99% Invisible - The Borrowed Nature of Biomimicry

Episode Date: August 4, 2026

Behind every perfect nature-inspired design is a far more complicated story. Subscribe to SiriusXM Podcasts+ to listen to new episodes of 99% Invisible ad-free and a whole week early. Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus.  Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

This is 99% Invisible. I'm Roman Mars. Back in 1989, the engineers of Japan's famous Shinkansen bullet train realized they had a problem. The train was moving so fast that when it went into a tunnel, it basically punched the air out the far end, creating little sonic booms. All across Japan, the Shinkanzen was rattling buildings and disturbing residents in the neighborhoods it passed through. An engineering team was brought in to design a quieter and more efficient train, and they had a secret weapon. A.G. Nakatsu, the general manager of the technical development department, was a bird watcher. As he thought about the redesign, Nakatsu took inspiration from elements of his favorite birds, including owl feathers and penguin bellies. But the bird that inspired the most important element of the redesign was the kingfisher.

Kingfishers are famous for the elegant way they dive into the water to catch fish. Their uniquely shaped beaks allow them to break the surface of the water with barely a splash. And so Nakatsu and the Shinkansen design team decided to model the nose of their bullet trains off the Kingfisher's beak. And it worked. The new Shinkansen trains were quieter and more efficient. That Kingfisher redesign is now seen as a classic example of what's known as by, biomimicry, the act of looking to the non-human world for solutions to human design challenges. Biomimicry is simply design that is inspired by nature. Right.

And I have to say that stories about biomimicry are catnip to design journalists like me. That is Kurt Kolestead, our resident design guy. Yep. And biomimicry, it's just this really inspiring concept, right? With all these fascinating examples, like the invention of the design. Elkrow being inspired by someone noticing how Burrs stuck to his dog's fur and to his jacket while he was out on a walk. Yeah. I mean, I love these stories.

We love these stories on the show. We've covered biomimicry a lot over the years because the stories are just very catchy. Like, there is something so seductive about the idea of designers borrowing from nature to solve a human problem. It's just a very neat, simple, and just compelling narrative. Yeah, for sure. But recently, I've been digging into a bunch of biomimicry stories, and they are not always quite as neat and simple as that bullet train story. The causality is often quite a bit murkier than the headlines would have you believe. And the relationship between nature and human inspiration is often a lot more complicated. Yeah, and that actually makes biomimicry sound more interesting to me, not less. Like, I like that idea of a complex story, way better. Yeah, I agree. Same here. So today we're going to dive deeper, go beyond some simple headlines, separate some fact from fiction, and yeah, go into some more nuanced cases. But to kick things off and ground us in the concept, I want to start with a relatively straightforward, yet lesser known example of biomimetic design.

So this story takes place in the early 1800s in London, England. which was not yet that modern city that we know with its sophisticated transit network or really even basic sanitation. But it was already the largest city in the world and the largest port in the world. And when people needed to cross the city's famous Thames River, near that port, they took the London Bridge. But that bridge was notoriously crowded. It was like a choke point for everyday citizens and also commercial traffic, which really burying. burdened people as well as, you know, the city's commerce. And so over time, it became clear that another crossing downstream was desperately needed.

Yeah, that makes sense to me. They needed another bridge. Totally. Except with the geography of the river and the port and the existing bridge, another bridge would have interfered severely with shipping access. So that solution was a non-starter. And the only real alternative was to tunnel under the river. But this is way before the tunnel to France or even the London Underground, so there was no precedent for tunnels going under active waterways.

Tunneling technology at this point was essentially an extension of mining technology, right, dealing with solid rock and soil, but not the undersides of rivers. And so they tried to use those surface traditional mining techniques to tunnel under the Thames, but it ended in disaster, and in some cases the deaths of workers. And experts eventually came to conclude that this type of tunnel represented an impossible challenge. An engineer named Mark Brunel even wrote that prior attempts, quote, had so completely failed that he conceived all further exertions on the subject quite fruitless, as in it would be pointless to even try.

