Speaker 1: Hey, you welcome to Stuff to Blow Your Mind. My
Speaker 1: name is Robert Lamb and I'm Joe McCormick, and it's Saturday,
Speaker 1: so we are heading into the vault for an older
Speaker 1: episode of the show. This one originally aired on April twelfth,
Speaker 1: twenty twenty two, and it's part one of a series
Speaker 1: we did on the question of whether plants have memories
Speaker 1: or anything analogous to memories. I remember thinking the series
Speaker 1: was really fascinating, so it should be a treat to
Speaker 1: re explore. Here you go. Welcome to Stuff to Blow
Speaker 1: Your Mind, a production of iHeartRadio. Hey, welcome to Stuff
Speaker 1: to Blow your Mind. My name is Robert Lamb and
Speaker 1: I'm Joe McCormick, and today we're going to be talking
Speaker 1: about an interesting and perhaps hidden property of plants. And
Speaker 1: to start us off, I wanted to read a selection
Speaker 1: from one of the lesser known works by the English
Speaker 1: Romantic poet Percy Bis Shelley. This is a poem called
Speaker 1: the Sensitive Plant. Rob Am, I write that you'd never
Speaker 1: heard of this one before. No, I you know, obviously
Speaker 1: I've read a little bit of Shelley here and there,
Speaker 1: but this must I'm assuming this is a deeper cut
Speaker 1: it is. I think it was one of the final
Speaker 1: things he wrote before his death, so this would have
Speaker 1: been I think sometimes in the early eighteen twenties, and
Speaker 1: it was published I believe as a standalone work at
Speaker 1: least at some point it was. I was reading through
Speaker 1: like a book version of it on that had been
Speaker 1: scanned into Google Books, and every other page on it
Speaker 1: was like washed out on the scan, so that was beautiful.
Speaker 1: But yeah, this one's kind of weird. It's it's not
Speaker 1: one of his best poems, but it has some really
Speaker 1: great lines in it. So I just wanted to read
Speaker 1: just a selection from it. It's too long to read
Speaker 1: in full, but this is an exerpt from the end
Speaker 1: of Part one of The Sensitive Plant by Percy BIS. Shelley.
Speaker 1: For the Sensitive Plant has no bright flower. Radiance and
Speaker 1: odor are not its dour. It loves even like love.
Speaker 1: Its deep heart is full. It desires what it has
Speaker 1: not the beautiful, the light winds, which from unsustaining wings
Speaker 1: shed the music of many murmurings, the beams which dart
Speaker 1: from many a star of the flowers whose hues they
Speaker 1: bear afar, the plumid insects, swift and free, like golden
Speaker 1: boats on a sunny sea, laden with light and odor,
Speaker 1: which pass over the gleam of the living grass, The
Speaker 1: unseen clouds of the dew, which lie like fire in
Speaker 1: the flowers till the sun rides high, then wander like
Speaker 1: spirits among the spheres, each cloud faint with the fragrance
Speaker 1: it bears, The quivering vapors of dim noontide, which like
Speaker 1: a sea over the warm earth, glide in which every
Speaker 1: sound and odor and beam move as reeds in a
Speaker 1: single stream, each and all, like ministering angels, were for
Speaker 1: the sensitive plant, sweet joy to bear, whilst the lagging
Speaker 1: hours of the day went by like windless clouds over
Speaker 1: a tender sky, And when evening descended from heaven above,
Speaker 1: and the earth was all rest, and the air was
Speaker 1: all love and delight, though less bright was far more deep,
Speaker 1: and the day's veil fell from the world of sleep,
Speaker 1: and the beasts and the birds and the insects were
Speaker 1: drowned in an ocean of dreams without a sound, whose
Speaker 1: waves never mark, though they ever impressed the light sand
Speaker 1: which paves it consciousness only overhead. The sweet nightingale ever
Speaker 1: sang more sweet as the day might fail, and snatches
Speaker 1: of its elysien chant were mixed with the dreams of
Speaker 1: the sensitive plant. Ah, very nice. Yeah, so I don't
Speaker 1: think it's one of Percy's best poems. Like I was saying,
Speaker 1: the rhythms a little too regular and singsongy. Sometimes. Some
Speaker 1: of the rhymes are a little obvious, you know, the
Speaker 1: rhyming love with above and all that. You could imagine
Speaker 1: like a an eighties rat bait thrown in the background
Speaker 1: some of those, or this could be a song like
Speaker 1: every Rose has its Thorn, you know, a monster ballad.
Speaker 1: But there are also lines. I really love the dew
Speaker 1: which lies like fire and the flowers, and the nighttime
Speaker 1: as an ocean paved under with the sands of consciousness.
Speaker 1: But it's esthetic qualities aside. I think it's really interesting
Speaker 1: that Percy is suggesting, in his unorthodox and emotionally charged
Speaker 1: view of the world, that this particular plant, the sensitive plant,
Speaker 1: which is a species of plant, may somehow have a
Speaker 1: kind of humanity of its own, like a soul or
Speaker 1: a mind, or, as I believe he implies later in
Speaker 1: the poem, an afterlife. So you might wonder why would
Speaker 1: he say that about this species of plant, which he
Speaker 1: acknowledges is not a particularly beautiful flower. It's it's a mimosa,
Speaker 1: so it's got a little pink, puffball kind of thing. Well,
Speaker 1: I think the answer is actually tied to some of
Speaker 1: the biological qualities of the sensitive plant as a species.
Speaker 1: So the sensitive plant is one of the mani names
Speaker 1: of Mimosa pudica, pudica being Latin for chaste or modest,
Speaker 1: shamefaced or bashful. And this is a flowering plant in
Speaker 1: the family Fabasi, which is the pea or lagume family,
Speaker 1: which means yes, this plant is a cousin of the
Speaker 1: common being. So we are we are dealing in bean
Speaker 1: can today, we're getting into into supernatural territory then, oh boy.
