Plant Intelligence

- [Anne] Hey friends, there's a new science of plant intelligence that's changing how we view everything green and growing, from huge creatures like trees and forests to tiny ferns and delicate mosses. Plants turn out to have intelligence on a scale we never imagined. They're actively aware of the world. They don't have ears, but they can kind of hear. They communicate with other living creatures across distances, they have social lives. It's kind of mind-blowing. Today, on "To the Best of Our Knowledge," "Plant Intelligence."

- [Announcer 1] From WPR.

- [Anne] It's "To the Best of Our Knowledge." I'm Anne Strainchamps. Look at a plant, and what do you see? Leaves, stems, branches, roots that stretch below ground. But there's something else, something harder to see but just as real, intelligence. Not unlike our own. Welcome to the new science of plant intelligence. Learn enough about it, and you will never see a plant the same way again. At least, that's what happened to Steve Paulson.

- [Steve] I think that common assumption is plants just have these automatic responses to stimuli in the environment around them. Decision-making means they can make choices. They have some, I would say, cognitive capacity to do that. Can you give examples of how that works?

- [Zoë] Sure.

- [Anne] This is science writer Zoë Schlanger.

- [Zoë] We watch plants make decisions all the time based on where they choose to grow. I love looking at trees, old trees. You can look up at their trunks and see, oftentimes, little stubs of branches with no leaves on them. And when you see that, you're seeing a place where light used to fall. So at some point, the tree decided it was time to make that branch because there was light there, and they could gather that and use it for photosynthesis. And eventually, based on how the overstory developed, that part got shaded out. That tree reallocated its resources away from that. That stump is now devoid of leaves, and they put their energy toward a different part of their body that could still collect light. There's more sophisticated choices being made always, too. I like to think about the Venus flytrap, which is, you know, such a charismatic plant because it eats animals, quite unlike most of the plants in our lives. And it does that using this modified leaf that looks like a maw, it looks like a mouth. It has little trigger hairs on the inside. So when something ends up in that maw, one of those trigger hairs might get flicked. But the plant understands, on an evolutionary level, that you don't want to close on something that's just a twig or a bit of leaf or something that's fallen in you, so you wait until that thing wriggles. And so, a second hair has to be flicked before that maw will close. But then still, it's so expensive, energetically, for that plant to digest an animal that it wants to really be sure. So something has to continue wriggling in it. More of these trigger hairs have to be flicked before digestion starts. Now, if suddenly everything goes quiet, the maw will reopen again, it'll reset. So there's something going on here that scientists do define as counting. They're able to count both the number of trigger hairs that have been flicked and the elapsed time, because if this all takes too long to happen, it resets itself, so that's addition and subtraction, a sort of short-term memory and decision-making, that is just remarkable.

- [Steve] Wow.

- [Anne] Zoë Schlanger is a staff writer at "The Atlantic" magazine. She spent years as a science journalist covering the climate crisis, which means one environmental disaster after another. It was a lot. So when the mounting dread and sense of doom threatened to pull her under, Zoë decided to pivot. She wrote a book called, "The Light Eaters: "How the Unseen World of Plant Intelligence "Offers a New Understanding of Life on Earth." And in plant science, she found what she'd been missing, a sense of wonder and re-enchantment.

- [Zoë] Something that would give me the experience of awe. And I'd initially fallen in love with ferns, and specifically with this tiny little fern called Azolla filiculoides, this teeny water-dwelling fern that grows in mats in shallow water, and it was absolutely gorgeous. I saw a photo of it with a scientific study. It's like this perfect green, scalloped little thing, the size of a thumbnail. And I found out that it had tipped the balance of gases in the Earth's atmosphere away from the intense concentration of carbon dioxide millions of years ago.

- Wow.

- And helped cool the planet. And that people were looking at whether it could do that again.

- [Steve] So you sort of fell in love with this fern, and how did you go from there to this whole larger world of plant intelligence?

- [Zoë] I decided I wanted to write a bit more about how incredible ferns were, and so I made a call to a fern researcher, and I very quickly realized I loved talking to botanists. And also I had stumbled upon the field at a moment when there were a lot of things happening. Plant scientists were debating whether or not plants could be intelligent or conscious, and I knew that when scientists use words like that, they don't do that lightly. These are big-deal, blockbuster words that contain all these philosophical elements, and for them to even be bringing it up, I knew there must be a reason. And indeed there was, there were incredible breakthroughs happening about plant communication and memory and sensing of all kinds that were making scientists really rethink what a plant is.

- [Steve] So those are such huge and complicated questions. Are plants not only intelligent, but are they conscious? As you say, I mean, these are really not just science questions, these are philosophical questions that get to some profound questions about the nature of reality.

- [Zoë] Absolutely, which, as you can imagine, we're provoking real fights. There's plenty of botanists sort of on both sides. One camp was saying it's time to expand our notions of intelligence to include a creature that doesn't have a brain. Plants, of course, don't have any brains. The other side was saying that's ridiculous. Why layer these human ideas of intelligence and what intelligence could be on this other taxon of life entirely? And then there was a much larger camp of botanists kind of sitting in between, waiting for this fight to blow over and just doing really remarkable plant science in the meantime that spoke for itself.

