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There’s no doubt that
plants are extremely complex. Biologists believe that plants
communicate with one another, fungi, and animals by releasing
chemicals via their roots, branches, and leaves. Plants also send seeds that
supply information, working as data packets. They even sustain weak members of
their own species by providing nutrients to their peers, which indicates a
sense of kinship.
Plants have
preferences—their roots move toward water, sensing its
acoustic vibes—and defense
mechanisms. They also have memories, and
can learn from experience. One 2014 experiment, for
example, involved dropping potted plants called Mimosa
pudicas a short distance. At first, when the plants were dropped,
they curled up their leaves defensively. But soon the plants learned that no
harm would come to them, and they stopped protecting themselves.
But does any of this
qualify as consciousness? The answer to that question seems to depend largely
on linguistics, rather than science—how humans choose to define our conceptions
of the self and intelligence.
Plant biotechnologist
Devang Mehta, for one, says the answer to the question of whether plants are
conscious “is unreservedly no.” In a February article for Massive Science
entitled, “Plants are not
conscious, whether or not you can sedate them,” he
vehemently opposes the notion that plants can be conscious or intelligent.
Mehta was responding to a New York
Times story (paywall) about a 2017 study in Annals of
Botany. Researchers had arrested plant motion with anesthetics—a new
take on a 1902 experiment by biologist and physicist Jagadish Chandra
Bose, who used chloroform to put plants to sleep. The Times wrote
that the vegetal response to anesthetics suggests that plants are intelligent.
Basically, the article argued that to lose consciousness, one must have
consciousness—so if plants seem to lose consciousness under anesthetics, they
must, in some way, possess it.
The Grey Lady was making
a major leap when it suggested that plants responding to anesthetics indicates
intelligence, according to Mehta. He explains:
For
one, definitions of consciousness and intelligence are hotly contested even
when talking about humans and animals. Second, plants lack a nervous system,
which has long seemed requisite for
discussion of animal-like behavior. Third, while the way in which many
anesthetics function in humans is still a
mystery, there is no reason why they or other chemicals shouldn’t
induce a response in any organism, let alone plants.
Mehta believes that
plants deserve respect. He just thinks confusing their qualities and abilities
with those of humans is unnecessary anthropomorphizing. Venturing into the
territory of philosophers, he argues that in order to qualify as “conscious,” a
thing must be aware of its self-awareness, or meta-aware.
Danny Chamovitz, director
of the Manna Center for Plant Biosciences at Tel Aviv University in Israel,
says that plants are neither conscious nor intelligent, though they are
incredibly complex. Plant awareness shouldn’t be confused with the human
experience of existence. He tells Gizmodo, “All
organisms, even bacteria, have to be able to find the exact niche that will
enable them to survive. It’s not anything that’s unique to people. Are they
self-aware? No. We care about plants, do plants care about us? No.”
The thing is, Chamovitz
can’t prove that plants don’t care about us. No one can, really. We know that
hugging trees, literally, makes us feel better. It has a medicinal
effect. But we can’t test the reciprocity of this—whether plants love
us back, or feel good when we care for them.
Green philosophy
Philosopher Michael
Marder, meanwhile, says we’re underestimating plants. The author of Plant
Thinking: A Philosophy of Vegetal Life, Marder tells
Gizmodo, “Plants are definitely conscious, though in a different way
than we, humans, are.” He notes that plants are in tune with their surroundings
and make many complex decisions, like when to bloom. Marder concludes, “If
consciousness literally means being ‘with knowledge,’ then plants fit the bill
perfectly.”
That said, Marder admits
that we can’t know if plants are self-conscious, because we define both the
self and consciousness based on our human selves and limitations. “Before
dismissing the existence of this higher-level faculty in them outright, we
should consider what a plant self might be,” he says.
Marder points out that
plant cuttings can survive and grow independently. That suggests that if plants
do have a self, it is likely dispersed and unconfined, unlike the human sense
of self. It’s notable, too, that many scientists and mystics argue that the
human feeling of individuality—of being a self within a particular body—is
a necessary
illusion.
He further argues that
because plants communicate with one another, defend their health, and make
decisions, among other things, they may well have some sense of self, too. He
explains:
The
project of an ongoing vegetal integration through feedback loops and other
communication strategies and mechanisms may be considered analogous to what we,
humans, define as self-consciousness. The trick is to let go of our fixed
association of biological, if not psychological, structures and the functions
they fulfill, imagining the possibilities of seeing and thinking otherwise than
with the eye and the brain. Maybe once we manage to do so, we will finally
become conscious of plant consciousness.
Stuck in the self
Because we are steeped in
an ancient tradition of human-centrism, we believe that our experience of life
is what defines consciousness, and that our brain’s processes are the height of
intelligence. But there is some evidence that other modes of existence are
equally complex, which suggests that other living things have arguably
intelligent or conscious experiences.
Evolutionary ecologist
Monica Gagliano insists that plants are intelligent, and she’s not speaking
metaphorically. “My work is not about metaphors at all,” Gagliano
tells Forbes. “When I talk about learning, I mean learning.
When I talk about memory, I mean memory.”
Gagliano’s behavioral
experiments on plants suggest that—while plants don’t have a central nervous
system or a brain—they behave like intelligent beings. She says that if plants
can summon knowledge about an experience repeatedly—as was the case with the
potted plants that stopped curling their leaves after they learned they would
come to no harm—then plants are clearly able to remember and learn from
experience.
Gagliano, who began her
career as a marine scientist, says her work with plants triggered a profound
epiphany. “The main realization for me wasn’t the fact that plants themselves
must be something more than we give them credit for, but what if everything
around us is much more than we give it credit for, whether it’s animal, plant,
bacteria, whatever.”
She’s aware of the
criticisms of fellow scientists, who warn against anthropomorphizing
vegetation. But she argues that there is no other doorway to understanding the
inner life of all these other beings. Thinking about ourselves provides a
subjective sense of a tree or a shrub’s inner life, but it doesn’t preclude the
possibility that vegetations may be leading a rich existence in its own right.
On the contrary, it propels us to explore the difficult questions about their
lives. “To me, the role of science is to explore, and to explore especially
what we don’t know. But the reality is that much research in academia tends to
explore what we already know because it’s safe,” she argues.
Acknowledging plant
intelligence could put us in an awkward position. Perhaps there is nothing we
can eat that isn’t some form of murder, not even salad. Moreover, if we
discover plant kinship relations are real, we’ll need to acknowledge that
cutting trees down for furniture means splitting up families. More than that,
expanding definitions of consciousness and intelligence could mean admitting
we’ve been limited in our worldview altogether. What if everything around us is
intelligent in its own way, and we’re just not smart enough to see it?
“I’ve been talking to
people who work with amoebas and the slime molds and it’s the same all
over,” Gagliano tells
Forbes. “These guys, the critters, are amazing. They do stuff that we
don’t even dream of. And by not dreaming of it, we assume that it does not
exist.”
