynthetic partner from radiation, which in turn allows the partner to continue feeding the fungus through photosynthesis. Fungi provide this protection in a variety of ways. For instance, they produce compounds that filter out UV radiation. Scientists are studying these compounds with the hope that they can include these compounds in sunscreens for humans.

In addition to informing the creation of products for humans, research on lichen’s survival strategies could shed light on how organisms might survive the next mass extinction event—climate change. A team of researchers recently investigated lichen fossils from one of Earth’s largest mass extinction events and analyzed how that event spurred changes in the DNA of lichenizing fungi. They found that this mass extinction event killed off some of the fungi that lichenize, but it also led to a boom in biodiversity for other lichenizing fungi.

Part 2: Why Fungi Matter

So far, we’ve explored the world of fungal biology. Next, we’ll explore the impact of fungal biology—in other words, why fungi matter and why it’s important to further invest in mycology. We’ve organized this section into three reasons why fungi matter. We’ll begin with the abstract world of ideas, describing how fungi expand our imaginations. Next, we’ll describe why all life on Earth depends on fungi. Finally, we’ll examine the potential of fungi to address various modern-day problems.

Reason 1: Fungi Expand Our Imaginations

According to Sheldrake, fungi expand our imaginations, pushing us to consider new ways of thinking about ourselves, other people, and non-human beings. Here, we’ll explore two concepts that fungi challenge us to question: individuality and intelligence.

Concept 1: Individuality

Sheldrake claims that we tend to think of an organism as an individual contained within the borders of its flesh. The concept of individuality presumes that being physically separate makes organisms independent actors. For instance, because you’re assumed to be an individual, you’re legally responsible for your choices. (Shortform note: This view that organisms are individuals has persisted throughout the field of biology since its emergence in the late eighteenth century. Historians note that for the past several centuries, biologists have largely used the terms “individual” and “organism” interchangeably.)

However, according to Sheldrake, fungi remind us that organisms aren’t physically separate from each other. Recall how photosynthetic symbionts live within lichenized fungi, and mycorrhizal fungi live within the roots of plants. Like fungi, humans depend on symbiotic relationships. For instance, we provide the microbes in our gut with room and board; in turn, they help us with digestion. (Shortform note: Sheldrake doesn’t explicitly define how he uses the term “gut,” in his book, but we can infer that he’s referring to the entire digestive system—what Giulia Enders describes in Gut as a complex system of muscles, organs, and bacteria.)

Because organisms aren’t physically separate, it’s inaccurate and unhelpful to think of an organism (such as a human) as an independent individual. Thus, according to Sheldrake, we should de-emphasize the concept of individuality in both science and society.

The Implications of De-emphasizing Individuality

Sheldrake suggests that it’s inaccurate and unhelpful to think of organisms as individuals, but he doesn’t explore in depth what it might look like to de-emphasize the concept of individuality in science and society. To illustrate what this perspective may look like in practice, we can look to the field of medicine, where experts are experimenting with designing healthcare systems that de-emphasize individuality.

According to one healthcare expert, doctors are typically trained to think of a patient as a separate individual, much like a machine. To heal the patient, you just need to fix what’s wrong with their body, like how a mechanic might repair a broken part in a machine. However, this approach, which emphasizes the individual, doesn’t always work. For example, imagine a patient, Dawn, who frequently ends up at the hospital due to alcohol poisoning. Even if a doctor expertly “fixes” Dawn by clearing her system of alcohol, this treatment won’t necessarily prevent her from suffering from alcohol poisoning in the future.

By contrast, some healthcare systems de-emphasize individuals by implementing treatments beyond the borders of their bodies. For example, one healthcare program in the UK places medical experts in non-healthcare settings (such as schools) to support efforts that promote preventative health. Returning to our earlier example, this type of healthcare system might invest money and resources in preventing alcoholism so patients like Dawn are less likely to end up in the hospital in the first place.

Concept 2: Intelligence

Fungi also challenge us to question our ideas about intelligence. According to Sheldrake, we typically define intelligence based on whether a living thing possesses a brain. Creatures like humans and dogs are intelligent, and creatures that lack brains (like fungi) lack intelligence.

However, Sheldrake claims that fungi exhibit a behavior that we typically associate with intelligence: decision-making. For instance, as we explored earlier, fungi use their hyphae to gather sensory input, then they respond by changing how they grow—either toward or away from stimuli. Sheldrake calls this a decision because fungi use the information they’ve gathered from sensory inputs to choose one course of action (such as growing toward a stimulus) over another (such as growing away from it). In calling this type of decision a form of intelligence, he references the Latin roots of the word intelligence, which means “to choose between.”

Given fungi’s ability to make decisions, Sheldrake argues that we should do away with our limiting binary of “intelligent” and “unintelligent” as well as the idea that you must have a brain to possess intelligence. Instead, we should instead think of intelligence as a spectrum. With this view, most organisms would be regarded as having some degree of intelligence based on their decision-making abilities.

