Radiolab - Grass Apes

Episode Date: September 25, 2026

When you think about grass, what do you think of? Pool parties? Suburbs? Allergies? What about: human history? It turns out, unassuming grass, which exists on every continent, has an epic story to tell. One of transforming the planet, and … us. From what we eat, to how our body might be shaped and the ways we perceive the world. Senior Correspondent Molly Webster speaks to biologist and writer David George Haskell in this tiny ode to Grass.This episode was inspired by “Grass Fed”, a Radiolab outdoor theatre performance at Little Island in New York City. “Grass Fed” featured biologist and writer David George Haskell; Foley artist Steven Wendt; and dance company, Pilobolus. Special thanks to all the artists, and to Little Island, Sarah Sandbach, Natalia Ramirez, and Soren Wheeler.EPISODE CREDITS: Hosted by - Molly WebsterReported by - Molly Websterwith help from - Jo Strogatz and Anisa VietzeProduced by - Sarah Qariwith help from - Jo Strogatz, Molly Webster Original vocals from - Jo Strogatzwith mixing from - Jeremy S. BloomFact-checking by - Nora Belblidiaand Edited by  - Pat Walters EPISODE CITATIONS:Articles - The Other Almanac 2026 (https://www.otheralmanac.com/), by David George Haskell a print-only magazine contains an essay All Hail Grass, Maker of Humans! by David George Haskell all about grass’s role in human history. Books - How Flowers Made Our World” by David George Haskell which has a chapter all about grass in it (it’s a flowering plant, if you didn’t know!)https://www.penguinrandomhouse.com/books/775876/how-flowers-made-our-world-by-david-george-haskell/Sign up for our newsletter!! It includes short essays, recommendations, and details about other ways to interact with the show. Signup (https://radiolab.org/newsletter)!Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today.Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing [e-mail] support for Radiolab’s science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.  Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Wait, you're listening. Okay. All right. Okay. All right. You're listening to Radio Lab. Radio Lab. From W. N. Y.

See? See? Yeah. Hey, I'm Molly Webster. This is Radio Lab. And today's show is inspired by an invitation that I got last spring, which was essentially to tell a story for a park about parks. It was a little more complicated than that,

but basically they were like, can you make a story out of the space that we're in, which happened to be this shady glade. It had a lawn down the middle and trees around the side and rocks and things. So I looked around the space and I was like, okay, maybe there's something to do with mushrooms or, I don't know, squirrels, it's New York City.

And as I was talking about these scintillating ideas with people, I started having a conversation with a horticulturist. And they said, you know what I think about all the time? Grass. And I completely ignored them because I thought, what could be interesting about grass? Then they started talking about how landscapers use grass and that grass is like an instrument that makes sound.

And I felt myself get a little pulled toward grass. Like, maybe there was something there I wasn't seeing. So I wrangled producers, Anisa Vita, and Joe Stroggats to go out into the parks of New York City and ask people this question. What do you think about grass? What do I think about grass? Grass? You mean this grass?

They got a lot of blank stairs. Do you feel like it's a weird? weird question to ask. That's all right. But people had a lot to say. Let me think. In general, I would probably be thinking about. They talked about rolling round.

Mowing lawns. My daughter. Grass memories. Plain cat. Girlhood. Feelings. Horses. Charing it.

Grass stains. Grudges. Their square teeth. Grind it. Grind it up. I like all the trees, the shrubs, flowers. Random associations. The other type of grass comes to mine.

I like this well. I like the smell. But no one. Feels great on your feet. Oh, God. I love it. Told us a story about grass itself. Grass. Grass.

Grass. Grass. It was like grass was everywhere, but also invisible. I mean, we even have a term in our culture, the green screen, right? Which is the screen that will be removed, that will be erased for the important stuff to stand out in the foreground. And I think grass, for many of us, is that green screen. Honestly, that's how I thought about grass, too, as that green screen, until I talk to this guy.

