The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth

The traditional understanding of intelligence is shaped by human-centric views. Historically, perceptions of animal intelligence were driven by a comparison to human intelligence. During the Enlightenment, scientists believed animals were like machines, driven by fixed biological instincts. Because Enlightenment thinkers were champions of rationalism, they did not believe animals shared humans’ cognitive abilities for reasoning. Anthropocentrism centralizes human experience, and Enlightenment thinkers exhibited anthropocentrism by diminishing anything that contrasted with a human version of intelligence. In The Light Eaters, Schlanger challenges this view with a question: What if intelligence does not have to look like human intelligence?

Schlanger’s question reflects an explosion of new research that suggests human perception has limited scientific inquiry and how we think about life, creativity, community, and thinking. Contemporary researchers like Frans de Wall, Mark Bekoff, and Michael Levin seek a more comprehensive understanding of what intelligence means—one that diverges from the limitations of human perception. De Wall, a primatologist, argues that human intelligence is indistinguishable from all animal intelligence. American biologist Mark Bekoff illuminates the complex emotional experiences of animals, while Michael Levin—a synthetic biologist—explores what all this means for artificial intelligence.

The Light Eaters is part of a larger trend to better understand the ecological world. It joins contemporary works like Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants by Robin Wall Kimmerer; Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures by Merlin Sheldrake; and The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from a Secret World in emphasizing the interconnectedness of organisms.

However, this shift in thinking is not without controversy. In 1972, researchers Peter Thompson and Christopher Bird published The Secret Life of Plants, using dubious science to support the hypothesis that plants experience complex emotional, cognitive, and conscious lives. This work turned scientists away from further study of plant intelligence. Schlanger writes about the disparate camps of thought surrounding the field of “plant behavior” and its implication that plants have the autonomy to make choices. For centuries, plants were viewed as passive entities responding to external stimuli. Critics argue that while plants’ responses may look like sophisticated intelligence, they are simply highly refined processes defined by millions of years of evolution.

Although intelligence has typically been measured by human metrics, a more expansive study reveals that creatures throughout the animal kingdom exhibit complex modes of thinking. Plants learn from the environment, adapt, and share information. Elephants, octopuses, crows, and even ants exhibit problem-solving abilities and advanced social behavior. Mycelium networks, which function as vast information systems, adapt and “choose” paths based on available nutrients, a form of intelligence. Although slippery terms like “intelligence” and “consciousness” are often understood within a human framework, scientists are exploring what these terms might mean when applied outside the human context.