Smarty Plants

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Speaker 6 It's 1972. A young British family is attempting to sail around the world when disaster strikes.
Their boat is hit by killer whales and it sinks in seconds.

Speaker 6 All they have left is a life raft and each other.

Speaker 6 This is the true story of the Robertson family and their fight to survive, hosted by me, Becky Milligan. Listen to Adrift, an Apple original podcast produced by Blanchard House.

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Speaker 10 Hey, Happy New Year.

Speaker 11 I'm Lativ Nasser. This, of course, is Radio Lab.

Speaker 11 We have got all kinds of surprises in store for you this year. Not even this year, like in the next few months, including the winner of our big year-long quasi-moon naming contest.
There is a winner.

Speaker 11 It's just not official yet. We will announce it the moment we are able to.

Speaker 11 But for now, As we take our first step into 2025, we wanted to rewind an episode we first released in 2018. It's about plants and their incredible roots.

Speaker 11 And besides the fact that it's just super fun to listen to, part of the reason we're replaying it is almost as a reminder of our roots as a show in things like humor and wonder, which we are going to be, you know, working our best to dig up and dish up over the next year.

Speaker 11 So to set us off on the right footing, here are Emeritus hosts, Jad and Robert with Smarty Plants.

Speaker 12 Wait, you're listening.

Speaker 4 Okay.

Speaker 4 All right.

Speaker 4 Okay.

Speaker 4 All right.

Speaker 14 Door listening to Radio Lab.

Speaker 13 Radio Lab. From

Speaker 15 W-N-Y-C.

Speaker 17 Re-Wind.

Speaker 8 Sorry.

Speaker 8 Where do you want us to say?

Speaker 17 It doesn't matter. One or the other.
That's the door.

Speaker 18 Go ahead.

Speaker 13 Testing.

Speaker 19 One, two, this is the headphones.

Speaker 13 I'm Jad. I'm Robert.
How is that better?

Speaker 20 Oh, much better. It's Radio Lab.

Speaker 14 Can I interrupt?

Speaker 19 Yes. But could I say something?

Speaker 13 Me first.

Speaker 17 Me first. Because I let you go.

Speaker 8 It's going to be another 20 minutes till I get to talk.

Speaker 12 A little while back, I had a rather

Speaker 21 boisterous conversation with these two guys.

Speaker 22 First of all, like, who are you?

Speaker 13 I'm Larry Eubel. Yeah.

Speaker 19 And I'm Alvin Eubel.

Speaker 23 So you are related and you're both in the plumbing business?

Speaker 19 Are we related?

Speaker 8 Yes, we are related, but we are in the home inspection business. Yeah.

Speaker 25 They're father and son. It's a family business.

Speaker 8 We are the principals of accurate building inspectors of Brooklyn, New York.

Speaker 19 And I've been in the construction industry ever since I'm about 16 years old. I'm 84.

Speaker 8 Okay. I'm not giving my age.

Speaker 26 But I wanted to talk to them because as building inspectors, there's something they see over and over and over.

Speaker 31 Yeah, all the time.

Speaker 14 That is actually a clue

Speaker 21 in what turns out to be a deep, deep mystery.

Speaker 15 Which is what exactly?

Speaker 21 Well, let us say you have a yard in front of of your house.

Speaker 33 Yours is the back of your house, but that's like in front.

Speaker 27 Okay.

Speaker 29 And right in the middle of the yard is a tree.

Speaker 19 And the tree happens to be a weeping willow.

Speaker 21 Just, for example. And not too far away from this tree, underground, there is a water pipe.

Speaker 19 A perfectly good pipe.

Speaker 34 Connecting your house to the main city water line that's in the middle of the street.

Speaker 21 The roots of this tree, of course, can go any way they want to go.

Speaker 25 They can go north, south, east, west, whatever.

Speaker 34 But the U-bells have noticed that even if a tree is 10 or 20, 30 yards away from the water pipe, for some reason, the tree roots creep with uncanny regularity straight toward the water pipe.

Speaker 19 The tree will wrap its roots around that pipe.

Speaker 40 Around and around and around.

Speaker 19 In a tangling of spaghetti, like almost...

Speaker 19 And each one of those lines of spaghetti is squeezing

Speaker 17 little bits.

Speaker 19 Each one an ounce, an ounce, an ounce, an ounce, an ounce, an ounce. Eventually,

Speaker 19 over a period of time, it'll crack the pipe

Speaker 19 like a nutcracker. Yes.

Speaker 34 You both see this happening all the time.

Speaker 8 And I have done inspections where roots were coming up through the pipe into the house.

Speaker 19 Into the house? It's amazing.

