Smarty Plants

Summary

Radiolab Episode Summary: "Smarty Plants" Radiolab, Hosted by WNYC Studios | Release Date: January 10, 2025

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Introduction: Revisiting Roots As Radiolab steps into 2025, the hosts Lulu Miller and Latif Nasser rewind to an evocative episode from 2018 titled "Smarty Plants." This episode delves deep into the intriguing world of plant intelligence, exploring how plants interact with their environment in surprisingly sophisticated ways. The episode aims to rekindle the show's foundational themes of humor and wonder, promising to unearth more such marvels throughout the year.

The Plant and Pipe Mystery The episode opens with a fascinating observation from Larry and Alvin Ubello, principals of Accurate Building Inspectors in Brooklyn. They recount how tree roots, even those planted yards away, exhibit a peculiar tendency to grow directly toward underground water pipes (03:20).

Robert Krulwich: “I have done inspections where roots were coming up through the pipe into the house.” (03:44)

Jad Abumrad shares a personal anecdote about his magnolia tree disrupting sewer pipes, highlighting a common yet mysterious plant behavior.

Jad Abumrad: “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.” (03:52)

Exploring Plant Intelligence Latif introduces Dr. Monica Gagliano, a research associate professor at the University of Sydney, whose experiments challenge conventional views on plant behavior. Gagliano's work suggests that plants can "remember" and "learn," exhibiting responses akin to intelligence despite lacking a brain.

Monica Gagliano: “We humans, we are 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.” (10:14)

Experiment One: Associative Root Growth Gagliano's first experiment investigates whether plants can consciously direct their roots toward water sources. Using a specially designed pot shaped like an upside-down "Y," she restricts root growth to two directions: toward a water pipe or away from it. Surprisingly, 80% of the plants directed their roots toward the water pipe, even when no moisture gradient was present.

Monica Gagliano: “I purposely removed the chance for a moisture gradient.” (07:30)

Despite initial skepticism, the results suggest that plants might possess a form of sensory perception enabling them to seek out vital resources efficiently.

Experiment Two: Mimosa Pudica and Learned Responses The second experiment explores learning and memory in plants using the Mimosa pudica, a plant known for its rapid leaf-folding response to touch. Gagliano subjected these plants to repeated gentle drops using a specialized apparatus, causing them to fold their leaves initially. Remarkably, after several drops, the plants ceased this defensive response, indicating they had learned that the drops were harmless.

Monica Gagliano: “After the first few, the plants already realized that that was not necessary.” (15:24)

When the experiment was repeated three weeks later, the plants retained this learned behavior, continuing to ignore the drops, suggesting a form of memory retention lasting nearly a month.

Experiment Three: Pavlov’s Conditioning with Pea Plants Inspired by Pavlov's classical conditioning with dogs, Gagliano conducted an experiment to see if plants could associate an arbitrary stimulus with a beneficial outcome. She used pea plants in a dark room, pairing the sound of a computer fan (an irrelevant stimulus) with the presence of blue LED lights (representing food). After several days of this pairing, the plants began to lean toward the fan alone, anticipating the light, even when the light was absent.

Monica Gagliano: “They remember straight away.” (19:23)

This experiment further supports the notion that plants can form associations between unrelated stimuli and beneficial outcomes, akin to learning.

Scientific Reception and Debates Gagliano's groundbreaking work has sparked curiosity and debate within the scientific community. Professor Emeritus Lincoln Taze from UC Santa Cruz commends the experiments but urges caution in interpreting the results, emphasizing the importance of avoiding anthropomorphism.

Lincoln Taze: “If you get too wrapped up in your poetic metaphor, you're very likely to be misled and to over interpret the data.” (28:36)

Despite criticism, some scientists acknowledge the potential for plants to exhibit forms of intelligence previously unrecognized, advocating for more rigorous replication of the experiments.

Metaphors and Perceptions of Plant Intelligence The episode navigates the thin line between creative metaphor and scientific terminology. While metaphors like "hearing" or "learning" in plants help conceptualize complex behaviors, they risk oversimplifying or misrepresenting the underlying mechanisms.

