Talking trees are no longer just a character in a Tolkien novel. They may very well be real. In fact, if you’re like me, your grandparents probably swore by the belief that the more you talk to your plants, the better they’ll grow. Scientists, too, have long wondered if communication with our green leaf friends goes both ways. And now it seems, we may have some answers.
Join us in this week’s The Global Tiller as we dig into plant neurobiology. Who are the pioneers of this research and what do the latest experiments tell us about how plants communicate? Are plants conscious and, if so, what does that mean for veganism?
One of the pioneers of research into plant neurobiology is physicist Jagdish Chandra Bose, who began working on plant physiology in Calcutta (now known as Kolkata), India, in as early as 1900. His exploration of the plant nervous system led to the creation of some instruments that allowed him to record plant responses to different stimuli. He discovered that plants — both small and big — have a nervous system akin to one in the lower animals. They not only respond to external objects but also possess rhythmic or pulsatory movements like heart beat in animals.
Fast forward to this century and Bose’s work is being endorsed with the latest research. According to a recent study published in Cell, plants are very much capable of making sounds. When they are thirsty or stressed, such as if their stems have been cut, they make "airborne sounds" to indicate their discomfort. The only reason why we cannot hear them is because the sounds are ultrasonic — about 20 - 100 kilohertz. This means that they are so high-pitched that very few humans could hear them but animals, such as bats, mice and moths, could potentially do. And if they do hear them, it must be a noisy world because plants can make up to 35 sounds per hour.
The scientists who made this discovery at Tel Aviv University in Israel looked specifically at cactuses, corn, tomatoes, tobacco and wheat. They put them in a basement lab with no background noise to determine if the microphones placed at a certain distance from the plants would hear these sounds, and they did. This makes this study a significant breakthrough than earlier ones that detected vibrations and unique movements but no airborne sounds.
What makes this discovery even more insightful is the fact that sound patterns peaked as stress increased. “In a dehydrating tomato plant, the sounds become noticeable by the second day, peak by the fifth day of dehydration and stop when the plant is completely dehydrated,” said Lilach Hadany, professor of plant sciences at Tel Aviv University who led the study. “The sounds thus appear associated with living plants.”
And this begs the question: are plants conscious? According to Italian scientist Stefano Mancuso, who has been described as a "poet philosopher" of the plant sentience movement, the ability of plants to emit and receive a message puts them closer on the spectrum to humans as compared to rocks. When it comes to consciousness, he argues that, even with humans, we are not exactly sure what consciousness is. But if we understand consciousness as something that we all have unless we’re asleep or under anaesthesia, we can potentially establish whether or not plants are conscious by looking at how sensitive they are to the same anaesthetics that work on humans. Mancuso’s research is ongoing and, he believes, he will be able to demonstrate by the end of this year whether or not plants can be put to sleep.
This is not to say that plants are not intelligent just because they don’t have a brain. Mancuso argues that, even without neurons and a brain, plants can acquire, process, and integrate information to shape their behaviour in a way that could be called intelligent. For example, the way in which Dodder vines sniff out their prey, or how the Venus flytrap does not chomp down as soon as it senses a fly but waits for the second encounter before clamping down.
Of course, when we begin to consider plants as conscious and capable of feeling pain, does veganism still remain the ethical option? Mancuso believes that, as animals, humans can only survive by eating other living organisms. But, since producing a kilo of beef requires killing a ton of plants, it makes sense to directly eat a ton of plants. He also points out that we should remember that plants evolved to be eaten, it’s part of the cycle. Plants produce fruits to be eaten by animals, who are then preyed upon by larger animals.
Humans prefer to believe they sit on top of this food chain but maybe it would be more helpful to shift our thinking away from a hierarchy to a cycle, where we are nothing but just one link in a chain. Where we survive not because we overpower others around us but because we cooperate to share our limited resources. And here too, we have a lot to learn from plants.
Until next time, take care and stay safe!
Hira - Editor - The Global Tiller
Dig Deeper
Scientists have discovered that these are the sounds that plants make when they are stressed, for example, when they are lacking water or have been cut recently. These plant sounds have been processed to make them audible to the human ear.
…and now what?
I have to admit, the first time I heard about plants crying, my first thought was: “This isn’t going to be easy to digest for vegan people.” Don’t get me wrong. I don’t have anything against veganism but conversations with some of the hardcore ones have sometimes left me feeling dismissed, like a poor, ignorant one still eating living animals. So I’d laugh in my head about their new predicament and my reflection never extended beyond that.
We have known since a long time that plants are living beings. We just didn’t know to what extent and this study lifts the veil on what is probably a part of, or the beginning of, the answer. To which question? Multiple ones, actually. What does it mean to be “alive”, what is consciousness and how do we envision our interactions towards other living things on Earth.
What does it mean to be alive or to be conscious? I will probably leave these ones for philosophers. But in the age of AI and intelligent machines (we talked about this last week), we are facing new types of persona, of identities, of forms of being that question our own perception of what it means to be us — the self-proclaimed only conscious being in the universe. This unique type of being so worthy that it thinks of itself coming right down and built from a universal mighty Creator.
But let’s leave all this aside and focus on a more practical question: how do we interact with beings that may not be as simple to understand as we thought, or as well-positioned in the “circle of life” as we thought. Our now outdated binary approach to everything (good versus bad, in or out, 0 and 1) is constantly challenged as we learn that nothing really fits in a box today.
Now when it comes to making choices, it becomes quite a challenge doesn’t it? If we believe living beings should not suffer, the choice becomes obvious that we stop eating animals. But now plants suffer too. And just because we can’t hear them, doesn’t mean we shouldn’t consider their suffering. Although, let’s be honest, we have ignored many human voices when we wanted to really make them suffer so there’s that.
What we need is to envision the world through different frames, better yet different perspectives. Frames help our limited brains make sense of the world but, let’s not forget, those limits are subjective and usually based on biases that rely only on our own senses, ideas and experiences. But the experience of living goes beyond what humans can sense. So we need to be willing to go beyond what makes sense to us and maybe start thinking about how to educate ourselves about our experience of the world. For too long, we have kept our own experience as a yardstick to define what’s usual and what isn’t. That’s how we ended up with racism and prejudice towards other human beings. We never managed to learn how to push our boundaries, how to understand our own contradictions.
So as we now learn that plants are more “conscious” than we thought, it’s not only our diets that we should question, but the way we learn how to interact with the world, how to make sense of it and finally question how the experience of being human, of being conscious of our selves in the world has to be renewed and redesigned. Then, and only then, we may be able to approach those more mundane question, such as food, identity and interactions in a way that will be more inclusive but also more fit for a world that is really, on a daily basis, revealed to us as a kaleidoscope of contradictions more than a clear set of laws and principles.
Philippe - Founder & CEO - Pacific Ventury
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