Speaker 15 Yes.

Speaker 15 This actually happened to me. The magnolia tree outside of our house got into the sewer pipes, reached its tentacles into our house and busted the sewage pipe.

Speaker 41 It just happens to a lot of people.

Speaker 39 It's almost as if these plants, it's almost as if they know.

Speaker 13 Where our pipes are.

Speaker 15 I see what's happening.

Speaker 33 What?

Speaker 15 Are you bringing the plant parade again?

Speaker 15 Is that what this is?

Speaker 31 Of course I am.

Speaker 15 You're doing the like, okay, first it was the roots under the ground all connected into a whole hive.

Speaker 13 I don't know why you have problems with this.

Speaker 15 No, it's because it's like every time I close my eyes, you're coming at it from a different direction.

Speaker 44 I do, I do.

Speaker 43 The plant parade.

Speaker 25 And I met a plant biologist who's going to lead that parade.

Speaker 21 She's done three experiments.

Speaker 27 And I think if I tell you about what she has done, you, even you, will be provoked into thinking that plants can do stuff you didn't imagine dream they could do.

Speaker 40 I know,

Speaker 40 I know you don't.

Speaker 13 All right, but let me just let me give it a try.

Speaker 43 Okay, I'm gay.

Speaker 46 Let's go to the first.

Speaker 34 This is the plant and pipe mystery.

Speaker 16 Hello, finally.

Speaker 14 Hello, hello, but long last.

Speaker 34 Now, you might think that the plant sends out roots in every direction.

Speaker 21 One of the roots just happens to bump into a water pipe and sends a signal to all the others, come over here, here's the water.

Speaker 36 Right. But that scientist I mentioned.

Speaker 47 My name is Monica Galliano. I'm a research associate professor at the University of Sydney.

Speaker 33 She took that notion out of the garden into her laboratory.

Speaker 47 Yeah, tested it in my lab.

Speaker 45 She took some plants, put them in a pot that restricted the roots so they could only go in one of just two directions, toward the water pipe or away from the water pipe.

Speaker 13 What kind of pot is this?

Speaker 28 It's kind of, it's shaped like...

Speaker 47 Like the letter Y, but upside down.

Speaker 21 So you get the roots can go either left or to the right.

Speaker 15 Oh.

Speaker 22 Now the plants, if they were truly dumb, they'd go 50-50.

Speaker 31 It would be all random.

Speaker 34 But after five days, she found that 80% of the time, the plants went or maybe chose to head toward the dry pipe that has water in it.

Speaker 24 So the question is.

Speaker 47 A plant that is quite far away from the actual pipe, how does it know which way to turn and grow its roots so that it can find the water?

Speaker 8 All right. My hypothesis is, is that what happens is quite...

Speaker 8 Can I have a few minutes?

Speaker 50 No. You got somewhere to go.

Speaker 50 You got somewhere to go.

Speaker 14 No. Good.

Speaker 8 If she's going to do this experiment, most likely she's going to use cold water. She's not going to use hot water because you don't want to cook your plants, you know, and it's more expensive.

Speaker 8 Why waste hot water?

Speaker 41 Well, by the way, should we establish, is it a fact in your

Speaker 17 head?

Speaker 19 He's right track. You have to understand that the cold water pipe causes even a small amount of water to condense on the pipe itself.
On the outside of the pipe.

Speaker 8 It's kind of like a cold glass sitting on your desk and there's always a puddle at the bottom.

Speaker 19 The glass is not broken. It's not a leaky glass.

Speaker 17 I mean the water is still in there.

Speaker 39 So there is some water outside of the pipe. It's condensation.

Speaker 36 Right.

Speaker 21 So what they're saying is even if she's totally sealed the pipe so there's no leak at all, the difference in temperature will create some condensation on the outside.

Speaker 27 And it's that little, little bit of moisture that the plant will somehow sense.

Speaker 19 If you look at a root under a microscope, what you see is all these thousands of feelers like hairs on your head looking for water, every one of them.

Speaker 19 And all all of a sudden, one of them says, Oh, I found a little water, and then all the other goes in the same direction.

Speaker 29 These sensitive hairs, he argues, would probably be able to feel that tiny difference.

Speaker 32 Yes.

Speaker 32 But Monica says, No, absolutely not.

Speaker 47 I purposely removed the chance for a moisture gradient.

Speaker 21 She made sure that the dirt didn't get wet because she'd actually fastened the water pipe to the outside of the pot.

Speaker 49 So it wasn't touching the dirt at all.

Speaker 15 Wait, so the

Speaker 15 this branching pot thing,

Speaker 15 the part where the water pipe was, the pipe was on the outside of the pot?