Speaker 1: Mimosa pudica is native to South and Central America and
Speaker 1: the Caribbean, though since transatlantic contact it has spread to
Speaker 1: all other parts of the world. I think it's pervasive
Speaker 1: throughout the tropics, and it's also known by tons of
Speaker 1: different names. It's called the humble plant, the shame plant,
Speaker 1: the touch me not, and all of these names connect
Speaker 1: to the most striking feature of this species, which is
Speaker 1: that it is a plant that recoils when touched. And
Speaker 1: this is one of a handful of examples of rapid
Speaker 1: movement in the plant kingdom, movement on the timescale that
Speaker 1: we would normally associate only with animals. So, if you
Speaker 1: want to picture it, the sensitive plant is a spiny
Speaker 1: little shrub that grows up to about a foot off
Speaker 1: the ground. It has these pink flower puffs and small
Speaker 1: forking branches with compound leaves. So to picture the leaves
Speaker 1: of this plant, they are the ones that kind of
Speaker 1: like a feather, you know, with a stalk running up
Speaker 1: the middle, and then lots of tiny, little pinile leaflets
Speaker 1: shooting out from that middle stalk, parallel to each other
Speaker 1: and perpendicular to the stalk, like the teeth of a comb,
Speaker 1: or like the barbs of a feather. And to see
Speaker 1: the sensitive plant in action, all you need to do
Speaker 1: is touch a finger on one of these branches, and
Speaker 1: suddenly what happens is the leaflets all fold inward like
Speaker 1: a closing suitcase. And then sometimes even the branch or
Speaker 1: the stalk that they're on will droop away, the stimulus
Speaker 1: will droop down. From what I can tell, there is
Speaker 1: not yet a full consensus on the main function of
Speaker 1: this shrinking behavior in the wild, like, why does it
Speaker 1: do that? But botanists have long suspected that it's some
Speaker 1: kind of defensive action by the plant to protect its
Speaker 1: leaves from grazing herbivores or insects. And this could actually
Speaker 1: work in multiple ways. So one of them is that
Speaker 1: maybe it works by physically moving the leaves away from
Speaker 1: a grazer. You know, something comes, spides, it's munching on
Speaker 1: the leaves, and this causes the leaves to kind of
Speaker 1: pull away from the mouth. Or it could work by
Speaker 1: hiding the leaves so you know, it is disturbed something
Speaker 1: is around, it might be trying to eat the plant,
Speaker 1: and by closing up it makes it less obvious where
Speaker 1: the leaves are. Yeah, and I guess one can imagine
Speaker 1: this working within the context of a you know, an
Speaker 1: enormous grazing animal that is eating a lot of plants.
Speaker 1: And it's maybe not gonna opt to really get particular
Speaker 1: about this one if this one has made itself smaller,
Speaker 1: you know, retreated into you know, amidst other plants, et cetera,
Speaker 1: Like it's just going to keep eating whatever is readily
Speaker 1: available to eat, right, But I think there's also a
Speaker 1: focus on insects maybe insects or also the reason it
Speaker 1: does this, and it could also work maybe by startling
Speaker 1: a predator like an insect or grazing her before because
Speaker 1: of course plants don't usually move rapidly like animals do.
Speaker 1: So you know, if you're an insect or whatever that's
Speaker 1: grazing and then suddenly there is movement on the timescale
Speaker 1: of animal movement in your in your vicinity, that might
Speaker 1: startle you and send you on the run. Yeah, on
Speaker 1: the timescale of animal movement. That's that's key. Because of course,
Speaker 1: the other main plant we think of in terms of
Speaker 1: this is the venus fly plant, which you know, we'll
Speaker 1: come back to, uh that. You know, that is a
Speaker 1: plant that is acting aggressively on the timescale of of
Speaker 1: of animals in an attempt to capture set an. But
Speaker 1: here we see the reverse. Here we see something that
Speaker 1: is that is acting, you know, defensively, that is moving
Speaker 1: away from us, that is not saying I want to
Speaker 1: touch you and envelop you, but I would rather not
Speaker 1: touch you at all. Yes, I would rather not. I
Speaker 1: would prefer not to. Yeah. So usually after a sensitive
Speaker 1: plant closes up its leaflets and droops away, it will
Speaker 1: reopen within some short time period, maybe only a few seconds,
Speaker 1: sometimes a few minutes, but it doesn't take long. It'll
Speaker 1: it'll open back up, get those leaves out there again,
Speaker 1: and start all over. And the sensitive plant also has
Speaker 1: a circadian rhythm to its closure, because it will close
Speaker 1: its leaves in the darkness and then reopen them in
Speaker 1: the daylight. Now, I found a wonderful post on j
Speaker 1: Store Daily by Rebecca Friedel about the history of Mimosa
Speaker 1: putica and also a similar Old World plant called Biophytum sensitivum,
Speaker 1: which is actually not a close relative of the sensitive plant,
Speaker 1: but does almost exactly the same thing with its leaves.
Speaker 1: So it looks like this would be a case of
Speaker 1: convergent evolution. But this article points to the work of
Speaker 1: a sixteenth century Portuguese naturalist living in India named Christo
Speaker 1: baal Acosta, who authored a book in fifteen seventy eight
Speaker 1: called Tractado de las Drogas e Medicinas de las Indias
Speaker 1: Orientales or Treatise on the Drugs and Medicines of the
Speaker 1: East and East Indies. I really wanted to find an
Speaker 1: English translation of this so I could quote it directly,
Speaker 1: because it sounds like it's a hoot, but I could not,
Speaker 1: So I'm going to have to rely on a couple
Speaker 1: of secondhand summaries, including a Friedel's article here. But anyway,
Speaker 1: in this book by Christo Baal Acosta in the sixteenth century,
Speaker 1: he describes a plant among the medicinal herbs of India
Speaker 1: called the yerba della more or the herb the herb
Speaker 1: of love? Do you ever say herb with the H pronounced? Sometimes?
Speaker 1: I'm afraid I'm going to keep doing that. Yeah, sometimes
Speaker 1: it slips out. Yeah, I don't know why. I try
Speaker 1: to fix this in my brain by like saying the
Speaker 1: name herb without the H pronounce. So like I go,
Speaker 1: I said, herb Herbert Hoover, Herbert Hoover. That'llfens it. Well, yeah,
Speaker 1: I mean it's easy to fall into because herbivore, herbivorec Anyway,
Speaker 1: why the herb of love? Why would it be called
Speaker 1: the herb of love? Well? Acosta says that, according to
Speaker 1: an Indian physician he talked to, the herb of love
Speaker 1: was a potent seduction drug with a one hundred percent
Speaker 1: success rate never fails. And after this passage, Acosta has
Speaker 1: an aside to assure readers of this medicinal catalog that
Speaker 1: he definitely never personally tried to use the sex herb, never,
Speaker 1: not once. Probably a good thing considering that other more
Speaker 1: well known sex herbs, if you will, are you know
Speaker 1: essentially poisons? Right? But aside from the dubious allegations about
Speaker 1: Cupid's aero type powers, this plant, the Herb of Love
Speaker 1: is remarkable for its ability to close its leaves rapidly,
Speaker 1: moving at the speed of an animal recoiling from a
Speaker 1: needle prick. And I was looking at another source which
Speaker 1: mentions Acosta. This is by JF. Veldkamp called Notes on
Speaker 1: Biophytom of the Old World, published in Taxon in nineteen
Speaker 1: eighty nine. I cite this just because Veldkamp tells a
Speaker 1: story that Acosta claimed he knew of a philosopher in Malabar,
Speaker 1: so region along the southwest coast of India. A philosopher
Speaker 1: who lived in Malabar who was so tortured by the
Speaker 1: mystery of the Herb of Love's rapid movement that he
Speaker 1: literally lost his mind trying to study it. He was like,
Speaker 1: how does it move? And that was it for him.