But Brunel was about to have an experience that would completely, completely change his mind. Okay, so what happened? Well, I think it's best if I let him explain it. So here's an excerpt from a letter that he wrote to his granddaughter later on, recalling his time working for the British Royal Navy. And I'm just going to have you read it. About the year 1812, being then employed in the dockyard at Chatham, I happened to see before

me a piece of condemned timber, a portion of the keel of a ship, wherein the worm, the Taredo Navalis, had made many erosion. And by erosion, he means tunnels, like tunnels through the wood. Okay, so in modern English, like, he saw a piece of timber that had been worm eaten along the docks. Yeah, pretty much, pretty much. Except that the so-called naval shipworm is not actually a worm. In reality, it's a strangely adapted bivalve mollusk. Oh, like a clam?

Yeah, yeah, except specialized for boring holes. And it works like this. Like its shell has evolved into a pair of grinding plates. And behind those plates trails this long, soft, elongated body that can reach a couple of feet in length. I mean, it sounds terrifying. It sounds something that I would eat eventually at a tick as an appetizer. Hopefully, right? Hopefully it wouldn't eat you, right?

I mean, you put some minionette on it. You know, like you scrape it out. It's going to be tasty. Well, yeah. And he didn't go quite that far. but he did pull out a magnifying glass, which is a thing that he was known to carry around, and went in for a closer look. And as he looked, he noticed that the walls of these boreholes that were carved by these worms seemed remarkably stable.

Even when they were in waterlogged and, like, rotting chunks of wood from old ships, they were protected. So here's Brunel again from that same letter. I then sent to myself that these little things have made little tunnels. so might we by adopting some corresponding means of protection. I mean, that's basically like the textbook definition of biomevergrain. So what did Brunel notice about how the shipworms made their tunnels? So the trick that he recognized and then set out to copy

was that shipworms do two things at the same time. Even as they scrape out the wood in front of them and move forward into that hole, they extrude a lining that coats and reinforces the, tunnel around and behind them. Okay. So while they dig, they also immediately shore up the tunnel around them, which describes basically all excavation. So how is this different from other attempts?

Yeah. Well, so think of it this way, right? Miners used to working in hard soil could get away with digging for a stretch and then stopping for a bit and then going back and putting up supports behind them. Right. And Brunel recognized that that kind of iterative system just was not going to cut it under the Thames because any gap in space or time between digging and shoring up invited disaster. And so with that in mind, in 1818, he went and patented a machine that would work more like a

shipworm, digging and then reinforcing simultaneously. So how did Brunel's machine do that? Well, the crucial piece was what he called a tunneling shield. Basically, it was this massive cast iron frame that was pressed flush against the face of the excavation. And under that shield, you would have dozens of miners chipping away at the front of the tunnel, while brick layers shored up the tunnel behind them. So as the excavation progressed, the shield would be pushed forward, and the newly exposed

sections were immediately lined with cemented bricks. And so it was all part of this smooth and continuous effort, like the shipworm, tunneling and shoring up behind itself simultaneously. That's so cool. Yeah, and really challenging because, you know, Brunel had to piece together this system from all these moving parts and people because the technology at the time was not up to making like a machine that could automate all of this, right? It had to be people doing manual labor. And ultimately, it worked. It took a really long time and it did not always go smoothly. But eventually Brunel completed the tunnel spanning over a thousand feet under the Thames. in 1843. And that was the first tunnel built underneath a river anywhere in the world.

Yeah, I mean, no. It was literally part in the pun, groundbreaking. Nobody on Earth had ever made and walked through a tunnel like this before. And it didn't stop there because Brudell's design that tunnel shield shaped

subsequent tunneling technology. Years later, when they built out subway systems in London and across the pond in New York, they used that same basic tunnel shield. That's so cool. And the funny thing is, modern machines have, if anything, converged even more on those

mollusks that originally inspired Brunel. Because now we have machines with attachments that place precast concrete panels as the borer tunnels onward. So it is like that all in one thing. Okay. So despite all the setbacks, we are really talking about a very straightforward case of biomimicry, like nature inspiring a human design. A guy sees something in nature, copies it, perfects it, boom, success.

