Smarty Plants

Summary

---

Radiolab – "Smarty Plants"

Release Date: February 14, 2018
Hosts: Jad Abumrad, Robert Krulwich (WNYC Studios)
Main Guests: Dr. Monica Gagliano, Jennifer Frazer, Atish Bhatia, Sharon De La Cruz, Peter Landegren

---

Episode Overview

In "Smarty Plants," Radiolab investigates the intelligence of plants, exploring the surprising ways in which plants sense, respond, and even appear to "learn" from their environment. Through lively storytelling, hands-on experiments, and conversations with researchers, the episode challenges our animal-centric view of intelligence and perception, asking: Can plants hear? Can they remember? Can they be trained? And, ultimately, what does it even mean to be "smart"?

---

Key Discussion Points & Insights

1. The Plant and the Pipe: Following Water Underground

• [02:00 – 04:15]
  Hosts speak with Larry and Alvin Ubell, home inspectors, who observe that tree roots almost always grow toward buried water pipes—even if the pipes are sealed and not leaking—damaging infrastructure as they do so.
• Experiment by Dr. Monica Gagliano
  • She creates controlled pots where roots can only grow one of two directions: toward a buried (but sealed) water pipe, or away.
  • Result: 80% of roots grow toward the pipe, even though there should be no detectable moisture.
• Question: How do plant roots "know" where to grow if not by sensing water?
• Hypotheses debated:
  • Condensation from cold pipes ([06:08], Larry & Alvin)
  • Sensitive root hairs detecting minute gradients ([07:08])
  • Gagliano’s response: She eliminated moisture gradients by placing the pipe outside the soil ([07:36]); yet roots still grew toward the pipe.

“Wait, so… the pipe was on the outside of the pot? And the plant still went to the place where the pipe was—not even in the dirt?”
— Jad Abumrad, [07:52]

• Further hypothesis: Plants may sense the sound or vibration of water moving in pipes.
  • Gagliano tests this with recordings of running water ([08:15]), finding that most roots grow toward the sound alone.

“So they just went right for the MP3 fake water—not even the actual water, just the sound of it.”
— Jad, [09:11]

2. Do Plants Have Ears?

• [09:20 – 10:31]
  Jennifer Frazer (Science Blogger) considers whether root hairs at the tips of roots might make them functionally similar to our ear hairs, catching vibrations.

“Maybe plant roots are like little ears. … Maybe each root is like a little ear for the plant.”
— Jennifer Frazer, [10:18]

• Hosts ponder: Without a brain or nervous system, how could a plant "choose" which way to grow?
• Dr. Gagliano: Calls out the human obsession with brains as sites of intelligence, suggesting plants might have different systems for processing information ([10:41], [11:05]).

---

3. Experiment #2: Do Plants "Learn" Like Animals?

• [16:27]
  Focuses on the Mimosa pudica—a sensitive plant whose leaves fold up when touched, a reflex to deter herbivores.
• Gagliano’s Experiment: She drops potted mimosas from a short height onto foam repeatedly.
  • Initially, plants fold up leaves with each drop; after some repetitions, they stop, as if realizing the drop isn't a threat ([19:33]).
  • To control for fatigue, she shakes the plant side-to-side—immediately, the leaves close again ([20:04]).
• Interpretation: The plants have “learned” dropping isn’t dangerous—and remember that for days.
• Replication attempt: Princeton group tries to recreate the experiment but cannot reproduce the result, likely due to inconsistent treatment ([21:36]).
• Gagliano’s Data: Her plants remembered the drop for at least 28 days ([23:16], [24:08]).

“It was almost like… let’s see how much I have to stretch her here before you forget. … Eventually she came back after 28 days. And they still remembered.”
— Monica Gagliano, [23:52]

---

4. Pavlov’s Plants: Classical Conditioning in Pea Plants

• [25:47 – 31:20]
• Inspiration: Pavlov’s experiment with dogs salivating at the sound of a bell.
• Gagliano’s Experiment:
  • Trains pea plants by pairing a fan and a light from the same direction; plant always grows toward fan+light.
  • After conditioning, she turns on the fan alone from a new direction—plants grow toward the fan, anticipating food (light), like Pavlov’s dogs ([30:08]).

