A growing group of plant scientists and philosophers hold that plants sense their surroundings in many ways, signal to one another, remember and adjust their behaviour, and that this deserves to be called intelligence, even without a brain. Many other plant biologists reject the word, and the further claims that plants learn by association or are conscious are strongly disputed. Therapeutic Shamanism goes further than either side, teaching that plants are conscious beings with their own kind of intelligence, different from ours and in no way lesser.
What do scientists mean by plant intelligence? #
Usually not thinking in the human sense, but behaviour that is flexible and fitted to the situation. Plants cannot run away, so they respond to the world by growing, turning, changing their chemistry and adjusting their timing. The philosopher of science Paco Calvo separates mere adaptation from cognition by asking whether the behaviour is anticipatory, preparing for changes to come, flexible, responding to many different factors, and goal-directed.1 Others use a wider definition still. On the definitions, and on how far intelligence might reach beyond the human, see Is the living world intelligent?
What can plants sense and do? #
Far more than most people assume. Plants sense light, gravity, touch, moisture, chemicals in the air and soil, and the presence of neighbours. They release scents that warn other plants of insect attack, signal electrically along their stems, and turn their growing tips constantly as they explore. The idea is not new. In 1880 Charles Darwin, writing with his son Francis, compared the tip of a root, which directs the movements of the whole root, to “the brain of one of the lower animals”.2 A century later it became known as the ‘root-brain hypothesis’, and the plant physiologist Stefano Mancuso and the biologist František Baluška have both explored it, though Mancuso is clear that plants have no organ that remotely resembles a brain. In his view, a plant’s abilities are spread through its whole body.2
One of the most striking demonstrations is Calvo’s. The sensitive plant, mimosa, folds its leaves when touched, and under the same anaesthetic that vets use on cats and dogs it stops responding, as Venus flytraps and other plants do too. If plants can be put to sleep, Calvo asks, perhaps they have a waking state.3
Where did the field come from, and why is it disputed? #
In 2006 a group of scientists including Mancuso and Baluška proposed a new field they called plant neurobiology, studying how plants gather, pass on and act on information.4 The following year thirty-six plant scientists signed a letter in the same journal, “Plant neurobiology: no brain, no gain?”, objecting that the name suggested nerves, synapses and a brain that plants do not have.4 The quarrel over the word ran so deep that in 2009 the society founded for the new field changed its name to match its journal, Plant Signaling and Behavior.5
The deeper disagreement is about meaning. Critics such as the plant physiologist Lincoln Taiz hold that calling plant behaviour intelligent risks over-reading the data and reading purpose into it; he charged Calvo’s laboratory with falling prey to ‘animism’. Calvo’s reply is that caution is right, and that he “happily” takes on the burden of proof, but that the critics tie intelligence to the quick movements our own senses can follow. Time-lapse film, in his view, does not make plants look like animals; it simply makes their behaviour visible to us.5
Can plants learn? #
Some experiments suggest they can, and some of the results are in dispute. The ecologist Monica Gagliano found in 2014 that mimosa plants dropped repeatedly, without harm, learnt to stop folding their leaves, and kept the lesson for weeks.6 In 2016 she reported something bolder, that pea seedlings could learn to link a breeze from a fan with light, as Pavlov’s dogs linked a bell with food. When the plant scientist Kasey Markel repeated the pea experiment in 2020 he found no evidence of this kind of learning. Gagliano and her colleagues replied that his set-up let in too much stray light and that the light did not reliably steer the plants, so it could not test the question.6 The research goes on. See What did Monica Gagliano’s experiments suggest about plants learning?
Are plants conscious? #
Here the scientists divide most sharply. In 2019 Taiz and his colleagues wrote that plants “neither possess nor require consciousness”, and a related paper soon after warned that “dubious ideas about plant consciousness can harm this scientific discipline”.7 Others replied, amongst them the plant scientist Anthony Trewavas and Calvo himself, defending the study of plant behaviour as a form of cognition and holding that the question of plant experience is open to research.7 Calvo has proposed a test that might one day help to decide it, and for now the question stays open. See What does Paco Calvo argue in Planta Sapiens?
What does Therapeutic Shamanism teach about plant intelligence? #
That plants are conscious, something animists have long known from experience, and that some scientists are now reaching a similar view. Hunter-gatherers did not see plants as lesser than animals, or as things lacking consciousness and awareness, but as “conscious beings with their own kind of intelligence”, part of the PeoplesThe Peoples. The Animal People, Plant People, Standing People (the Trees) and Stone People: our elder kin, of whom the Human People are the youngest and least wise. A family, not a hierarchy. Read the full answer, with great teaching and healing gifts.8 Some scientists now recognise that plants are conscious too, though in a different way from us.9
The difference matters. Most tests of consciousness look for self-awareness, the human kind, so they find plants lacking. Plant consciousness is collective. Each plant is a tiny part of a far larger whole, its species, much as a single cell is part of a body.10 Plants also live at a much slower pace than animals, and one reason science missed how intelligent they are is that we had not slowed down enough to see it. Mancuso says the same, that “Plant lives unfold in another dimension of time”.11 To understand a plant from the inside, as Therapeutic Shamanism does in journeys, a person has to slow right down and let go of the animal drive to keep doing. See What are Plant People, and what gifts do they bring? and What are grokking, dieting and research in working with the Peoples?
Where the scientists argue over whether the word intelligence fits, animism does not need to settle it first. Plants are persons to be in relationship with, whatever their minds turn out to be.
