One of my favorite images of Zoë Schlanger, climate reporter at The Atlantic and my dear friend, sees her on her hands and knees in a sun-dappled field the first week of December, planting garlic. Everything is burnt orange and brown and crisp, the ground crunchy with frost, and the Connecticut farm where we were temporarily living was going into hibernation for winter. This was the last possible moment to tuck the single cloves beneath the soon-to-be-frozen soil, and it was important to get them in before the first freeze.
“What the garlic needs, in order to sprout, is the memory of winter,” Schlanger writes in her book The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth.
Plants that rely on vernalization, this taste of cold before spring, must have a way to note the passage of time so that they can emerge only once the thaw is lasting. They keep track of days to bloom when spring is certain—and not, for instance, during a two-day warm fluke in February, increasingly a risk with climate change. “The fact that plants can remember brings them closer to us, makes them more legible somehow,” Schlanger writes.
But it’s humbling to remember that they are a kingdom of life entirely their own, the product of riotous evolutionary innovation that took a turn away from our own branch of life when we were both barely motile, single-celled creatures afloat in the primordial sea. We couldn’t be more biologically different. And yet their patterns and rhythms of life have certain resonances with our own.
This is the productive tension that drives the central question of The Light Eaters—are plants intelligent?—and from there opens others: what is intelligence, anyway, and how does it relate to consciousness? What would it mean for plants to have something like either? How might we understand ourselves as truly interdependent, and what do we risk if we don’t? Is it possible that our very notion of the boundaries between self and other might require reconsideration?
Burnt out from reporting on the climate crisis, Schlanger takes us from Brooklyn to Californian sagebrush country to a botanical garden in Berlin to the rainforest of southern Chile, to explore the thrilling and fraught world of research into plant intelligence, and comes to some fascinating and perhaps surprising conclusions. Zoë and I first met over a decade ago, and have been talking nonstop since.
We recently discussed the regional dialects of plants, the implications of the brainless mind, and whether individuality is just a myth. (This conversation has been edited and condensed.)
–Lucy McKeon
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Lucy McKeon: The Light Eaters is dedicated to your wonderful grandparents, whom I’ve been lucky to meet. Could you say a bit about their influence on your life and work?
Zoë Schlanger: My grandparents on my father’s side are both visual artists. Their names are Jeff Schlanger and Anne Humanfeld. They live in an old turn-of-the-century train station in the last patch of woods in an otherwise very suburban subdivision-type place just north of the Bronx.
It’s always been a magical place to me, because of their entanglement with it. They’ve been there for nearly sixty years. It’s filled with their art—picture a cavernous hall of an old, once-grand train station, but full of paintings to the ceiling, and ceramic pots and sculptures.
And that’s just the inside. Outside their kitchen door the train platform extends to function as a sort of mammoth porch. They’ve let the lichens and mosses come colonize it, there are veins of sedums growing out of cracks in the cement, and they’ve both become so attuned to the plants and animals in this little patch of remaining woods that they know when it’s a big year for chipmunks or if the birds of prey seem to have won out this time.
Anne’s garden is a living changing thing, growing right out of the old track bed. I grew up eating blueberries off a particular bush there that must be older than I am, it’s been there my whole life. They taught me how to notice beauty, both through art and through the everyday world. To be curious about small things. How to recognize the gracefulness of the curve of a plants’ stem or the way a clay bowl feels in my hand, and why those two things are connected.
My main hesitation is about whether or not we as people can step back from our own points of reference enough to appreciate the incredibly alluring difference between us and plants.
LM: Through the process of writing the book, you come to understand “plant intelligence” as different from human intelligence—rather than some lesser version of the same, it’s a parallel set of processes (decentralized, network-based) that plants use to take in information and respond to their environments. But the scientific community is hesitant to apply terms like “intelligence” and “consciousness” to plants. Can you speak about that hesitation a bit, how you feel about it after writing this book?
ZS: Science is a conservative institution, for good reason. Scientists see themselves as a bulwark against quackery, and I think many of them recognize that they have this duty to write the first draft of new bits of knowledge, on which more knowledge will be based. If there’s a crack in the foundation, that’s very bad. So they are careful.
There’s a resistance to using human-centric terms for plants, because they don’t want to mislead—or more accurately, they don’t want the non-scientific imaginations of us laypeople to run away from us. Plants aren’t little humans. They’re not even little animals. But we use metaphor to understand the world, to bring the unknown closer to us.
Plants are the ultimate unknown. And they’re certainly doing remarkably clever things. They have no brain, and yet some plants can count. Some can store memories. Some can communicate with each other about threats, and sometimes they do it in such a way that is leading researchers to believe they might have regional dialects of more general plant languages.
These languages are in the form of chemical compounds they expel into the air, so you see where it gets tricky. They’re using a completely different set of evolutionary equipment. But they’re doing it in a remarkably complex, sensitive way.
Personally I’d be ready to call that intelligence. It doesn’t look like our intelligence, but it is its own thing: plant intelligence. My main hesitation is about whether or not we as people can step back from our own points of reference enough to appreciate the incredibly alluring difference between us and plants, the space that makes them alien, but also their surprising resonance with our own lives.
LM: Can you say more about the ways plants exhibit “intelligent” characteristics?
ZS: I love to think about how they manipulate other species. A yellow monkeyflower can lie to a bee about how much pollen it has in its flowers, by emitting compounds that, to a bee brain, translates to “heaps of pollen.” Making pollen is expensive, energetically, for the plant. So the monkeyflowers lie. The bees arrive anyway, achieving pollination for the flower, but it’s a bait-and-switch. There’s not heaps of pollen there.