Speaker 1: No word on whether that guy ever used it for
Speaker 1: Cupid zero type purposes. Yeah, because again, and this will
Speaker 1: going to be something that will will discuss later as well.
Speaker 1: I mean it's it's acting in a way that other
Speaker 1: plants do not act. It seems unnatural, right, I mean
Speaker 1: if I had never seen a rapidly moving plant before
Speaker 1: and I just stumbled across one of these in the
Speaker 1: wild saw it folding up like that, I would be
Speaker 1: freaked out. I don't know what to think of this.
Speaker 1: I mean, it's hard to imagine because I grew up
Speaker 1: with venus flytraps, you know, Like I remember when I
Speaker 1: was a kid and I would have like one of
Speaker 1: those really boring weekend days where my mom wanted to
Speaker 1: go to the plant nursery and get some plants around
Speaker 1: the house. And I think my consolation there was that
Speaker 1: a couple of times I got a little potted venus flytrap. Yeah.
Speaker 1: They're pretty fun little plants. They always have a huge
Speaker 1: container of them out at the at the Bananical Garden
Speaker 1: in Atlanta for the kids to interact with and inevitably
Speaker 1: stick little sticks into their into their their their mouths,
Speaker 1: if you will. Right, so, we know about that one.
Speaker 1: But if you're previously unfamiliar with a plant like that,
Speaker 1: or or one of these leaf closing plants like Mimosa
Speaker 1: pudica or biophytum. I imagine it would be shocking. Yeah,
Speaker 1: I mean, we are hardwired really to topact that sudden
Speaker 1: movement in the grass might be something dangerous. It might
Speaker 1: be a snake, for example, Like, that's the first place
Speaker 1: my mind goes. If I'm on a walk and there's
Speaker 1: some sort of rustling in the bushes, it might be
Speaker 1: a snake, or it's something like a chipmunk or a squirrel.
Speaker 1: Probably not a squirrel because they're a bit bolder, but
Speaker 1: certainly the snake is never far from one's mind. Very true.
Speaker 1: So anyway, for several centuries there was confusion about how
Speaker 1: to taxonomize this plant that Christal ball Acosta was talking about,
Speaker 1: the Herb of Love, and Freedell points to an eighteen
Speaker 1: twenty five volume of the Botanical Register which says, hey,
Speaker 1: we know about this plant from South America called the
Speaker 1: Mimosa pudica. It does that leaf shutting thing. So maybe
Speaker 1: this herb of love that Acosta is talking about in
Speaker 1: India in the sixteenth century is actually the same plant.
Speaker 1: After all, it does seem that pretty quickly after transatlantic contact,
Speaker 1: the mimosa spread all around the globe. But now that
Speaker 1: doesn't seem to be the case. Botton are pretty clear
Speaker 1: that the herb of love was actually this other species
Speaker 1: I mentioned a minute ago, Biophytum sensitivum and Freedel rights.
Speaker 1: This was funny quote. Perhaps the erotic claims Acosta made
Speaker 1: so enthralled some that they failed to turn the page
Speaker 1: to the next entry on Erba mimosa, a likely description
Speaker 1: of the actual mimosa putica. Do your homework, guys, come on.
Speaker 1: But anyway, I was thinking about this mechanism, so immediately
Speaker 1: when I see a plant with rapid movement like this,
Speaker 1: the leaf closing behavior, I wonder how on earth does
Speaker 1: it do that? Because, of course we can move rapidly,
Speaker 1: but we can only do that because we have a
Speaker 1: nervous system and a muscular skeletal system muscles. Plants don't
Speaker 1: have either one. There are no muscles and a plant.
Speaker 1: So what mechanism could a plant use to contract on
Speaker 1: the order of seconds. Well, scientists have actually figured out
Speaker 1: the answer to this one. The types of movement on
Speaker 1: display in the sensitive plant and the rapid moving plants
Speaker 1: like the venus flytrap are known as seismoonastic movements, and
Speaker 1: these are an example of a bigger category of nastic movements,
Speaker 1: which can be defined by their difference from another type
Speaker 1: of plant movement called tropisms. Now, tropisms, I think we've
Speaker 1: all seen in action. You know what this is? View
Speaker 1: ever had house plants? A tropism is growth in a
Speaker 1: specific direction based on an external stimulus. So plants will
Speaker 1: grow toward a light source. In fact, right in front
Speaker 1: of me. Right now, I have a potted plant here
Speaker 1: on my desk, and over time its leaves all start
Speaker 1: reaching out for the lamp next to it, until I
Speaker 1: turn the pot around, and then gradually they all start
Speaker 1: to hook back in the opposite direction. And it just
Speaker 1: now struck me for the first time. That might sound
Speaker 1: kind of cruel, like I'm toying with it, but I
Speaker 1: really don't think the plant's feelings are hurt. Another example
Speaker 1: this would be trees seeing to grow around up power lines. Sure, yeah,
Speaker 1: So plants can grow in different directions responding to objects
Speaker 1: or stimuli in their environments. Nastic movements, in contrast to tropisms,
Speaker 1: are not oriented in the direction of a stimulus, but
Speaker 1: rather are fixed reflexes that are determined by the plant's anatomy. So,
Speaker 1: for example, a venus fly trap shows a nastic response.
Speaker 1: It doesn't go off in a particular direction to catch
Speaker 1: a fly, but rather, when it senses movement in its
Speaker 1: trap area, the hinge closes. So it has a predetermined,
Speaker 1: a directionally predetermined movement that is in keeping with the
Speaker 1: plant's anatomy, not in an adaptable direction. And the sensitive
Speaker 1: plant is another example of a nastic response. And I
Speaker 1: think it's interesting to note that the stimulus direction dependent
Speaker 1: movements of plants tend to be very slow, very very slow,
Speaker 1: and based on growth. Well, the few plants that are
Speaker 1: able to move rapidly in all cases that I'm aware of,
Speaker 1: certainly in most cases their movement is constrained to these
Speaker 1: directionally fixed reflexes. Now, of course, we animals have the
Speaker 1: best of both worlds, right, We can move rapidly and
Speaker 1: we have the flexibility to respond in whatever direction makes
Speaker 1: sense given the stimulus. But you know that's because we're
Speaker 1: different types of creatures, different anatomy, different energy requirements and
Speaker 1: so forth. But okay, that's nastic movements now, seis monastic
Speaker 1: movements are nastic movements that are triggered by touch or
Speaker 1: by vibration. Now again without muscles. How it all this work?
