Posts Tagged ‘behavior’

Lessons from Plants in Pain, or What We Talk About When We Talk to Ourselves

December 14th, 2011 | Meera

Roald Dahl, sovereign of the strange idea played out in matter-of-fact sentences, once wrote a story about a man named Klausner who invents a sound machine. With it he’s able to hear rarefied notes—tremors of the air that otherwise range, like so many things, outside the limits of human perception. When he turns on his invention, Klausner finds himself initiated into an entire universe he hadn’t known existed: a universe of plant communication.

You might think, on the face of it, that this would be a fine and lovely thing. You might think of how you generally experience the green and the growing, and imagine Klausner entering a soundscape filled with music, strains that match the beauty of a field of wildflowers or the elegance of autumn leaves. But instead, he mostly apprehends the noises of plants in distress. “Fierce grinding discords” fall on his ears: he’s shocked by the shrieks that roses make when they’re clipped off the bush. He’s tormented by pity when he hears the awful moans of a tree trunk split by his own axe.

Dahl leaves the question of whether the machine really works open to interpretation—but what I like about the story doesn’t rest on the definition of Klausner as either brilliant or insane. The thing that’s stayed with me, long years after I first read The Sound Machine, is Dahl’s bleak view of what speaks loudest in this world, what he thinks drives the “speech” of all living things—and that is pain.


343 (Mimosa plant, before)

Most disasters, even if they’re built on long and quiet years of brewing, eventually befall us with what feels like too little warning. A stroke slams down upon the pathway blood must take to brain, a guillotine that splits a thought in two. Your partner’s eyes, warm as summer lakes, freeze over for no reason you can fathom. A midnight switchblade sticks its cutting edge between your ribs; you gasp awake, pinned by the sharp awareness that you’re inside the wrong life. Tomorrow you might lose your job, your home. Be diagnosed with cancer. Even if you know the air is humid with the vapors of oncoming injuries, each one remains invisible until the day it’s churned into a storm.

I don’t think we’d be better off if we could see the future. I’m pretty sure I, anyway, would be flattened by the weight of full omniscience. But some small bit of notice, a clear advisory or two—watch out, here’s danger on the way!—now that, I’d take. Wouldn’t you? I think that wish must have something to do with why so many of us sit ourselves down to write quite undeliverable letters to the people we once were—an act that’s whimsical and sweet, and yet somehow forlorn.

Maybe it’s also why I’ve come to be, especially of late, a great collector of stories about other people’s hurts. (A cheerful philately.) If you’ve been wounded, come and bend my ear. I want to hear your warnings. And sometimes I eavesdrop on damages that strangers speak of. Years ago I spent almost half an hour lingering over my coffee—which was bad—because the girl at the table next to mine, fresh off her honeymoon, was wiping hot tears from her face and telling her companion how miserable she was to be married. She wasn’t my friend. It wasn’t my problem. And I’m not at all proud to have been riveted. But it was impossible not to be. My body rang (unobtrusively, I hope) with borrowed sorrow, and I still recall her cadences.

I think that moment meant so much to me because, respectfully, Tolstoy was not entirely correct about unhappiness. Life doesn’t feel the need to plan new slights and sicknesses to suit each one of us. Its threats recycle. I’m a realist: I know that, private though they feel, my troubles hover at the average, coinciding with those of my species. Whatever has battered some other Homo sapiens may soon come for me, and I would like to start preparing my defenses.

If this sounds ghoulish to you, well. I understand. But you should know that I am not alone in paying close attention to the suffering of my peers for my own sake. I stand with graceful trees: with willows, alders, poplars, sugar maples. The sweetest and most useful crops, as well—pea pods, beans, tomatoes, cotton—are selfish just like me. And ears of barley, ears of corn—these listen, too, to their beleaguered neighbors.

Klausner (tender soul!) was driven nearly mad by sadness when he overheard plant pain. He called a doctor for his broken tree and made him paint iodine in the wound. Plants themselves know better what to do.


It was in the early 1980s that a few scientists first began to report on trees that seemed to send each other stress signals. One was a zoologist named David Rhoades, at the time studying Red alder (Alnus rubra) and Sitka willow (Salix sitchensis) defense mechanisms at the University of Washington. Rhoades fed caterpillars leaves from trees their brethren had previously attacked. He found that they began to lose their appetites, and often died prematurely. Presumably this was because of some chemical compound the trees were able to release into their leaves as a form of rapid resistance—precisely the kind of thing he’d been looking for.

