“When I use a word,” Humpty Dumpty insisted in a rather disdainful tone of voice, “it means just what I choose it to mean—no more, no less.”
"The question," Alice insisted, "is whether you can make words mean so many different things."
"The question," Humpty Dumpty concluded, "is who's in charge… that's all."
Alice in Wonderland
Alin, a 10th-grade student, stopped me in the hallway this morning to ask my opinion about an interview published in El Heraldo de Aragón on May 18th (2017). The journalist, Patricia Luna, had come up with an eye-catching headline: “Plants are much more sensitive than animals.” In the article's introduction, Luna heightened the interest by posing the following questions:How do plants communicate? Are they intelligent beings? Do they have a social life? Do they collaborate altruistically with others of their own species?
It's easier to find inconsistencies in others than in your own. That's why, generally, when someone refers to these kinds of articles, it's because they want to highlight the inconsistencies in your animal-product-free lifestyle so they don't have to question their own daily habits.
But Alín doesn't have this attitude. Although he's not my student, he's attended activities about animal welfare outside of school hours, sent me emails asking questions about the topic, and shared his perspective. He's clearly interested in the subject. Our conversations have given me that strange feeling that someone is raising the possibility of plant sentience to learn about it, not to silence his conscience or find personal satisfaction in supposed contradictions in others.
I had heard myself say that what makes us different from most other living organisms is the capacity to feel (we say "most" because animals like sponges don't feel). But I had come across an interview that contradicted what I had argued. Moreover, the person interviewed had a clearly superior background on the subject than I did. The journalist introduced him as follows: "Stefano Mancuso (Italy, 1965), director of the International Laboratory of Plant Neurobiology at the University of Florence (Italy) and one of the world's leading authorities on plant neurobiology."
There are many articles about "plants that feel"; some are written by people with an esoteric viewpoint and therefore don't deserve a response. Others, however, are authored by recognized scientists (generally biochemists or biologists specializing in botany) who apparently don't share this viewpoint and therefore should be analyzed. Some of these articles present objective data, but in interpreting the facts and expressing empirical observations, they resort to confusing terms, prioritizing those that evoke emotions in the reader, despite the existence of more precise alternatives.
However, when we read that a “plant neurobiologist” speaks literally of friendships between plants, we tend to accept that the term used is appropriate. We are unaware that there may be various motivations that lead an author to seek out more appealing words for the reader. Some of these reasons may be legitimate. The richness of technical vocabulary for a particular field may be very high, yet only a small part is accessible to the non-expert public. This allows researchers to use the appropriate terminology in technical publications, but they must resort to accessible vocabulary when trying to contribute to scientific outreach.
That researcher—like Mancuso—could be the head of a scientific team, responsible for securing funding for her research project. In that case, she could benefit from media attention and, to that end, could communicate the results of her studies using expressions and terms that generate greater public interest. A headline like “A complex plant metabolic pathway has been discovered that, when faced with aggression X, generates a specific response, even at a lower intensity than that required to produce a response in the animal kingdom” doesn't grab attention. However, when we read the headline“Plants are much more sensitive than animals,” it is more likely to conclude that the content of the article deserves our attention.That's why authors who evoke emotion find more media attention than those who prioritize accuracy.
Although it may seem obvious, we must remember that the field of scientific research and communication is made up of people. Among these people, there are those who feel—usually rightly so—that society doesn't recognize their efforts and results as it should. This may also be the case for Mancuso. Perhaps, after many years of rigorous research, he's tired of seeing how the media pays so much attention to articles published by his colleagues in the field of ethology, while botanical publications barely generate any interest. But the author knows that by subtly playing with words—or interpreting facts in unusual ways—he can get journalists from other countries to contact him, without even needing to publish a new article, as happened with the interview we're referring to. By using striking expressions, he can get society to stop considering the plant world as something boring and can even surpass the fascination generated by animals.
In some cases, frustration can become an obsession, leading some authors to defend absurd positions, believing they have proven all their colleagues wrong on a particular topic. In the mid-19th century, Samuel Rowbotham decided to carve out a place for himself in history by claiming that the Earth is flat and that all the evidence provided by figures like Pythagoras, Copernicus, and Galileo was false. Despite the fact that we now have satellite images showing the curvature of our planet, and many other irrefutable proofs that our planet is an oblate spheroid, the number of adherents to the Flat Earth "theory" continues to grow. In fact, the group of scientists who defend this view has been organized since 1956, when astronomer Samuel Shenton founded the International Flat Earth Society. Since then, they have published dozens of "scientific" articles, and hundreds of geographers, astronomers, physicists, and others have joined this movement.
Although it may seem amusing, there is a problem behind these people, because it means – as with alternative "medicines" – that those who dedicate themselves to research and scientific dissemination are constantly forced to refute these pseudoscientific positions instead of using that time, energy and resources to advance scientific knowledge.
