The Light Eaters – Book Review
By: Darlene Belton, Master Gardener
So, you think you know something about plants? I thought I did too, until I read Zoё Schlanger’s The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth.
The concept of plant intelligence is controversial, even paradigm shattering, yet the research of this new branch of botany reported on by Schlanger is robust, though its scientists are cautious of strong skepticism from the mainstream. “Rarely,” Schlanger writes, “does one get a glimpse of a field in true turmoil”.
Her interviews and site visits with scientists around the world pepper the book’s chapters. Though not equally bold in naming what they’ve seen, Schlanger says, “Not a single botanist was anything less than agape at what they were learning that plants are capable of.”
Hard evidence of plant agency, even a type of survival-based intelligence, is described everywhere: Boquila trifoliata, the Chilean jungle vine that literally changes the shape of its leaves to mimic its host, thereby protecting itself from predation; Nasa poissoniana, that times its output of nectar to the visitation patterns of its pollinators; the ‘maternal care’ exhibited by plants such as on the arid hot Colorado ridges that bend down to deposit their seeds right at their bases to provide shade to their growing seedlings then extra nutrients when the parent plant dies and decays – these are but a few examples found in the book.
Plants couldn’t be more unlike us, Schlanger attests, an entirely different Kingdom that diverged from animals at the dawn of life on earth and have used this time to advantage in ways we are only now appreciating.
Frozen in the place they first sprout, bathed in their nurturance (sunlight from above and minerals from below), plants have learned to defend themselves from predators and disease and to exploit both wind and animals to pollinate and disperse their seeds, ensuring their survival and astounding success.
This success is due to more than genetics, Schlanger reports; individuality and plasticity are the keys.
Every gardener has noticed how individual plants of any one variety perform differently; some individuals are more resilient, more creative in finding ways to survive. In fact, genetic analysis has confirmed that the genes of progeny are permanently altered by the parent plant’s successful problem-solving. To our chagrin, however, noxious invasive plants are masters of plasticity. Schlanger notes that within a few generations of arrival they ‘figure out’ the opportunities of their new environment and alter their genetics enough to overtake gardens, fields, and forests.
Why do we have so much trouble accepting the concept of agency in plants, even when we have personal observations of concrete examples? Schlanger attributes this to culture, our Western science-based understanding of the world. This approach of course has brought many rewards to human lives, but there are downsides to a reductionist, non-holistic world view.
Perhaps the greatest stumbling block for scientist and lay person alike, Schlanger writes, is trying to imagine how a plant organizes inputs from its external environment into an appropriate response without the central coordination of a brain – and we have no answer yet, she adds.
Do plants see, hear, even emit sounds? Newly available, highly specialized scientific instruments record hard evidence of something akin, but also not yet explained, according to Schlanger. Caterpillars chewing on neighbouring plants can somehow stimulate plants not yet attacked to alter their body chemistry to create natural pesticides for protection. Plants will grow away from shade and back toward sunlight as well as emit detectable intense vibrations when a leaf is torn off. They harness and direct other chemical processes to communicate, electricity and fluids to move, plus much more, utilizing a generalized rather than concentrated coordination system. “After all,” Schlanger quotes plant scientist Tony Trewavas as saying, “A brain is only one way to build a network.” He then adds, “It’s all about respect. If we’d only respect plants more…”
Schlanger summarizes, “Plants speak in chemicals, move in electricity and the flow of fluid in their bodies”. They are intelligent “in the meaning of alert, awake to the world, spontaneous, responsive, decision-making”, she writes, adding, “Every inward breath of mine was first breathed out by plants.”
Published: May 2025