In the 1951 novel, The Day of the Triffids, author John Wyndham paints a terrifying picture of a world in which giant, walking, man-eating plants take over the planet Earth. Roger Corman’s 1962 film, Little Shop of Horrors, spins a similar yarn- a carnivorous plant who thrives on human blood becomes sentient, speaking to its caretaker and hypnotizing him to commit murder in order to feed him. While these tall tales are certainly nothing more than fantasy, it is hard not to wonder about the potential intelligence of plants when watching a venus fly trap ensnare and consume its prey.
We know that plants can sense their environment, they can remember, learn, and even pass this knowledge on to other members of their species. Obviously, plants do not have brains or nervous systems- which for some researchers, makes these behaviors all the more fascinating, since it implies a physical mechanism for intelligence so far unknown to science.
Some species of plants will release unappetizing chemicals when they sense they are being eaten. In 2014, a team of researchers used pre-recorded sounds of caterpillars chewing to prove that the plant’s reaction is actually triggered by the munching sounds of bugs. While there is still no explanation for how the plants manage to hear without sense organs, this study, and many others like it, have shown beyond a doubt that plants do in fact respond to sound. What’s more, they are able to use complex electrical signals to communicate this information to other plants- in some cases sending information miles away.
Scientists involved in this sort of research were laughed at just a decade ago, but today, the idea of plants perceiving their environment, reacting to it, and communicating with each other in seemingly intelligent ways has become accepted as scientific fact. The burning question of the moment is not “if” plants have some complex form of perception, but rather uncovering how this intelligence might work.
One plant biologist spent nearly 50 years observing truly inexplicable, seemingly conscious reactions from plants – concluding they not only demonstrate intelligence, they even appear to be psychic.
Cleve Backster founded the CIA’s polygraph unit shortly after World War II, and he built a successful career training military and law enforcement on the proper use of polygraph lie detector tests. He would often joke that his career was built on lies. But he would ultimately be remembered for a far more ambitious, and highly controversial, body of research.
Backster was working late one night in 1966. There was a large dracaena near his desk, and for some reason, he began to wonder how long it took for water to make its way from the plant’s roots to its tallest leaves. His polygraph equipment was designed to detect the slightest changes in moisture levels, and Backster theorized he may be able to detect the movement of water through the leaves of his plant.
When he attached the electrodes to the leaf, the results were far from what he expected: at first there was a burst of activity, which slowly calmed down and then flatlined. The experiment was a failure- the water could not be detected reaching the leaf. But just a few minutes later, another quick response was recorded on the polygraph machine. This time, the shape of the reading was familiar- it looked like an emotional response from a human subject.
Now intrigued, Backster set forth to replicate the response he had just seen. He tried dipping a leaf in some warm coffee, but the plant did not respond. He thought of taking a more drastic measure and imagined burning the plant with a match. At the exact moment he had this thought, the polygraph registered a dramatic response- it seemed as if the plant had read his mind, reacting in terror to the thought of being burned.
Working until well after sunrise, Backster continued his attempts to elicit response- and he kept encountering inexplicable results. That morning he would start developing the hypothesis which would drive his research for the next 47 years: Not only did plants show signs of consciousness and intelligence- they appeared to have some kind of psychic connection to humans and other living things in their environment.
In the interest of protecting his reputation, Backster kept these findings quiet as he continued testing a variety of plants in different circumstances. He tried other species of plants- he tried different times of day and different locations- he brought in other people to ensure he wasn’t some sort of plant-whisperer. The one constant in all of his experiments was that the plants did indeed react. After months of testing with high quality observations, Backster came to several conclusions about this phenomenon:
The plants responded most vigorously to images, as opposed to words or feelings. An imagined picture of the plant in a certain situation would record the strongest reaction. Curiously, the plants were able to distinguish between a genuine intention and an empty threat- if you imagined burning the plant, but had no actual intention of doing so, the plant would not react. Spontaneity played a role as well- repeatedly trying to elicit a response with the same stimulus would provide weaker results. Reminiscent of the boy who cried wolf, the plants would begin to tune out threats that did not result in direct action.
Perhaps the strangest effect to come from these studies, Backster found that the reactions were not limited by space or time. In one experiment, he measured a friend’s houseplants while their owner was traveling across the country. On three separate occasions, the polygraph recorded strong reactions at the exact moment his friend touched down on three different runways.
Backster expanded this research into increasingly strange dimensions. He found that a single leaf separated from the plant would register reactions from stimuli applied to the rest of the plant. He would later observe the same reactions in blood or semen taken from human subjects. In a downright bizarre turn of events, he discovered that yogurt, comprised of living bacteria, was incredibly sensitive to its emotional environment, eliciting strong responses to humans arguing nearby.
All of this lead him to a grander unified theory he termed “Primary Perception”: in his experience, all living things, whether plants, yogurt, our blood, or the simplest single celled organisms have some sort of conscious perception. His life’s work became a quest to prove that every living cell in our universe is connected in some fundamental and intelligent way.
Backster knew his research would be the target of extreme skepticism, and he became necessarily obsessed with his experimental methodology. He consulted with a great number of scientists to confirm he was operating in a super-controlled environment worthy of the most serious scientific research. Backster constructed elaborate automation systems to remove the human element from his experimental scenarios- building complex mechanisms for timing and executing events that were meant to elicit a response. He even went so far as to pay strangers, with no knowledge of the experiments, to purchase and transplant the subject plants, so as to eliminate the possibility that they may be psychically tipped off to what was in store for them.
After years of rejections from scientific journals, the International Journal of Parapsychology would print Backster’s first published work: a peculiar little experiment in which he recorded the empathetic response of plants to live shrimp being boiled nearby. Once published, the media was immediately fascinated with his work- and after years of secrecy and obsessive testing, Backster’s theories were thrust into the public eye.
Backster would have a huge influence on popular culture- most notably exemplified by the best selling book and film The Secret Life of Plants- but scientists would require replicated experiments before accepting these incredible hypotheses. Two research groups quickly heeded the call to replicate Backster’s shrimp study, with neither achieving successful replication. This set the tone for the rest of his career. Virtually the entire scientific community would reject Backster’s research due to consistently failed replication of his results.
While it is true that the incredible claims from his experiments have not held up to the rigorous scrutiny of the scientific method, Backster admits his research fundamentally resists testing via scientific replication. As he has often observed, the plants seem to be able to distinguish a legitimate intention from a phony threat. He has also demonstrated that they respond most strongly to spontaneous events, as opposed to the planned and repeated stimuli required for a replication study. Backster went to great lengths to produce these necessary conditions for his own research- and scientists taking a skeptical view to his work would often ignore these important factors in their pursuit of replication.
Yet despite the lack of recognition from his peers, Backster continued his experiments until his death in 2013- self-funding all of his work through his day job in polygraph training. And while the mainstream scientific community rejects Backster’s findings, his theory of Primary Perception is aligned with the research of Rupert Sheldrake and others who view consciousness as a force outside the bounds of our current accepted physics.
In ancient times, Peruvian shamans attributed their knowledge of medicinal plant usage to direct communication with the plants themselves- an unbelievable claim which nonetheless explains how they were able to deduce advanced chemical properties hundreds of years before the science to do so existed. Today, not even the most cutting edge mainstream science can lay claim to understanding how our own human consciousness works. Perhaps by looking more seriously at the apparent intelligence of plants, we could unlock some of the mysteries of our own conscious minds.