- [Steve] So there is one book that kind of hovers over this field, and it did for decades, "The Secret Life of Plants," which made all kinds of outlandish claims that plants could hear, they could see, they preferred Beethoven over rock and roll. What kind of impact did that book have?

- [Zoë] This was a phenomenal success on the popular market, this book, that had never happened for a botany book before, there was a feature film about it. Stevie Wonder wrote the soundtrack. It's a pretty fabulous album, I have to say. The problem was that there was a lot of pseudoscience in this book. There's a lot of kind of stretching claims or relying on half-baked experiments. In one case, a former CIA agent used a polygraph test on a plant and concluded that the plant could read his malevolent thoughts. And this made such an impression on the public and was taken at face value. And that's a disaster for research scientists who care so much about accuracy. And it was a bit of an embarrassment. The funding agencies that fund our sciences closed their doors. They didn't want to be affiliated with research that sounded like it was the kind of woo-woo "Secret Life of Plants" research anymore. That was this kind of taboo that clinged to these sciences for decades afterwards.

- [Steve] Hmm, so what were some of the breakthroughs that started to happen that suggested, didn't just suggest, I mean, showed, that plants really are intelligent in ways that we never would've dreamed of before?

- [Zoë] There are so many papers now looking at what it looks like when a plant makes a decision, for example, which is a very new way of thinking about plant activity. Things like foraging, the way that roots absolutely actively forage for their food. It's not a sort of passive filter-feeding, so to speak. Roots are wonderful for watching plants make decisions. They can sense moisture gradients from very far away and move towards them. There's even some evidence that they can sense acoustic vibrations. In other words, what to us is sound, the sound of running water, plant roots are able to approach that, even in the absence of physical moisture, like in a sealed pipe. Which is, of course, not news to any plumbers who deal with root intrusion on a regular basis, but-

- [Steve] Wait, wait, just so I understand this, you're saying plants can hear, they have some version of their own ears?

- [Zoë] Well, yes, this is where we get into very slippery language. What does hearing mean to us? It means having ears and a brain to translate that noise into meaning. Plants don't have a brain, and they technically don't have ears, but they do respond to acoustic vibrations. Sound is vibration, and that is information plants, we now know, can use, and this has birthed a field called phytoacoustics, which is really a fascinating one. Researchers have now found that plants can respond to the sound of their predator chewing and will boost their immune system in response to the sound of this chewing caterpillar.

- [Steve] Wow. Just so I understand this, so they would, what, send out signals through their leaves, roots, to activate this immune response to resist this particular caterpillar?

- [Zoë] Yeah, that's exactly what happened, was that the researchers placed real caterpillars on the plant and then took them off, and what often happens with plants is they get primed from a first experience to respond more strongly later.

- [Steve] Wait, so they remember what happened before?

- [Zoë] Essentially, yes, that is one way to interpret that, plant memory, and there's a lot of compelling research on plant memory now. But these particular researchers then placed guitar clips, pickups, piezos onto the leaves of this plant and played the sound, the acoustic vibration, of those caterpillars chewing, and on that second stimulus, the plant activated its immune system, which can mean anything from making its leaves bitter to make them less edible, reducing the nutrition of their leaves to slowly starve their predators. It can also mean releasing acoustic warnings, these alarm calls that float through the air, these compounds that can be interpreted by other plants, so they boost their immune systems too, even before the predator has a chance to reach them.

- [Steve] That's so interesting because I guess I would've assumed that, okay, even if plants can send signals, it would be through chemicals. You're saying it's through sound, it's through hearing the sound, hearing these guitar riffs, that actually would stimulate this immune response.

- [Zoë] Yeah, so this applies to lots of other ecological sounds that plants have evolved with. There's been research on evening primrose, which are these beautiful little teacup-shaped flowers. Each evening primrose was able to increase the sweetness of its nectar by three times when it sensed the sound of a bee buzzing near it. Researchers found that that bowl shape, that perfect little teacup of the flower, might be that shape precisely for the same reason satellite dishes are concave. When they plucked out a few of the petals and broke that symmetry, the plant was no longer able to receive that vibration as information. And that researcher was perfectly comfortable saying she saw a field of ears now whenever she saw a field of flowers.

- [Steve] Wow. Can plants also make sounds?

- [Zoë] This is very new field of work, but one researcher has done a paper, or one team of researchers has found that plants do make sounds that might contain information. So when there's fluid moving in the stem of a plant, which there always is, there's also air bubbles, and those air bubbles pop, and these are called cavitation clicks. They make a sound, it's kind of like the sound of popcorn popping if you amplify it enough for humans to hear. And so, this is very nascent, very early research, but there's some chance that the sounds that plants make are in fact information-laden, which would open up a whole new world of research because that would mean animals are very likely to hear that. If we can hear it, animals can hear it, and that could affect ecological relationships.