Speaker 43 That's right, outside.

Speaker 15 And the plant still went to the place where the pipe was not even in the dirt? Yeah.

Speaker 19 That is strange.

Speaker 8 Was it just the vibration of the pipe that's making it go toward it?

Speaker 19 They would have to have a signal.

Speaker 41 Maybe there's some kind of signal, different kind of signal traveling through the soil.

Speaker 21 Monica thought about that and designed a different experiment.

Speaker 47 Again, if you imagine the pot, my experimental pot.

Speaker 33 with the forked bottom.

Speaker 47 Yeah, but then have two very different options for our plant.

Speaker 27 On one side, instead of the pipe with water, she attaches an MP3 player with a little speaker playing a recording of the sound of water.

Speaker 14 And then on the other side, Monica has another MP3 player with a speaker, but this one plays.

Speaker 47 Nothing.

Speaker 45 So she's got her plants in the pot and we're going to now wait to see what happens.

Speaker 34 Remember that the roots of these plants can either go one direction towards the sound of water in a pipe or the other direction to the sound of silence.

Speaker 53 On the fifth day, they take a look and discover most of the roots, a majority of the roots, were heading toward the sound of water.

Speaker 47 Exactly. Exactly.

Speaker 15 So they just went right for the MP3 fake water, not even the actual water, just the sound of it?

Speaker 49 Just the sound.

Speaker 13 That's interesting.

Speaker 19 That's interesting. That is interesting.

Speaker 16 But

Speaker 48 how would a plant hear something?

Speaker 34 Like, they don't have ears or a brain or anything like...

Speaker 21 They couldn't hear like we hear.

Speaker 47 Well, maybe.

Speaker 9 They definitely don't have a brain. No question there.

Speaker 9 But...

Speaker 9 They do have root hairs. This is Jennifer Frazier.
I am the blogger of the artful amoeba at Scientific American.

Speaker 36 And she was willing to entertain the possibility that plants can do something like hear.

Speaker 9 So what do we have in our ears that we use to hear sound?

Speaker 14 Little hairs.

Speaker 9 Little hairs. Yes.
Right?

Speaker 9 And if you go to too many rock concerts, you can break these hairs and that leads to permanent hearing loss, which is bad.

Speaker 9 So maybe the root hairs, which are always found right at the growing tips of plant roots, maybe plant roots are like little ears. Maybe each root is like a little ear for the plant.
I don't know.

Speaker 15 That is cool. That is definitely cool.

Speaker 20 Okay, good.

Speaker 15 The thing I don't get is in animals, the hairs in our ear are sending the signals to a brain, and that is what chooses what to do. That's true.

Speaker 15 If a plant doesn't have a brain, what is choosing where to go?

Speaker 28 I don't think Monica knows the answer to that.

Speaker 27 But she does believe that, you know, that we humans...

Speaker 47 We are a little obsessed with the brain. And so we

Speaker 47 are under the impression, or I would say the conviction that the brain is the center of the universe and if you have a brain and a nervous system you are good and you can do amazing stuff.

Speaker 47 And if you don't have one, by default, you can't do much in general.

Speaker 47 It's a very biased view that humans have in particular towards others.

Speaker 15 But still, I mean,

Speaker 15 to say that a plant is choosing a direction, I don't know. I mean,

Speaker 15 like when a plant bends towards sunlight,

Speaker 15 we've all seen house plants do that, right?

Speaker 15 Would you say that the plant is seeing the sun? No, I mean, it's just it's reacting to things and there's a series of mechanical behaviors inside the plant that are just bending it in a direction.

Speaker 15 I mean, couldn't it just be like that?

Speaker 21 I think that's fair.

Speaker 56 And I think if I move on to the next experiment for Monica, you're going to find it a little bit harder to object to it.

Speaker 56 We need to take a break first, but when we come back, the parade that I want you to join will come and swoop you up and carry you along in a flow of enthusiasm.

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Speaker 6 It's 1972. A young British family is is attempting to sail around the world when disaster strikes.
Their boat is hit by killer whales and it sinks in seconds.

Speaker 6 All they have left is a life raft and each other.

Speaker 6 This is the true story of the Robertson family and their fight to survive, hosted by me, Becky Milligan. Listen to Adrift, an Apple original podcast produced by Blanchard House.

Speaker 6 Follow and listen on Apple podcasts.

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Speaker 11 Lutthiff Radio Lab back with Jad and Robert.

Speaker 15 Yep. So today we have a triptych of experiments about plants that apparently,

Speaker 15 Jerry's still out, are going to make me rethink my stance on plants. Yes.
So we're up to experiment two now, are we not?

