In 1973, The Secret Life of Plants was published, claiming that plants could hear music — indeed, had preferred genres — and could respond to humans’ thoughts, among other blockbuster assertions. Once it was exposed as pseudoscience due to experiments that couldn’t be replicated, the book became the ultimate scarlet letter in the world of botany. For decades, any researcher who even appeared to posit that plants may have “intelligence” or some type of agency in their environment was ridiculed and professionally ostracized. It’s this massive overcorrection in response to The Secret Life of Plants that Zoë Schlanger masterfully deconstructs in The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth.
Through painstaking research about plants themselves and with an anthropologist’s touch to reveal the humans behind that research, Schlanger demonstrates that we are finally beginning to understand the full range of plants’ astonishing capabilities and interactions with the world around them. Schlanger starts with the concept that plants release chemicals in response to stimuli like pests attacking them. This idea doesn’t seem outlandish now, but in the 1980s, when David Rhoades first proposed that trees’ chemical signals throughout a forest fended off a caterpillar infestation, it most certainly did. Yet this ability was confirmed by more and more research.
From there, the reader learns about how electric signals move through plant cells in response to touch just like animal cells, although the process is slightly different (plants lack nerve synapses and, of course, centralized brains). But this points to one of the book’s most interesting questions: what if an entire plant is a non-centralized “brain,” a body capable of transmitting information based on sensory perception? When Schlanger describes scientists recording videos of electrical signals illuminating in plants like lightning bolts following a leaf injury, the idea of plant intelligence doesn’t seem far-fetched at all. It sounds like plant cells communicate throughout their bodies, just like animal cells can.
If plants can feel, what other senses might they have? Thanks to researchers like Heidi Appel, there is proof that plants can hear — or perhaps more accurately, that they can perceive acoustic sounds. We learn about Appel’s experiments showing plants making defensive chemicals in response to the sound of caterpillars chewing. There is also Monica Gagliano’s evidence of pea plant roots growing towards the sound of running water underground.
In the midst of the fascinating botanical studies, we also get a glimpse into the personal animosities and ingrained prejudices in academic botany. Gagliano is pilloried as too mystical by many of her colleagues because she shared spiritual-religious viewpoints of plants in her memoirs, despite being an accomplished scientist. It’s stories like these that remind readers that behind scientific discoveries are people, with all of their imperfections and preconceived notions, and that science itself evolves too.
Co-evolution comes into play when Schlanger describes plants’ ability to “see” albeit without eyes as we think of them. She discusses the research around Boquila trifoliata in Chile, which can change its appearance like a chameleon. Ernesto Gianoli, who leads these efforts, thinks microorganisms such as bacteria inside the plants can be working with plants’ genes to express different characteristics based on which plant a boquila is trying to mimic. As we think about how the microbiome of the human gut is finally being researched, or how mycorrhizal fungi and plant relationships are now better understood, these ideas of microbes and plants having symbiotic relationships makes sense, even if they are surprising.
Intra-species relationships play a role with pollinators, too. As any native plant lover knows, asters and goldenrods bloom beautifully together in fall. It turns out that when they grow together, they attract more bees than a field of only asters or only goldenrods. The visual display appeals to all of us, from humans to insects, and drives behaviors in other organisms that benefit the plants themselves.
This habit of cooperation is discussed in the later chapters, where Schlanger describes plants that work together for the benefit of their fellow family members. Rather than a cut-and-dry “survival of the fittest” narrative, we see plants changing their growth patterns so as to not crowd out or shade others, and that different species won’t always out-compete each other. She notes, “Resources like food and water and light play a role, but not just as an incitement to selfishness.”
This doesn’t just improve ecosystems or explain why natural areas are healthiest when they’re full of species diversity. We learn about japonica rice that produces more grains when related plants are grown near each other — rather than growing more roots and competing for resources, they focus their energy growing upward with room for all, hence better grain yields. As climate change threatens food supplies, these discoveries become increasingly valuable.
All of these stories — the experiments, the fieldwork around the world, the characters of the scientists striving to learn more — come together to create a narrative that will sound familiar to gardeners: each plant is unique, and plants can thrive in intelligent ways even if we can’t yet put our finger on exactly how they’re doing it. Plants are intimately embedded in the ecological systems they find themselves in, and we still have much to learn about how they live and persevere.
This book isn’t about native plants per se, but its emphasis on ecological connections and communities will appeal to all who seek out creating healthy environments. It won’t have you playing classical music for your houseplants, like misguided readers in the 1970s, but it will increase your fascination with and respect for the plants in your life even more.
Rose Rankin is a freelance writer outside of Chicago and a member of the Wild Ones Greater Kane County Chapter. You can follow her on Instagram @bringbackprairies.