- [Steve] What you're describing is how plants actually behave in a lot of ways that animals do. I mean, obviously one of the big differences between plants and animals is plants can't move around. They're kind of stuck in one place. I know there are a few rare exceptions, but somehow they compensate for that.

- [Zoë] Right, and this brings us back to that thing you mentioned earlier, plants don't have brains, but there's reason to believe that that makes sense for their evolutionary heritage. We evolved brains in part perhaps because we had to travel across landscapes and run around and forage for food and flee from predators, but plants are stuck in one place and perhaps they didn't need this portable package to carry with them with central processing. I mean, they have this very distributed sensing throughout their bodies. They're modular, they can lose a limb if they need to, and it won't really harm them. And yet, somehow all of this sensing that's going on with their disparate parts is integrated into the whole. In other words, if a limb senses something somewhere, the whole rest of the plant is able to respond appropriately to what's being sensed. What researchers don't yet understand is how that's possible, how you have integrated decision-making and responding despite not having a brain.

- [Steve] Well, it makes me wonder if plants actually have their own version of a nervous system. That's what a nervous system does for animals, right? Sort of sends out all these different signals and maybe actually plants do have a nervous system, but it's just, I dunno, made of different parts or something.

- [Zoë] I'm so glad you brought that up because I was able to travel to a lab at University of Wisconsin, Madison, to the lab of Simon Gilroy, who studies calcium waves in plants, which sounds like a very esoteric thing, but it's very fundamental. He works with these plants that are imbued with fluorescent green proteins from jellyfish. Those proteins glow when calcium is passing through a cell, which is sort of a proxy potentially for electricity. Of course, our nervous systems are electrically mediated, our nerves, it's all about electrical signaling. Plant bodies appear to have something like this too. They use some of the same neurotransmitters as we use in our brains.

- [Steve] Wow.

- [Zoë] Glutamate, for example, is present in plants. And so I went to this lab, and we went into this dark microscope room, and I got to pinch one of these modified plants with tweezers that had been dipped in glutamate and watch as this glowing green eminence just radiated out from the place where I pinched the plant with my tweezers to spread out through the entire plant. So this was like a little tail crest plant, maybe the size of a small tea plate, and within two minutes, the whole rest of the plant had received the signal of my pinch, and I could watch it actually happen. And that really changed my life. It was the first time I was able to see a plant respond in real time thanks to this fluorescent green protein that was added. But, of course, plants are presumably doing this all the time. Touch is not something that goes unnoticed by a plant. The plant is registering that touch and sending the signal of that touch throughout its body. You can watch the branching pattern of the leaves' veins and watch the signal go through those veins, and it's unmistakably similar looking to a very basic version of a nervous system. And it's provoked people, not just in the plant sciences, but also in neuroscience to ask the question of whether it's time to expand the definition of a nervous system to include plants.

- [Steve] So, you've mentioned that plants can hear sounds. Can they see?

- [Zoë] You are, again, touching on this absolutely red-hot debate at the moment. While reporting, I went down to a temperate rainforest in southern Chile to meet a plant and the researcher that studies it called Boquila trifoliolata. It's this vine that has just recently been discovered to morph its body to mimic whatever it grows beside. And this is a totally wild proposition for plant science. There's never been a plant that's been found to spontaneously mimic its neighbors. Some have one-to-one mimicry relationships, but we're talking about a vine.

- Wait, just so I understand, what you're saying is there's another plant that has totally different leaves, but somehow this vine, this chameleon vine, can kind of generate leaves that look just like this other species' leaves?

- [Zoë] Exactly, yes. So, if you're there in the forest with me looking at it, the Boquila vine will have leaves that kind of look like pea leaves, they're very normal little oval trifoliate leaves, and then it'll wind its way, as vines do, towards another plant, and as it's approaching the plant, the leaves on that part of the vine will suddenly take on the shape and texture and vein pattern and thickness and glossiness of the leaves it's growing beside, of this other species entirely. And then the vine can turn again and sort of swerve into another plant, and suddenly the leaves in that section of the vine are again wildly different and mimicking that other plant that it's now growing near. So the same vine plant can mimic up to four different species. And then as a whole, the species has been found to mimic now something like two dozen different plants. And each time the researcher who studies it goes to this forest, he finds new examples. So this has provoked a debate around whether or not plants can see. On some level, this is visual information, that's the most basic explanation that one can think of-

- Yeah.

- [Zoë] Is the color of a leaf, the texture of a leaf, the shape of it, those are visual cues. You know, plants have more photoreceptors on their leaves than we have in our eyes. They do have incredible fine sensing of light. They know if they're being shaded by a cloud, or they know if something is the color red or the color blue. So, you know, these researchers say it's not such a stretch. Maybe they can see in images.