Speaker 33 That is correct.

Speaker 36 So we are going to meet a beautiful little plant called a mimosa puddica, which is just a perfectly symmetrical plant with leaves on either side of a central stem.

Speaker 47 Yeah, mimosa has been one of the pet plants, I guess, for many scientists for like centuries.

Speaker 29 Because this peculiar plant has a surprising little skill.

Speaker 47 Yeah, a reflex,

Speaker 9 an anti-predator reaction, like a defensive mechanism. As soon as it senses that a grazing animal is nearby.

Speaker 34 If a nosy deer happens to bump into it, the mimosa plant folds its leaves, curls all its leaves up against its stem.

Speaker 9 The whole thing immediately closes up and makes it look like, oh, there's no plant here.

Speaker 9 Just a boring set of twigs. Nothing delicious at all.

Speaker 33 So the deer's like, oh, well.

Speaker 40 Never mind.

Speaker 16 Right.

Speaker 46 And you can actually see this happen. So.

Speaker 45 you can get, anybody can get one of these plants, and we did.

Speaker 37 And if you just

Speaker 18 touch it. Can I try it? Yeah, go for it.

Speaker 54 Even just one leaf. Like that.

Speaker 28 You can actually watch this cascade.

Speaker 13 Whoa.

Speaker 54 Where all the leaves close in.

Speaker 44 Yeah, look at that. They all went closed.
Yeah.

Speaker 32 It's sort of startling to see.

Speaker 18 That's so eerie.

Speaker 34 So that voice belongs to Atish Bhatya, who is with Princeton University's Council on Science and Technology.

Speaker 21 We showed one of these plants to him and a couple of his colleagues, Sharon De La Cruz

Speaker 58 and Peter Landigren.

Speaker 13 Yeah, there you go.

Speaker 18 That's neat.

Speaker 55 Because we wanted them to help us recreate Monica's next experiment.

Speaker 48 Okay.

Speaker 26 So maybe could you just describe it just briefly, just what you did?

Speaker 47 Well,

Speaker 47 I created these horrible contraption.

Speaker 9 Apparently, she built some sort of apparatus.

Speaker 9 I guess you could call it a mimosa plant drop box.

Speaker 41 Picture one of those parachute drops that they have at the state fairs or amusement parks where you hoist it up to the top.

Speaker 41 Except in this case, instead of a chair, they've got a little plant-sized box.

Speaker 9 Into which she put these sensitive plants.

Speaker 58 So the plants are now buckled in, minding their own business, and then Monica would

Speaker 47 drop them.

Speaker 21 Just about, you know, seven or eight inches.

Speaker 47 Landing very comfortably onto a padded base made of foam. So no plants would actually hurt in this aspiring.

Speaker 27 But the drop was just shocking and sudden enough for the little plant to close all its leaves.

Speaker 29 Do its reflex defense thing.

Speaker 43 Then Monica hoists the plant back up again and drops it again.

Speaker 55 And again.

Speaker 55 And again.

Speaker 13 And after not a whole lot of drops,

Speaker 31 The plant, she noticed, stopped closing its leaves.

Speaker 47 So after the first few, the plants already realized that that was not necessary.

Speaker 15 The plants.

Speaker 15 The plants stopped. What is it they did?

Speaker 22 They stopped folding up.

Speaker 31 She thinks that they somehow remembered all those drops and it never hurt, so they didn't fold up anymore. They'd learned something.

Speaker 47 Exactly, which is pretty amazing.

Speaker 15 Couldn't it just be an entirely different interpretation here? Quite quite the plants have to keep pulling their leaves up and they just get tired, they run out of energy.

Speaker 9 Yeah, it might run out of fuel. Exactly.
It's a costly process for this plant.

Speaker 27 But she figured out they weren't tired because after dropping them 60 times, she then shook them left to right and they instantly folded up again.

Speaker 9 It would close up.

Speaker 22 So it's not that it couldn't fold up, it's just that during the dropping, it learned that it didn't need to.

Speaker 16 Yeah.

Speaker 58 That's a learning is something I didn't think plants could do.

Speaker 47 They do

Speaker 18 high-tech.

Speaker 21 So we figured, look, if it's this easy and this matter of fact, we should be able to do this ourselves and see it for ourselves.

Speaker 54 So

Speaker 49 that's where the scientists from Princeton come in.

Speaker 25 Peter, Sharon, and Atish.

Speaker 34 They designed from scratch.

Speaker 23 A towering parachute drop in blue translucent Lego pieces.

