44 pages • 1 hour read
Zoë SchlangerThe Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth
Nonfiction | Book | Adult | Published in 2024A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Prologue-Chapter 2Chapter Summaries & Analyses
Prologue Summary
Schlanger contrasts her experiences as a climate reporter with her current research into plant intelligence. She discusses the ongoing problem with environmental research: Its singular focus on death and destruction negatively impacts those doing the reporting. Schlanger felt as though she had compartmentalized her emotions and could no longer access them. To rediscover curiosity and wonder, she turned to plants. She had always loved plants, even the invasive tree of heaven that grew by her front stoop in New York City. Her casual study soon turned into an obsession.
Schlanger turns her attention to the first question of botany: What is a plant? As researchers learn more about the complexity of botanical life, defining what a plant is becomes increasingly challenging. Controversy over the classification of plants captivated Schlanger early on: “Who doesn’t feel both drawn to and repulsed by the unknown?” (4). This was Schlanger’s first look into the complexity of life and the slippery nature of absolutes. She soon discovered another point of contention—plant intelligence—and wondered how an ideology of complexity might illuminate the topic.
While walking through the Hoh Rain Forest in the Pacific Northwest, Schlanger notes the complex ecology of the life around her. Everything functions in relation to everything else—plants, soil, bacteria, fungi, and animals. Rather than limiting herself to studying plants alone, Schlanger leans in to this complexity.
Chapter 1 Summary: “The Question of Plant Consciousness”
Schlanger’s work as a climate change reporter posed a significant personal problem: She was becoming emotionally detached from the stories she reported on. Hoping to rediscover a sense of engagement and wonder, she turned to plants, which had always brought her joy. During her lunch break, Schlanger read scientific articles from scholarly journals about new discoveries in botany. Two weeks into her newfound hobby, she learned about Azolla filiculoides, the world’s smallest fern. This plant sent her down an irreversible path.
Schlanger read everything she could about ferns. While reading Oliver Sacks’s Oaxaca Journal, she discovered that Sacks experienced something many naturalists had—a feeling of oneness with nature. Schlanger noticed moments like Sacks’s coursing through naturalist literature, including Annie Dillard’s Pilgrim at Tinker Creek and Andrea Wulf’s The Invention of Nature.
Her newfound interest in botany helped her recapture the sense of wonder she had lost as a climate change reporter: “I was regaining material intimacy with the natural world by looking at plants. It wasn’t a way to ignore environmental catastrophe; it was a way to reattach myself to the stakes” (23). Ferns, in particular, captivated Schlanger. After signing up for a class on ferns at the New York Botanical Garden, she learned that, instead of seeds, ferns use sperm and spores to reproduce. Even more striking, they can inhibit the sperm of other fern species by releasing hormones.
The ability of ferns to sabotage other plants caused Schlanger to wonder about plant intelligence. The 1973 release of The Secret Life of Plants had a profoundly negative impact on this area of study. The book, filled with dubious research, had a lasting effect on the science community. Schlanger soon learned to steer clear of words like “consciousness” or “intelligence” when speaking to botanists because a mere mention was enough to end a conversation.
Scientists fear they run the risk of anthropomorphizing plants by using this language. Plant “behavior,” too, is controversial, but a new wave of research in the area is gaining traction. As Schlanger grappled with what plants really were, she decided to quit her job and turn her attention to plants.
Chapter 2 Summary: “How Science Changes Its Mind”
The history of plants is one of ingenuity and chance. Approximately 1.5 billion years ago, an alga-like cell swallowed a cyanobacteria and sparked the evolution of a half million species. Five hundred million years ago, when plants left the ocean, they transformed an atmosphere of nitrogen and carbon dioxide into an oxygen-rich one that gave rise to animals, including humans. Mutual reciprocity then developed between plants and animals. Through photosynthesis, plants separate carbon dioxide, release oxygen through stomata, and create sugar—what animals need to survive. Furthermore, their ability to take nitrogen from the air provided the building blocks for animal life. In return, animals release carbon dioxide back into the air for plants to process.
Plants face many challenges. This is seen through the work of Hawai’i’s Plant Extinction Prevention Program. When Kaua’i formed out of volcanic rock, it was an isolated island devoid of plant life. When errant seeds made it to the island, they encountered prime growing conditions without the damaging effects of disease or insects. Kaua’i became a garden for many unique plants that grew unencumbered until climate and human impact threatened their vulnerable existence.