- [Steve] Can I just say, this is crazy? This is mind-blowing, what you're saying about this vine, that it can somehow transform its leaves, its structure, basic structure, and turn into something that looks nothing like the way its leaves ordinarily look. I mean, I just, like, that doesn't seem possible.

- [Zoë] I was as shocked as you were. To see it in real life, it's absolutely striking. A leaf can be this tiny little oval thing, and then all of a sudden, on the same plant, can stretch out to be 15 or 16 times the size to match whatever plant was growing beside it. And this suggests something really unheard of. We think about leaf shape as something so basic to a species, but this suggests some sort of extreme plasticity, that something as basic as the shape of something can morph spontaneously to match its surroundings.

- [Steve] Yeah, wow. So you spent years doing all this research, writing your book. I'm wondering what you came away from in all of this. I mean, obviously there's, at this basic level, sort of the sense of the natural world is much more alive than we probably knew before. Raises all kinds of questions about evolutionary history. But I'm wondering if there's anything more specific or more direct for you in terms of how you rethink your place in the world or just the world around you.

- [Zoë] Yeah, I think it was a profoundly humbling experience for me to be reconnected in a very strong way with how little we know as humans. You mentioned evolutionary history, but it is a really profound sense, this idea of evolutionary progress is not this linear concept with humans sort of at the pinnacle. We are not necessarily the most advanced. Really, evolution is this constant seeking out of options for flourishing, and plants represent the end node of one branch of doing that, in which they are each the pinnacle of their evolutionary process. And it sort of settled me back as a human into this bigger web of life in which evolutionary biological creativity is really the incredible thing, and our creativity is just one version of that. So that was, it imbued a lot of humility into me. It also just sort of re-enchanted my everyday life of walking through parks and my neighborhood, living even with my houseplants.

- [Steve] Did you go out and get more houseplants?

- [Zoë] Some of this knowledge can prevent a person perhaps from collecting too many houseplants because you suddenly feel this immense weight of responsibility. But yes, I do very much enjoy living with plants. It did cut down on the number of times I will touch a plant. You have plants in your house, they unfurl a new leaf. It's very soft, it's lovely, you might want to touch it. But I now fully understand that that is not going unnoticed by that plant and is probably stressing it out and boosting its immune system. So, sometimes I think twice about that.

- [Steve] It's interesting what you're saying, though, because depending on how far you want to take some of these discoveries that you've been reporting on, there are ethical implications here. It's obviously totally unrealistic to stop eating plants, but is there a morality to all of this?

- [Zoë] Right. It does bring plants into the realm of our ethical and moral regard to start thinking of them as entities with agency, with lifestyles of their own, social lives, which they certainly do have, a sort of desire to survive just like every other biological entity on the planet. I think it does raise these questions of what our ethical responsibilities are towards them. We have to farm them to feed ourselves. We have to grow them to build our houses and our clothing. But there is a degree of excess to that practice or exploitation where this can tip into a relationship that is not just one of respect, but one of complete disregard. I think about that a lot in my coverage of climate change. Deforestation, without a second thought, is one example of that.

- [Steve] So we've been talking about the frontiers, the edges of what science is discovering about the amazing capacities of plants. There are some areas that may be pushed beyond science. I know there are lots of people who draw spiritual sustenance from these findings. They talk about a mystical bond with the plant beings. This is especially true in a lot of indigenous cultures. I know this makes scientists extremely nervous. I mean, it sort of hearkens back to "The Secret Life of Plants," but does this have any resonance for you?

- [Zoë] Certainly the many, many indigenous cosmologies that regard plants as a form of kin and often as a form of ancestors. I also learned a lot by reading books by indigenous authors on plant sciences, including this idea by an Anishinaabe author who is relaying how her Great Lakes area people regard plants as older brothers to humans. This idea that we are somehow hierarchically on top is a tragic inversion of the reality, which is that we are entirely dependent on plants. They produce all of the oxygen that we breathe, they produce all of the sugar that nourishes our every moment. I mean, our entire bodies are built out of and run on plant sugars, and plants are the only living things that we know of that can convert sun and water and air into sugar. Every other form of sugar we've ever taken into our bodies has been recycling that plant sugar. Even if you eat an animal product, for example, that animal, somewhere down the line, was getting its sugar from a plant. So there are so many ways in which indigenous science acknowledges that dependency, and our western cultural inheritances have divorced themselves from that. But there's plenty of room to look at the science and look at what indigenous scientists have also told us and marry those two things. And you come up with just a much more realistic picture of our place in the world.

- [Steve] Thank you, this has been absolutely fascinating.

- [Zoë] It's wonderful to talk with you. Thanks for having me.

- [Anne] Zoë Schlanger is a staff writer at "The Atlantic" and the author of "The Light Eaters," and she was talking with Steve Paulson. So what changes when you think of plants as relatives?

- [Suzanne] Hello, come on in.

- [Anne] Hey. There is a big conversation opening up about our moral and ethical responsibilities to creatures with roots and leaves.