Speaker 11 So this is our plant dropper and we can move it up and we can drop it.

Speaker 21 So we strapped in our mimosa plant.

Speaker 57 A little seatbelt for him for the ride down.

Speaker 44 And then...

Speaker 15 Alright, and then someone has to count. I'll count.

Speaker 21 And then we let it drop.

Speaker 30 Five, four, three,

Speaker 18 two,

Speaker 30 one,

Speaker 18 drop.

Speaker 33 Five, four, three.

Speaker 58 And we dropped it once and twice, again,

Speaker 58 and again.

Speaker 48 We were waiting for the leaves to, you know, stop folding.

Speaker 20 We dropped.

Speaker 21 We dropped.

Speaker 18 But I don't know.

Speaker 13 It didn't happen.

Speaker 15 It was curling up each time when it every time.

Speaker 54 It just kept curling and curling.

Speaker 48 Didn't seem to be learning anything.

Speaker 15 So you couldn't replicate what she saw?

Speaker 24 Nothing happened at all.

Speaker 31 So we went back to Monica.

Speaker 28 Yeah. We, as you know, built your elevator.

Speaker 16 I heard.

Speaker 21 We told her what we did. What happened to you didn't happen to us.

Speaker 27 Now, can you imagine what we did wrong?

Speaker 47 Like, for example, my plants were all in environment control rooms, which is not a minor details. They're not experiencing extra changes.

Speaker 47 For example, I don't know if that was the case for your plants.

Speaker 48 We kept switching rooms because we weren't sure whether you wanted to be in the highlight or weak light or some light or no light.

Speaker 47 I wonder if that was maybe a bit too much.

Speaker 50 Was it possible

Speaker 47 that maybe the plants correctly responded by not opening because something really mad was happening around it and it's like, uh this place place is not safe.

Speaker 34 Truth is, I think on this point, she's got to,

Speaker 32 she's right.

Speaker 43 One time, the plant literally flew out of the pot and upended with roots exposed.

Speaker 15 It seems like one of those experiments where you just aborted on humanitarian issues.

Speaker 21 So I think what she would argue is that we kind of proved her point.

Speaker 27 We were so inconsistent, so clumsy, that the plants were smart to keep playing it safe and closing themselves up.

Speaker 47 So actually, I think you were very successful with your experiment. You found exactly what the plants would do under your circumstances, which were, I don't know, let's say a bit more

Speaker 47 tumultuous than mine.

Speaker 21 And she goes on to argue that had we been a little bit more steady and a little bit more consistent, the plants would have learned and would have remembered the lesson.

Speaker 41 Because what she does next is three days later, she takes these plants back into the lab.

Speaker 47 The idea was to drop them again, just to see

Speaker 47 the difference between the first time you learned something and the next time.

Speaker 27 Like would they figure it out faster this time or maybe slower?

Speaker 13 Yeah.

Speaker 27 So she takes the plants, she puts them into the parachute drop, she drops them

Speaker 24 and she says this time they relaxed almost immediately.

Speaker 47 Yeah, they remember straight away.

Speaker 20 Straight away.

Speaker 47 All of them know already what to do.

Speaker 27 They remembered what had happened three days before, that dropping didn't hurt, that they didn't have to fold up, so they didn't.

Speaker 29 Yeah.

Speaker 34 And then she waited a few more days and came back. They still remembered.

Speaker 18 Yeah.

Speaker 34 Few more days?

Speaker 47 Yeah. And it was almost like, let's see how much I have to stretch her here before you forget.

Speaker 27 Eventually, she came back after 28 days.

Speaker 14 28 days.

Speaker 36 Yes. And they still remember.

Speaker 27 They still did not close when she dropped them.

Speaker 28 That's what she says.

Speaker 59 What was your reaction when you saw this happen?

Speaker 21 That's producer Annie McEwen.

Speaker 59 This retention of knowledge.

Speaker 47 My reaction was like, oh, sh ⁇ .

Speaker 47 That was my reaction.

Speaker 47 Because the only reason why the experiment turned out to be 28 days is because I ran out of time.

Speaker 47 So they might remember even for much longer time than 28 days.

Speaker 15 So she's saying they remembered for almost a month?

Speaker 32 Yeah, I mean, can you remember what you were doing?

Speaker 15 No, I actually, like, even this morning, I'm

Speaker 13 like, poof, gone. Like, that's a thing.

Speaker 15 But supposing that she's right. Yeah.

Speaker 15 Where would a little plan even store a memory?

Speaker 53 Well, that's what I asked her.

Speaker 39 I do want to go back, though, to

Speaker 56 for something like learning.

Speaker 27 Like, I don't understand.