Speaker 1: How does the nastic movement actually happen? Well, here we
Speaker 1: come to a really excellent new word I learned. The
Speaker 1: word is terger spelled tur gr. It's a good like
Speaker 1: a leather diaper, Barbarian name. But it also it is
Speaker 1: a name for something that happens within plants. It's related
Speaker 1: to the word turgid or turgidity, and so within plants
Speaker 1: there is a principle called turger pressure. And one simple
Speaker 1: way to think about turger pressure is that it is
Speaker 1: like water pressure inside a plant. So you think about
Speaker 1: the difference between a wilted flower baking dry in the sun.
Speaker 1: You know it's parched, and you see it drooping over,
Speaker 1: and then you think about what that flower does after
Speaker 1: you water it. If things go well. Usually you give
Speaker 1: a wilted plant water and its leaves and stems stops
Speaker 1: sagging and they become rigid again. It stands straight up
Speaker 1: the you know, the it's it's almost like it's inflated
Speaker 1: like a balloon. Yeah, And in some plants it's it's
Speaker 1: it's amazing the difference just a quick watering can have.
Speaker 1: We have a linen bomb, and I always find that
Speaker 1: that one among our plants is the first to just
Speaker 1: immediately seem to give up the ghost and start wilting away.
Speaker 1: But then you know, you give it enough water and
Speaker 1: it's just back, just a bushy and full of fly
Speaker 1: as ever totally. In fact, you might have even observed this,
Speaker 1: not with a live plants, but giving some veggies in
Speaker 1: the kitchen a soak or even just to wash. This
Speaker 1: is a good trick for resurrecting what appeared to be
Speaker 1: wilted salad greens that are past their prime. You might
Speaker 1: think they're no good, you know, you got to toss them.
Speaker 1: You would be surprised how salvageable some greens are after
Speaker 1: a soak in cold water. Really like like spinach, the
Speaker 1: surf of spinach. I don't know if I ever tried
Speaker 1: it on spinach, but I've tried it on other types
Speaker 1: of greens, like you know, arugula and things like that
Speaker 1: that are you know, they're starting not not like if
Speaker 1: they're getting slimy, you know, but if they're just like
Speaker 1: they're clearly they're getting desiccated and wilted. It looks like, oh,
Speaker 1: these are going to be no good. Soak them in
Speaker 1: some cold water. They might come back to life and
Speaker 1: be crisp again. Okay, I didn't know about this trick,
Speaker 1: but now I will have to try this sometime. But anyway, So,
Speaker 1: turger pressure is when a plant's cells are swollen with
Speaker 1: water so that in the inside of the cells, within
Speaker 1: the plasma membrane, the water pressure is actually pushing out
Speaker 1: against the cell wall. And so when turger pressure is high,
Speaker 1: the plant is said to be turgid, and so to
Speaker 1: come back to the sensitive plant when the leaves are
Speaker 1: touched or disturbed and electrochemical chain reaction is set off,
Speaker 1: It's sensed by cells in the leaves and then it
Speaker 1: sets off this electrochemical chain reaction that eventually ends in
Speaker 1: water gushing out from so called motor cells at the
Speaker 1: base of the leaflets that were previously turgid. So the
Speaker 1: sudden loss of turger pressure the cells purging their water
Speaker 1: contents causes the leaflet to move, basically to collapse at
Speaker 1: it's hinge, and this is known as turger movement. So
Speaker 1: in a strange way, you can think about it like
Speaker 1: the plant moving by causing itself to very selectively and
Speaker 1: rapidly wilt like a parched plant. Then over the course
Speaker 1: of the following minutes, turger pressure can be restored and
Speaker 1: the leaves go rigid again, and they go back to
Speaker 1: their extended state. But to come to the next thing,
Speaker 1: even more astonishing than the plant's ability to behave physically
Speaker 1: in ways that seem more at home in animals with muscles,
Speaker 1: is potential evidence that the Mimosa pudica may also, in
Speaker 1: a qualified sense, behave mentally in ways that seem more
Speaker 1: at home in animals with brains. Specifically, there has been
Speaker 1: research arguing that this plant, an organism entirely without a
Speaker 1: brain or without a nervous system, actually has its own
Speaker 1: rudimentary form of memory. And we'll talk about one of
Speaker 1: the studies allegedly showing this in a minute, But first
Speaker 1: I thought it might be good to spend a few
Speaker 1: minutes disentangling concepts about the alleged mental or cognitive properties
Speaker 1: of plants, because I think once you get into this area,
Speaker 1: you run a whole gamut of different types of claims
Speaker 1: of extremely variable evidential backing. Yeah, and you also get
Speaker 1: into into areas of confusion over like what constitutes animal
Speaker 1: intelligence and human intelligence and so. Yeah, so I thought
Speaker 1: it might be helpful to sort through some sort of
Speaker 1: general ideas regarding the nature of plants in Western thought.
Speaker 1: Fourth century BC thinker Aristotle, of course, casts along shadow,
Speaker 1: and he wrote that plants have a vegetative soul or
Speaker 1: two threpticon, which I believe just means the vegetable soul,
Speaker 1: not to be confused with two megatherion, which means the
Speaker 1: great beast in Greek and is of course a Celtic
Speaker 1: Frost album. But I couldn't help but think of that
Speaker 1: when I was reading about two threpticon. Yeah, a lot
Speaker 1: of these well, so there were people in like the
Speaker 1: nineteenth century and stuff who were very interested in the
Speaker 1: sensitive plant, and I think a lot of them made
Speaker 1: references back to Aristotle, like this is what Aristotle was
Speaker 1: talking about. Plants have a soul, they can feel right,
Speaker 1: but of course yes and no right, because they are
Speaker 1: two important things to keep in mind about all of it.
Speaker 1: First of all, he attributes nourishment and reproduction to the
Speaker 1: plant soul, and we have to remember that the Greek
Speaker 1: notion of a soul or suka is rather different than
Speaker 1: modern or even early Christian notions of a soul. We're
Speaker 1: not talking about like an inner ghost person that moves
Speaker 1: on and has an afterlife, that sort of thing. This
Speaker 1: would be more like the concept of a mind or
Speaker 1: or would it be like the idea of an animating breath.
Speaker 1: There are a lot of different ideas of things that
Speaker 1: get translated into English as soul from the ancient world. Yeah.
Speaker 1: I was reading about this in an excellent paper that
Speaker 1: I will probably continue to refer to in this series
Speaker 1: by Michael Martyr from twenty twelve in Plant Signal Behavior
Speaker 1: titled Plant Intentionality and the Phenomenological Framework of Plant Intelligence.