Jad Abumrad: “Could there be a brain or could there be ears or you know, just sort of like going off the deep end there.” (29:02)

Gagliano counters by suggesting that intelligence can manifest in diverse ways beyond human-centric models, advocating for an open-minded exploration of plant capabilities.

Conclusion: Rethinking Plant Behavior "Smarty Plants" challenges listeners to reconsider the traditional perceptions of plant behavior and intelligence. Through meticulously designed experiments, Dr. Monica Gagliano presents compelling evidence that plants possess sophisticated responses to their environment, potentially indicative of learning and memory. While the scientific community remains cautious, the episode underscores the importance of questioning and expanding the boundaries of what we consider intelligence.

Jennifer Fraser, artful amoeba blogger, encapsulates the essence of the episode:

Jennifer Fraser: “Plants are really underrated. When I write a blog post, my posts that get the least traffic, guaranteed are the plant posts.” (32:00)

The episode closes by celebrating the intricate and often overlooked complexities of plant life, urging listeners to appreciate the silent yet intelligent beings that share our world.

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Notable Quotes:

• Robert Krulwich: “I have done inspections where roots were coming up through the pipe into the house.” (03:44)
• Jad Abumrad: “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.” (03:52)
• Monica Gagliano: “We humans, we are 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.” (10:14)
• Monica Gagliano: “They remember straight away.” (19:23)
• Lincoln Taze: “If you get too wrapped up in your poetic metaphor, you're very likely to be misled and to over interpret the data.” (28:36)
• Jennifer Fraser: “Plants are really underrated. When I write a blog post, my posts that get the least traffic, guaranteed are the plant posts.” (32:00)

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Final Thoughts "Smarty Plants" serves as a thought-provoking exploration into the hidden lives of plants, challenging preconceived notions and inviting listeners to marvel at the silent intelligence that thrives beneath our feet and around us. Radiolab masterfully combines investigative journalism with innovative sound design to illuminate the fascinating intersections of science, nature, and curiosity.

Transcript

[Latif Nasser]

Listener supported WNYC Studios.

Hey, Happy New Year. I'm Latif Nasser. This, of course, is Radiolab. 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 Quasimoon naming contest. There is a winner. It's just not official yet. We will announce it the moment we are able to. 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. And besides the fact that it's just a 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. So to set us off on the right footing, here are emeritus hosts Jad and Robert with smarty plants.

Wait, you're listening? Okay. All right.

[Jad Abumrad]

Okay.

[Latif Nasser]

All right. You're listening to Radiolab radio from wny. Rewind.

[Robert Krulwich]

Sorry. What do you want us to say?

[Jad Abumrad]

Doesn't matter.

[Monica Gagliano]

One or the other, that's the matter. Got it.

[Alvin Newbell]

Testing, 1, 2. This is the headphones here.

[Latif Nasser]

All right. Got that.

[Jad Abumrad]

I'm Jad.

[Latif Nasser]

I'm Robert.

[Robert Krulwich]

How's that? Better?

[Latif Nasser]

Oh, much better.

[Jad Abumrad]

This is Radiolab.

[Robert Krulwich]

Can I interrupt?

[Alvin Newbell]

Yes, but could I say something?

[Robert Krulwich]

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

[Latif Nasser]

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

[Robert Krulwich]

I'm Larry Ubell.

[Alvin Newbell]

Y. I'm Alvin Newbell.

[Latif Nasser]

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

[Alvin Newbell]

Are we related?

[Robert Krulwich]

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

[Latif Nasser]

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

[Robert Krulwich]

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

[Alvin Newbell]

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

[Latif Nasser]

Okay.

[Robert Krulwich]

I'm not giving my age, but I.

[Latif Nasser]

Wanted to talk to them because as building inspectors, there's something they see over and over and over. Yeah, all the is actually a clue in what turns out to be a deep, deep mystery.