In other parts of the world, plants have developed a vast array of defenses. Plants use thorns, sticky sugars, slippery petals, and other variations to keep dangers at bay. They are unique for their anatomical decentralization. Cutting one leaf off a plant will not kill it; in fact, the plant will grow a new leaf—one that will be slightly adapted from the one before. Darwin noted that root tips function like brains, sensing and moving around objects toward the most nutrient-rich spaces; he equated the maneuvering of the root tip with cognition, a suggestion his contemporaries disagreed with.
Schlanger explains that one reason plant intelligence has been slow to take off is plant blindness. Botanists frequently cite plant blindness and its impact on their ability to acquire funding for research. Unlike many Indigenous groups that prioritize plant and non-human life, Western culture demotes non-human entities to lower tiers in an anthropocentric hierarchy. However, Western culture easily could have gone in a different direction.
After Aristotle established the ladder of life, he left the running of his school to a philosopher named Theophrastus who published some of the earliest known works devoted to plants. Theophrastus saw plants as a separate category of being—not the same as human, but not less either. In the ancestral line of Western thought, however, Aristotle’s ladder and belief in the superiority of humanity over all other forms of life persisted, not Theophrastus’s ideologies.
This does not mean Western thought cannot change course. Recent developments in animal intelligence, including the declaration of consciousness for all mammals and birds by a group of scientists at the University of Cambridge in 2012, indicate an evolution in the field. Botanists remain divided in two camps: those who are willing to acknowledge the possibility of plant intelligence and those who are vehemently opposed.
Prologue-Chapter 2 Analysis
The Light Eaters blends philosophy and science, reflecting a larger shift in scientific inquiry as scholars turn to systems thinking, complexity theory, and ecological understanding for answers. These approaches emphasize The Complexity of Ecology, showing how the study of plants, humans, fungi, animals, microbiomes, genetics, and other systems combines to create a more complex understanding of consciousness, intelligence, and social behavior. This shift reflects a culture that grows increasingly connected and globalized every day. As it does, it becomes clear that reductionist thinking—deconstructing things into distinct, isolated pieces—reveals only one part of the puzzle.
By looking both at these individual pieces and examining how they fit together with other elements, scientists gain a better understanding of the causal relationship between systems. Schlanger’s thesis supports the argument that examining the world through this new lens is key to facing climate change and other issues. She asserts, “In this ruined global moment, plants offer a window into a verdant way of thinking. For us to truly be part of this world, to be awake to its roiling aliveness, we need to understand plants” (5). For Schlanger, it was necessary to change her understanding of the interconnectedness of the world. Increasingly disheartened by the devastating climate disasters she reported on, Schlanger sought hope—and found it in plants.
This hope is revealed through the spiritual, philosophical, and scientific stories she blends to explore the question of Plant Consciousness. Schlanger aims to make sense of the rift over the topic. She is careful in how she talks to botanists, avoiding certain words that she knows will end the conversation early, such as “communication” and “intelligence.” However, Schlanger’s language reveals where her argument is headed early in the text. Her incorporation of naturalists and nature prose signals a spiritual understanding.
Schlanger opens Chapter 2 by detailing the evolution of plants and their reciprocal relationship with the animal kingdom, which creates a foundation for the theme, The Complexity of Ecology. Schlanger emphasizes that it is not enough to write a book about only plants because doing so fails to acknowledge the complex systems that give and receive in mutual reciprocity. For example, plants’ role in the creation of sugars, which are essential to animal life, shows how deeply intertwined plants and animals are—even if that reciprocal exchange does not always involve conscious awareness. During those moments when this reciprocity is brought into self-awareness, Schlanger feels something special occurs. When she walks through forests, she is humbled by the complex ecological systems around her and the ways she is both a part of and separate from these systems. This experience, along with her daily research into plants, recaptures a childlike sense of wonder, but there is something more to this feeling—a blend of the scientific and spiritual.
Schlanger’s comparison of her own feeling to Annie Dillard’s Pilgrim at Tinker Creek reveals this pattern. In her work, Dillard describes feeling overcome while watching light filter in through tree branches. In that moment, Dillard felt at one with the world around her. Schlanger explains that many naturalists describe this feeling of connectivity. By invoking their work, Schlanger establishes that she is seeking answers beyond the concrete. She is looking for a more collective way of thinking about life. Furthermore, even as she explains the slipperiness of language in the scientific community, she uses this language liberally throughout the text. She simultaneously acknowledges how polarizing certain terms can be while using them to explore ideas. By embracing dualities rather than running from them, Schlanger practically exhibits her own argument for systems thinking while embracing the blurry lines between science and mystery.