Speaker 58 Learning, as far as I understand it, is something that involves memory and storage. And I do that in my brain.

Speaker 31 That's the place where I remember things in my brain. Or do you?

Speaker 26 Yes, I do.

Speaker 28 Is it brain?

Speaker 16 I think.

Speaker 43 Is your dog objecting to my analysis?

Speaker 13 That's okay.

Speaker 47 Picasso, pigs.

Speaker 47 Picasso, enough of that.

Speaker 47 Pigs.

Speaker 16 Hey,

Speaker 47 it's okay. It's okay, puppy.

Speaker 18 It's okay.

Speaker 47 Picasso, enough of that now.

Speaker 47 Sorry.

Speaker 45 Actually, Monica's dog leads perfectly into her third experiment, which again will be with a plant, but it was originally done with a dog.

Speaker 9 So, Havlov started by getting some dogs and some meat and a bell.

Speaker 58 Science writer Jen Frazier gave us the kind of the standard story.

Speaker 9 And his idea was to see if he could condition these dogs to associate that food would be coming from the sound of a bell. So he brought them some meat.

Speaker 45 They would salivate and then eat the meat.

Speaker 9 Then he would bring them the meat and he would ring a bell.

Speaker 13 And again, drooling, eating.

Speaker 9 And he would repeat this.

Speaker 51 Ring, meat, eat.

Speaker 31 Ring meat eat.

Speaker 40 Ring meat, eat.

Speaker 9 Finally, one time he did not bring the meat, but he rang the bell.

Speaker 21 Sure enough, the dogs began to drool.

Speaker 9 They had learned to associate the sound of the bell

Speaker 9 with when they actually saw and smelled and ate meat.

Speaker 47 Exactly.

Speaker 43 Now that's a very, you know, animals do this experiment, but it got Monica thinking.

Speaker 47 Would the plant do the same?

Speaker 21 Could a plant learn to associate something totally random, like a bell, with something it wanted, like food?

Speaker 14 Yeah.

Speaker 58 Are you like aggressively looking around for like do you wake up in the morning saying now what can I get a plant to do that reminds me of my dog or reminds me of a bear or reminds me of a bee no really

Speaker 47 and I guess that's who I feel I feel sort of kind of good to say this is like no no I don't I don't do that but Monica says what she does do is move around the world with a general feeling of huh

Speaker 32 what if

Speaker 35 So she decided to conduct her experiment.

Speaker 47 Pretty much like the concept of Pavlo with his dog applied.

Speaker 35 But instead of dogs, she had pea plants in a dark room.

Speaker 13 Yeah.

Speaker 21 And for the meat substitute, she gave each plant a little bit of food, in this case, a little blue LED light.

Speaker 47 Light is obviously representing dinner.

Speaker 26 So light is, if you shine light on a plant, you're like feeding it.

Speaker 47 Yeah, plants really like light, you know, they need light to grow, so otherwise they can't photosynthesize.

Speaker 34 So for three days, three times a day, she would shine these little blue lights on the plants.

Speaker 9 From a particular direction.

Speaker 27 And she noticed that

Speaker 55 the plants would always grow towards the light.

Speaker 9 Anyone who's ever had a plant in a window knows that.

Speaker 39 And the salivation equivalent was the tilt of the plant?

Speaker 47 Exactly.

Speaker 47 And then I needed to, the difficulty, I guess, of the experiment was to find something that will be quite irrelevant and really meant nothing to the plant to start with, like the bell for the dog.

Speaker 47 So after much trial and error with clicks and hums and buzzes, all sorts of randomness.

Speaker 36 She found that the one stimulus that would be perfect was a fan.

Speaker 47 A little fan, the same one that I used in computers like, you know, really tiny.

Speaker 38 She determined that you can take a little computer fan and blow it on a pea plant for pretty much ever and the pea plant would be utterly indifferent to the whole thing.

Speaker 47 The plants didn't care.

Speaker 21 Then she placed the fan right next to the light so that...

Speaker 47 The light and the fan were always coming from the same direction.

Speaker 21 And with these two stimuli, she put the plants, the little pea plants, through a kind of training regime.

Speaker 45 Little fan goes on,

Speaker 56 light goes on, both aiming at the pea plant from the same direction and the pea plant leans toward them.

Speaker 45 Then she takes a little light and a little fan and moves them to the other side of the plant. Turns the fan on, turns the light on, and the plant turns and leans that way.

Speaker 47 Yeah, fan first, light after, and moved around, but always matched in the same way together.

Speaker 56 Fan, light, lean. Fan, light, lean, fan, light, lean.