[Jad Abumrad]

Which is what exactly?

[Latif Nasser]

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.

[Jad Abumrad]

Okay.

[Latif Nasser]

And right in the middle of the Yard is a tree, and the tree.

[Alvin Newbell]

Happens to be a weeping willow, just for example.

[Latif Nasser]

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. 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.

[Alvin Newbell]

The tree will wrap its roots around.

[Latif Nasser]

That pipe, around and around and around.

[Alvin Newbell]

In a tangling of spaghetti, like, almost. And each one of those lines of spaghetti is squeezing little bit. Each one announce an ounce, announce an ounce, announce, announce. Eventually, over a period of time, it'll crack the pipe like a nutcracker.

[Robert Krulwich]

Yes.

[Latif Nasser]

You both see this happening all the time.

[Alvin Newbell]

Yeah.

[Robert Krulwich]

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

[Latif Nasser]

Into the house.

[Alvin Newbell]

It's amazing.

[Robert Krulwich]

Yes.

[Jad Abumrad]

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.

[Latif Nasser]

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.

[Jad Abumrad]

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

[Latif Nasser]

Well, of course I am.

[Jad Abumrad]

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

[Latif Nasser]

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

[Jad Abumrad]

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

[Latif Nasser]

I do.

[Jad Abumrad]

I do with the plant parade.

[Latif Nasser]

And I met a plant biologist who's going to lead that parade. 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. I know you. I know you don't. All right, but let me give it a try.

[Jad Abumrad]

Okay, I'm game.

[Latif Nasser]

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

[Monica Gagliano]

Hello. Finally.

[Latif Nasser]

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. The water.

[Jad Abumrad]

Right.

[Monica Gagliano]

But that scientist I mentioned, My name is Monica Gagliano. I'm a research associate professor at the University of Sydney.

[Latif Nasser]

She took that Notion out of the garden into her laboratory.

[Monica Gagliano]

Yeah, tested it in my lab.

[Latif Nasser]

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.

[Jad Abumrad]

What kind of pot is this?

[Latif Nasser]

It's kind of a shape like the.

[Monica Gagliano]

Letter Y, but upside down.

[Latif Nasser]

So you get the roots can go the left or to the right. Oh. 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 has water in it. So the question is, a plant that.

[Monica Gagliano]

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?

[Robert Krulwich]

All right, my hypothesis is that what happens is. Can I have a few minutes? No. You got somewhere to go? You got somewhere to go?

[Alvin Newbell]

No.

[Robert Krulwich]

Good. 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. Why waste hot water?

[Latif Nasser]

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

[Alvin Newbell]

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.

[Robert Krulwich]

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

[Alvin Newbell]

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

[Robert Krulwich]

The water is still in there.

[Latif Nasser]

So there is some water outside of the pipe. It's condensation. Right. So what they're saying is, even if she 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.

[Alvin Newbell]

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 says, ooh, I found a little water. And then all the other one goes in the same direction.

[Latif Nasser]

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

[Alvin Newbell]

Yes.

[Latif Nasser]

But Monica says, no, absolutely not.

[Monica Gagliano]

I purposely removed the chance for a moisture gradient.

[Latif Nasser]

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.

[Jad Abumrad]

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

[Latif Nasser]

That's right. Outside.

[Jad Abumrad]

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

[Latif Nasser]

Yeah.

[Jad Abumrad]

That is strange now.

[Robert Krulwich]

Or is it just the vibration of the pipe that's making it go toward it? They would have to have something, you know, you got, you know, maybe there's.

[Latif Nasser]

Some kind of signal, different kind of signal traveling through the soil. Monica thought about that and designed a different experiment.

[Monica Gagliano]

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

[Latif Nasser]

Yep. 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.

[Monica Gagliano]

Of the sound of water.

[Latif Nasser]

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 routes were heading toward the sound of water.

[Monica Gagliano]

Exactly. Exactly.

[Jad Abumrad]

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

[Latif Nasser]

Just the sound that sounds.