I am David George Heskel. I'm a writer and a biologist. And David is Grass's number one fan. Because Grass is, when you do start to learn about their lives, their transformative effect on the whole planet, and their role in catalyzing human evolution. Suddenly they become extraordinarily fascinating. David says, if we ignore grass, if we look past it, we don't just miss out on the story of grass,

but we miss out on one of the most incredible stories of human history. Indeed, if you had to pick one group of plants that we could count as our co-creators, a group of plants that are vitally important to the appearance of humans on this, planet, it would have to be the grasses. And that story starts, according to David, a very, very, very long time ago. When you go way back, so if you go 30 million years ago, our ancestors and the ancestors

of all the apes were mostly forest-dwelling creatures, eating insects, eating fruit. And back then, there weren't many grasslands around. But then, there weren't many grasslands around. Things started to change. These little patches of grass has started to appear in the forest. The planet was cooling, the polar ice caps were expanding, and places were getting just a little drier. And then 10, 20 million years ago, those grasslands expanded more and more.

So different timescales on different continents, but the overall pattern is a move away from very wooded planet to a planet that's wooded but has a lot of different grasslands mixed in as well. But does that mean grasses are like stronger than trees and they just started taking over and like saying trees, get out of here. We're taking over your space or was something else happening that led to this reconstruction of the landscape? So grasses have all sorts of inner tricks to take advantage of external changes. So for example, over this time period, the concentration of carbon dioxide in the atmosphere really dropped. And grass is a really good at sucking up carbon dioxide and using it to make sugars.

They're also very good in seasonally arid climates. These are climates where it can be very lush and rainy part of the year, but then you go for months where it's just dry, dry, dry, and that's the kind of situation where you get fire moving in. And the genius of most crosses is that they figured out how to thrive in a very fire-prone environment by keeping their growing tissue very low to the ground or in the ground. So if fire comes through, all those disposable leaves get burned up. They're gone.

But when the fire moves on, the sensitive tissues from which new stems, new roots, new leaves will grow, they're unharmed, and the grass sprouts right back up. So after grasslands appeared, lots of mammals like horses and hippopotamuses and other creatures, it started moving out of the forest and eating the grass. But grass blades, you know, they're long, they're stringy, but they're also tough, and they've got little bits of glass-like material inside them. Glass. All grasses have these little pieces of silicate, which is essentially like grass.

Glass. It's very hard to say grass and glass, right? Grass, glass, blah, blah, blah, blah, yeah. There's little bits of silicate in the blades of all grasses. Of almost all grasses. And some have more than others. And this is a defense against, you know, the wind tearing the grass up, but also against animals being overenthusiastic and grazing too much on them.

Really? It makes me think of like, you know, when I was growing up, like my dogs would eat grass to throw up. Like, they would eat grass and then vom. Yeah. So your dogs are probably actually eating it to purify their gut. It can act as a dewormer because it will cause the animal to vomit or it will poop it out the other end and all of that grass tangle physically

will just bind up with some of those worms and get rid of them. Oh my God, you're literally just like scraping out your insides, which you can't reach with your hand. Yep. That's cool. Yeah. Puging dogs aside, many mammals are actually good at eating grass. They got tougher teeth for, for sure.

For some, they evolved very complex, multi-parted stomachs with bacteria and protests that can digest grass. Wait, do you think that we tried to eat the grass like our ancestors did? And how did that go? Yeah, well, it probably gave us some stomach upsets. I'd imagine for some ancestors, grass, just grass leaves were part of the diet, also some other vegetation. I mean, they can be nutritious, but so can a lot of other things that don't have. have glass-like particles inside of them, so we didn't really bother. But there's another way to eat grass, and that is to eat the seeds.

So through some series of experimentation that we don't really know about, our ancestors started to eat grass seeds, and this is where the story of grass and humans really heats up. So the grass sends up a flower stalk and it flowers. It makes. held little eggs on the flower stalk and pollen joins with the egg. And then the grass seeds are held up on what was the flower stalk. And those seeds contain two really important parts. There's the embryo, which will grow into the new little baby grass plant. But then most of the inside of the seed is a food store that the mother plant puts into the seed,