- [Suzanne] I'm Just eating my... I'm sorry, I'm-

- Yeah, take your time.

- [Anne] No, no, no. We're heading out for a morning walk with the founder of the Mother Tree Project, next-

- [Suzanne] You want some breakfast?

- [Anne] On "To the Best of Our Knowledge" from Wisconsin Public Radio. Thank you, I had a, I had a bowl of granola. And PRX.

- [Suzanne] Little grove... Little grove of trees that I really like.

- [Anne] It's an October morning in Ojo Caliente, New Mexico, not my natural terrain.

- [Suzanne] I take a lot of pictures of trees.

- [Anne] Not Suzanne Simard's either. She is a forest ecologist from British Columbia. That's beautiful. We're at a writer's retreat for women sponsored by the Kalliopeia Foundation and out for a little walk to look at some native trees.

- [Suzanne] I went to the Amazon last year.

- Yeah?

- [Suzanne] Flew over this vast rainforest, and I was just like, oh, you know, that's what it used to be like when I was a kid up in Canada.

- [Anne] Suzanne Simard is one of the most famous forest ecologists in the world, one of the first to discover the so-called "wood wide web," the mycorrhizal fungal networks that trees use to communicate with one another.

- [Suzanne] So now it's all clear cuts. We've only got like two percent left. It's just so heartbreaking. Her work inspired the movie "Avatar." Richard Powers based a character on her in his Pulitzer Prize-winning novel, "The Overstory." It was Suzanne's concept of "Mother Trees" that really seized everybody's imagination.

- [Suzanne] This ecosystem has changed so much that we should be thinking about this.

- [Anne] Thinking of the forest as a kinship network. Families of giant elder trees sheltering and caring for younger ones. The implications for forest management are huge.

- [Suzanne] How about here?

- [Anne] Sure.

- [Suzanne] I don't think this is exactly the tree clump I was thinking about, but this is fine.

- [Anne] Okay.

- [Suzanne] Yeah, I just wanted-

- [Anne] Changing paradigms is hard work. It's why Simard founded the Mother Tree Project, why she's working with First Nations communities and indigenous scientists to build a new model for the world's forests.

- [Suzanne] The dominant paradigm in forests now, which is that trees are competitive and you've gotta manage them like tree farms and grow them for products and then feed the economy, and it's a very tree farm kind of model, and theoretically it's all based on managing the competition between trees, and it resulted in massive industrial plantations across where I live. First, clear cutting. Get rid of it all, you know?

- Yeah.

- For the profits. And then also used science to say, "Oh, these fast-growing new plantations need lots of light, "so we've gotta get rid of all these other plants." So then came the herbicides. And then, "Oh, well they're not growing "as fast as we thought," then came the fertilizers, and even now you hear this, you know, "Well, if the trees aren't sequestering "and storing enough carbon, add more fertilizer." To me, it's not the way we should be going. We should be talking about working with the natural system, the regenerative aspect of the forest, which is what I study. And so that immediately puts me against the prevailing paradigm.

- [Anne] That paradigm, we can make it bigger. We can talk about it as a paradigm that's at the foundations of western science, right? Evolutionary biology, for instance, it's a dominance model.

- [Suzanne] Yeah, and you know, we were talking about this the other day, like Darwin, who is cited constantly about his model of natural selection, survival of the fittest, and he actually understood ecosystems as a myriad of interactions, not just competition. He wrote about that, and yet it was cherry-picked for that thing that fit the economic models developing at the time, in the late 1800s. Capitalism was really taking off, and so they fit together. And so it, it became kind of a twisted theory. It feeds into and supports this view of cutting down all our primary forests and replacing them with fast-growing tree plantations that are based on the dominance model, survival of the fittest. And it has huge, massive repercussions for us, today, in society. You know, I just looked at "The Guardian," our forests have just shifted from being global sinks to being neutral, if not, sources for CO2. That is a travesty, that's a tragedy, and yet we don't have to do it this way. We have other choices, and we need to make these other choices.

- [Anne] You've been working with First Nations in British Columbia, right? As part of the Mother Tree Project.

- Mm-hmm.

- That represents a whole different, I mean, we're talking about paradigms. It's a different-

- It is.

- Knowledge paradigm.

- [Suzanne] Yeah. It's a knowledge paradigm, and it's also a rights and title, "whose land is this," paradigm. Who is making the decisions? So, when North America was colonized, or any colonial activity around the world, or even in our economic growth model, we have people from the outside making decisions for forests, and they'll say, "Okay, we want this much rate of return. "We wanna harvest this much wood." They're not there on the ground looking at what's happening to communities. Conversion of native forests in Ecuador to eucalyptus, it's causing all these ripple effects into these small family farms. It's the unraveling of the communities. That is not considered in this economic model from the outside, that we're gonna make as much money from extraction of forests as possible.

- [Anne] It's that, and it's also seeing your great insight that has earned you so much approprium within forestry and within traditional science, but was a completely different model-

- Yeah.

- [Anne] That it's not about-

- Yeah.