Yeah, and that's why I wanted to start here, honestly, because I wanted to ground us in a success story, where nature really was this direct inspiration for a human design. But there are a lot of other stories that don't perfectly follow that neat, direct trajectory, stories where the relationship between nature and human design inspiration is not quite so clear-cut. Okay, so I'm very excited to muddy the waters a little bit. So what is next? Well, a different sort of fishy biomimicry with some real twists and strange turns,

starting back in 2005 when Mercedes-Benz made a big splash with their bionic, which was this new concept car that boasted a biomimetic origin story. They claimed their design was the first of its kind to attempt a, quote, complete transfer from nature to technology, end quote. Well, that sounds like vague nonsense. I don't even know what that means. Yeah, well, the argument was essentially that biomimicry usually involves borrowing like a single feature or behavior from an animal, like a bird's feather or a whale's fin.

But that their new car was modeled on an entire organism, the boxfish. Here's a picture of it. If you were picturing a boxy fish because it's called a box fish, you're right on the money. I mean, like, it is a floating cube with fins. Yeah, exactly. And it's part of this family of really awkwardly angular fish, including the cowfish and the trunk fish. Yeah. I mean, you know, compared to the naval shipworm, this thing is adorable.

I mean, it's like bright yellow with spots on it. But I have to admit, this thing doesn't look aerodynamic at all. Like, this seems like the opposite of an animal that you would model a car on. So what was the logic behind modeling a vehicle on this boxy shape? Well, big picture, you know, the engineers at Mercedes were into this idea of biomimicry, and so they started scouring the animal kingdom for inspiration. And they wondered if a fish, for example, could provide that inspiration for a car design. But cars have to be boxy.

They're spaces that house humans. And a long sleek fish is just never going to translate. into a functional car. And so if there is a boxy fish that has evolved to be aerodynamic and boxy, that really could be a breakthrough that works all around. Okay, but what made them think that the boxfish was aerodynamic? Yeah, well, it started with some real serious scientific research that they came across that was being done into the boxfish.

In particular, a study being run by a team spanning UCLA, Caltech, and woods hole. And so they discovered that there are nuances to the shape of the boxfish that help stabilize it. Basically, boxfish have these ridges that are called keels that run along their sides, and these help create little eddies, which help them horse correct as they swim through the water. Which I suppose is what you want to keep a car running smoothly, like on a highway. It's like you want it to be stable. So that makes some sense.

Precisely. And after reading the peer-reviewed research papers, Mercedes-E. engineers even reached out and called up one of the researchers to learn more about their study, and then they took a step further and did research of their own. They had drag tests around 3D models of these fish that suggested that despite their squarish face, they were surprisingly streamlined, at least in controlled conditions. And so, in the end, Mercedes designers concluded that the boxfish, for all of its boxiness, represented a, quote, aerodynamic ideal, end quote.

And the bionic is the car that they built, the Mercedes built. Yeah, yeah, exactly. They didn't just design it. They actually built it. And here's a picture of what it looks like, right? It's a car which, true to its inspiration, is relatively boxy, as you can see. And it also has these angled ridges along the side that came from the boxfish, more or less. Yeah, yeah.

I mean, so I'm looking at a picture now. It is definitely boxy. It's pretty cute. I mean, it sort of looks like a lime green BW bug with, you know, some war-square-ish features. Kind of like a van bug, you know, kind of. Yeah. Yeah. Yeah, that's a great description.

And honestly, I also think it's pretty cute. And I'm not the only one. When Mercedes put this car out into the world in the spotlight at a big public event, it was a hit. The bionic design got featured in Nat Geo. it was like installed in the MoMA. And for a while, it was probably the most widely circulated example of automotive biomimicry in the world. Yeah, but I haven't seen one of these. So I'm assuming it never got out of the concept car stage, right?

