It’s time to retire the hierarchical classification of living things.
By Peter Wohlleben
In 2018, a German newspaper asked me if I would be interested in having a conversation with the philosopher Emanuele Coccia, who had just written a book about plants, Die Wurzeln der Welt (published in English as The Life of Plants). I was happy to say yes.
The German title of Coccia’s book translates as “The Roots of the World,” and the book really does cover this. It upends our view of the living world, putting plants at the top of the hierarchy with humans down at the bottom. I had been giving a great deal of thought to this myself. Ranking the natural world and scoring species according to their importance or their superiority seemed to me outdated. It distorts our view of nature and makes all the other species around us seem more primitive and somehow unfinished. For some time now, I have not been comfortable with viewing humans as the crown of creation, separating animals into higher and lower life-forms, and treating plants as something on the side, definitively banished to a lower level.
And so I found the conversation with Coccia most refreshing when he visited our Forest Academy. A small bearded man, Coccia turned up in a blue suit and blue checkered tie, completely inappropriate attire for the outdoors, even though we had agreed that we would take a walk in the forest together. Although he is from Italy and now teaches in France and writes in French, he also speaks fluent German because at one time he studied and worked in Freiburg.
After our first cup of coffee, we were soon deep into our main topic: trees and plants in general. Coccia argued that our biological classifications are not grounded in science. They are strongly influenced by theology and are dominated by two ideas: the supremacy of the human race and the world as a place humans must bend to their will. And then there is our centuries-old compulsion to categorize everything. When you combine these concepts, you get a ranking system that puts humankind at the top, animals in the middle, and plants way down at the bottom.
I listened, fascinated by what he had to say. Here was a man of my own heart. I would prefer it, I told Coccia, if science categorized species one beside the other. That would still allow an order, a system of sorting, without imposing any kind of a hierarchy. He immediately agreed. He reiterated his belief that the ordering system we have today is not scientific but rather influenced by cultural, historical, and religious values. For Coccia, the hard boundary between the plant and animal world does not exist. He believes plants can experience sensations and even reflect on them. And he is not the only one who thinks this.
Did the plants wake up as we do when we come to after a general anaesthetic?
František Baluška is also very good at making inconceivable connections. Baluška, a plant cell biologist at University of Bonn, has for some time now been of the opinion that plants are intelligent—after all, they can process information and make decisions. But do plants have consciousness? That takes the discussion to a whole different level. If we could prove that plants have consciousness, we would have to radically change the way we interact with them, because we’d find ourselves facing the same kinds of issues that we face with factory farming in conventional agriculture.
Baluška, together with colleagues from around the world, including Stefano Mancuso from the University of Florence, has come a little closer to answering the question about plant consciousness. Baluška and his colleagues sedated plants that feature moving parts, such as Venus flytraps. These plants catch their prey in a trap that snaps shut as soon as insects touch trigger hairs on the inner side of their double-lobed leaves. The two sides of the leaf fold together in a flash, capturing the insect between them, and the plant then digests its prey. The anesthetics the scientists used, which included some that are used on people, deactivated electric activity in the plants so that the traps no longer reacted when they were touched. Sedated peas showed similar changes in behavior. Their tendrils, which usually move in all directions as they slowly feel their way through their surroundings to find supporting structures to grow on, stopped searching and started to spiral on the spot. After the plants broke the narcotics down, they resumed their normal behavior.
Did the plants wake up as we do when we come to after a general anesthetic? This is the critical question, because in order to wake up, you need one thing above all others: consciousness. And it was exactly this question that a reporter from The New York Times posed to Baluška. I really liked his answer: “No one can answer this because you cannot ask [the plants].”
I excitedly imagined what Baluska’s kind of plant research would look like: well-equipped laboratories with plants all over the place monitored by elaborate apparatuses finally giving up their secrets. That was something I absolutely had to see. On a sunny afternoon in 2018, I parked my car in front of his institute. I took a musty-smelling elevator to the fourth floor. Then (according to the email I received from Baluška), I was to turn right when I stepped out of the elevator and take a flight of wooden stairs up to his office. The corridor straight in front of the elevator door led to neat, uniformly gray rooms of the kind you expect to see in universities. The wooden staircase to the right led to an out-of-the-way corner in the huge building complex. Up there, on a tiny landing, Baluška greeted me with his strong Slovakian accent.
He led me into the conference room and we sat side by side at a huge round table. I was eager to hear what he had to say. After all, I had cited his research in my book The Hidden Life of Trees and repeatedly mentioned his groundbreaking research when I attended events. His results sounded so fantastic that I sometimes wondered if I had interpreted them correctly when I translated them into everyday language for the general public. Baluška immediately put my fears to rest.