[Alvin Newbell]

That's interesting.

[Robert Krulwich]

It's interesting.

[Alvin Newbell]

That is interesting.

[Latif Nasser]

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?

[Jennifer Fraser]

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

[Latif Nasser]

This is Jennifer Fraser, I am the.

[Jennifer Fraser]

Blogger of the Artful Amoeba at Scientific American.

[Latif Nasser]

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

[Jennifer Fraser]

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

[Latif Nasser]

Little hairs.

[Jennifer Fraser]

Hairs, 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.

[Jad Abumrad]

That is cool. That is definitely cool. Okay, 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.

[Latif Nasser]

That's true.

[Jad Abumrad]

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

[Latif Nasser]

I don't think Monica knows the answer to that, but she does believe that.

[Monica Gagliano]

We humans, we are 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.

[Latif Nasser]

Okay.

[Monica Gagliano]

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

[Jad Abumrad]

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

[Latif Nasser]

I think that's fair. And I think if I move on to the next experiment for Monica, you are 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.

Latif, Radiolab back with Jad and Robert.

Yep.

[Jad Abumrad]

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.

[Latif Nasser]

Yes.

[Jad Abumrad]

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

[Latif Nasser]

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

[Monica Gagliano]

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

[Latif Nasser]

Because this peculiar plant has a surprising little skill.

[Jennifer Fraser]

Yeah, a reflex, an anti predator reaction.

[Monica Gagliano]

Like a defensive mechanism.

[Jennifer Fraser]

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

[Latif Nasser]

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

[Jennifer Fraser]

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.

[Latif Nasser]

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

[Jennifer Fraser]

Right.

[Latif Nasser]

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? Yeah, go for it. 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 Bhatia, 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, the 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.

[Monica Gagliano]

Well, I created this horrible contraption.

[Jennifer Fraser]

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

[Latif Nasser]

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

[Jennifer Fraser]

Box into which she put these sensitive plants.

[Latif Nasser]

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.

[Monica Gagliano]

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

[Latif Nasser]

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.

[Monica Gagliano]

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

[Jad Abumrad]

The plants stopped. What is it they did? They stopped.

[Latif Nasser]

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

[Monica Gagliano]

Exactly. Which is pretty amazing.

[Jad Abumrad]

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

[Latif Nasser]

Like what?

[Jad Abumrad]

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

[Jennifer Fraser]

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

[Latif Nasser]

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.

[Jennifer Fraser]

It would close up.

[Latif Nasser]

Oh, 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.

[Monica Gagliano]

They do.

[Latif Nasser]

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 design from scratch. It's like Lego. 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.

[Jad Abumrad]

A little seatbelt for him for the ride down.

[Latif Nasser]

And then someone has to count. And then we let it drop. 5, 4, 3, 2, 1, drop. 5, 4, 3. And we dropped it once and twice again and again. We were waiting for the leaves to, you know, stop folding. We dropped, we dropped. But I don't know, it didn't happen.

[Jad Abumrad]

It was curling up each time.

[Latif Nasser]

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

[Jad Abumrad]

So you couldn't replicate what she saw.

[Latif Nasser]

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

[Monica Gagliano]

I heard.

[Latif Nasser]

We told her what we did. What happened to you didn't happen to us. Now can you imagine what we did wrong?

[Monica Gagliano]

Like for example, my plants were all in environment controlled 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.

[Latif Nasser]

We kept switching rooms because we weren't sure whether you wanted to be in high light or bleak light or some light or no light.

[Monica Gagliano]

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.

[Latif Nasser]

Truth is, I think on this point she's got a. She's right. No. One time the plant literally flew out of the pot and upended with roots exposed. It 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.

[Monica Gagliano]

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.

[Latif Nasser]

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.

[Monica Gagliano]

The idea was to drop them again. Just to see the difference between the first time you learned something and the next time.

[Latif Nasser]

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

[Monica Gagliano]

Yeah.

