Nearly 100 years after Sir J.C. Bose proposed the radical idea, new evidence has surfaced that plants can think.
The dodder vine sniffs out a victim (1st) before strangulating it (above)
Professor Virginia Shepherd knows it isn’t easy being green in the world of physics: she’s a plant neurobiologist who wants to reinstate the idea that plants have a sophisticated electrical signalling system similar to the human nervous system. It is a controversial idea, first proposed by the multifaceted physicist Sir Jagadish Chandra Bose nearly a century ago.
“Bose had argued all along the importance of electrical signalling in plants, and the world has now come around to this view. I consider him my guru,” said Shepherd, a biophysicist at Sydney University in Australia, while delivering a lecture — titled Reflections on the Many-in-ones: J.C. Bose and the roots of Plant Neurobiology — to commemorate the scientist’s 150th birth anniversary last week at the Bose Institute, Calcutta.
Bose had shown that electrical activities are associated with the dipping of mimosa leaves and the rhythmic movement of desmodium leaflets, and that these plants have an electromechanical pulse, a nervous system, a form of intelligence and are capable of remembering and learning. “The idea was not well received and even ridiculed by the contemporary scientific establishment — perhaps because of a colonial or a racist bias against his work,” she suggested. Said Sibaji Raha, a physicist and the director of Bose Institute, “Bose extended his specialist knowledge of physics of electromagnetic radiation — which first made radio communication possible – into insightful experiments on the life processes of plants.”
Shepherd first got to know about Bose’s electrophysiological experiments 16 years ago when she stepped into the world of biophysics in her university. Ever since then she’s been trying to decipher how plant cells communicate with one another, how they sense touch, and how they transmit electrical signals.
Soon after she took up research, Shepherd discovered that she was not alone in the emerging field of plant neurobiology. “I found a growing body of research showing how plants perceive their circumstances and respond to their environment in an integrated fashion. And some sort of a structure of information network operates within the plants,” said Shepherd. Indeed, scientists around the world began discovering how the tiny strangle weed can sense the presence of friends, foes, and food, and make adroit decisions on how to approach them. Siblings of the sea rocket can recognise other plants that have grown from its own mother’s seeds and don’t compete with each other as fiercely as unrelated plants do. The ground-hugging mayapple was found to plan its growth two years into the future, based on computation of weather patterns. “The most remarkable finding, however, was the parasitic dodder vine’s ability to sniff out victims,” said Shepherd.
Last year, in a symposium on plant neurobiology, researchers at Pennsylvania State University showed a chilling video footage in which a dodder vine (Cuscuta pentagona) sinisterly sniffed for its prey and grabbed a succulent tomato plant. “It was amazing to watch that given the choice of wheat and tomato, the dodder picked the tomato,” she said.
However, in spite of such definitive evidence, most plant biologists are loath to believe that such responses to the environment are the result of active intentional reasoning. “Bose had proposed way back in the 1920s that plants are sensitive explorers of their world, co-ordinating movements and responses like intelligent organisms. The recent findings vindicate his work, reaffirming that plants have an integrated communication system. They have also been found to use the hormone auxin, akin to serotonin — a human neurotransmitter that transmits nerve signal,” says Shepherd.
Virginia Shepherd :->
Yet sceptics say it’s less a product of intelligence than mechanical directives. “For centuries, plants have been regarded as passive creatures. Their development is thought to be predetermined, with only temporary interruptions in response to stress,” Anthony Trewavas, a plant biochemist at the University of Edinburgh and a prominent scholar of plant intelligence, wrote in the journal Nature. The root of the problem is the assumption that plants have, or should have, human-like feelings in order to be considered intelligent life forms.
Shepherd believes that further damage was done by the 1970s hit book The Secret Life of Plants and the film based on it, which propagated quite unscientifically that greenery had feelings and emotions. Ever since then many scientists started avoiding discussions on plant intelligence. “Basically it was a clash of philosophies between materialistic and holistic thoughts, exactly like what happened in Bose’s time,” expounded Shepherd.
“But the attitude of scientists is changing quite substantially,” added Shepherd. Three years ago the Society for Plant Neurobiology was established to discuss research on plant signalling and behaviour at the molecular, genetic, cellular and electrophysiological level. “The society holds an annual meeting every year to discuss both sides of the controversy,” she added. Their heated arguments reiterate how Bose’s research is relevant till this day. “Intelligence isn’t only about having a brain, or eyes or ears,” she clarified. “If you define intelligence as the capacity to solve problems, plants have a lot to teach us,” she added.
Sources: The Telegraph (Kolkata, India)