“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.”
— Monica Gagliano, [30:26]

---

5. What Counts as “Intelligence”? The Debate

• [32:22 – 35:08]
  Lincoln Taiz, UC Santa Cruz, voices skepticism—not of the experiments per se, but of the language (metaphors of “hearing,” “learning,” “behavior,” etc.), warning against over-interpretation.
• Value of Metaphor: Producer Annie McEwen suggests that using animal-like metaphors helps open creative possibilities for experiments ([33:17]).

“Maybe it makes her sort of more open-minded than someone who’s just looking at a notebook.”
— Annie McEwen, [33:40]

• Ethical/Philosophical Implications:
  Larry Ubell comments that maybe intelligence is not unique to humans; perhaps we’re not smart enough yet to understand plants' intelligence ([35:08]).

“So they may have this intelligence. Maybe we’re just not smart enough yet to figure it out.”
— Larry Ubell, [35:34]

---

Notable Quotes & Memorable Moments

• On Plant Perception:

  “If a nosy deer happens to bump into it, the mimosa plant folds its leaves, curls all its leaves up against its stem.”
  — Robert Krulwich, [17:02]

• On the Implicit Threat to Human Exceptionalism:

  “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.”
  — Jennifer Frazer, [37:11]

• On Human Hubris:

  “You think this is a hubris corrector?”
  — Robert, [37:31]
  “Yeah.”
  — Larry Ubell, [37:35]

---

Timestamps for Key Segments

| Segment | Time | |----------------------------------------|--------------| | Introduction / Set-Up | 01:18–04:15 | | Root Sensing & Water Pipe Mystery | 04:15–09:50 | | Can Plants Hear? | 09:20–10:31 | | Brains vs. Distributed Intelligence| 10:31–11:36 | | Mimosa ‘Learning’ Experiment | 16:26–24:08 | | Pavlov’s Plants Conditioning | 25:47–31:20 | | Scientific Skepticism & Metaphor | 32:22–35:08 | | Big Picture & Philosophy | 35:08–38:02 |

---

Episode Tone

• Curious and wonder-filled, with the hosts bringing both skepticism and playful awe to the table.
• Conversational and experimental, as they attempt to reproduce the science themselves.
• Reflective, openly questioning human biases and the boundaries of scientific language.

---

Conclusion

"Smarty Plants" turns conventional notions of intelligence upside down, offering compelling evidence that plants can perceive, “learn,” and even be trained. Through interviews and experiments, the episode blurs the line between plant and animal abilities—raising deep philosophical questions about consciousness, memory, and the hidden life in our gardens and forests.

Takeaway:
Plants might not have brains, but evidence is mounting that they're much “smarter” than we think. Perhaps, as the hosts discover, this isn’t a threat—but an invitation to humility and wonder.

---

Transcript

[A]

Introducing Fidelity Trader Plus.

[B]

With customizable tools and charts you can access across all your devices.

[A]

Try our most powerful trading platform [e-mail] TraderPlus investing involves risk, including risk of loss. Fidelity Brokerage Services, llc. Member NYSE SIPC at the Home Depot.

[B]

Y gracias a su systema de conexion Rapida yarmado fasil podras pasar masti empo de la temporada. Todo lo qu? Neces. Black Friday and the Home Depot.

[C]

Hey, Radiolab, it's Molly Webster. Before we start the episode, I have a question for you. Somewhat impolite, probably wouldn't ask you this in person. Question. And that question is, are you trying to have a kid? Because if you are, I wanna hear from you. So if you are trying, and you'd be interested in talking to us totally confidentially, you can email [e-mail] and we'll tell you more. That's tryingadiolab.org thanks.

[B]

Wait, you're listening?

[D]

Okay. All right.

[B]

Okay.

[D]

All right.

[A]

I'm listen.

[C]

Radio Lab.

[B]

Radio from wny.

[E]

Where do we want. Where do you want us to sit?

[F]

One or the other.

[E]

That's it.

[G]

Got it.

[F]

Thank you.

[G]

Testing, 1, 2. This is the headphone save.

[F]

All right.

[G]

Got that.

[A]

I'm Jad.

[B]

I'm Robert.

[E]

How's that?

[B]

Better? Oh, much better.

[A]

This is Radio Lab.