Speaker 1: And in this he writes that the soul in this context,
Speaker 1: in Aristotle's context, is quote a set of active capacities
Speaker 1: of an organism, not an invisible entity connected to the divine. Okay,
Speaker 1: that makes sense. So the soul is sort of like
Speaker 1: the essence of the organism. It's like what the form
Speaker 1: of the organism apart from its physical body. Right. And
Speaker 1: while the vegetative soul here is defined by nourishment and reproduction,
Speaker 1: animals and humans additionally have capacities of sensation and rational
Speaker 1: thought added atop these baser soul characteristics. Now, I think
Speaker 1: an interesting division there is that, So it's attributing animals
Speaker 1: and humans with sensation and rational thought. I think a
Speaker 1: lot of people have made what seemed to me to
Speaker 1: be pretty spurious claims about evidence for rational thought in plants.
Speaker 1: But I would say it's completely uncontroversial that plants experience
Speaker 1: a form of sensation. They can gather information about their environment,
Speaker 1: and they do constantly. Yeah, but in Aristotle's hierarchy, you
Speaker 1: have basically of animals, and then you have plants, and
Speaker 1: they of minerals. And there's also this added caveat that
Speaker 1: aspects of the vegetative soul continue on into forms that follow,
Speaker 1: which which might not be all that helpful in what
Speaker 1: we're thinking about here, but perhaps bears mentioning. Now, aristotle
Speaker 1: shadow again is long, and we see his ideas carried
Speaker 1: on into medieval Europe. Thirteenth century CE thinker Thomas Aquinas
Speaker 1: wrote in Puma Theology that quote, the very fact that
Speaker 1: the acts of the vegetative soul do not obey reason
Speaker 1: shows that they rank lowest lowest, lower than minerals. Or
Speaker 1: was he not lower than minerals? But I think it
Speaker 1: was in reference to animals and of course humans. Yeah. Now,
Speaker 1: one thing that that Martyr points out is that while
Speaker 1: the Aristotle view here, you know, it kind of used
Speaker 1: plants as baser and that they're only carrying out nourishment
Speaker 1: and reproduction. But he writes that that's that's actually it's
Speaker 1: actually quite impressive within the modern context of certainly planned
Speaker 1: intelligence research, because these impulses nourishment and reproduction quote entail
Speaker 1: complex decisions related to the avaiability of resources. Now that's
Speaker 1: interesting because that could be on one hand, very true,
Speaker 1: but also could easily be misinterpreted to lead people to
Speaker 1: unjustified conclusions. And I want to get into a little
Speaker 1: more disentangling on concepts in a minute here, but yeah,
Speaker 1: flag that. Yes, Martyr also adds quote Additionally, plants express
Speaker 1: almost all known neurotransmitters, confirming the extension of twothrepticon well
Speaker 1: beyond the activities Aristotle and his followers allotted to them. Hence,
Speaker 1: the lines of demarcation between the higher and the lower capacities,
Speaker 1: between consciousness and non consciousness, and by implication, between biological
Speaker 1: regna are not as rigid as classical thinkers believed. And
Speaker 1: there are a few other strains of more modern thought
Speaker 1: that Martyr shares He points out that, according to late
Speaker 1: eighteenth and early nineteenth century German philosopher Hegel, plants are passive,
Speaker 1: they have negative selfhood, and they lack quote an organismic whole. Okay,
Speaker 1: I don't know what that means, but that's Hegel. Yeah,
Speaker 1: not a not a plant fan. Nineteenth century English naturalist
Speaker 1: Charles Darwin, on the other hand, this I believe was
Speaker 1: like a later thing that he wrote about. But he
Speaker 1: had the root brain hypothesis that held that the root
Speaker 1: apex of a plant served as a brain like oregon,
Speaker 1: that was both sensitive and capable of navigating soil in
Speaker 1: search of resources. Now, I think it might be going
Speaker 1: a little overboard to call it brain like, but Charles
Speaker 1: Darwin was clearly enthralled by plants like the venus flytrap,
Speaker 1: Like he got really excited about what this means. And
Speaker 1: maybe we can come back to Darwin in part two
Speaker 1: of this because I think some of his ideas might
Speaker 1: connect more to to some of the research we're going
Speaker 1: to talk about later on. Yeah, it's my understanding, and
Speaker 1: I believe the author mentions this that some of these
Speaker 1: ideas that Charles Darwin had regarding this root brain hypothesis
Speaker 1: like they've people have come back to them in modern
Speaker 1: plant intelligence research and said, well, yeah, there's more to
Speaker 1: this than the people of Darwin's day thought. Then there's
Speaker 1: also a nineteenth century German philosopher, Frederick Nietsche, who is
Speaker 1: very much I believe, inspired by Darwin. In this wrote
Speaker 1: that a plant's nourishment and growth are expressions of its
Speaker 1: will to power, or the wills whore mocked, which he
Speaker 1: identifies as the core driving force behind human beings. Oh
Speaker 1: my god, So this this potted plant in front of me,
Speaker 1: when it reaches for the lamp and then I turn
Speaker 1: it around, I am thwarting its will to power, but
Speaker 1: I am like the naysaying crowd that it must rebel
Speaker 1: against and show its might. Yeah, and every day you
Speaker 1: don't kill it, you make it stronger. Right now. In
Speaker 1: Eastern thought, there are of course strong traditions of all
Speaker 1: of this, as discussed in, among other many sources, in
Speaker 1: Richard Nespit's The Geography of Thought. China's Taoism and Japan's
Speaker 1: Shintoism both emphasize the spirits of animals, plants, natural objects,
Speaker 1: and artifacts. And for my part, I've been reading a
Speaker 1: little bit about this um earlier when I was looking
Speaker 1: for things to cover for artifact and monster fact episodes.
Speaker 1: But you know, I don't want to steal any thunder
Speaker 1: from some possible potential episodes long or short form about these.