But Rhoades was surprised to discover that the very same thing happened to caterpillars fed the leaves of undamaged control trees, planted a little distance away. Could the attacked trees be emitting some kind of pheromonal warning that their counterparts could “hear?” Could they be telling their fellows to put up a fight against their leggy foes?

This study inspired a similar experiment on potted poplars (Populus euroamericana) and sugar maples (Acer saccharum) by a pair of researchers at Dartmouth. Jack Schultz and Ian Baldwin found higher concentrations of mildly toxic compounds called phenols in trees whose leaves they had torn. They saw the same thing when they checked on unscathed trees, after they were exposed to air pumped in from the chamber where the damaged trees were housed.

The scientific community as a whole reacted to these findings with great skepticism, some of which was not undeserved: methodological problems and an over-confident interpretation of statistics tainted both sets of results. But there was also, apparently, not a little ridicule, with some ecologists scoffing over the idea of “talking trees” and animal behaviorists closing ranks around the definition of communication.

In hindsight, this part of the negative response was somewhat less justified. In the first fourteen years that followed Rhoades, Schultz, and Baldwin’s reports, only three studies regarding plant-plant communication were published (perhaps because of the disbelieving atmosphere they would have emerged into). But times have changed. According to this overview of the literature on the subject, that figure increased to nearly 50 papers between 2005 and 2010.

At this point, the evidence that plants can receive, act on, and benefit from specific signals produced by their distressed coequals is pretty compelling. We’ve learned, for instance, that corn seedlings primed with compounds released by damaged plants give off more of their own defense hormones and chemicals when subsequently slashed with a razor blade or painted with caterpillar regurgitant. (Science is cruel.) We’ve learned that certain unrelated species, like sagebrush and tobacco, can interpret each other’s cues about dangers like hungry herbivores or clipper-happy researchers. We’ve even learned that well-watered pea plants, having overheard a warning from a thirsty neighbor, can pass on that message to still other plants, further away—although this game of vegetable Telephone seems to be played through the medium of soil, not air.

In my favorite recent study, which delights me more because of how the plants defend themselves than how they talk about it, Lima beans infested with spider mites—as well as those exposed to leaves from infested plants—react by activating a set of genes that trigger the emission of a volatile organic compound. This compound, in turn, attracts spider mite predators that come and hoover up the pests.

How wonderful is that? I call it very wonderful, especially since our own apartment has witnessed the expiration of a beloved dwarf Meyer lemon tree that succumbed to a spider mite blitzkrieg. If we’d had two trees, I wonder if one could have saved the other?

Maybe what Dahl got wrong was not the thought that pain is the seabed of all our most essential speech. Maybe where he erred was in suggesting that the anguish Klausner heard was simply that: anguish, pure expression with no purpose and no useful end.

I think of myself sitting at a coffee table, leaning in, despite my better judgment, and breathing in the chemistry of someone else’s heartache. In my mind, now, I see it as a moment of anointment, an inoculation. I think this even though I have no way of measuring what changed in me because of it.

Our bodies fail. Our partners leave. We wake up sick, or shipwrecked. Shocked. And I am hungry to be put on guard, to know when something wicked this way comes.


It’s clear that unscathed plants do eavesdrop, like me, on strangers in distress, and make themselves stronger when they hear of trouble. What’s less clear is what is happening for the plant in pain. Is its anguished warning—Watch out, danger!—really meant to serve as counsel to the ones around it? It’s possible, of course, that some plants evolved to give off stress signals altruistically, because neighbors are often kin, and one example keeps the group as a whole safe. But many times, letting a neighbor in on danger makes you more vulnerable. A Lima bean plagued with spider mites might not want its compatriots to be protected by mite-eaters. (One lemon tree might have saved another, but reluctantly.)

Instead of selfless exhortations, the story of plant stress signals seems at once more simple and more strange. The thing is, a plant that’s hurt and sending out a warning is very likely talking to itself.

Most plants have sophisticated vascular systems, and that’s often how they transmit chemical messages. But volatile compounds, diffusing through air, can travel faster than molecules moving against gravity through tiny tubes. Airborne signals also allow parts of a plant that don’t have a direct connection to each other to speak. Why, though, would a plant need to warn itself? What does that even mean? Well, think of this: A caterpillar munching on one leaf will probably move on to another, a little ways off. That second leaf has time—not much, it’s true, but some small span—to put up its own garrison against the tyranny of tearing insects. That second leaf is far from doomed. And it could use some notice. A body needs to take care of itself.