[Latif Nasser]

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

[Monica Gagliano]

Yeah. They remember straight away.

[Latif Nasser]

Straight away.

[Monica Gagliano]

All of them know already what to do.

[Latif Nasser]

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.

[Monica Gagliano]

Yeah.

[Latif Nasser]

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

[Monica Gagliano]

Yeah.

[Latif Nasser]

Few more days.

[Monica Gagliano]

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

[Latif Nasser]

Eventually, she came back after 28 days. 28 days?

[Monica Gagliano]

Yes.

[Latif Nasser]

And they still remember. They still did not close when she dropped them. That's what she says.

[Jad Abumrad]

What was your reaction when you saw this happen?

[Latif Nasser]

That's producer Annie McKeown.

[Jad Abumrad]

This retention of knowledge.

[Monica Gagliano]

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.

[Jad Abumrad]

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

[Latif Nasser]

Yeah. I mean, can you remember what you were doing a month?

[Jad Abumrad]

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

[Latif Nasser]

Like that's a thing.

[Jad Abumrad]

But supposing that she's right.

[Latif Nasser]

Yeah.

[Jad Abumrad]

Where would a little plant even store a memory?

[Latif Nasser]

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.

[Monica Gagliano]

Oh, do you?

[Latif Nasser]

Yes, I do. You is a brain, I think. Is your dog objecting to my analysis?

[Monica Gagliano]

That's okay, Picasso. Pigs. Picasso. Enough of that. Pigs. Hey, it's okay. It's okay, papi. It's okay. Picasso. Enough of that now. Sorry.

[Latif Nasser]

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.

[Jennifer Fraser]

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

[Latif Nasser]

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

[Jennifer Fraser]

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.

[Latif Nasser]

They would salivate and then eat the meat.

[Jennifer Fraser]

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

[Latif Nasser]

And again. Drooling, eating.

[Jennifer Fraser]

And he would repeat this.

[Latif Nasser]

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

[Jennifer Fraser]

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

[Latif Nasser]

Sure enough, the dogs began to drool.

[Jennifer Fraser]

They had learned to associate the sound.

[Latif Nasser]

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

[Jennifer Fraser]

Meat, with when they actually saw and smelled and ate meat.

[Monica Gagliano]

Exactly.

[Latif Nasser]

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

[Monica Gagliano]

Would the plant do the same?

[Latif Nasser]

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

[Monica Gagliano]

Yeah.

[Latif Nasser]

Are you, like, aggressively looking around for, like, do you wake up in the morning and say, 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?

[Monica Gagliano]

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

[Latif Nasser]

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.

[Monica Gagliano]

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

[Latif Nasser]

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

[Monica Gagliano]

Yeah.

[Latif Nasser]

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

[Monica Gagliano]

Light is obviously representing dinner.

[Latif Nasser]

So light is if you shine light on a plan, like feeding it.

[Monica Gagliano]

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

[Latif Nasser]

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

[Jennifer Fraser]

Lights on the plants from a particular direction.

[Latif Nasser]

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

[Jennifer Fraser]

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

[Latif Nasser]

And the salivation equivalent was the tilt of the plant.

[Monica Gagliano]

Exactly. 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.

[Latif Nasser]

So after much trial and error, with clicks and hums and buzzes, all sorts of randomness, she found that the one stimulus that would be perfect was a fan.

[Monica Gagliano]

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

[Latif Nasser]

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

[Monica Gagliano]

The plants didn't care.

[Latif Nasser]

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

[Monica Gagliano]

And the fan were always coming from the same direction.

[Latif Nasser]

And with these two stimuli, she put the plants, the little pea plants, through a kind 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.

[Monica Gagliano]

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

[Latif Nasser]

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

[Monica Gagliano]

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

[Latif Nasser]

And Monica wondered, in the plant's case.

[Monica Gagliano]

If there was only the fan, would.

[Latif Nasser]

The plant anticipate the light and lean.

[Monica Gagliano]

Toward it or would just be going random?

[Latif Nasser]

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.