Speaker 1: But you know, we have strong folkloric, legendary, and mythological
Speaker 1: concepts of plant animal hybrids, which, of course, with all hybrids,
Speaker 1: they certainly perform various functions in symbolic, metaphoric and supernatural thought,
Speaker 1: but they also raise the question inevitably of animalness in
Speaker 1: plants and plantness in animals. You know, like you you
Speaker 1: can't think of something like say a screaming man Drake,
Speaker 1: or say the vegetable lamb of Targary. You know this
Speaker 1: this sheeplike thing that is growing out of the ground
Speaker 1: that is a plant but also seems like an animal,
Speaker 1: Like you can't. I don't think you can really have
Speaker 1: a concept like that without it's sort of by blurring
Speaker 1: the lines, by invoking the hybrid, making you think about
Speaker 1: the characteristics of the opposite side that are present in
Speaker 1: this side. Yeah. Yeah. In fact, I think several years
Speaker 1: back we did an October episode called something like the
Speaker 1: Killer Tree that was a Legends of Trees that would
Speaker 1: eat people. It's a surprisingly common recurring motif, though apparently
Speaker 1: has no basis in real biology. No, but I mean
Speaker 1: certainly not at the not not on the the animal
Speaker 1: time scale of things, but I guess on the plant
Speaker 1: time scale of things. Yeah, you can get into more
Speaker 1: nuanced discussions of plants eating people, plants eating human corpses
Speaker 1: and that sort of thing, right, but not the active
Speaker 1: predation like in that Oh it's that is like a
Speaker 1: William freed Can movie about the killer tree that that
Speaker 1: gobbles people up. Oh my gosh, I don't remember this one. Okay, yeah,
Speaker 1: we'll have to revisit. But there, Yeah, there are clearly
Speaker 1: a lot of killer trees and tree I mean you
Speaker 1: have things like the ants, right, yea trees walking around
Speaker 1: like humans. And yeah, all these concepts. They they they're
Speaker 1: performing a number of different functions. But I think one
Speaker 1: of them is that it inevitably makes you think about
Speaker 1: about plants and animals, what do they have in common?
Speaker 1: In what ways do they differ in? Indeed? Yeah, in
Speaker 1: what ways might they be more alike than we often realize.
Speaker 1: Another thing is that as we're going forward talking about
Speaker 1: research potentially indicating something like a plant basis for memory
Speaker 1: or learning. I think we also have to be very
Speaker 1: careful because the whole the realm of plant, so called
Speaker 1: plant cognition research, I think, has a history that is
Speaker 1: filled with stuff that is not so great. Like there
Speaker 1: are a number of different concepts regarding the hidden complexity
Speaker 1: of plants that people seem to get confused with each other.
Speaker 1: And this is unfortunate because these topics range from what
Speaker 1: appears to me to be maybe controversial but at least
Speaker 1: potentially evidence backed biology, and that would be things like,
Speaker 1: you know, some of the memory research we're going to
Speaker 1: talk about, all the way over to pure pseudoscience and
Speaker 1: paranormal stuff. And just to give some quick flavor of
Speaker 1: the latter end of that spectrum, I'm reminded of something
Speaker 1: we talked about briefly in an episode that we did
Speaker 1: a long time ago. Robie, remember when we did the
Speaker 1: Science of Stranger Things at New York Comic Con. Yes,
Speaker 1: I do remember this, So it was in the context
Speaker 1: of that episode we were talking about government research into
Speaker 1: psychic and paranormal phenomena during the Cold War, which absolutely
Speaker 1: did happen, and the extent of it is hilarious. But
Speaker 1: I read a couple of whole books about this. Of course,
Speaker 1: one if you want to quick read that's very funny
Speaker 1: is The Men Who Stare at Gohost by John Ronson.
Speaker 1: But also there was a book by Annie Jacobson that
Speaker 1: was a big, complete, sort of history of the Stanford
Speaker 1: Research Institute and all of these normal government research projects
Speaker 1: that were fueled by Cold War paranoia but looked into
Speaker 1: They looked into things like remote viewing and telekinesis and
Speaker 1: stuff like that, and unfortunately, I think a lot of
Speaker 1: that was just was just tricks and poorly designed experiments.
Speaker 1: But but but one brief episode from this, one of
Speaker 1: the people we talked about in that episode was a
Speaker 1: CIA interrogation expert named Cleave Baxter, who specialized apparently in
Speaker 1: narcotic and hypnotism based interrogation techniques and then later in
Speaker 1: the polygraph and according to a twenty thirteen New York
Speaker 1: Times article I was reading about Baxter by Josh Eels,
Speaker 1: Baxter developed a method for conducting polygraph sessions called the
Speaker 1: Baxter zone comparison technique, which according to this article, is
Speaker 1: still used in polygraph tests today. So cool. Anyway, later
Speaker 1: in his career, Baxter quite famously became upset with the
Speaker 1: idea that plants could read our minds, and he claimed
Speaker 1: to show it with experiments. So the discovery of this
Speaker 1: The story goes like this. One night in nineteen sixty six,
Speaker 1: Baxter stayed up all night, he was drinking coffee, and
Speaker 1: he got an amazing idea. He would hook a potted
Speaker 1: plant up to a polygraph machine. I guess, I don't
Speaker 1: know if he was going to see if it was
Speaker 1: telling lies, or maybe you just I don't know. So
Speaker 1: allegedly this plant was a quote corn plant or dressina fragrans, which,
Speaker 1: in a confusing twist, is completely different from the plant
Speaker 1: za maze, which is the grain plant that produces maize
Speaker 1: or corn, the food. So this is called a corn plant,
Speaker 1: but it's not the corn that would be planted in
Speaker 1: as a crop. The corn plant had been a gift
Speaker 1: from his secretary, intended to brighten up his office, which
Speaker 1: I have not seen pictures of. I don't know what
Speaker 1: was in there, but I'm imagining a kind of dungeon
Speaker 1: full of chairs with leather straps on them and needles
Speaker 1: full of quack truth serums. So yeah, you can imagine
Speaker 1: some plants would be nice, Yeah, you want to get
Speaker 1: some corn down there. So from here I just want
Speaker 1: to quote from the article by Eels summarizing this experiment. Quote.