Most disasters befall us with what feels like too little warning. But maybe that’s because, wrapped up in where we hurt right now, we don’t imagine taking steps to care for what is still undamaged. I know; we are not plants, with separate fates for separate parts. When I’m in pain, it feels as if I ache completely, my entire consciousness consumed by one calamity. And yet. Could there be, do you think, something in this selfish signaling? Some way for us to be like willows and like alders?

I’m not entirely sure. But this past year, and nearly two, has felt like injury to me; so now seems like the time to test the case. I’d rather not be Klausner’s roses, crying out futility. I’ll trust instead that there is strong and healthy matter that remains in me, and let the weaker parts speak loudly to them. More importantly, I’ll try to listen and to learn. Because it’s not, I think, too late to start talking to myself.

And you? Ah. If you eavesdrop, let it be.


Mimosa plant, after

Highly recommended further reading: This wonderful article about visionary biologist Chandra Bose, and his experiments in plant sensation and behavior.

On Seeing Yourself

June 16th, 2009 | Meera

I don’t know what it’s like for you, but there are days when it feels I’m like meeting someone for the first time. Her features seem foreign to me, and that, in its way, is not so far from the truth.

I don’t know what it’s like for you: there are days when I am most comfortable if the sight is brief. Best if I have a specific task, like brushing my teeth or plucking at the ragged curve of my eyebrows until one bends to match the other; best if I can file the required report and move on, before too much is seen: Go ahead and wear that shirt. It looks well on you. No, there is no scratch on your cheek. It must have been a momentary twitch of a nerve… Yes, you look as tired as you feel. More tired. There it is. It’s not that I am ashamed, understand; my self-esteem is not a dress that has fallen and must be tugged back up. It’s not that I never stare; oh, stare I do. But there’s something unnerving about it.

I don’t know what it’s like for you. For me it’s a question of manners. Too direct a gaze creates an impossible challenge: which pair of eyes will drop first? I know that both are mine. Yet how strange is what I perceive—that I am at home inside one set of arms and legs, and at the same time these very limbs are hanging quite happily on a separate frame. That I am twinned.

Mirror, Mirror

I live quite comfortably with this contradiction, of course; but I suppose I haven’t always.

Babies aren’t born with what psychologists (somewhat ploddingly) call “mirror self-recognition.” It takes many months before they’re able to draw an unfaltering line between their reflections and themselves, to comprehend that the stare that meets their own so fearlessly does not belong to another human being. It’s not just a question of waiting until certain inevitable developments take place in the brain, either—though that is important. A light bulb doesn’t just blaze on one day and transform stranger into self. No; in fact, developing the ability to recognize one’s own body in the mirror seems to be a surprisingly rational undertaking, and one that builds over time.

In 1979—the year I was born, naked of a sense of self— two scientists named Lewis and Brooks-Gunn tumbled a series of burbling 12-month-old babies in front of a mirror, to see what they could see. The vast majority of them, the experimenters observed, engaged in something they called “contingent play”—so named because the movements of a reflection are contingent upon one’s own movements.

Having noticed that there was a being opposite them in the glass, and having perceived that the behavior of this being seemed oddly familiar, the babies would proceed to carry out clever studies of their own. Staring at their reflections, they would perform the same series of movements over and over again, each time watching intently to see if the strange creature in front of them would follow their lead correctly. They bobbed their heads up and down, bounced their chubby bodies enthusiastically, carefully waved their arms back and forth, all the while with eyes growing wide as they began to clarify and confirm the fact that they possessed a perfectly synchronous imitative partner who would do all that they did at just the same moment. These early play sessions seem to be a necessary first step towards claiming one’s reflection as one’s own.

(They are not sufficient, for it is possible to recognize that your movements dictate those of another without recognizing that the two are one and the same. The full understanding that the face opposite you in the mirror is your own does not generally arrive until late in the second year of life, according to subsequent studies. When that understanding comes, it can truly be described as self-consciousness. One common test of mirror self-recognition is to dab a spot of rouge on a child’s nose, then place them in front of a mirror. A sheepish, or frustrated, rubbing at the spot is the positive indicator researchers are looking for.)

But listen; am I the only one who is astounded by the canny, systematic tests those children conducted? Am I the only one who went straight to the mirror to reenact them, nursing a tiny thrill and half-hoping to catch my other self shifting her neck just a heartbeat too late? Because I’ll tell you what the Lewis and Brooks-Gunn study says to me. It says that seeing yourself does not come easily.