This story is also repeated in the field of “plant neurobiology,” of which Mancuso is a part. In 2007, a group of 33 experts in plant physiology published an article entitledPlant neurobiology: no brain, no gainin the journal TREND in Plants Science. The text, despite refuting the very concept of "plant neurobiology" with data and scientific reasoning, could also be included in the category of a manifesto, due to the indignation it conveys towards those who, like Mancuso, place an abstraction at the level of science.
The text begins: “The past three years have witnessed the birth and spread of a provocative idea in botanical science. It has been suggested that higher plants have nerves, synapses, the equivalent of a brain located in their roots, and intelligence. The idea has attracted a number of adherents, meetings have been held in different countries to address the matter, and an international society dedicated to “plant neurobiology” has even been founded. (…) We begin by stating simply that there is no evidence whatsoever that plants possess structures such as neurons, synapses, or a brain.”
It can also happen that an author feels such passion for their field of study that they seek equally passionate terms to convey their knowledge. It is not uncommon, for example, for ecologists to use metaphorical expressions such as "the marine ecosystem is suffering," "the Earth is crying out," or even "Mother Earth is asking for our help." Among those who use these expressions, there is a segment aware that the Earth cannot suffer or ask for help, but they consider it appropriate to speak in this way because they assume it is understood that they are using the words with meanings different from their usual ones. Therefore, this use of terms does not call into question the scientific competence of the ecologists involved; it calls into question our capacity for interpretation.
But as mentioned earlier, there is a smaller segment of the scientific community that literally believes our planet is crying out for help, like a drowning person. There are also doctors who advocate numerology, urine therapy, Reiki, or prayer as valid ways to treat certain illnesses. These views do call into question the author's scientific competence, but they also call into question our capacity for critical thinking. Someone's qualifications do not absolve us of the responsibility to evaluate the soundness of their position.
To delve deeper into these issues, the interview with Stefano Mancuso is an invaluable resource. When asked, “So, is sensing your (plants’) only means of survival?”, he responds, “Indeed, they sense changes in their environment long before others, allowing them to prepare. In this sense, plants are conscious organisms. Every plant knows exactly what the physical world around it is like and is able to detect changes in other organisms around it, such as other plants. They are able to change their physiology to counteract the change and survive.”
These words can, in fact, be applied to all living beings. Because the physiological capacity to interact with the environment that the author describes is a vital function, the function of interaction. Life requires that those who possess it be able to respond to environmental variations. The moment an organism fails to respond appropriately to external stimuli, the system collapses and the organism dies.
The author isn't saying anything untrue; he's simply choosing to use the term "feeling" to refer to this vital function. The problem is that feeling involves not only responding to stimuli but also the capacity to have positive or negative experiences. However, the researcher here doesn't explicitly argue that plants can experience sensations of pleasure and pain; perhaps he avoided it out of a sense of shame, knowing that this capacity had to wait at least until the Cambrian evolutionary explosion 540 million years ago, with the emergence of central nervous systems capable of transforming external stimuli into sensations.
He doesn't hesitate to use terms like "friendship," "communication," "altruism," or "intelligence" to talk about studies that have been known for decades. For example, he says, "(Plants) have a very rich social life; they are capable of interacting with each other in the same way as animals, and sometimes in a much more complex way. For example, plants normally compete for territory with other types of plants and species, and even within the same species if they are not related. If they are part of the same group, then they don't compete, but rather share the territory amicably."
Numerous studies demonstrate the ability of some plant species (as well as fungi and bacteria) to eliminate other species and promote the presence of evolutionarily closer relatives (generally of their own species) or of evolutionarily distant organisms whose presence benefits them (as in the symbiotic relationship of lichens). We only need to walk through a pine forest to see how fallen pine needles prevent the growth of competing plant species while encouraging the proliferation of organisms of their own kind. These are indisputable facts. What can be debated, however, is the conclusion that these biological processes reflect friendship or enmity.
Another example is his allusion to “communication” between plants. This term might lead the reader to think of an intention on the part of the sender and a rational interpretation of the message by the receiver. In the field of ethology, no one hesitates to use the term “animal communication,” and the use of “animal language” is becoming increasingly common. This is because it is known that there is intentionality involved. Those of us who live with dogs have seen them ask for water or food in many different ways. No one doubts that they are aware of what they are doing and that they do it with a specific intention.
Various studies show how some plants (and bacteria) produce a chemical response to an external threat, and this chemical is then used by other organisms as a stimulus to prepare for that same threat. The fact that the first organism is unintentional doesn't diminish the fascinating nature of the process. The problem is that Mancuso's fascination seems to lead him to use impassioned language that can misinterpret objective facts.
If we accept Mancuso's view that communication is a biological process like the one described, perhaps we should create another word to refer to what animals do, because using the same term won't make the mechanism the same; or at least we should be aware that it's a different meaning than the one we're used to. Animals, like plants, develop responses to chemical stimuli released by other animals or found in the environment. But when we talk about communication in the animal kingdom, we're not referring to those hormonal responses; we're referring to processes involving the central nervous system.