[Monica Gagliano]

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

[Latif Nasser]

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

[Monica Gagliano]

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

[Latif Nasser]

But she's got a little red headlamp on.

[Monica Gagliano]

Yeah.

[Latif Nasser]

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

[Monica Gagliano]

And then I saw that these little.

[Latif Nasser]

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]

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. 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 peas, but it was actually a majority.

[Latif Nasser]

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

[Monica Gagliano]

Yep, pretty much.

[Latif Nasser]

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

[Monica Gagliano]

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.

[Latif Nasser]

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

[Monica Gagliano]

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

[Latif Nasser]

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

[Lincoln Taze]

Yes.

[Latif Nasser]

And some of them. This is Lincoln Taze.

[Lincoln Taze]

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

[Latif Nasser]

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

[Lincoln Taze]

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

[Latif Nasser]

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

[Lincoln Taze]

Right. For example, words like hearing or learning behavior.

[Latif Nasser]

And this he's not a huge fan of.

[Lincoln Taze]

Yes. If you get too wrapped up in your poetic metaphor, you're very likely to be misled and to over interpret the data. I mean, it's a kind of romanticism, I think, you know, it goes back to anthropomorphizing plant behaviors.

[Jad Abumrad]

But I wonder if her using these metaphors again, producer Annie McKeown 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. Is it can.

[Latif Nasser]

It's just like metaphor is letting in the light as opposed to shutting down.

[Jad Abumrad]

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.

[Lincoln Taze]

I think you can be open minded, but still objective. I mean, I. I think there's something to that. I think there are some cases where romanticizing something could possibly lead you to some interesting result.

[Latif Nasser]

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

[Alvin Newbell]

Yes, that would be an interesting.

[Robert Krulwich]

Don't interrupt. They have to edit this together. Let them talk.

[Jad Abumrad]

Yeah.

[Robert Krulwich]

How much longer? Because I have an appointment.

[Latif Nasser]

All right, that's it. One thing, just out of curiosity. As we were winding up with our home inspectors, Alvin and Larry Ubello, 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 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.

[Alvin Newbell]

Oh, yes.

[Latif Nasser]

That there was a kind of a moral objection to thinking it this way. 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. I'm just wondering, do you share any of that?

[Robert Krulwich]

No, I don't. Because she may come up against 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 unique to humans, 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 with plants. They may have this intelligence. Maybe we're just not smart enough yet to figure it out.

[Jad Abumrad]

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

[Latif Nasser]

Okay, let's do it. Big thanks to ATI Batya, to Sharon Delacruz, and to Peter Landegrin 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.

[Jad Abumrad]

You're thanking Summer Rain?

[Latif Nasser]

I am.

[Jad Abumrad]

Did the plants sneak that one in?

[Latif Nasser]

No, no, no. Summer is a real person and her last name happens to be spelled.

[Jad Abumrad]

Oh, okay.

[Latif Nasser]

R 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 and toward 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.

[Jennifer Fraser]

Plants are really underrated. When I write a blog 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? No.

[Latif Nasser]

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

[Jennifer Fraser]

Yeah. 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.

[Lemon]

Hey, I'm Lemon and I'm from Richmond, Indiana. And here are the staff credits. Radiolab was created by Jad Abumrad and is edited by Soren Wheeler. Lulu Miller and Latif Nasser are our co hosts. Dylan Keith. Keith is our director of sound design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bressler, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu Nyan Sambandan, Matt Kielty, Rebecca Lacks, Annie McEwan, Alex Neeson, Sara Khari, Sarah Sandbach, Anisa Vitza, Arianne Wack, Pat Walters and Molly Webster. Our fact checkers are Diane Kelly, Emily Krieger and Natalie Middleton.

[Monica Gagliano]

Hi, my name is Tresa. I'm coding from Colchester in Essex, uk. Leadership support for Radiolab Science programming is provided by the Gordon and Betty Moore Foundation Science Sandbox Samantha Foundation Initiative and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.