Yeah, that's right. There is no commercial car that evolved out of this. The bionic was really never truly made to go on the roads. It was just a concept car that got a bunch of attention and had a bunch of stories written about it. But, you know, like that from their perspective was kind of the whole idea in the first place. Mercedes might not have gotten a commercial car to sell, but they did get this great story that helped associate their brand with being like eco-friendly and cutting edge and tied into this legacy of natural design that had evolved in like the organic elements over the eons. Okay. But so far, this seems like a pretty straightforward biomimicry story.

Well, it would be if the story ended there. And for Mercedes, it basically did. But the fish scientists, like scientists do, kept going. And 10 years after the bionics big reveal, researchers with new technologies published new findings that painted a very different picture. The old data wasn't wrong exactly. It was just woefully incomplete. And long story short, it turns out that the boxfish, in its totality is definitely not a, quote, aerodynamic ideal.

In fact, if anything, it's basically the exact opposite. So what did they find out? Well, the new team led by a biomorphology researcher named Sam Van Wassenberg, modeled that blunt boxy front plowing head on through the water. And look, it does do okay aerodynamically, as Mercedes had concluded, if it's going straightforward. But as soon as the fish turns its head, its aerodynamics are totally destabilized.

Which doesn't sound like a great model for a car. Yeah, or definitely not the one they were envisioning, because it turns out that the boxfish's superpower is maneuverability, not aerodynamics. And if you actually watch them, they're not straight-line swimmers or speed racers. They are these reef fish, and they spend their days threading their way through reefs and evading predators. These are animals that need to turn on a dime.

So they're super agile, and they flick their fins and rotate themselves in three dimensions, which is very cool and totally useful to them. But, yeah, it's not what you're looking for in a car. But the car you want a shape that can travel fast and, you know, run smooth in one direction, even in high winds, just sort of stay on course. And the box fish, for those purposes,

was essentially the worst fish to choose. So the biotic, it came out. It had a big splash. It was like sent around, I'm sure, online a lot. When the new research came out, did Mercedes respond to it at all? Oh, no. Not at all. And in fact, the Bionics official web page still describes the boxfish as having a, quote, highly streamlined body shape.

Wait, so they still have a webpage for this thing? Yeah. Yeah, it's still up there. It's still like part of their marketing material. It's like the story of this thing was always the point. It was never about whether the car actually worked. So this kind of biomimicry story, would you classify it as more typical than like the TAMS tunnel success? Like is this the type of thing that is mostly what happens when we try to use biomimetic design?

Yeah, I would say that, you know, failures are definitely more common than successes. But there's also like other kinds of non-successes, like basically sort of fake stories. of having biomimetic inspiration, or at least like vastly simplified ones, right? Right. Like just telling a biomimicry story about a product just so it sounds more interesting. Exactly. And there are a lot of those. And a classic example is this startup that claimed to have invented a water bottle based on the Namib Desert Beetle,

which is this insect that has actually evolved a way to capture water out of thin air. It collects and combines droplets on its back. and then those trickle down to its mouth so it can drink them. And so these water bottles were, you know, going to do that same thing, essentially, and fill themselves up. Right. Like, since I haven't heard of a self-filling water bottle, I assume that that just didn't work.

Yeah, no, no, it did not actually work. But it did get so much coverage in Wired and NPR and BBC. And like the list goes on. They even raised millions of dollars on the backs of those Beatles. So, yeah, the water bottle, like the bionic, it was really more about PR than real biomimicry. And honestly, it had less pretensions to even tie to science, I think, than the bionic did. Yeah, yeah. Okay, so we have one example of successful biomimicry with the tunnel.