[E]

Can I interrupt?

[G]

Yes, but could I say something first?

[E]

Me first. Because I let you go. It's going to be another 20 minutes till I get to talk.

[B]

A little while back, I had a rather oyster conversation with these two guys. First of all, like, who are you?

[E]

I'm Larry Ubell.

[G]

Yeah, and I'm Alvin Ubell.

[B]

So you are related and you're both in the plumbing business.

[G]

Are we related?

[E]

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

[B]

Yeah, they're father and son. It's a family business.

[E]

We are the principals of Accurate Building Inspectors of Brooklyn, New York.

[G]

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

[B]

Okay.

[E]

I'm not giving my age.

[B]

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

[G]

Yeah.

[E]

All the time.

[B]

That is actually a clue in what turns out to be a deep, deep mystery.

[A]

Which is what exactly?

[B]

Well, let us say you have a yard in front of your house. Yours is the back of your house, but let's make it in front.

[H]

Okay.

[B]

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

[G]

And the Tree happens to be a.

[B]

Weeping willow, just for example. And not too far away from this tree, underground, there is a water pipe, a perfectly good pipe connecting your house to the main city water line that's in the middle of the street.

[A]

Mm.

[B]

The roots of this tree, of course, can go any way they want to go. They can go north, south, east, west, whatever. But the Yubels 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.

[G]

The tree will wrap its roots around.

[B]

Around and around and around in a.

[G]

Tangling of spaghetti, like, almost. And each one of those lines of spaghetti is squeezing little bit. Each one an ounce, an ounce, an.

[D]

Ounce, an ounce, an ounce, an ounce.

[G]

Eventually, over a period of time, it'll crack the pipe like a nutcracker.

[A]

Yes.

[B]

You both see this happening all the time.

[G]

Yeah.

[E]

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

[B]

Into the house.

[G]

It's amazing.

[E]

Yes.

[A]

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.

[B]

This happens to a lot of people. It's almost as if these plants. It's almost as if they know where our pipes are.

[A]

I see what's happening. What, are you bringing the plant parade again?

[B]

Is that what this is? Well, of course I am.

[A]

You're doing the, like. Okay. First it was the roots under the ground all connected into a whole hive thing.

[B]

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

[A]

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

[B]

I do.

[A]

I do, with the plant parade.

[B]

And I met a plant biologist who's gonna lead that parade. She's done three experiments, 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 dreamed they could do. I know you. I know you. All right, but let me just. Let me give it a try.

[A]

Okay, I'm game.

[B]

So let's go to the first. This is the plant and pipe mystery.

[D]

Hello. Finally.

[B]

Hello. Hello. But long last. Now, you might think that the plant sends out roots in every direction. 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.

[A]

Right.

[B]

But that scientist I mentioned.

[D]

My name is Monica Gagliano. I'm A research associate professor at the.

[B]

University of Sydney, she took that notion out of the garden into her laboratory.

[D]

Yeah, tested it in my lab.

[B]

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.

[A]

What kind of pot is this?

[B]

It's kind of a shape like.

[D]

Like the letter Y, but upside down.

[B]

So you get. The roots can go to the left or to the right.

[A]

Oh.

[B]

Now, the plants, if they were truly dumb, they'd go 50, 50. It'd be all random. Right. But after five days, she found that 80% of the time the plants went, or maybe chose to head toward the dry pipe. That.

[D]

So the question is, 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?

[E]

All right, my hypothesis is that what happens is. Can I have a few minutes?

[G]

No.

[E]

You got somewhere to go? You got somewhere to go?

[G]

No.

[E]

Good. If she's going to do this experiment, most likely she's going to use cold water. She's not gonna use hot water. Cause you don't wanna cook your plants, you know, and it's more expensive. Why waste hot water?

[B]

Well, by the way, should we establish. Is it a fact in your. Okay, go ahead. You wanna contest?

[G]

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, it's.

[E]

Kind of like a cold glass sitting on your desk, and there's always a puddle at the bottom.

[G]

The glass is not broken. It's not a leak on the glass.

[E]

The water is still in there.

[B]

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

[C]

Right.

[B]

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

[G]

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. And all of a sudden, one of them said, oh, I found a little water. And then all the other water goes in the same direction.