Cloud Gate Shenanigans (2)

Let’s put it this way: to know an apple, say, is straightforward. Hold it in your palm; take in its dangerous crimson; scrutinize its glossy skin. It is entirely self-contained. Its apple-y nature is self-evident. To know your own face in the mirror is different. You have to slide into the apprehension sideways, gather together a body of physical evidence and reason your way towards the truth:

When I nod, she nods. When I stare, she stares back. Her arms follow my arms; her legs stretch as far as mine. This plant does not move when I move; it is not part of me. This other person moves without my say-so; he is not part of me. Only she, with her skin so brown and her feet curling under her like frightened mice—only she moves with me. So. This is who I am. These are the things I am made of. These are my boundaries in space.

I don’t remember collecting those proofs. I don’t remember building my sense of self like this, brick by brick with my baby-brain. But I believe that I did, and you as well. And I’ll tell you something else: I believe that we’re in good company. Elephants, apes, and dolphins can learn to see themselves through contingent play, too.

Also, robots. Robots can learn to see themselves. Are you smiling yet? Listen, at the very least, one robot can that I know of—its name is Nico. I read about Nico in this charming paper, published last year. In it, two Yale computer scientists show how, with the help of three algorithms that deftly compare data to experience, a robot “can learn over time whether an item in its visual field is controllable by its motors, and thus a part of itself.”

First, Nico spends some time—four minutes, to be precise—waving its arm back and forth and carefully noting the shape of its own movements. Then, it’s ready to look itself in the eye, so to speak. Nico is placed in front of a mirror, whose contents are captured in a streaming image by a wide-angle lens embedded in what would be Nico’s right eye. Carefully monitoring that video stream, the robot continues to motor its arm around in random directions, checking for precisely contingent movements in the reflected scene. It consults the algorithms in its memory, calculating the probability that what it sees is really Nico. Very quickly, then, the robot is able to accurately determine whether it happens to be looking at itself, an inanimate object, or an animate other.

Once it has understood the form of its own arm, learned the way in which its joints shift position—once it has traced the essential outline of its own metallic body—Nico can be said, in a very real sense, to recognize itself. And after that understanding has set in, no one (not even a sly researcher insinuating himself into the scene and painstakingly mimicking Nico’s movements) can fool it. Nico knows exactly what it is.

But achieving that knowledge demands two things, both of which are clearly spelled out in the title of the Yale paper: time and reasoning.

Seeing yourself doesn’t come naturally; it’s not fundamental to your understanding of the world in general. And it can’t be accomplished simply by having someone else tell you who you are in the glass; it’s not a fact you swallow, but a judgment you come to. At first—ask a baby; ask a robot—it’s not at all silly to narrow your eyes at that odd-looking stranger and wonder why they’re copying what you do. At first, surely it’s right and proper to be suspicious of the shade in the mirror.

When it comes right down to it, I mean, you might be wrong about the whole thing.

Here’s the thing: When I think of myself, what comes to mind is less a single clear and shining image of my own face than a shifting sensation of me-ness: a complex amalgamation of memories, ideas, and sensory impressions. I am the one around whom my husband’s arms wrap, the pressure of his musculature against my own clearly defining the shape of my body. I am the one who lay at the foot of my parents’ bed as a child, listening to the hum and click and drip of their ancient air-conditioner and imagining the sounds growing larger and larger until they merged with my own heartbeat. I am the one who frets for hours before phone calls, sweaty and pale, who dances while she cleans, who hates hair in her face and still remembers the sharp, dusty taste of the whiskey sours she used to drink because she liked the way they made her tongue twist up inside her mouth.

I am the one who feels the way I feel, thinks the way I think, not—or not just—the one who looks the way I look. And how do I look, anyway? No matter how many tests I run, no matter how much I grow to trust the image before me in the glass, the sight of my own face is always mediated through layer after layer of tin, silver, glass, copper, paint. I’ve never seen it without a mirror as middleman, without a bender and broker of light. What if the person I’m seeing isn’t who I think it is at all? Why should their mere resemblance to me be sufficient identification?

I live quite comfortably with this suspicion, of course; but not everyone does.

People with a extremely rare disorder known as Capgras delusion come to believe that those whom they love have been replaced by impostors. These strangers are identical to my mother, my sister, my brother, Capgras sufferers say, but they are not them. They are different people entirely. Their features—remarkably similar! The close resemblance is uncanny! But no; they are certainly not the ones I know. They are frauds. I do not recognize them.