We have the Mercedes example, which is really, you know, a success in marketing, but not really successful as a product. So what's next? Something that is, honestly, a little more complicated and less straightforward than either of those. Okay, we'll get to that after the break. So we're back talking about biomimicry with Kirk Holstead. So our final story is about a structural design that you can find basically anywhere in the aerospace industry. If you peel back a panel on a Boeing plane or a NASA shuttle, you'll see an array of hexagons. And these are called honeycomb sandwich panels. They look like and will instantly remind you of beehives.

Yeah, so honeycomb panels. I've definitely seen them before. I think anyone who's paid attention to structures at all have seen them before. Oh, yeah. Were they inspired by bees? Well, that seemingly simple question is actually surprisingly difficult to answer. Because if you think about it, like, people have been admiring and examining honeycombs since ancient times. Like the earliest written account we have of why they might create hexagonal shapes dates back to 37 BC. And it was around this time that geometers had figured out. that hexagons are one of only three shapes that you can tile continuously

and without gaps. There are squares which of course you can visualize in a grid. Yeah, like our logo. Yeah, yeah. And triangles, which like if you can picture a truss or if you just kind of alternate up and down, you can see those tiling forever, right? And then there are hexagons.

And of all that set, hexagons are the ones that give you the most space as in the most area per unit of edge. Which means that if you're tiling an array of shapes, these are the ones that let you use the least material. So for bees, that's more efficient and it makes building easier. But humans benefit from that same efficiency and other structural features, which we'll

get to later. So in this case, because this is a super efficient structural solution to lots of problems, bees and engineers, you know, kind of just came up with the same solution. That makes total sense to me. But in the midst of the modern era, another. contingent came along and saw honeycombs as examples of intelligent design. In the 1800s, one clergyman slash naturalist lauded bees as, quote, heaven-instructed mathematicians, end quote. Darwin actually saw this line of thinking as a big threat to his work, even in the 1850s as he was writing on the origin of species.

Huh. So why would the bees being good at geometry be a problem for evolution? Great question. And so basically, if evolution is incremental, right, how do bees arrive at a perfect geometry? Like, what are the steps they take? Because, you know, a slightly off incomplete hexagon isn't a natural step towards making a good hexagon. It's just a bad shape. And so where do we find the in-between versions?

And if there aren't any, the natural theological argument goes, somebody or some God must have handed the bees the answer. Also, I suspect there was kind of a gut-level intuition behind all of this. Like, if you look around at the natural world, you see curders and fractals and all these chaotic things, but precise angular polygons are pretty weird. and rare. And so they seemed just visually, like an exception to the norm, right? Right, right. So I can sort of see the argument or why it was complicated. And that was what

had Darwin worried? Yeah. In fact, so much so that he actually kept bees to research and experiment on while he was writing origin. And what he observed is that bees don't build hexagons outright. They actually dig roundish holes that are, well, basically B-shaped, right? Yeah. But when a bunch of them do that, you know, in a grid, they end up bumping into each other. And as they approach their neighbors, they naturally make walls around those shared edges, and that turns into hexagons. Right. So they never really build a hexagon shape. Like they dig a round hole and you put up some walls for support. And they're surrounded by other neighbors who are doing. the same thing, and the sides of the circular holes kind of push against each other and flatten

out so that you get a hexagon shape. Exactly. None of which is to say that honeycombs aren't natural wonders. In fact, Darwin was a huge fan, and after he finished his research with these bees, he organized a whole section of origin around them and their honeycombs in which he argued that these were amazing examples of the power of evolution. And here's a little excerpt from that chapter. He must be a dull man who can examine the exquisite structure of a comb

so beautifully adapted to its end without enthusiastic admiration. We hear from mathematicians that bees have practically made their cells of the proper shape to hold the greatest possible amount of honey with the least possible consumption of precious wax in their construction. And, you know, there were already all of these connections, but when Darwin published origin, honeybees and hexagoners, became stuck together in one of the most popular science books of the century and were essentially inextricably linked ever since. So when hexagonal panels are created around a century after Darwin,

of course, they get named honeycomb panels. Right, right. I mean, you're just naming them after what they look like, you know? Like, that makes sense to me. But in terms of biomimicry, in terms of our subject today, were the aerospace engineers who were using the honeycomb shapes, were they building off of the logic of bees, or were they building off the legacy of human researchers who came before them?

