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.
Themes
The Constant Motion of Biological Creativity
Significant genetic changes in human biology can take thousands to tens of thousands of years. For humans, genetic changes that affect large populations generally require many generations to become widespread. Lactose tolerance in one such trait that took thousands of years to develop. Plants operate on a different timeline. They can develop genetic mutations at a much faster rate, creating signific genetic shifts in their immediate offspring. For example, plants that have been repeatedly munched on by a species of caterpillar will employ a series of defenses in their genetic offerings, producing offspring with prickly hairs or bitter tannins to ward off future predators. This is just one example of how plants are constantly engaging in a process of biological creativity, responding to environmental factors and finding unique solutions to their problems: “What we end up with is a sort of balance in constant motion. All this pushing and pulling and coalescing, as I have come to understand, is a sign of tremendous biological creativity” (2). This idea indicates a more fluid and ever-changing concept of ecology, a stark contrast to human evolution and a new way of thinking about how various systems intersect.
Boquila trifoliata, a common vine found in the Chilean rain forest, is a striking example of accelerated adaptation. Boquila leaves can mimic the leaves of various plant species, including trees, shrubs, and ferns. Some of this mimicry is just an approximation, but it effectively ensures the plant’s longevity. Other plants use other forms of biological creativity. The male gingko tree can sprout a female limb, ensuring its reproduction. Some plants alter their chemical compounds to poison or deter predators. Japanese knotweed rapidly responds to its environment, unbothered by foreign habitats with new predators. These plants use biological creativity to alter their own makeup as well as that of their environments.
Schlanger explains that plants have more agency than people think. After all, they singlehandedly created the atmosphere in which they thrive. Their development of this atmosphere enabled animal life, including the pollinators that help ensure plants’ evolutionary viability. Schlanger argues that this constant motion is directed toward life, not death. Plants are keen to survive, and their biological creativity is guided by their compulsion to live. By engaging with plants’ relentless pursuit of life, Schlanger discovered a profound contrast to her work as a climate journalist, which centered on the numerous ways humans are destroying the planet. Focusing on plants’ adaptability and changeability rejuvenated her career and changed her perspective, and it could give all humanity hope for the planet’s future.
The Complexity of Ecology
Human history is, in many ways, a history of individualism. Schlanger points to Aristotle’s ladder of life as an example of how humans have positioned their own existence above all others. However, Western philosophy has also championed individualism, prioritizing the needs and desires of one over the collective. Plants, however, live in a much different manner. Schlanger argues that plants exhibit a more collective understanding of their environment and their role within it. They are active participants in a dynamic, complex system, interconnected with their surroundings.
Schlanger’s exploration of plant consciousness reveals that plants are not isolated entities but integral parts of a larger systemic network. She argues that plants, like other species, make decisions that impact their own ecology. They make choices about where to grow, how to grow, and what chemicals to create and emit. Through their actions, plants influence both their own survival and their broader environment. They warn one another of predators. They make choices that will benefit family members. They respond to their surroundings, and their surroundings respond in turn.
The emergent properties of these ecological systems, revealed through Schlanger’s research into biological creativity, is a key component of this theory of complexity. In the final chapter, Schlanger questions whether compartmentalizing scientific inquiry limits understanding. If scientists took cues from plants and embraced ecological understanding, then humans could better see how complex ecological systems are impacted by the smallest shifts and decisions.
Indigenous science models an approach that is not new but traditional. Indigenous scientific approaches emphasize the interdependence of all beings—the complicated network of interactions between humans, plants, animals, and all forms of life. Complexity and ecology are not strictly scientific fields of exploration; they are also cultural, spiritual, and philosophical.
Schlanger mirrors this approach in The Light Eaters, blending these disciplines to develop her thesis. While examining polarizing language in the scientific community, she uses that language to draw connections between plants and humans. Her work integrates complexity and ecology by framing plants as active participants in a diverse system, not passive organisms. She writes, “A single plant is a marvel. A community of plants is life itself. It is the evolutionary past and future entangled into a riotous present in which we are ourselves also entangled” (259). These elements suggest that consciousness and ecological adaptation are part of a large web of interactions, not the processes of an isolated individual.
Plant Consciousness
Philosophers have argued about the nature of consciousness for thousands of years. Aristotle believed consciousness was tied to rational thought. Descartes emphasized the ability to distinguish between dualities as the core of consciousness: the mind and the body, the self and the other. John Locke argued that consciousness derives from sensory experience, while David Hume suggested it is born from perception. Schlanger uses plants to explore all these ideas, revealing the complexity of plant intelligence, behavior, and experience.
For example, the sensory experience of plants is revealed through their sense of touch. The aptly named sensitive plant curls inward when a person runs a finger along its spine. Plants can sense wasp egg sacs on their limbs and develop hard callouses around them, suffocating the larvae. Schlanger suggests that plants may even be able to “see” light, using it to mimic the leaves of other plants or make choices about where to grow. Although this sensory experience is different from how humans perceive exterior stimuli, plants’ sensory systems allow them to adapt and thrive, making them dynamic and responsive.
Schlanger uses numerous research studies and rhetorical tools to develop an argument for plant consciousness. Plant memory, for example, suggests plants understand time and how to use it to their advantage. They can count the minutes between pollinators or the number of warm days to distinguish a warm spell from the natural cycle of seasons. Plants prioritize the survival of their relatives and embrace eusocial characteristics. Adaptive behavior and decision-making suggest plants have agency, which can be seen in how they adjust their growth patterns to light or temperature. They even seem to “hear,” registering the vibrations of both predators and water sources.
Schlanger admits that research into plant consciousness is highly controversial. A wave of dubious research in the 1970s effectively halted funding for new studies into plant behavior and consciousness. She realized this as she talked to scientists who ended conversations early when she used certain words that could be misconstrued to suggest they believed in certain claims about plant life. Even the words “intelligence” and “communication” are extremely polarizing among scientists.
However, Schlanger correlates plant consciousness with complexity and ecology. Rather than relying on a central nervous system and a localized hub like the human brain, plants utilize a more internal ecological approach. Their entire anatomies participate in a complex system of understanding and reacting to the world. A plant’s behavior is not the sum of its individual parts. Its consciousness, Schlanger suggests, is a comprehensive and emergent property of a larger ecological system.