- The individual.

- [Suzanne] You know, that model of all is connected. I grew up in the old growth forest, and I came from a family of horse loggers, and we were peasants. And I look back through my family history all the way back to France, we were peasant woodcutters for, you know, thousands of generations, from what I could trace back to. And so I just came from that, that view that you just have to make a living. You know, you just do selective harvesting, you feed the family. But, of course, we were also part of the colonial system of appropriating land from the Indigenous people, which is a history that, you know, I find shameful and try to give back what I can for what the colonists took. But anyway, yes, seeing the forest as a connected place was a natural thing, 'cause I grew up in these huge, these massive old growth forests with all these connections right in front of you. Like you can't miss it. If you think it's separate, you're not looking. But what I was missing, and that I've learned since then, is that governance of our societies handed down through generations of wisdom, of knowing the land and looking after the resources, carrying out responsibilities to look after those resources. People are collectively working to ensure that there's a stability in the food system, there's stability in wealth, that if salmon don't come back to this stream this year, well, the neighbors are gonna say, "Come and fish in my stream." That reciprocity is an essential part of it. The respect for the land. Those deep, deep cultural institutions didn't exist in my colonial family. And now that I'm older, I'm learning it and seeing it as I work with my Indigenous colleagues.

- [Anne] So one thing I've been curious about is you've talked about that experience of growing up in that old growth forest as an experience of reverence.

- [Suzanne] Yeah. That's a spiritual thing.

- Yeah.

- And when I'm here, you know, we're standing under trees, it's a spiritual connection to these, these spirits that are our brothers and sisters, these trees. So, yes, I've always had that spirituality, but I have not named it.

- [Anne] Well, working in science.

- Yeah.

- And you were already going against the dominant paradigm.

- [Suzanne] I mean, I've actually been recent critiques by scientists saying that I'm too spiritual, I'm too mystical. If you do that, you're dangerous to the forestry world. And I'm just like, man, you know, that's the part that we're missing. That's why we're in so much trouble is that we forgot that all of these relations are spiritual beings connected to us and connected to each other, and if we just treated them as though they were our brothers and sisters, we would not be in this situation we're in right now.

- [Anne] It's amazing, thinking about the power a word can have. I've been struck over and over again by the absolute genius of your calling them "mother trees." How did that-

- How did it happen?

- [Anne] Yeah.

- [Suzanne] Yeah, I've been working with my grad students. I've had so many grad students working on trying to describe relationship in forests. We were trying to quantify these connections below ground.

- [Anne] You're talking about those mycorrhizal networks.

- [Suzanne] The mycorrhizal networks, and we found out from mapping the networks that the big trees were the hubs of the network, which makes sense because they're highly photosynthetic. They put proportionately more energy below ground in the below-ground ecosystems feeding those networks. They have massive root systems, massive connections, intense connections with their neighbors, and that there's this flux of carbon and water and nutrients back and forth through these networks and through the soil and all kinds of pathways. But what emerged was these big old trees, and of course, people have been for millennia understanding the significance of big old trees. You know, in many cultures they name them grandmother trees or grandfather trees. And then I made a little film with a journalist. We were talking about these big old trees, and I was describing their significance in the regenerative capacity of the forest. Like they shed seed around them, and then they nurture, through these networks, their offspring. And we've done many studies to show this, and this journalist was saying, "Well, you call these hub trees, but that's so boring. "These are really mothers of the forests. "Why don't you call them mother trees?" His name is Dan McKinney, and I said, "Yeah, okay." And we made a little film called "Mother Trees Connect the Forest" in 2010. So, I wasn't thinking about gender or, you know, people have layered since then, you know, projected on me the meaning of that. Really, it was just about trying to convey, in a metaphorical way, that the forest rebirths itself. The old trees live their long, long lives, they die, and as they die, the whole cycle continues of rebirth, and the forest is regenerative. And then as I started working with the nations, my Indigenous colleagues, I started learning that actually they've been known as mother trees or grandmother trees-

- Really?

- For a long, long time. Yeah, people understand what that means. Everybody has a mother.

- [Anne] It is a really powerful metaphor because there's so much compressed into it, concentrated, but also, since we've been talking about different paradigms, I always focused on the mother tree aspect. Suddenly what's hitting me is their age.

- Yeah.

- The oldness. And I think that's because you and I are the same age. You know what I mean, so-

- Yeah.

- And we both have grown children.

- Yeah.

- [Anne] And we're both aware of living-

- Yeah.

- In aging bodies, which I think does-

- Yeah.

- [Anne] Kind of begin to change your sense of the value of older organisms.

- Yes.

- And certainly your awareness of what it's like to live in a culture.

- Yeah. Yeah.

- That denigrates, and to a certain extent, despises age and aging bodies.