is literally taking food out of their own, their body, the grass plants body and putting it into the seed that when the seed leaves and lands somewhere, the embryo will eat that food store to power its first few days and weeks of life. So the mother is sending the offspring out with little food supplies, like a little lunchbox or something. Except it's a lunchbox that is eight times the size of the kid who's carrying it. Is that unusual for seeds? I think in my mind, I would kind of expect that that's how a seed works. So grasses have got especially big food stores, which can be 80% of the inside of the seed filled with starch and proteins and some oils. And when our ancestors discover these nutritious little packets, they were like, oh, this is something we can eat. And I think learning and realizing

that most of our food comes from grasses completely transformed. and transformed how I even experience eating dinner. Wait, say more on that. What do you mean most of our food? So at lunchtime and at dinner time and at breakfast, the oats in your oatmeal, that's a form of grass. The bagels are made from wheat, which is another kind of grass. Rice is a grass. Corn, maize, those are grasses.

So one food after another, and if you add it all up, a very large portion of calories that humans consume around the world come directly from grasses. In fact, wheat, corn, and rice together comprise about 60% of all the calories that humans eat on this planet. Oh, wait, are they grasses like the grass in my backyard grass, or are they like a different type of grass? There are different species, but it's basically the same body plan. If you were to not mow your lawn, it would grow up. It would produce little flower stalks. And those flower stalks would mature and have lots of tiny little seeds attached to this stalk sticking up above the leaf blades. That is essentially corn, wheat, and rice.

Just a little bit. Yeah, it's a bigger version of that that has, you know, over the last 10,000 years, at least, humans have been working with these plants to get fatter kernels and kernels that stay on the stem rather than falling off when they mature, all sorts of things that benefit us. Wait, to do the list again. And what are food items that are grasses, corn, wheat, and rice? And oats and millet and barley and sorghum and sugar cane. So like sugar, like the sugar I eat comes from a grass?

Yes. If you're eating high fructose corn syrup, which is probably not a great idea, that came from corn. But sugar cane, just imagine your lawn, but then it gets about a thousand times bigger and stockier. And then cow, you know, beef and lamb and even chicken. These are animals that even though we might be eating meat, they either ate grass out in a pasture or were fed corn or oats or other kinds of plant-derived food. Yeah, mostly grass-based, but with soybeans and other things. But almost everything on our plate are founded on grasses.

The idea of eating grass makes me think about when you go over to your friend's house and like their parents feed you. And you're like, ooh, it's like the grass mothers are feeding the grasses, but I get to go over and be the friend that comes over after school and like benefits from like that mother's cooking. And you know, the grasses are doing that for all of us. I mean, so they are mothering their own offspring, their own seeds, but they're also mothering us when we eat pasta or tamales or a nice rice dish. We are being nurtured by grass motherhood. So grasses took over the planet, and they became the foundation of our diet. And in a very real sense, we are actually made of grasses.

We are grass-fed just as much as a grass-fed cow. But grass has also shaped us in a deeper way, one that may have helped us to become, well, us. That part of the story is after our break. I'm Molly. This is Radio Lab. And we are back with David George Haskell and our ancestors who are spending more and more of their time out in the grasslands. If you're in the grassland, there's no more branches to cling on to. so your forelimbs are freed up to do clever things with your hands. And so in a way, being bipedal probably evolved to walk around in the grassland.

Really? Yep. Okay, so obviously there are many, many different things that led us to being bipedal. In regards to grass, you know, there's this idea that maybe grasses were tall, and so we wanted to see above them, and so we got up on our hind legs to do that. but more so if you're out in an open field, it is much more energy efficient to move through space on two legs instead of four. In fact, our bodies have become so good at walking on two legs.

I recently learned that our feet have tons and tons of receptors in them that are sensitive to the topography of grass down to being able to feel a single blade. And that sort of foot sensitivity is still true today. Like physical therapists for certain mobility issues will actually prescribe barefoot walking in grass. I mean, the times that I've walked on grass, it's extraordinary the amount of information that we're getting from our feet. And of course, the bottoms of my feet are quite soft because I wear shoes a lot.