[B]

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

[G]

Yes.

[B]

But Monica says, no, absolutely not.

[D]

I purposely removed the chance for emosia gradient.

[B]

She made sure that the Dirt didn't get wet because she'd actually fastened the water pipe to the outside of the pot, so it wasn't touching the dirt at all.

[A]

Wait, so this branching pot thing, the part where the water pipe was. The pipe was on the outside of the pot?

[B]

That's right. Outside.

[A]

And the plant still went to the place where the pipe was not even in the dirt?

[B]

Yeah.

[A]

That is strange now.

[E]

Or is it just the vibration of the pipe that's making it go toward it?

[G]

They would have to have something.

[B]

Maybe there's some kind of signal, different kind of signal traveling through the soil. Monica thought about that and designed a different experiment.

[D]

Again, if you imagine the pot, my experimental pot with the forked bottle. Yep.

[B]

But then have two very different options for our plant. On one side, instead of the pipe with water, she attaches an MP3 player with a little speaker playing a recording.

[D]

Of the sound of water.

[B]

And then on the other side, Monica has another MP3 player with a speaker, but this one plays nothing. So she's got her plants in the pot, and we're going to now wait to see what happens. 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. 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.

[D]

Exactly. Exactly.

[A]

So they just went right for the MP3 fake water. Not even the actual water. Just the sound of it.

[B]

Just the sound.

[G]

That's interesting.

[E]

It's interesting.

[G]

That is interesting.

[B]

But how would a plant hear something like they don't have ears or a brain or anything? Like they couldn't hear like we hear?

[F]

Well, maybe they definitely don't have a brain. No question there. But they do have root hairs.

[B]

This is Jennifer Fraser.

[F]

I am the blogger of the Artful Amoeba at Scientific American.

[B]

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

[F]

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

[B]

Little hairs.

[F]

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

[A]

That is cool. That is definitely cool.

[B]

Okay.

[A]

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.

[B]

That's true.

[A]

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

[B]

I don't think Monica knows the answer to that, but she does believe that, you know, that we humans, we are.

[D]

A little obsessed with the brain. And so we 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. And if you don't have one by default, you can't do much in general.

[B]

Okay.

[D]

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

[A]

But still, I mean, to say that a plant is choosing a direction, I don't know. I mean, it like when a plant bends towards sunlight. We've all seen houseplants do that, right? Would you say that the plant is seeing the sun?

[F]

No.

[A]

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

[B]

I think that's fair. 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. 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.

[D]

Hi, this is Ashley Harding from St. John's Newfoundland, Canada. Radiolab is supported in part by the Alfred P. Sloan foundation, enhancing public understanding.

[F]

Of science and technology in the modern world.

[B]

More information about [e-mail].

[F]

Radiolab is supported by BILT. Nobody wants to pay rent, but if you have to, Bilt works to make it more worthwhile. By paying rent through Bilt, you can earn flexible points that can be redeemed toward hundreds of hotels and airlines, a future rent payment, your next Lyft ride, and more. But it doesn't stop there. You can dine out at your favorite local restaurants and earn additional points, get VIP treatment at certain fitness studios, and enjoy exclusive experiences just for built members. Every month, earn points on rent and around your neighborhood, wherever you call home, by going to joinbilt.com Radiolab. That's J-O-I-N-B-I-L-T.com Radiolab.

[H]

Radiolab is supported by rippling Finance. Teams often spend weeks chasing receipts, reconciling spreadsheets and fixing errors across disconnected spend tools. This can be frustrating and that's not software as a service, that's sad software as a disservice. If you've been thinking about replacing stitched together tech stacks with one platform for all departments, Rippling can help. Rippling is a unified platform for global hr, payroll, IT and finance, helping people replace their mess of cobbled together tools with one system designed to help give leaders clarity, speed and control. By uniting employees, teams and departments in one system, Rippling works to remove the bottlenecks, busywork and silos in business software. With Rippling, you can choose to run hr, IT and finance operations as one, or pick and choose the products that best fill the gaps. Right now you can get 6 months free when you go to rippling.com Radiolab learn more at RIP P L I N G.com Radiolab terms and conditions apply.