Speaker 1: In human subjects, a polygraph measures three things pulse, respiration rate,
Speaker 1: and galvanic skin response otherwise known as perspiration. If you're
Speaker 1: worried about being caught in a lie, your levels will
Speaker 1: spike or dip. Baxter wanted to induce a similar anxiety
Speaker 1: in the plant, so he decided to set one of
Speaker 1: its leaves on fire, But before he could even get
Speaker 1: a match, the polygraph registered an intense reaction on the
Speaker 1: part of the dressina. To Baxter, the implication was as
Speaker 1: indisputable as it was unbelievable. Not only had the plant
Speaker 1: demonstrated fear, it had also read his mind. So Baxter
Speaker 1: became convinced that plants had psychic powers, consisting of a
Speaker 1: sensibility that he called primary perception, which they could use
Speaker 1: to read our minds and emotions from Afar and upon
Speaker 1: this disc every he did what any responsible seeker of
Speaker 1: the truth would do. He went straight to the popular media,
Speaker 1: and there was a book based on his claims, and
Speaker 1: apparently he did a TV spot, multiple TV spots, but
Speaker 1: I like Johnny Carson and stuff, but one of them
Speaker 1: I wanted to note was, apparently with Leonard Nimoy, was
Speaker 1: this in search of. I don't know if the timeframe
Speaker 1: is right for that. I don't know if the timeframes
Speaker 1: right either, but yeah, Ansling makes me think of in
Speaker 1: search of. And unfortunately, skeptical scientists were unable to reproduce
Speaker 1: his results. They tried to do the same thing and
Speaker 1: got nothing. But if you poke around about this on
Speaker 1: the internet, you will find many believers even today, still
Speaker 1: overflowing with faith in Baxter's claims. It's one of those
Speaker 1: ideas that lots of people just seemed to like. It
Speaker 1: feels really true and wholesome and good to believe. Yes,
Speaker 1: plants can think, they can feel, they can know what
Speaker 1: we're thinking if we tell them, or maybe even if
Speaker 1: we don't tell them, if we just think it really hard,
Speaker 1: they can detect it somehow. But obviously there are there
Speaker 1: are major problems if you're trying to put together a coherent,
Speaker 1: scientifically informed worldview. First of all, I would say the
Speaker 1: theoretical basis is weak. Like you know, we could always
Speaker 1: discover something new, but it is not clear that there's
Speaker 1: any kind of physical mechanism that could allow something like that.
Speaker 1: And then the second part is just the empirical basis,
Speaker 1: like the controlled experiments by skeptics don't find the same thing.
Speaker 1: So yeah, this appears to be nonsense. I can't help
Speaker 1: but wonder if okay, this experiment was sixty six. Frank
Speaker 1: Herbert's Dune was first published in sixty five, and of
Speaker 1: course has the very early on in the novel, has
Speaker 1: the scene where we have the benijesra at test of
Speaker 1: the box and the com jabbar the box, which of
Speaker 1: course makes you feel like your hand is burning and
Speaker 1: on fire. And here in this test behalf part of
Speaker 1: the plant is actually caught on fire. Wow, that's interesting.
Speaker 1: Yeah yeah. And the box is supposedly a kind of
Speaker 1: polygraph of its own yeah yeah, yeah yeah, And of
Speaker 1: course you have the benegestrate, yeah, truthsayers and so forth. Though,
Speaker 1: I think in our episode on that did we both
Speaker 1: come to the conclusion that we think that the real
Speaker 1: power is the box actually does nothing and it's just
Speaker 1: all it's all the reverend mother like she's the real test. Yeah.
Speaker 1: I think it's ultimately unknown, but we did. I think
Speaker 1: we both liked that idea the most. Yeah, it felt
Speaker 1: the most herberty of the ideas. It's just a prop
Speaker 1: But anyway, So to come back to all this, so
Speaker 1: we're going to be talking about plant memory research. But
Speaker 1: I think I want to be clear that if you
Speaker 1: say that a plant could have such a thing as
Speaker 1: a memory or an ability to learn, that is truly
Speaker 1: surprising and fascinating. But it is not the same thing
Speaker 1: as saying or showing that plants can quote think, that
Speaker 1: plants are conscious, that plants have emotions, or that they
Speaker 1: get upset when you say or do negative things around them,
Speaker 1: all of which are claims that people have tried to
Speaker 1: make over the years, but which seemed to me to
Speaker 1: be lacking in evidential basis, with the possible exception of
Speaker 1: quote thinking under some very broad or inclusive definitions of
Speaker 1: what counts has thought. Yeah. Like Another area related to
Speaker 1: this is the relationship between plants and sound. So can
Speaker 1: plants respond to sound, Yes, they can, But can do
Speaker 1: plants then benefit from listening to music? No, there's there's
Speaker 1: no evidence for that. But I mean, this was an
Speaker 1: idea that was very much in the zeitgeist, especially in
Speaker 1: the nineteen seventies. That's where there was actually a wonderful
Speaker 1: album that came out, an early electronic music album by
Speaker 1: Mort Garson, who is a you know, early synth wizard
Speaker 1: who did a lot of a number of different projects
Speaker 1: under different names, but he put out this this album
Speaker 1: titled Mother Earth's Plantasia, and it is supposed to be
Speaker 1: music that you play for your house plants, and your
Speaker 1: house plants then benefit from it. I don't think house
Speaker 1: plants actually get nothing out of listening to this album,
Speaker 1: but it's a wonderful ambient, experimental electronic album for humans.
Speaker 1: I love this. I would say I'm all for playing
Speaker 1: music for your plants. I don't think it does anything
Speaker 1: for the plants, but playing music for your plants might
Speaker 1: do something nice for you. Yeah, yeah, just like the plant.
Speaker 1: The presence of the plants certainly can have a very
Speaker 1: pleasant effect on the human psyche. So can ambient music.
Speaker 1: So double up, have them both and benefit. But anyway,
Speaker 1: before we end part one of the series, I did
Speaker 1: want to look at at least one of the studies
Speaker 1: that claims to find evidence for what you might call
Speaker 1: memory learning or habituation in plants. And in the next
Speaker 1: episode we'll come back and talk about some reaction, criticism,
Speaker 1: and follow up of these types of ideas. So this
Speaker 1: is not without its accompanying controversy, but I thought it
Speaker 1: would be at least worthwhile to look at like what
Speaker 1: the evidential claims of the recent research are. Earlier we
Speaker 1: mentioned that scientists are actually not one hundred percent sure
Speaker 1: why Mimosa pudica closes its leaves, though it is generally
Speaker 1: believed to be some kind of defensive reaction to prevent
Speaker 1: the leaves from being eaten by grazing herbivores or insects.
Speaker 1: So if that's the case, you might wonder, well, why
Speaker 1: don't the plants just keep their leaves folded up all
Speaker 1: the time, then they'd be protected always. Why do they
Speaker 1: have to do it rapidly suddenly? Well, because if they
Speaker 1: were to keep their leaves closed all the time, the
Speaker 1: plant would be drastically reducing its ability to collect sunlight
Speaker 1: and feed through photosynthesis. And this is the classic risk
Speaker 1: reward paradigm that we know well with all kinds of animals.
Speaker 1: You have a small prey animal that might be much
Speaker 1: safer if it stays in its cozy little burrow all day,
Speaker 1: but if it never leaves, it foregoes opportunities to get food.