According to Sheldrake, redefining intelligence in this way could improve how humans interact with the natural world. He believes that we may respect fungi and other organisms more if we think of them as intelligent decision-makers with agency rather than unintelligent, passive beings. We may be less likely to destroy ecosystems and more likely to increase our study of non-human life so we can better understand other organisms’ needs.

Other Definitions of Intelligence

The question of “What is intelligence?” is often debated, and there’s no single definition of intelligence. Some dictionary definitions, for instance, make the brain and the mind central to the word’s definition. Other dictionary entries highlight decision-making. Some definitions are even inclusive of non-human intelligence, instead defining the word as the ability to adapt to one’s environment. Let’s see how Sheldrake’s proposed definition of intelligence—as a spectrum of decision-making abilities—compares to how experts on plant biology and human psychology conceptualize intelligence.

Plant intelligence: Michael Pollan, author of The Omnivore’s Dilemma and In Defense of Food, shares Sheldrake’s view that our typical definitions of intelligence tend to ignore the varieties of intelligence non-humans display. Pollan argues that intelligence may be a property of all life, including plant life. He cites research in plant biology suggesting that plants possess abilities we typically only associate with large-brained beings:

• First, plants may process information. For instance, some plants release defensive chemicals in response to caterpillars nibbling on their leaves.

• Second, plants may remember information. For example, ferns can change how their leaves fold in response to surrounding movement depending on whether that movement has harmed them (or not) in the past.

Human intelligence: Some psychologists share Sheldrake’s contention that we should eschew the binary of “intelligent” and “unintelligent.” However, they don’t propose defining intelligence along a spectrum; instead, they propose the idea that there are multiple types of intelligence, and different people possess different combinations of intelligence.

For instance, in Emotional Intelligence, Daniel Goleman says that humans possess two main types of intelligence. Cognitive intelligence is how well you learn information, whereas emotional intelligence is your awareness of your own and others’ emotions.

According to some experts on human intelligence, recognizing multiple types of intelligence also affirms the value and humanity of neurodivergent people—those whose brains work or develop differently from the majority, such as people with autism and dyslexia. For instance, one writer claims that employers should learn about how intelligence presents in neurodivergent people so they don’t pass over candidates who could contribute unique skillsets to their workplace.

Reason 2: All Life Depends on Fungi

According to Sheldrake, all life on Earth depends on fungi. For example, fungi support life in the following ways:

Supporting plants: Nine out of 10 plants depend on the mycorrhizal fungi living in their roots. Without these relationships, plants would struggle to stay hydrated and nourished. (Shortform note: Recent research reveals that mycorrhizal fungi are able to serve this role because their hyphae host bacteria that help these fungi access nutrients and send them into plant roots.)

Holding the soil together: Underground networks of tightly woven mycelia hold the soil together. Without mycelia, rainwater would strip the land of its soil. (Shortform note: In addition to preventing erosion, underground mycelia also help the soil retain rainwater. By “gluing” soil particles together, mycelia essentially create a dense, three-dimensional maze that slows the rate at which water travels through the soil.)

Preventing the buildup of dead matter: Fungi decompose dead matter. Without these decomposers, forests would be buried under mile-high mounds of dead plant matter. (Shortform note: Although other types of organisms decompose matter, many of them depend on fungi to break down matter first. Many species of fungi are called primary decomposers because they’re often the first to begin breaking down this plant matter. Next, secondary decomposers such as beetles and nematode worms feast on the “pre-chewed” matter.)

Reason 3: Fungi Offer Solutions to Modern-Day Problems

In addition to continuing to serve their roles supporting plants, soil, and the cycle of life, fungi can also be used to address modern-day problems. According to Sheldrake, the more time and resources we invest in studying fungi, the better we’ll be able to solve pressing problems. In this section, we’ll focus on fungi’s potential to address two of these problems: mental illness and environmental destruction.

Problem 1: Mental Illness

According to Sheldrake, there’s strong evidence that psilocybin mushrooms—also known as magic mushrooms—can effectively treat mental illnesses such as depression and anxiety. These mushrooms naturally contain psilocybin, a psychedelic compound. Human use of psilocybin isn’t new: Many indigenous cultures have used it (and continue to use it) for spiritual traditions and medicine. However, the scientific study of psilocybin is relatively new—most studies have been conducted in only the past several decades.

(Shortform note: Some scientists argue that research on psychedelics such as psilocybin is often exclusionary. They say that scientists who study psilocybin and other psychedelics often fail to credit indigenous people for their knowledge of and experience with psychedelics. They also critique how this research is run, arguing that white people are overrepresented among the participants enlisted to benefit from psychedelics. They propose making this field more inclusive by involving indigenous communities in designing and implementing research on psychedelics. This argument adds a new dimension to Sheldrake’s claim that we should invest more in researching fungi: We should also invest more in making that research more inclusive.)

Many recent scientific studies reveal that psilocybin offers both short-term and long-term benefits for patients suffering from mental illnesses such as depression:

• Short-term benefits: While they’re under the influence of psilocybin, patients report experiencing feelings of bliss, amazement, and connection to the universe. (Shortform note: A recent study suggests that psilocybin might also boost your creativity while you’re under its influence.)
• Long-term benefits: Patients also report having an improved outlook on life and fewer symptoms associated with depression and other mental illnesses.