So I realize, wow, I've really needed to do some work here to reclaim my a grass ape ancestry. I love thinking of us as grass apes, not jungle apes, because I think I think about apes living in mostly forests or just at the edge of grasslands. Yeah. And it's just this fun idea. Absolutely. If we were named for our primary food source and for the habitat in which we evolved,

we would be the grass apes. Best softball team in the county, yeah. Yeah. Homo Poaceae. Poetia is the family of grasses, which distinguishes us from the grass apes. The bonobos of chimpanzees. Homo poesia. I'm trying to get that into the common language.

Yeah. So Gen Z is winning with their touch grass campaign is what I'm hearing. Yep. We have spent so much time in grasslands that grasses are sort of squeezed inside of us into our furthest corners. So much so that if you're playing in your backyard or lying in a field, somewhere, your body is connecting to grass in a deep, timeless way on many different levels. For example, listen to the soundscape in the park. I'm imagining Prospect Park here.

The planes flying over to LaGuardia every two minutes. You have people honking at Grand Amic Plaza. But then you put your head down close to the grass, and the grass absorbs absorbs high-frequency sounds. and it dampens and softens all the other sounds around us. If you think about the texture on the surface of the grass, each grass blade is pointing in a somewhat different angle. And so the sound waves bounce off in all kinds of different directions, and we experience that as a softening of the sound,

and you lose some frequencies, especially the higher pitched frequencies, get absorbed by the grass. So if I go and lay in some grass, it's not just calming because I'm not doing anything and I'm away from buildings. It's calming because it's literally dampening and quieting the sounds. The sound is different, a lot less harsh. You're also inhaling the aromas of the grass itself, especially if you rub the grass. A lot of those aromas bind to our nerve cells.

Some of them might even get into our bloodstream. and those calm us down and you've got soil aromas particularly if it rained a couple of days ago the soil is activated so the microbes and the fungi and the fungi and the soil that are working with the grassroots right that's all part of one big community

we're smelling those as well and that's our original human habitat right grasslands that are healthy and growing really well so we're immersing ourselves in the aroma that was the sign of good life for our ancestors for literally hundreds of thousands of years, if not millions of years. It is the last day of summer.

The sun still feels hot on my skin. My shoes are off. I'm in shorts and a tank top. And I'm sitting in some grass. I'm going to try the credits out here. This episode was produced by Sara Khari with reports. recording and production help from Joe Strogatz, Anisa Vitsa and me, Molly Webster, vocals by Joe Strogatz, editing by Pat Walters, and fact-checking by Nora Belbledia.

You can find David George Haskell down at Emory University in Atlanta. I bet you there's a lot of grass down there. Or in a bookstore, his latest book is how flowers made our world, the story of nature's revolutionaries. This episode is based on a live show we did all about grass. It was at Little Island in New York City. It featured David, foley artists, Stephen Wendt, and Dance Company, Pallobulus. Special thanks to Sarah Sandback and Natalia Ramirez, and of course, grass.

Another plane is going by, but I'm going to keep going. Our newsletter this week is absolutely nothing to do with grass, but I still think you should sign up. RadioLab.org slash newsletter. There's ants all over my bag, and I'm going to go. See you next time. This is Radio Lab. I'm Molly Webster. Goodbye.

Hi, I'm Josh, and I'm from Plainfield, New Jersey, and here are the staff credits. Radio Lab is hosted by Lulu Miller and Latif Nasser. Soren Wheeler is our executive editor. Sarah Sandback is our executive director. Our managing editor is Pat Walters. Dylan Keefe is our director of sound design. Our staff includes Jeremy Bloom, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindunyanandam, Matt Kielty, Mona McGaulcher, Annie McEwen, Alex Nissen, Sarah Kari, Natalia Ramirez, Joanna Strogetz, Anisa Vizza, Ariane Wack, Molly Webster, and Jessica Young, with help from Ayah Appleby, Malamette.

Our fact checkers are Nora Belblydia, Hillary Elkins, Rachel Gross, Diane Kelly, Emily Krieger, Natalie Middleton, and Sophie Sam Hi, I'm Aubrey, calling from Salt Lake City, Utah. Leadership support for Radio Lab's science programming is provided by the Simon Foundation and the John Templeton Foundation. Foundational support for Radio Lab was provided by the Alfred P. Sloan Foundation.