Speaker 35 Same as the problem of the bell, the meat, and the salivation.

Speaker 47 So then at one point when you only play the bell for the dog or you, you know, play the fan for the plant, we know now for the dogs, the dogs is expecting, so it's predicting something to arrive.

Speaker 47 And Monica wondered in the plant's case, if there was only the fan, would the plant anticipate the light and lean toward it? Or would it just be going random?

Speaker 31 After three days of this training regime, it is now time to test the plants with just the fan, no light.

Speaker 35 So Monica moves the fans to a new place one more time.

Speaker 36 They're switched on.

Speaker 32 And the pea plants are left alone to sit in this quiet, dark room, feeling the breeze.

Speaker 47 And then the next day. I remember going in on at the uni on a Sunday afternoon.

Speaker 40 And she goes into that darkened room with all the pea plants.

Speaker 47 So, you know, I'm in the dark.

Speaker 34 But she's got a little red headlamp on.

Speaker 51 Yeah.

Speaker 34 And she moves about the room to have a look.

Speaker 35 Peering down at the plants under the red glow of her headlamp.

Speaker 23 And then I saw that these little plants, my little peas, had indeed turned and moved toward the fan, stretching up their little leaves as if they were sure that at any moment now, light would arrive.

Speaker 47 And it's good it was Sunday. And I remember it was Sunday because I started screaming in my life.
I said, oh, I might disturb my plants.

Speaker 47 I got out and I thought, there's no one here on Sunday afternoon. I can screen my head off if I want to.
And so, I was really excited. I was like, Oh my god, these guys are actually doing it.

Speaker 47 And so, of course, that was only the beginning.

Speaker 47 Then, we actually had to run four months of trials to make sure that you know that what we were seeing was not one P doing it or two P's, but it was actually a majority.

Speaker 43 So, you just did what Pavlov did to a plant: you got the plant to associate the fan with food, yeah,

Speaker 47 pretty much.

Speaker 23 But once again, I kind of wondered if since the plant doesn't have a brain or even neurons to connect the idea of light and wind or whatever,

Speaker 21 where would they put that information?

Speaker 38 Like, how can a plant, how does a plant do that?

Speaker 47 I don't know.

Speaker 20 I don't know yet.

Speaker 47 But what I do know is that the fact that the plant doesn't have a brain

Speaker 47 doesn't a priori say that the plants can do something.

Speaker 47 The fact that humans do it in a particular particular way, it doesn't mean that everyone needs to do it in that way to be able to do it in the first place.

Speaker 47 There are multiple ways of doing one thing, right?

Speaker 18 Huh.

Speaker 27 So we're really, like, this is, we're really at the very beginning of this.

Speaker 47 Yeah, I know.

Speaker 47 That's why there is often more questions than answers, but that's part of the fun as well.

Speaker 21 Monica's work has actually gotten quite a bit of attention from other plant biologists.

Speaker 45 Yes.

Speaker 23 And some of them, this is Lincoln Taze.

Speaker 61 I'm a professor emeritus of plant biology at UC Santa Cruz.

Speaker 46 Say they're very curious but want to see these experiments repeated.

Speaker 61 It's a very interesting experiment, and I really want to see whether it's correct or not.

Speaker 38 Us too.

Speaker 34 He's got lots of questions about her research methods, but really his major complaint is her language, her use of metaphor.

Speaker 14 Right.

Speaker 60 For example, words like hearing or learning behavior.

Speaker 27 And this, he's not a huge fan of.

Speaker 61 Yes, if you get too wrapped up in your poetic metaphor, you're very likely to be misled and to over-interpret the data.

Speaker 60 I mean,

Speaker 61 it's a kind of romanticism, I think. You know, it goes back to anthropomorphizing plant behaviors.

Speaker 59 But I wonder if her using these metaphors

Speaker 59 is perhaps a very creative way of

Speaker 59 looking at at a plant and therefore leads her to

Speaker 59 make up these experiments that those who wouldn't think the way she would would ever make up, and therefore she might in the end see something that no one else would see.

Speaker 25 Is it can be like metaphor is letting in the light as opposed to shutting out the light.

Speaker 59 Kind of even like, could there be a brain or could there be ears or, you know, just sort of like going off the deep end there, but maybe it makes her sort of more open-minded than someone who's just looking at a notebook.

Speaker 61 I think you can be open-minded, but still objective. I mean, I think there's something to that.

Speaker 61 I think there are some cases where romanticizing something could possibly lead you to some interesting results.

Speaker 39 So you're like a metaphor cop with a melting heart.

Speaker 60 Yes.

Speaker 19 That would be an interesting.

