Plants, in the words of Professor Jack S. Schultz, "are very slow animals." Schultz spent four decades studying the interactions between plants and insects. The scientist is familiar with the peculiarities of this process.
According to the researcher, plants fight for territory, are in search of food, evade predators and catch prey. Like animals, they demonstrate their behavior and can perceive the world.
The opinion of the scientist Olivier Hamant
“To see all this, you just have to make a quick movie about a growing plant,” says enthusiast Olivier Hamant, a scientist at the University of Lyon in France. Indeed, the time-lapse camera captures plant behavior in full, as anyone who has seen the Life series by David Attenborough can testify.
“Plants require sophisticated sensory devices that are tuned to different conditions to respond properly,” says Schultz.
So what is a plant? If you believe Daniel Chamovitz of Tel Aviv University, then his existence is not that different from ours.
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When Chamovitz set out to present his 2012 book What's Plant Knows, in which he explores how plants interact with the world, he was in awe. “I was incredibly careful about guessing what the public would react to,” he says.
Plants can feel
The study of plant perception has come a long way since the 1970s. In recent decades, more and more scientific works have been submitted to the public that describe the feelings of plants. The motivation for writing such works is not simply to demonstrate that "plants have feelings." Instead, the question arises as to why and how the plant senses its environment.
Heidi Appel and Rex Cockcroft, Schultz's colleagues in Missouri, have conducted research into hearing in plants. “The essence of our work was to justify why plants are affected by sound,” says Appel. Classical music doesn't really matter to the plant, but exposure to a hungry caterpillar produces a different response.
Scientists Appel and Cockcroft found that the buzzing of caterpillars triggers the release of chemicals from plant leaves that are needed to repel attacks.
We have noses and ears, but what does a plant have?
Consuelo de Moraes of the Swiss Federal Institute of Technology in Zurich, along with his collaborators, also claims that plants are endowed with senses. In parallel with the ability to hear approaching insects, they also have a sense of smell. Plants are able to smell the volatile compounds released by neighboring plants.
A 2006 study demonstrated how a parasitic plant known as a vine sniffs out a potential host. The vine begins to wriggle in the air before winding around the host and extracting nutrients from it.
“It is clear that there is nothing special about these plants. They just breathe or hear something and then act according to the situation, as we do,”says de Moraes.
Do plants and animals have something in common?
Of course, there are many important differences between plants and animals. “We really don't know how similar the mechanisms of smelling in plants and animals are, because we don't really understand the mechanisms that plants are endowed with,” says De Moraes.
But some features of science are still clear. For example, plant photoreceptors are well studied. Nevertheless, this area also deserves great scientific research.
Researchers Appel and Cockcroft hope to find parts of the plant that respond to sound. Samples have been identified that hint at the community of representatives of the flora and fauna. Probable candidates are receptor proteins found in all plant cells. They transform the smallest deformations generated by sound waves that envelop the object in electrical or chemical signals.
Scientists are testing whether plants with disrupted receptors can respond to insects. The plant doesn't seem to need an organ as bulky as the ear.
Another ability that plants possess is the "sixth sense." Some of us are endowed with it. Although the molecular structure of plants is very different from ours, they also have mechanical receptors that respond to changes in their environment.
In 2014, a team from the University of Lausanne in Switzerland showed that when an Arabidopsis plant is attacked by a caterpillar, it exhibits electrical activity, which is inherently not a new idea,”says physiologist John Burdon-Sanderson.
In this case, the leading role is played by molecules called glutamate receptors. Glutamate is an essential neurotransmitter in the central nervous system, but plants do not possess it.
Plants and animals are made up of a surprisingly limited set of molecular building blocks that are very similar. Electrical communication evolved in two different ways, using a set of building blocks that are believed to predate the split between animals and plants about 1.5 billion years ago.
“Evolution has triggered the development of a number of potential communication mechanisms, and while you can use them in different ways, the endpoint is the same,” says Chamovitz.
The realization that similar similarities exist, and that plants have a much greater ability to perceive the world around them than it seems at first glance, led to statements by some scientists about "plant intelligence" and even spawned a new scientific discipline.
The presence of electrical signaling in plants led to the emergence of "plant neurobiology" (the term is used despite the absence of neurons in plants). And today there are many biologists who experiment with plants in order to study aspects such as memory, learning.
Such scientific views have even led scientists from Switzerland to establish guidelines aimed at protecting the "dignity of plants."
Although the terms "plant intelligence" and "plant neuroscience" are considered metaphorical by many, they are still found in the writings of many biologists. Take Chamovitz's statement: “Do you think plants are smart? I think plants are complex. The complexity of all the mechanisms that plants are endowed with should not be confused with intelligence."
What is the danger of such bold theories?
The danger of such theories is that plants are ultimately seen as inferior versions of animals, which completely distorts our understanding of the plant world.
Plants may lack the nervous system, brain, and other traits we associate with complexity, but they show superiority in other areas. We are more like plants than we would like to think. Plants have different priorities, and their sensory systems reflect this.
Therefore, while plants face many of the same problems as animals, their sensory demands are equally shaped by the mechanisms that differentiate them. “Rooting plants implies that they really need to be much more aware of the environment than you or I,” says Chamovitz.
“The danger for people drawing the parallel between plants and animals is that if they continue to work like this, they may miss the true essence of plants,” says Hamant.
“I would like plants to be recognized as more amazing, interesting, exotic living things,” the scientist concludes. Genetics, electrophysiology, and the discovery of transposons began with research on plants, and all of this scientific research proved to be revolutionary for biology in general.
Conversely, the realization that we have something in common with plants can be an opportunity to recognize that we are more like plants than we would like to think, just as plants are like animals.