[C]

Hey, I'm Molly Webster and this is an ad by BetterHelp. So it happens every year. The seasons are changing, the days are getting shorter, and basically once it becomes dark outside of my window, I feel like the rest of the world disappears and I'm just alone and there's nothing left to do but watch television. This November, Better Help is asking everyone to reach out to our people. That could be your family, your friends, your neighbors, and to resist this call of the cocoon. And yeah, reaching out can take some courage. I've got text messages from January I haven't responded to and you know what? I'm going to write them back right now. Hi, sorry I've been missing. How are you? Why don't we all do this sooner? Therapy is the same way. BetterHelp makes it easier to take that first step. You just fill out a short questionnaire and they find a licensed therapist who they think you'll like. Our listeners get 10% off their first month at betterhelp.com Radiolab that's betterhelp.com Radiolab.

[H]

Radiolab is supported by Planet Visionaries, the podcast created in partnership with the Rolex Perpetual Planet Initiative. The show is hosted by Alex Honnold, who you may recognize from Free Solo, where he climbed El Capitan without ropes. Now he's turning his focus to the biggest challenge of all protecting the only planet we've got. Every episode brings you stories that prove climate optimism isn't naive, it's a strategy. The episodes span the globe, from Arctic scientists and Amazon forest guardians to entrepreneurs reimagining fashion and food systems. You'll hear from explorers, scientists, activists and storytellers who are working to reshape the future in practical, human ways. In One episode, Alex sits down with wildlife photographer Bertie Gregory to discuss how animals can teach humans resiliency, empathy and hope. In partnership with the Rolex Perpetual Planet Initiative. Check out Planet Visionaries Listen or watch on Apple, Spotify, YouTube, or wherever you get your podcasts.

[A]

3, 2, 1. JAD radio lab.

[E]

Yep.

[A]

So today we have a triptych of experiments about plants that apparently. Jury's still out. Are going to make me rethink my stance on plants.

[B]

Yes.

[A]

So we're up to experiment two now, are we not?

[B]

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

[D]

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

[B]

Because this peculiar plant has a surprising little skill.

[F]

Yeah, a reflex, an anti predator reaction.

[D]

Like a defensive mechanism.

[F]

As soon as it senses that a grazing animal is nearby, if a nosy.

[B]

Deer happens to bump into it, the mimosa plant folds its leaves, curls all its leaves up against its stem.

[F]

The whole thing immediately closes up and makes it look like, oh, there's no plant here. Just a boring set of twigs, Nothing delicious at all.

[B]

So the deer's like, oh, well, never mind.

[F]

Right.

[B]

And you can actually see this happen. So, okay, so you can get. Anybody can get one of these plants. And we did. And if you just touch it. Can I try it?

[D]

Yeah, go for it.

[B]

Even just one leaf like that, you can actually watch this cascade. Whoa. Where all the leaves close in. Like, look at that. They all went closed. Yeah, it's sort of startling to see. That's so eerie. So that voice belongs to Atish Batya, who is with Princeton University's Council on Science and Technology. We showed one of these plants to him and a couple of his colleagues. Sharon de la Cruz, sky or the Sky. And Peter Landegren. Yeah, there you go. That's neat. Because we wanted them to help us recreate Monica's next experiment. Okay, so maybe could you just describe it just briefly, just what you did.

[D]

Well, I created this horrible contraption.

[F]

Apparently she built some sort of apparatus, I guess you could call it a mimosa plant. Dropbox.

[B]

Picture one of those parachute drops that they have at state fairs or amusement parks where you host hoisted up to the top. Except in this case, instead of a chair, they've got a little plant sized.

[F]

Box into which she put these sensitive plants.

[B]

So the plants are now, you know, buckled in, minding their own business and Then Monica would drop them just about, you know, seven or eight inches, landing.

[D]

Very comfortably onto a padded base made of foam. So no plants would actually hurt in this experiment.

[B]

But the drop was just shocking and sudden enough for the little plant to close all its leaves, do its reflex defense thing. Then Monica hoists the plant back up again and drops it again and again and again. And after not a whole lot of drops, The plant, she noticed, stopped closing its leaves.

[D]

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

[A]

The plants stopped. What is it they did?

[B]

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

[D]

Exactly. Which is pretty amazing.

[A]

Couldn't it just be an entirely different interpretation here?