Speaker 17 Don't interrupt. They have to edit this in together.

Speaker 16 Let them talk.

Speaker 8 Yeah. How much longer? Because I have an appointment.

Speaker 39 All right. That's it.

Speaker 27 One thing, just out of curiosity.

Speaker 34 As we were winding up with our home inspectors, Alvin and Larry Yubel, we thought maybe we should run this metaphor idea by them.

Speaker 56 On the science side, there's a real suspicion of anything that's anthropomorphizing at a plant.

Speaker 21 They just don't like to hear words like mind or hear or see or taste for a plant because it's too animal and too human.

Speaker 21 And the classic case of this is if you go back a few centuries ago, someone noticed that plants have sex.

Speaker 46 Oh, yes.

Speaker 21 That there was a kind of a moral objection to thinking it this way.

Speaker 21 And I'm wondering whether Monica is going to run into, as she tries to make plants more animal-like, whether she's just going to run into this malice from the scientific experience.

Speaker 27 I'm just wondering, do you have this, do you share any of that?

Speaker 8 No, I don't because

Speaker 8 she may come up against it, people who think that intelligence is unique to humans. And so I don't have a problem with that.

Speaker 8 I've been looking around lately and I know that intelligence is not unique to humans.

Speaker 17 Okay.

Speaker 8 So I don't have an issue with that. And every day that goes by, I have less of an issue from the day before.

Speaker 8 So I don't have a problem. The problem is, is with plants.
So they may have this intelligence. Maybe we're just not smart enough yet to figure it out.

Speaker 15 Well, okay, that's a parade I'll show up for.

Speaker 51 Okay.

Speaker 43 Let's do it.

Speaker 58 Big thanks to Atis Batya, to Sharon DeLa Cruz, and to Peter Landogren at Princeton University's Council on Science and Technology.

Speaker 35 Also, thanks to Christy Melville and to Emerald O'Brien and to Andres O'Hara and to Summer Rain.

Speaker 15 You're thinking Summer Rain?

Speaker 13 I am. Did the plants sneak that one in?

Speaker 34 No, Summer is a real person, and her last name happens to be spelled

Speaker 35 R-K-A-Y-N-E.

Speaker 47 I see.

Speaker 27 This story was nurtured and fed and ultimately produced by Annie McEwen.

Speaker 22 She actually trained this story in a rather elaborate experimental setup to move away from the light and to where the light breathes against all of its instincts.

Speaker 25 Oh, one more thing. Thanks to Jennifer Frazier, who helped us make sense of all this.

Speaker 26 You should definitely go out and check out her blog, The Artful Amoeba, especially to the post, The Forlorn Ones, about plants.

Speaker 47 Plants are really underrated.

Speaker 9 When I write a blog post, my posts that get the least traffic guaranteed are the plant posts.

Speaker 9 No matter how amazing I think that the results are, for some reason, people just don't think plants are interesting.

Speaker 9 And to me, here are three more reasons that you can say, no, really, plants are amazing. And this world is amazing.

Speaker 9 And that living creatures have this ability for reasons we don't understand, can't comprehend yet. That's amazing and fantastic.
And

Speaker 9 Does it change my place in the world? Does it threaten my sense of myself or my place as a human that a plant can do this? No.

Speaker 9 Does it threaten your sense of humanity that you depend for pretty much every single calorie you eat on a plant?

Speaker 39 No. So you think that that this you think this is a hubris corrector?

Speaker 43 Yeah, I mean, what?

Speaker 9 So they can't move. Well, some of them can, first of all, and big deal.
Can you make your own food? No.

Speaker 62 Hey, I'm Lemon and I'm from Richmond, Indiana, and here are the staff credits. Radio Lab was created by Jad Abhimrod and is edited by Soren Wheeler.
Lulu Miller and Latz of Nasser are our co-hosts.

Speaker 62 Dylan Keefe is our director of sound design. Our staff includes Simon Adler, Jeremy Bloom, Becca Pressler, W.

Speaker 62 Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhun Yanan Sambandan, Matt Kielty, Rebecca Lacks, Annie McEwen, Alex Neeson, Sara Kari, Sarah Sandback, Anissa Vitza, Arianne Wack, Pat Walters, and Molly Webster.

Speaker 62 Our fact checkers are Diane Kelly, Emily Krieger and Natalie Middleton.

Speaker 63 Hi, my name is Treza. I'm calling from Colchester in Essex, UK.

Speaker 63 Leadership support for Radiolab science programming is provided by the Gordon and Betsy Moore Foundation, Science Sandbox, Seymour's Foundation Initiative and the John Templeton Foundation.

Speaker 63 Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

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