The extent of the delusion is such that, confronted with their own reflections, Capgras patients are apt to startle violently. Why, I’ve never seen this person before! they may exclaim, in horror and disgust. Some engage in the same kind of contingent play that babies do, pinching themselves and waving their arms, keeping a chary eye on the ghoul in the mirror—but unlike babies, they will not be satisfied by the paltry evidence of their own eyes. And when repeated gazes into a mirror call up the same disagreeable stranger again and again, people with Capgras may accuse their likenesses of deliberately appearing in their lives solely to stalk and torment them. Capgras delusion steals a person’s ability to see their own true selves, and replaces it with an uninvited guest who cannot—will not—leave them alone. I confess, I sympathize.

But how exactly does this happen? Capgras patients are otherwise, for all intents and purposes, normal—whatever that means. Their vision is not impaired, and neither is their cognitive functioning; nor are any aspects of their memory. Their negative emotional response to their loved ones and their own reflections is bizarre, to say the least, but in some sense it’s also perfectly lucid and reasonable. It matches, after all, precisely the way you would expect someone to react if everyone in their inner circle of intimates had been replaced by an impostor. (And wouldn’t you yell if your beloved reflection suddenly turned into someone you knew, deeply and profoundly, wasn’t you at all?)


So what causes this extraordinary disconnection between vision and belief, between seeing a person, recognizing their features, and correctly identifying them as someone whom you know and love? The inimitable UCSD behavioral neurologist V.S. Ramachandran has a lovely theory about this. Look, he says: Sensory information about objects the eye sees is transmitted from the retina into visual centers in the temporal lobes. Here, the object is identified: This looks like a teapot, this looks like a poodle, this looks like my sister. Capgras patients can accomplish this part of seeing perfectly well.

But after an object has been identified, the brain continues to work. It sends its decoded information to the limbic system, which is a complex network of brain structures that enables the perception and expression of emotions. One of the first places this visual information passes through is the amygdala (the name means almond-shaped, which it is). Ramachandran explains that the amygdala is responsible for labeling the emotional content of what the eye has seen. This object is beloved, the amygdala concludes, and should trigger affection; this one is despised, and should trigger hate.

This visual data, then, becomes colored with a layer of emotional interpretation; it travels on towards other structures in the brain. At its final stop, what began with a glance at a face sets in motion at last the physiological responses that enable a person to actually experience the appropriate emotion: things like a speedier heart rate, higher blood-pressure, and a light film of sweat covering the skin. (For what is emotion but the brain, talking to the body, talking to the brain?)

You might imagine that a rather odd sensation might occur if this process were disrupted somewhere after the point where an object is decoded and before the point where the emotion that ought to be associated with it is actually experienced. Ramachandran did. He asks:

Is it possible that in this patient there has been a disconnection between the face area of the temporal lobes and the part concerned with the experience of emotion? Perhaps the face area and the amygdala are both intact, but the two areas have been disconnected from each other. When (the patient) looks at his mother, even though he realizes that she resembles his mother, he does not experience the appropriate warmth, and therefore says ‘Well, if this is my mother, why is it I’m not experiencing any emotion? This must be some strange person.’

I think of a person like this, and how they must feel when they stare at the mirror, eyes fixed full upon their own faces and hearts as hard as stone. Do they never, now, experience the comfort of being alone with themselves?

It hasn’t been proven, so far, the hypothesis that the Capgras delusion is caused by the neurological disconnect that Ramachandran describes—but its elements catch at my heart. It’s not enough to simply identify a person in order to truly know them. The brain needs more. It’s not enough to match the movements of a reflection to your own in order to recognize it as yourself. The brain needs more. Seeing yourself does not come easily. It requires time. It requires reason. And, beyond all that, it requires some measure of affection.

Knowing this, I return to my counterpart in the mirror—the one who still seems so strange to me sometimes—and am moved to tenderness. I look on her for a long moment, studying the shape of her lips, the brown of her eyes. I forgive our separation, forget the times when her eyes have challenged mine or mine hers, and gaze.

Because if I do not see her, how will I love her?

And if I do not love her, how can I see her?

If you’re fascinated by reflections, I can do no better than to recommend the deep and intricate treatment of the subject in Mirror, Mirror: A History Of The Human Love Affair With Reflection. I found my copy in the stacks of Powell’s Books in Portland, OR, on my honeymoon.