In Planta Sapiens (2022), the philosopher of science Paco Calvo argues that our idea of intelligence has been built around brains, and that by any fair test plants behave intelligently, anticipating, weighing many signals at once and acting towards goals, using electrical signalling along their stems that works much like a nervous system. He holds that whether plants are conscious cannot yet be known, but that it cannot be assumed they are not, and that the possibility should change how we treat them. He keeps his distance from animism, whilst Therapeutic Shamanism starts from the experience that plants are conscious beings, the Plant People.
Who is Paco Calvo? #
A philosopher of science at the University of Murcia in Spain, where he directs the Minimal Intelligence Laboratory, known as MINT Lab, which studies plant behaviour. Planta Sapiens: Unmasking Plant Intelligence was written with the writer and illustrator Natalie Lawrence, who drew its illustrations, and is told in Calvo’s own voice.1
The book opens with a demonstration he gave in Mauritius in August 2019, with a mimosa placed under a bell jar with an anaesthetic vets use on horses, cats and dogs, after which it no longer folded its leaves when touched; later he did the same with a Venus flytrap, whose trap stopped snapping shut. Even bacteria can be anaesthetised, and in his words, “To be alive is to be susceptible to anaesthesia.” If a plant can be put to sleep, he asks, does it normally have some kind of waking state?1
What is plant blindness? #
His name for the way most people barely notice plants at all. “We can see plants, of course, but we don’t notice them”, unless they flower spectacularly or get in the way. Part of the reason is our senses, which are tuned to fast movement; part is history. For centuries the West ranked all living things on the Great Chain of Being, with God and the angels at the top, humans below them, and plants at the bottom, only one rung above minerals, a scale of value that measured everything by how far it resembled humanity.2
The blindness is cultural, not universal. Calvo notes that other peoples have seen plants very differently, in some cultures as kin with a shared heritage, in others as persons with souls of equal standing. Yet souls are not his point. “We needn’t believe in souls to change the way we value and understand other life.”2
How does he tell intelligence from mere adaptation? #
With a criterion. Behaviour counts as cognitive, for Calvo, when it is anticipatory, preparing for changes to come; flexible, responding to many different factors; and goal-directed, aimed at changing things and not simply reacting to them.3 His favourite example is the Cornish mallow, Lavatera. During the night it turns its leaves to face where the sun will rise, before sunrise, and plants kept in total darkness in the laboratory go on facing the absent sunrise for several days.4
He reports the ecologist Monica Gagliano’s finding that mimosa plants learn to stop folding their leaves at a harmless disturbance and remember it for weeks, and her bolder report that pea seedlings learnt to link a fan’s breeze with light. He also prints that his own laboratory “has not yet replicated” the pea result.5 See What did Monica Gagliano’s experiments suggest about plants learning?
Do plants have something like a nervous system? #
Something that does a similar job. Calvo concedes at the outset that plants have no brain. But electrical signalling is not only a property of nerves, even in animals, as the beating heart shows, so there is no reason to deny it to plants because they lack neurones. Signals travel through a plant’s vascular bundles, the xylem and phloem that carry water and sugars, using some of the same signalling molecules as animal nervous systems. In his words, these bundles “are not neurones, but they have neurone-like features”, and he calls the whole arrangement a phytonervous system.6
Drawing on his work with the neuroscientist Karl Friston, he describes plants as running an internal model of their world and checking it against what they sense: “Like us, they are prediction machines with the ability to self-correct.” They need no layered cortex to do it, only signals flowing in both directions, “like opposing moving walkways in an airport.”7 And his laboratory looks less at what is inside a plant than at how it is bound up with its surroundings, following the psychologist William Mace: “ask not what’s inside your head, but what your head’s inside of”.8
What does he think it might be like to be a plant? #
He takes up the philosopher Thomas Nagel’s question, whether there is something it is like to be a creature, and comes at plants by way of the octopus, an animal whose intelligence is spread through its arms. The octopus shows that a very different nervous system can still do what we call conscious things, and a climbing vine, with its probing tendrils, might be similar.9 He insists on individuals: “You can’t actually imagine what it is like being just any plant, you can only imagine what it is like to be one specific plant at a time.” Mimosas of the same kind, in the same conditions, behave differently, and “plants are far from a uniform green mass.”9
Does he say plants are conscious, and what do his critics say? #
The question, for him, is open. Critics such as the plant physiologist Lincoln Taiz and his colleagues argue that subjective awareness needs a nervous system with something like a brain, that a plant’s way of life has no need of consciousness, and that calling plant behaviour intelligent risks reading purpose into it; Taiz charged MINT Lab with falling prey to ‘animism’.10 Calvo agrees that caution is right and says he “happily” takes on the burden of proof. His reply is that speeded-up film does not make plants look like animals, only makes their slow behaviour visible to us, and that there is no evidence that no brain means no awareness. “We cannot yet know if plants are conscious. But we also cannot assume that they are not.”10
He has proposed a test, PLANT-IIT, adapting a theory that measures consciousness by how far a system integrates information, whatever it is made of. His overall verdict is carefully worded: “it is very unlikely that plants are not far more aware than we intuitively assume.”11 See What does science say about plant intelligence?
What follows for how we treat plants? #
A real ethical problem, as he sees it. When he gives talks, the first hands up belong to vegans and vegetarians, whose case rests on plants being unable to suffer. There are no ethics committees for plant research in Australia “or almost anywhere else”, yet in 2008 a Swiss federal ethics committee declared that plants, as living beings, have a dignity to be respected for their own sake.12 He ends the book hoping that if we understand what it is like to be a plant we will learn how to live “in ways that work with the organic world rather than destroying it”.13 See What does animism say about killing and eating?
How does Planta Sapiens connect with Therapeutic Shamanism? #
On blindness and on slowness, closely. Most people struggle to recognise consciousness in anything very different from themselves, and plants are conscious in their own way.14 Plants also live at a much slower pace than animals, and the reason we had not realised how intelligent they are is that we had not slowed down enough; to understand a plant from the inside, a person has to slow right down.15 Calvo’s time-lapse films make the same point from the laboratory.
His Great Chain of Being is the ladder Therapeutic Shamanism sets out to take down. The idea that up is good and down is bad, that the sky is holy and the earth is not, lies behind the move from what the historian Yuval Noah Harari describes as a ‘spiritual round table’ to a spiritual hierarchy with humans at the top.16 In its place stands kinship: “This is not about hierarchy, but about family”, with humans the youngest and least wise 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.17 See What is the myth of human supremacy?
Where does Therapeutic Shamanism see things differently? #
First, on animism itself. Calvo does not want “to start a new animistic cult of nature worship”, and argues that “we must acknowledge that plants are animate without slipping into animism”; he sees animist religions as born of projecting ourselves onto the world.18 In Therapeutic Shamanism animism is far more than a belief. Animists experience the world as alive and conscious, and the aim is to experience it, not just to believe it.19 See Is giving things human personalities the same as animism?
Second, on where consciousness stops. Calvo draws his line at life, at beings that keep their own inner balance, which leaves out stones and rivers.20 In shamanism everything is made of Spirit, and so everything is conscious.21
Third, on the individual plant. Calvo stresses the individual plant, with its own way of behaving. Therapeutic Shamanism places plants far towards the collective end of a continuum from self-awareness to collective-awareness. Each plant is like one cell in a much larger body, and all the grass on the planet is part of one single consciousness.22 See What is an Oversoul?