They also defend themselves in ingenious ways. One experiment found that a cress plant could sense the sound of its specific predator chewing—just the sound!—and pump its leaves full of anti-caterpillar compounds in response. To the plant, sound is pure vibration. But the truth is, sound is pure vibration to us too. The difference is that we have a brain to route that vibration-information to, and plants do not. So how do plants do this? We don’t know.
Tomatoes have been found to encourage cannibalism in caterpillars. So they have caterpillars eating them, and then the caterpillars look up from the leaves and turn to eat each other. Caterpillars are known cannibals, but only when there’s not enough to eat. But the plant, through some incredible evolutionary adaptation, exploits this, prompting them to cannibalism early.
A lot of plants can recognize whether they’re planted next to their genetic kin or not, and in some cases will respond to their sibling-plants differently than stranger-plants, sometimes behaving more politely toward them, by not shading them out. Kin recognition is something we expect to see in animals, not plants. I could go on and on.
LM: One of my favorite things about your book is how, through studying plant intelligence, you come to conclude that improvisation and collaboration—rather than Darwinian competition—are integral to life. Can you speak about arriving at this, and its greater implications?
ZS: I love this question. One of the most surprising things I learned while talking to ecologists for this book was that we probably have overemphasized competition as a driver of evolution. The “nature red in tooth and claw” idea has eclipsed everything else Darwin wrote in the popular imagination, much of which points toward a more entangled, mutually dependent view of life.
Considering the sentience of these plant-creatures leaves me with a far less hierarchical view of the world. We’re not atop some ladder of evolution…
But here we are, having conveniently shoved that aside for generations, only to discover that life is much more collaborative than we thought. Plants don’t just compete; some researchers found that sunflowers will politely share a patch of nutrients if they and another sunflower are exactly equidistant to it. If one plant is closer, that plant will dominate the patch. But put them in direct “competition” as it were, and they won’t greedily monopolize; they’ll share.
Even the abundance of a particular species in an area doesn’t mean that species has won out. It may be dominant for now, but one researcher I spoke to has found that community dynamics are an ever-shifting thing, responsive to every factor in an environment. Change anything, and the makeup of the group changes. Fluidity and transformation seem to be the rule, rather than competition.
LM: Relatedly, you argue that natural interdependence calls into question our more general and pervasive understanding of individuality—an idea that was central to an earlier piece of yours that I edited for the New York Review of Books, about fungi. Can you say a bit about this?
ZS: The hardest part about writing a plant book was deciding where a plant begins and ends. Plants are so locked in with their environment. They’re incredibly porous, in that way: Fungi are hooked into their roots, bacteria and viruses are working on them all the time. Fungi in some cases are actually doing things we might think of as fundamental to that plant: One paper found that when a grass that couldn’t grow in salt water had its root-fungi swapped for those of a grass that could, it too was able to grow in saline conditions.
The notion of a biological individual quickly starts to fall away. Everything is mixture. The human body is a perfect example; many of our cells are not in fact ours. We are full of other creatures, who are often carrying out functions we believe to be fundamental to our selfhood. No individuality. It’s a very enlivening though.
LM: What would it mean to take plant intelligence seriously—on a larger systemic or smaller personal scale? How has your daily life changed as you’ve written this book? What would it mean to trust people “to handle a complicated truth,” as you write?
ZS: For me, the result has been a new feeling of humility. Something as simple as walking past the climbing vines that have scaled the chain-link fence by an empty lot near my house really does leave me with a sense of admiration. A park is now the site of endless plant drama. There’s so much going on, where there was once just a wash of green.
Considering the sentience of these plant-creatures leaves me with a far less hierarchical view of the world. We’re not atop some ladder of evolution; evolution is not a program of linear improvement with us at the top. Here are thousands of examples of other ways of living, weirder and more cunning in some cases than our own weird way. That humility helps. Who are we to indiscriminately destroy all this roiling life? All this ingenious striving?
It begins to feel absurd, barbaric to fell a thirty-year-old tree for toilet paper or decking. To clear a boreal forest to make burnable pellets. It adds respect into the equation. Once you feel respect, you can’t unfeel it. The circle of ethical regard just keeps widening.
Another way to feel that respect is to consider that plants make every molecule of sugar you’ve ever consumed. Our bodies run on glucose that plants first spun out of thin air and sunlight. Every thought that’s passed through your brain—an organ run on glucose—was made possible by plants. We are dependent on them, it’s not the other way around.
That’s why I do hope the plant scientists who are hesitant about unleashing the full implications of their discoveries on the general public will rethink their position, at least a little. I don’t want people to carry away some caricaturish vision of omniscient plant life, either. But what might happen, culturally and socially, if more of us knew what plants do, what they’re doing all the time?
LM: What are you thinking about or working on now?
ZS: I got into this to take a sort of mental break from climate reporting. I was burnt out, numb to it. But this has awakened something in me. The part of myself that’s been quiet since childhood has reemerged, the part that recognizes the aliveness of every living thing. Knowing plants have this alacrity, this sense of agency over their lives, has reenchanted everything. I don’t think I feel more hopeful about climate change. But I feel more connected to exactly what we stand to lose. All this life, for what?
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The Light Eaters: How the Unseen World of Plant Intelligence Offers a New Understanding of Life on Earth by Zoë Schlanger is available via Harper.