[E]

Like what?

[A]

The plants have to keep pulling their leaves up, and they just get tired. They run out of energy.

[F]

Yeah, it might run out of fuel.

[A]

Exactly.

[F]

It's a costly process for this plant.

[B]

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.

[F]

It would close up.

[B]

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. Yeah, that's a. Learning is something I didn't think plants could do.

[D]

They do.

[B]

Oh, this looks so high tech. 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, so. Oh, my God. That's where the scientists from Princeton come in. Peter, Sharon, and Atish. They designed from scratch a towering parachute drop in blue, translucent Lego pieces. So this is our plant dropper. And we can move it up and we can drop it. So we strapped in our mimosa plant.

[A]

A little seat belt for him for the ride down.

[B]

And then someone has to count. I'll count. And then we let it drop. 5, 4, 3, 2, 1. Drop. 5, 4, 3. And we dropped it once and twice again. Dropped and again. We were waiting for the leaves to, you know, stop folding. We dropped, we dropped.

[A]

But I don't know.

[B]

It didn't happen.

[A]

It was curling up each time.

[B]

When it went every time, it just kept curling and curling. Didn't seem to be learning anything.

[A]

So you couldn't replicate what you saw.

[B]

Nothing happened at all. So we went back to Monica. Yeah, we, as you know, built your elevator.

[D]

I heard.

[B]

We told her what we did. And what happened to you didn't happen to Us. Now, can you imagine what we did wrong?

[D]

Like, for example, my plants were all in environment control rooms, which is not a minor details. They're not experiencing extra changes. Or, for example, I don't know if that was the case for your plants.

[B]

It depends how often we kept switching rooms because we weren't sure whether you wanted to be in the high light or weak light or some light or no light.

[D]

I wonder if there was maybe a bit too much. Was it possible that maybe the plants correctly responded by not opening because something really mad was happening around it? And it's like, this place is not safe.

[B]

Truth is, I think on this point, she's got a. She's right. One time the plant literally flew out of the pot and upended with roots exposed. Feels like one of those experiments where you just aborted on humanitarianism. So I think what she would argue is that we kind of proved her point. We were so inconsistent, so clumsy that the plants were smart to keep playing it safe and closing themselves up.

[D]

So actually, I think you were very successful, 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 tumultuous than mine.

[B]

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

[D]

The idea was to drop them again, just to see, like, the difference between the first time you learn something and the next time.

[B]

Like, would they figure it out faster this time or maybe slower.

[D]

Yeah.

[B]

So she takes the plants, she puts them into the parachute drop. She drops them, and she says this time they relaxed almost immediately.

[D]

Yeah. They remember straight away.

[B]

Straight away.

[D]

All of them know already what to do.

[B]

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.

[D]

Yeah.

[B]

And then she waited a few more days and came back. They still remembered. Yeah, Few more days.

[D]

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

[B]

Eventually she came back after 28 days. 28 days, yes. And they still remember. They still did not close when she dropped them. That's what she says.

[F]

What was your reaction when you saw this happen? That's producer Annie McKeown, this retention of knowledge.

[D]

My reaction was like, oh, that was my reaction. Because the only reason why the experiment turned out to be 28 days is because I ran out of time. So they might remember even for much longer time than 28 days.

[A]

So she's saying they remembered for almost a month.

[B]

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

[A]

No, I actually, like, even this morning, it's already, poof, gone.

[B]

Like that's a thing.

[A]

But supposing that she's right.

[B]

Yeah.

[A]

Where would a little plan even store a memory?

[B]

That's what I asked her. I do want to go back though, to. For something like learning. Like, I don't understand learning, as far as I understand it is something that involves memory and storage. And I do that in my brain. That's the place where I remember things in my brain.

[D]

Oh, do you?

[G]

Yes, I did.

[B]

Is it brain? I think. Is your dog objecting to my analysis?

[D]

That's okay, Picasso. Pigs. Picasso, enough of that.

[C]

Pigs.

[D]

Hey, it's okay. It's okay, puppy. It's okay. Picasso, enough of that now. Sorry.

[B]

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.

[F]

So Pavlov started by getting some dogs and some meat and a bell.

[B]

Science writer Jen Fraser gave us the kind of the standard story.

[F]

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.