I mean, yes. I would say both, all the above. And I rather dig that ambiguity. Like, there is no simple straight line from nature to humans. And, you know, after 2,000-plus years of honeycomb history bringing us to the modern aerospace industry, you might think that that would be the end of the story. But I have one last little twist for you. Oh, awesome. Okay, I want to hear more.

Yeah. So in the late 2010s, this 3D printing expert named Drouv Batee got to thinking about honeycombs. And he wondered if there was maybe more to them than this platonic ideal of this particular six-sided polygon. So he sought out an expert, an endomologist named Clint Pennick, who was working. working at an actual biomimicry center at Arizona State. And Clint was shocked to discover that Drew, who had built a whole career on honeycomb structures, had never even seen an actual honeycomb in real life. You know what? I worked in science for a long time.

This actually does not surprise me. Right. Yeah. Because, you know, most engineers, they don't need to bother with bees. They know the shape, right? But Clint sees this and he starts showing droove actual honeycombs, and together they begin to look at how these vary by species, and they observe that real honeycombs are actually quite a bit different from those sort of rigidly repetitive human-made honeycomb panels. All right. So how did they differ?

Well, the easiest difference is at the corners, at these intersections that are sharply angled in human honeycomb panels, but in nature often have different degrees of round-tecum. Yeah. I mean, that makes sense to me because, as Darwin described, you know, like the bees are kind of making a circle and it turns into a hexagon. So like not having other circles around you means that the edges are more rounded. Yeah, yeah, yeah. And so Clint and Drew used 3D printing to replicate those curves. And what they found is that they can offer real structural benefits. So ultimately, the pair got NASA funding to look even more closely. And they x-rayed and characterized these different combs from. dozens of different species of bees and wasps, and they documented all kinds of smaller details, like the variations in the wall thicknesses and the way that separate comb sections are, like, joined together. And sure enough, subtler elements of the comb shape

were found to improve structural performance with potential aerospace applications. Wow. So, like, even in the space age, bees are building better hexagons than we do. Yeah, I mean, it depends upon the bee and the application. But we are definitely still learning stuff from them, which is crazy. Huh.

I love that story. I mean, it makes me think about the, you know, the very simple biomimicry story that we started with, the sort of Kingfisher, Bullet Train story. You know, it's cool. It's easy to convey. But it's pretty flat and flavorless by comparison. Yeah. Well, I mean, I don't know if I'd go that far because there's something I really still dig about those straightforward biomimicry stories.

But sure, yes, there is something also richer, ultimately, about ones like, the honeycomb story where you have human creativity and nature ending up in this more complex back and forth conversation with one another. Yeah, like a recursive discussion between nature and humans about, you know, the virtues of shapes, I guess. Kurt, this was so much fun. I appreciate this tour through various kinds of biomimicry. Of course, Roman. Anytime. 99% Invisible was reported this week by Kurt Kolstad, produced by Jacob Medina Gleason and edited by Emmett Fitzgerald. Mix by Martine Gonzalez.

Music by Swan Real. Fact-checking by Graham Hesha. Kathy 2 is our executive producer. Delaney Hall is our senior editor. The rest of the team includes Chris Barube, Jason DeLeon, Christopher Johnson, Vivian Lay, Losha Madon, Joe Rosenberg,

Kelly Prime, Talon and Rain Stradley, and Me Roman Mars. The 99% of the visible logo was created by Stefan Lawrence. We are part of the Serious XM podcast family, now headquartered six blocks north, in the Pandora Building,

in beautiful, uptown, Oakland, California. You can find us on all the usual social media sites, as well as our own Discord server. There's a link to that, as well as every past episode of 99PI at 99PI.org.