How does psilocybin cause these positive effects? Research shows that this compound reduces activity in people’s default mode network (DMN), a part of the brain associated with self-awareness and self-related thoughts. When psilocybin suppresses activity in the DMN, other areas of the brain begin connecting. This changes your thinking in two main ways:

• Your ego fades. You think less about yourself (such as your identity and limits), and you instead think about the world around you and how interconnected it is. (Shortform note: One study reveals that this effect only happens if you take a medium to high dose of psilocybin; by contrast, low doses lead you to think about yourself more.)
• You “offroad” beyond your well-worn thinking pathways. For instance, if you’re typically pessimistic, you may find yourself having more optimistic thoughts.

(Shortform note: Sheldrake describes in depth how psilocybin suppresses activity in the DMN, but he doesn’t explore in depth the role psilocybin plays in the next step—the formation of new connections in your brain. A recent study involving mice found that psilocybin changed the mice’s dendrites—the part of a neuron that connects it to other cells. Specifically, psilocybin increased the number of spines extending from the dendrites, making it more likely they’ll form new and more connections with other neurons. This research suggests that psilocybin can contribute to neuroplasticity: a rewiring of the brain. This may explain, for example, how psilocybin can cause long-term changes, such as making you more optimistic.)

The Popularity and Risks of Psilocybin

In recent years, there’s been a rise in the number of cities, states, and countries legalizing or decriminalizing the use of psilocybin, making it easier for people with mental illnesses to access these long-term benefits. For example, Colorado legalized recreational psilocybin use in late 2022. Other places have legalized psilocybin for medical uses only. For instance, in early 2023, Australia made it legal for psychiatrists to prescribe psilocybin for patients with depression and PTSD.

While psilocybin is gaining popularity as a treatment, it’s not without its risks. Sheldrake extols the benefits of this substance but doesn’t explore in depth what these risks are. According to experts and psilocybin users, you can experience the following temporary states and side effects while high on psilocybin:

• Having a “bad trip,” which can make you feel anxious and paranoid. Overdosing can increase your chances of having a bad trip.

• Discomfort, such as headaches, nausea, and stomach pain

• Changes in your body, such as dilated pupils, increased heart rate, and weakness

Fortunately, these risks are unlikely to cause fatalities: As of 2020, there were no reported deaths from psilocybin use. However, experts and users still advise proceeding with caution and doing ample research before using psilocybin, especially if you have a pre-existing condition such as a seizure disorder or a heart condition.

Problem 2: Environmental Destruction

Finally, according to Sheldrake, fungi have the potential to reduce environmental destruction and rehabilitate areas devastated by environmental disasters. People are already using fungi for these purposes, and Sheldrake argues we should continue investing resources in finding fungal solutions to environmental problems. Here, we’ll explore three ways people are using fungi to solve environmental issues.

Mycoremediation: This is when fungi digest and break down human messes, from chemical spills to trash heaps. For instance, in Mexico City, a white rot fungus feasted on mounds of diapers, reducing their starting mass by 85%—and producing edible, disease-free mushrooms in the process. (Shortform note: Some types of mycoremediation don’t only clean up human messes—they also generate profit. For instance, a recent study suggests that reishi fungi effectively consume diaper waste and food waste, and in doing so they produce high-quality, profitable medicinal mushrooms.)

Mycofiltration: This is when a dense mat of mycelium is used to filter contaminants out of water. (Shortform note: Some researchers are hopeful that efforts involving mycofiltration can not only filter contaminants, but they could also address environmental racism. This is when Black, Indigenous, and communities suffer from disproportionately more health issues because they’re more likely to live near environmentally hazardous areas, such as areas with contaminated water. Because mycofiltration filters are cheap, they could offer these communities affordable methods for filtering water until longer-term solutions address the root causes of this contamination.)

Mycofabrication: This is when mycelia are used to create building materials, packaging, and textiles that replace less environmentally-friendly materials such as wood, plastic, and leather. (Shortform note: Materials produced through mycofabrication have an additional advantage over the less environmentally-friendly materials they aim to replace: They’re less likely to become unavailable due to supply chain issues. The Covid-19 pandemic exposed the vulnerability of supply chains, making materials like wood more expensive and less available. Mycofabricated materials are less likely to be impacted by supply chain issues because they require less energy to produce and they can be produced faster than the materials they’re replacing.)

How You Can Contribute to Knowledge of Fungi

Throughout his book, Sheldrake emphasizes both the potential of fungi to solve many pressing problems and how our lack of knowledge about fungi limits how much we can access these solutions. He identifies increased research and collaboration among scientists as ways to increase our knowledge of fungi. However, there are also ways that everyday people and fungi enthusiasts can contribute to our understanding of fungi.

For instance, consider helping document fungal biodiversity. There aren’t enough professional mycologists to document fungal biodiversity, but everyday fungi enthusiasts can help by making information on fungi easier for trained experts to access. You can contribute to this effort by taking clear photos of fungi, noting the location of the fungi you photographed, and uploading the information to a database such as iNaturalist or Mushroom Observer.