[B]

They would salivate and then eat the meat.

[F]

Then he would bring them the meat.

[B]

And he would ring a bell and again, drooling, eating.

[F]

And he would repeat this.

[B]

Ring, meat, eat. Ring meat, eat. Ring meat, eat.

[F]

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

[B]

Sure enough, the dogs began to drool.

[F]

They had learned to associate the sound.

[B]

Of the bell, which has, you know, for dogs, has nothing to do with meat.

[F]

With when they actually saw and smelled and ate meat.

[D]

Exactly.

[B]

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

[D]

Would the plant do the same?

[B]

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

[D]

Yeah.

[B]

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. Or it reminds me of a bear or reminds me of a bee.

[D]

Not really. And I guess that's who I feel sort of kind of good to say this. It's like, no, no, I don't do that.

[B]

But Monica says what she does do is move around the world with a general feeling of, huh, what if? So she decided to Conduct her experiment.

[D]

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

[B]

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

[D]

Y.

[B]

She gave each plant a little bit of food, in this case a little blue LED light.

[D]

Light is obviously representing dinner.

[B]

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

[D]

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

[B]

So for three days, three times a day, she would shine these little blue.

[F]

Lights on the plants from a particular direction.

[B]

And she noticed that, unsurprisingly, the plants would always grow towards the light.

[F]

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

[B]

And the salivation equivalent was the tilt of the plant.

[D]

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

[B]

So after much trial and error with clicks and hums and buzzes, all sorts.

[D]

Of randomness, she found that the one.

[B]

Stimulus that would be perfect was a fan.

[D]

A little fan, the same one that they are used in computers, like, you know, really tiny.

[B]

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.

[D]

The plants didn't care.

[B]

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

[D]

And the fan were always coming from the same direction.

[B]

And with these two stimuli, she put the plants, the little pea plants, through a kind of. Of training regime. Little fan goes on, the light goes on. Both aiming at the pea plant from the same direction, and the pea plant leans toward them. 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.

[D]

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

[B]

Fan light, lean. Fan light, lean. Fan light, lean. Same as the Pavlov, the bell, the meat, and the salivation.

[D]

So then at one point, when you only play the bell for the dog or, 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.

[B]

And Monica wondered, in the plant's case.

[D]

If there was only the fan, would.

[B]

The plant anticipate the light and lean.

[D]

Toward it or would just be going random.

[B]

After three days of this training regime, it is now time to test the plants with just the fan, no light. So Monica moves the fans to a new place one more time. They're switched on, and the pea plants are left alone to sit in this quiet, dark room, feeling the breeze.

[D]

And then the next day, I remember going in at the uni on a.

[B]

Sunday afternoon, and she goes into that darkened room with all the pea plants.

[D]

So, you know, I'm in the dark, but she's got.

[B]

Got a little red headlamp on.

[D]

Yeah.

[B]

And she moves about the room to have a look, peering down at the plants under the red glow of her headlamp.

[D]

And then I saw that these little.

[B]

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.

[D]

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 plans. I got out and I thought, there's no one here on Sunday afternoon. I can scream 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. And so, of course, that was only the beginning. Then we actually had to run four months of trials to make sure that, you know, that what we were seeing was not one pea doing it or two Ps, but it was actually a majority.

[B]

So you just did what Pavlov did to a plant. You got the plant to associate the fan with food.

[D]

Yep, pretty much.

[B]

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, that where would they put that information? Like, how can a plant. How does a plant do that?

[D]

I don't know. I don't know yet. But what I do know is that the fact that the plant doesn't have a brain doesn't. A priori says that the plants can do something. The fact that humans do it in a 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. There are multiple ways of doing one thing. Right, huh?

[B]

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

[D]

Yeah, I know. That's why there is often more questions than answers. But that's part of the fun as well.

[B]

Monica's work has actually gotten quite a bit of attention from other plant biologists. Yes. And some of them. This is Lincoln Tay's. I'm a professor emeritus of Plant biology at UC Santa Cruz say they're very curious but want to see these experiments repeated. It's a very interesting experiment, and I really want to see whether it's correct or not. Us too. He's got lots of questions about her research methods, but really his major complaint is her language, her use of metaphor.

[H]

Right.