- [Suzanne] Yes, it's true, but not all cultures are like that. In the nations I'm working with on the West Coast, or in the interior of British Columbia, the elders are the revered, the grandmother, the grandfather, the chief. Their wisdom is essential in bringing up the next generations, and the kids need us. Anybody who's a parent knows that even, like I'm 64, my kids are in their mid-20s, they still need me, but for different reasons than they did when they were little. In a tree, an old tree holds so much biodiversity, more than a young tree. So as they get older, they have all kinds of structures that they create. Like this Cottonwood has lots of furrows in its bark.

- So thick.

- A young, yeah, so thick and deep, and young trees are smooth, they're growing fast. And so these furrows are homes to bats and insects and a whole host of biodiversity. The crowns of the trees, they're huge and complex. There's birds all over them. The young ones don't have that biodiversity, they don't have the resources to hold it. Below ground, the microrisal fungi, there's certain ones that only grow on old trees because-

- Really?

- [Suzanne] Yeah, so there's an enormous biodiversity associated with oldness. And that biodiversity is a wisdom and it's a resilience because it's part of the whole cycle of life. If you think of the carbon cycle, all these creatures are part of that carbon cycle of breaking down the primary productivity, turning it into other energy forms and feeding it through the system.

- [Anne] And so when you, when you have a forestry model that says, "Oh, let's cut down all the old ones "and keep young ones," you're doing exactly the opposite of what-

- Yeah.

- We should do.

- Yeah. It's like putting our old folks into old folks' homes and shutting them away.

- Oh wait, we do that.

- [Suzanne] Yeah, hey wait, we do, we do that? Yeah, like when, actually in the Mother Tree Project, we're looking at the effects of clear-cut logging, or various styles of, we call them silviculture systems, how to harvest the forest, whether you leave some old ones behind, how do you leave them behind, or do you clear cut it? Or do you leave it? And what happens to those carbon pools? And what happens to the biodiversity in the soil? And what happens to the birds and the mammals and the plants? So we're tracking all of that.

- [Anne] That's a giant science project.

- Yeah, it is.

- I mean, it must be an unprecedented scale.

- Yeah.

- [Suzanne] Yeah, and it follows a climate gradient. So it goes from the border with the US and Canada, the 49th parallel, up to about the 57th parallel. So we had got nine forests along this climate gradient in Douglas fir.

- Wow.

- [Suzanne] Across that area, it's an area about the size of Denmark, and we're following, applying all these different ways of harvesting and tending the forest and then following impacts. And we're working with the nations in some of those to protect and nurture the values that they see.

- [Anne] And this must be like a hundred-year project.

- I imagine it-

- You must feel like it will outlive you.

- Yeah.

- [Suzanne] I, oh yes. I imagined it as a hundred-year project. My close colleague, Chief Rande Cook, talks about the 500-year plan. So it's long, long, long-term project. I have lots of students, even my daughters are part of this, and they will be the next stewards of this project. And then they'll train and mentor, and they'll be the next stewards, so-

- Wow.

- Yeah. Yeah.

- [Anne] If you're just joining us, I'm talking with Suzanne Simard. She's the renowned forest ecologist whose work is transforming how we view trees and forests. And she is about to tell me about one of the most transformative experiences of her life, a vision of the deep interior life of a tree.

- [Suzanne] That was mind-blowing.

- [Anne] I'm Anne Strainchamps, and this is "To the Best of Our Knowledge" from Wisconsin Public Radio and PRX. We're standing in a small grove of cottonwoods. You can probably hear the birds chattering. And thanks to the incredible research that Suzanne and her students and colleagues have been doing, we now know that these trees are intelligent in ways we once thought only humans were. And so it strikes me as frustrating that we have to learn this from the outside, as it were, you know, by piecing together clues and evidence. I mean, what if we could ever manage to communicate with trees, just imagine, what would we learn? I was saying something like that when Suzanne told me about a shamanic experience she had just a few years ago, and not too far from my home.

- [Suzanne] Actually, I've had several shamanic experiences in the latter part of my life, but the first one was actually in Madison.

- [Anne] Ah, really?

- [Suzanne] Yeah, so I came to that conference there, and there was a shaman. She drummed. There was no ayahuasca involved or anything, just a pure shamanic experience. And we, in the audience, I dunno, there probably were 70 people there, she had us relate to some plant. So she's drumming, and I had been studying Douglas fir my whole life, I grew up around these species, and as she's drumming, I was immediately in the tree. It took me only seconds to get there.

- [Anne] What did you see, what did you feel?

- [Suzanne] When I went into the tree, I was just part of the heartwood, and I was looking at the heartwood. The heartwood is the central part of the tree, the xylem, that's where the water comes up through the tree. And in the Douglas fir, it's rich burgundy tree rings. And so I'm looking at this rich burgundy tree rings and trying to find my way in them. That was mind-blowing. And then last year, I actually went to Ecuador, and I had the opportunity to also work with a couple of shamans. And I had a much more expansive experience with the tree, where I wasn't just in the heartwood, I was moving through the tree and looking at all the cells and going into the cells and looking at the organelles and the chloroplasts and seeing how it worked. And I was in the connections below ground and moving from tree to tree and up through the crown of the tree and into the atmosphere, the whole connection between the sky and the soil, I was right in it. I was the tree. And then I had this other experience where I flew from the forest of Ecuador in the great tropical rainforest, which are immense and magical, and you're part of the pulse of the forest when you're in there, and I flew to the, you know, over my province of British Columbia where this devastating clear-cutting is happening, and I flew to the Arctic Circle where the trees are small. And I had this vision of all these trees standing up again. Slowly, the trees stood back up, and the people were there working with the trees to stand our ecosystems back up and healing climate change. It was an incredible vision.