“Plant intelligence” is another favorite topic among those who work in “plant neurobiology.” Paco Calvo, a professor at the University of Murcia, a philosophy graduate, and a member, along with Mancuso, of the “Minimal Intelligence Lab,” also defends the existence of “plant intelligence.” Because they readily compare it to animal intelligence, and given that there is a general consensus in the field of ethology that the intelligence of a dolphin or a human is superior to that of a nematode, we might be tempted to email Mr. Calvo to ask him if the cognitive abilities of a chard are superior or inferior to those of a tomato plant, or if it would be possible to determine the intelligence quotient of a maritime pine. I took the trouble to send him these questions.
Dr. Calvo could have responded with an elaborate and imaginative excuse to justify that “plant intelligence” cannot be quantified in either absolute or relative terms (something that can be done with animal intelligence), or he could have been honest and acknowledged that the “intelligence” they were talking about has no relation to what we commonly understand as intelligence and is therefore not comparable to animal intelligence. But the professor simply replied with a disappointing and terse, “Who are you?” I don't know if this response was because the professor was able to detect the mockery in the question, despite my attempt to conceal it in my writing, or if he thought only a disturbed person could pose such ridiculous questions. However, these ridiculous doubts are consistent with his stance.
Calvo and Mancuso weren't the first to use terms from the animal kingdom to describe botanical processes. Jean-Marie Pelt, nicknamed the Konrad Lorenz of plants, managed to astonish the public with the secrets hidden within the plant kingdom. Later, using television, the magnificent David Attenborough would do the same. None of these authors would have succeeded in conveying their knowledge and sparking popular interest in botany had they refrained from using sensationalist language. But the fact that they had no other option doesn't absolve their audience of the responsibility to study their message with critical analysis and a degree of skepticism.
Actually, the use of metaphor—or exaggeration—also occurs in the study of animal behavior. I recall a story told by an ethology professor, an expert in myrmecology, about the mating of the monarch butterfly. He recounted how two German students had obtained two cocoons with their respective pupae inside, in the midst of metamorphosis. On the first night of the full moon, the adults emerged. One was a male butterfly, and the other a female. The male flew out of the bedroom window and, attracted by the female's pheromones, traveled more than ten kilometers to the second student's house. The professor's explanation was engaging and very precise regarding the hormonal response, but it was embellished with expressions like, "The female sent her mate a letter carried by the wind, telling him where to find her. The male went in search of her and managed to enter the room, where they made love until dawn." The objective facts are indisputable, the professor's knowledge of the subject is also indisputable, but one has to wonder if the words did not reflect his personal enthusiasm and the influence of the harmful ideal of romantic love.
All the answers that researcher Mancuso provides in the aforementioned interview are similar. They have an unquestionable scientific basis, but they are embellished with expressions and terms that can lead to confusion.
Of the “errors” he makes, perhaps the most significant is the first: using the words “feeling” and “consciousness” when referring to processes of interaction with the environment inherent in all living beings. This is an error with significant ethical consequences. Because only those who feel can experience sensations of pleasure or pain, and since our actions can benefit or harm them, they must be considered morally. Just as a blind person has no interest in a beautiful landscape, or someone without advanced mathematical knowledge has no interest in attending a course on Euclidean space, someone who lacks the capacity to enjoy life cannot have any interest in life.
When an art expert tells us what a painting “tells” us, or remarks that Michelangelo’s sculptures “are alive,” we understand that it’s just a figure of speech. Even if that expert were to argue that the term “life” is perfectly applicable to a sculpture, we would understand that this “life” would never be the same as what we usually mean when we talk about life. But if a botanist claims that plants “feel,” there seems to be a greater social receptiveness to accepting the term in its literal sense. They may do so out of honest ignorance; they don’t know what the word “feel” really means, or they are unaware that plants lack a nervous system or similar biological structures that could perform the same function. But they may also do so because accepting the idea that plants feel helps them conclude that eating an animal they have killed for that purpose is no worse than eating a plant.
In reality, just as they know that the "life" of Michelangelo's sculptures has nothing to do with the life of living beings, they know that the capacity of plants to "feel" cannot be equated with the capacity of animals to feel.
But let's do a final exercise. Let's suppose for a moment that they're right. Even though it seems ridiculous, let's accept that by pulling up a chard stalk, we're causing it as much pain as we cause a lamb by cutting its throat in a slaughterhouse. Let's imagine that plants can feel in the same way that animals do. Let's forget all the publications that demonstrate the relationship between the nervous system and the capacity to feel, and pay attention only to those minority articles that seem to say what some people want to hear. Let's accept that sentience is independent of the nervous system. Even in that case, using plant products would be more consistent with using animal products. Because to produce animals, it's necessary to feed them thousands of plants.