[B]

For example, words like hearing or learning behavior. And this he's not a huge fan of. Yes.

[G]

If you can get too wrapped up in your poetic metaphor, you're very likely to be misled and to over interpret the data.

[B]

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

[F]

But I wonder if her using these metaphors again, producer Annie McEwan, is perhaps a very creative way of looking at. Looking at a plant and therefore leads her to make. 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.

[B]

Is it like metaphor is letting in the light as opposed to shutting down?

[H]

Yeah, kind of.

[F]

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.

[B]

I think you can be open minded, but still objective.

[G]

I mean, I think there's something to that. I think there are some cases where romanticizing something could possibly lead you to some interesting result.

[B]

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

[G]

Yes, that would be an interesting.

[E]

Don't interrupt. They have to edit this together. Let them talk. Yeah, how much longer? Because I have an appointment.

[B]

All right, that's it. One thing, just out of curiosity. As we were winding up with our home inspectors Alvin and Larry Ubell, we thought maybe we should run this metaphor idea by them. There's. On the science side, there's a real suspicion of anything that's anthropomorphizing in a plant. 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. And the classic case of this is if you go back a few centuries ago, someone noticed that plants have sex.

[G]

Oh, yes.

[B]

That there was a kind of a moral objection to thinking it this way. And I'm wondering whether Monica is gonna run into. As she tries to make plants more animal. Like whether she's just gonna run into this malice from the scientific. I'M just wondering, do you share any of that?

[E]

No, I don't because 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. I've been looking around lately and I know that intelligence is not uni.

[B]

Humans.

[E]

Okay? 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. 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.

[A]

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

[B]

Okay, let's do. Big thanks to Atish Batya, to Sharon Delacruz, and to Peter Landegren at Princeton University's Council on Science and Technology. Also thanks to Christy Melville and to Emerald o' Brien and to Andres o' Hara and to Summer Rain.

[A]

You're thanking Summer Rain?

[B]

I am.

[A]

Did the plants sneak? That one in?

[B]

Summer is a real person and her last name happens to be spelled.

[A]

Oh, okay.

[B]

A, Y, N, E. I see. This story was nurtured and fed and ultimately Produced by Annie McKeown. She actually trained this story in a rather elaborate experimental setup to move away from the light into a light breeze against all of its instincts. Oh, one more thing. Thanks to Jennifer Fraser, who helped us make sense of all this. You should definitely go out and check out her blog, the Artful Amoeba. Especially to the post the forlorn ones about plants.

[F]

Plants are really underrated. When I write a blog post, post my posts that get the least traffic guaranteed are the plant posts. No matter how amazing I think that the results are, for some reason, people just don't think plants are interesting. And to me, here are three more reasons that you can say no. Really, Plants are amazing and this world is amazing. And that living creatures have this ability for reasons we don't understand, can't comprehend yet. That's amazing and fantastic. And 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. Does it threaten your sense of humanity that you depend for pretty much every single calorie you eat on a plant?

[D]

No.

[B]

So you think that this. You think this is a hubris corrector?

[E]

Yeah.

[F]

I mean, what, so they can't move? Well, some of them can, first of all, and big deal. Can you make your own food? No.

[B]

Sam. To play the message, press 2. Start of message. My name is jennifer frazier. Hi, this is larry ubel and alvin ubell of accurate building inspectors, and I am a science writer. Radiolab was created by jed abumrad and produced by soren wheeler.

[F]

Dylan heath is our director of sound design.

[B]

Maria matass. Maria matasser, maria matasa. Maria matassa.

[E]

Padelia is our managing director.

[F]

Our staff includes include simon adler, becca.

[B]

Brussler, rachel cusick, david david gabel, gabelle, david verbal gable, david gavel, ethel hapke, tracy hunt, matt kielpe, matt keeley, robert kerwich, annie mcguinn or mcguin, lattice nasser, melissa o', donnell, marianne wack, pat walter, and molly weber.

[F]

With help from amanda aranchik, shima oui.

[B]

Naya hughes, jennifer jake, arlo, niga batali.

[F]

Phoebe wang, and katie ferguson.

[B]

Our fact checker is michelle harris. And lastly, a friendly reminder, have you.

[F]

Hugged your house plant today?

[B]

End of message.