- [Anne] Oh my God, how extraordinary. I want so much to believe that was a vision of the future, don't you?

- [Suzanne] Well, I, yes, I think it is. It is the vision of the future. In the meantime, we have a lot of work to do.

- [Anne] Yeah.

- [Suzanne] And I think the world, the planet, will get there, but it's how much we suffer in the meantime. You know, my kids, our kids, the next generations, how much will they suffer? And I think we, as people, are responsibilities to say, "What can I do to reduce that?" To not have it be so devastating so that people are dying in waves and hurricanes and droughts and fires, but having good lives, where they're working with the land and in the forest and doing the good work of standing these forests back up again, repairing the ecosystems, creating wealth, and when I say "wealth," I mean abundance.

- Right. Yeah.

- [Suzanne] We can do that, it's a choice.

- [Anne] The other thing about it that struck me was this experience of deep time. 'Cause I think that you went back to the beginning of this tree.

- Yeah.

- When it was just first a shoot.

- Yeah.

- [Suzanne] Yes, I started as a little germinant, and grew to a great 500 years old, putting on tree rings as I aged. The center of a tree is called the pith, that's the first year of life. And so, went through those lives, those 500 years of putting on great growth and packing on more rings and becoming a great energy center of the forest. And then, you start to decline, and you put more energy into defending yourself because you're a little weaker, and you start to lose some bark and you lose a branch. But you're still this big living system, right? You're hosting then all the bats and the birds, and as you get older, you're more of a greater host of biodiversity. And then you eventually die and fall to the ground. At that point, you become even a greater host for biodiversity 'cause all the critters come in and feed off your body, and the seeds germinate on your great decaying body, and then your children are growing out of you. That's how I wrote that little piece.

- [Anne] One thing that I've been thinking a lot lately is how narrow our idea of time has become. We've created screens that we look at all the time that chop our attention and monetize our attention into smaller and smaller increments. And we are losing these very deep perspectives on time. And we really need to be able to imagine them again. And so that's part of what I thought was so extraordinary-

- Yeah.

- [Anne] About what you wrote.

- [Suzanne] I was at this thing with Lynne Twist, who is the head of the Pachamama Alliance. She told this story that really I think helps with that. And she said, "Close your eyes, imagine you're looking back "at your ancestors. "Go back like seven generations. "Your grandmother, your great-grandmother, "your great-great-grandfather, "and imagine all that they put into raising their children "and their children raising their children "and looking after the grandchildren, "trying to lift you up to be "the best that you can be as a human." So that puts time in a perspective. You're connected all those generations back to their aspirations, that they're imagining you and your life being everything you can be. And then imagine your children and your grandchildren move forward to the next generation, seven generations, as the Anishinaabe people look, time suddenly collapses into this, you are more than just now. You are many generations back, and you are many generations forward. You're in this big time continuum. Just like you're in a big space continuum too, connected to all your neighbors in relationship, in community. And I think if we can, you know, remember this-

- We have this, it's hidden in plain sight.

- Yeah.

- In our language, "family tree."

- [Suzanne] Yeah.

- That's what we call it.

- Yes. It's a tree, exactly, that's a really good point. Yeah, a family tree.

- [Anne] Mmm. Thank you so much. That's really-

- You're welcome.

- [Anne] Really beautiful, thank you.

- Thank you.

- [Anne] Suzanne Simard has forever changed our understanding of trees and forests. If you wanna go deeper, she wrote a wonderful scientific memoir called "Finding the Mother Tree," and keep an eye out for the sequel. She was working on it when we talked at a women's writer's retreat hosted by the Kalliopeia Foundation. In the coming months, we'll be bringing you more conversations with the other women who were there, women who are devoting their lives to resacralizing our relationship with the Living Earth. Our partners in this project are the Kalliopeia Foundation and the Center for Humans and Nature. As always, thanks to you for listening. "To the Best of Our Knowledge" is produced at Wisconsin Public Radio by Shannon Henry Kleiber, Charles Monroe-Kane, Angelo Bautista, Steve Paulson, and me, Anne Strainchamps. Our technical director and sound designer is Joe Hardtke, with help from Sarah Hopeful. Additional music this week comes from Kirk Osamayo, Jack Anderson, Sarah Daddario, Maydon, Rod Hamilton, and Tiffany Seal. Be well and join us again next time.

- [Announcer 3] PRX.