Speaker 1: It needs to go out to do the things it
Speaker 1: must do to sustain its life cycle and reproduce. So
Speaker 1: it's got to find food, it's got to find mates,
Speaker 1: and you know you're not going to get that just
Speaker 1: sitting in your hole. You could say the same is
Speaker 1: true for this plant. So the evolutionary logic that drives
Speaker 1: the folding behavior of the leaves and the sensitive plant
Speaker 1: will reward the folding in scenarios where it actually protects
Speaker 1: the leaf from predation, but it will punish unnecessary folding,
Speaker 1: which wastes precious opportunities to harvest the sunlight. And we've
Speaker 1: already seen a couple of demonstrations of this balance. One
Speaker 1: is that the leaves tend to fold at night time,
Speaker 1: when there's no point in being exposed because there's no
Speaker 1: sunlight to absorb. And another is that once the leaves
Speaker 1: close in response to a seismic stimulus, they reopen again,
Speaker 1: usually within a few minutes. They're ready to get back
Speaker 1: to the buffet. But to continue the logic of this
Speaker 1: risk reward balance, it would also obviously benefit the plant
Speaker 1: if it had a mechanism for discriminating between a potentially
Speaker 1: dangerous seismic stimulus and a harmless one. And you can
Speaker 1: imagine scenarios in the wild where plants are repeatedly shaken
Speaker 1: in some way or subjected to physical contact with objects
Speaker 1: in the environment, maybe by wind or something in a
Speaker 1: way that is not actually a threat to the plant,
Speaker 1: where closing the leaflets every time that happened would be
Speaker 1: pointless and harmful to survival. So do these plants have
Speaker 1: a mechanism that allows them to discriminate like that? And
Speaker 1: according to this following study, it looks like maybe they do. So.
Speaker 1: This was a study published in Ecologia in twenty fourteen
Speaker 1: by Monica Gagliano, Michael Renton, Marshall dip Chinsky, and Stefano
Speaker 1: Mancuso called experience teaches plants to learn faster and forget
Speaker 1: slower in environments where it matters. So the authors write
Speaker 1: in their abstract quote, the nervous system of animals serves
Speaker 1: the acquisition, memorization, and recollection of information. Like animals, plants
Speaker 1: also acquire a huge amount of information from their environment,
Speaker 1: Yet their capacity to memorize and organized learned behavioral responses
Speaker 1: has not been demonstrated. In mimosa pudica the sensitive plant.
Speaker 1: The defensive leaf folding behavior in response to repeated physical
Speaker 1: disturbance exhibits clear habituation, suggesting some elementary form of learning.
Speaker 1: So how do they actually demonstrate this, Well, they did
Speaker 1: a series of experiments, but one of their models is
Speaker 1: they took potted specimens of Mimosa pudica and they mounted
Speaker 1: them on this contraption that would repeatedly drop the potted
Speaker 1: plant a distance of fifteen centimeters onto a padded surface.
Speaker 1: And these drops were organized into repeated sessions of multiple exposures.
Speaker 1: And sure enough, the plants, after they were repeatedly exposed
Speaker 1: to the same fifteen centimeter drop, started reopening their leaves
Speaker 1: more quickly and eventually started ignoring the stimulus more or
Speaker 1: less entirely, just keeping their leaves open during a drop.
Speaker 1: And that's really interesting. It might seem to indicate that
Speaker 1: the plant is becoming habituosed to this particular thing. It's like, okay,
Speaker 1: being dropped fifteen centimeters is just something that happens. Now,
Speaker 1: This is just how things are. I know what it
Speaker 1: feels like. It doesn't hurt me. I'm over it, by
Speaker 1: the way that I guess I am anthropomorphizing there, So
Speaker 1: I don't mean to imply that it is actually reasoning
Speaker 1: out in semantic logic like that, but that's to give
Speaker 1: you the idea that it's somehow becoming habituated to something
Speaker 1: that's happening over and over again without hurting it, and
Speaker 1: it's just learning to ignore that thing. Now, there's an
Speaker 1: obvious other explanation if this was all they discovered. What
Speaker 1: if this was just the plant's leaf closing mechanism getting
Speaker 1: worn out over time, It's just becoming exhausted and running
Speaker 1: out of the juice that it needs to use to
Speaker 1: close its leaves. Well, the researchers they thought about this,
Speaker 1: and they controlled for this by introducing a new novel
Speaker 1: stimulus after the plant became habituated. This was the shake,
Speaker 1: so different from the drop, but it would also stimulate
Speaker 1: the seismonastic closure or of the leaflets to shake the
Speaker 1: potted plant. And they found that even when a plant
Speaker 1: had become desensitized to the drop, apparently through habituation, it
Speaker 1: would still close its leaves just like normal when given
Speaker 1: a shake. So this would seem to help rule out
Speaker 1: the idea that it's just the plant's leaf closure mechanisms
Speaker 1: becoming exhausted by repeated use. Now, there are some more
Speaker 1: interesting details from this one that we might get into
Speaker 1: in the next part of this series. For example, they
Speaker 1: found that apparently this habituation to the fifteen centimeter drop
Speaker 1: was still present weeks later after the initial sessions, and
Speaker 1: that it was variable and adaptable depending on the hostility
Speaker 1: of the conditions, like the light conditions in which it
Speaker 1: was happening. But maybe if we get into those, we
Speaker 1: can do that in part two, because I think we
Speaker 1: need to wrap up part one for now, but I'm
Speaker 1: so excited all the things we get to talk about
Speaker 1: when we come back next time. More research on plants
Speaker 1: in memory. If plants do in fact possess some rudiment
Speaker 1: reform of memory and learning, how what is the physical
Speaker 1: basis of that, given of course that they don't have brains,
Speaker 1: And what would that mean for our understanding of what
Speaker 1: intelligence and its subdivided parts are. Yeah, yeah, this should
Speaker 1: continue to be a fun exploration. And this is an
Speaker 1: exploration that we've we've been talking about doing for years,
Speaker 1: and I know we've had some listeners right in requesting
Speaker 1: that we cover this topic. So it's great to finally
Speaker 1: be able to dive in. All right, So we're gonna
Speaker 1: go and close it out, but we'll be back next
Speaker 1: time with more on this topic. In the meantime, if
Speaker 1: you want to check out other episodes of Stuff to
Speaker 1: Blow Your Mind, our core episodes come out on Tuesdays
Speaker 1: and Thursdays, we have a rerun that comes out of
Speaker 1: vault episode. On the weekend, we do listener mail on Monday,
Speaker 1: we do a short form artifact or monster fact on Wednesday,
Speaker 1: and on Friday we set aside most serious matters and
Speaker 1: just discuss a weird film on Weird House Cinema. Huge
Speaker 1: things as always to well, actually to our regular producer
Speaker 1: Seth Nicholas Johnson, and thanks to our guest producer today
Speaker 1: Paul decand Paul really appreciate you sub an in for
Speaker 1: us today. If you would like to get in touch
Speaker 1: with us with feedback on this episode or any other,
Speaker 1: to suggest a topic for the future, or just to
Speaker 1: say hello, you can email us at contact at stuff
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