In 1991, the multinational Old Mutual investment group approached the Zimbabwean architect Mick Pearce with an audacious assignment. The group wished to construct a retail and office complex called the Eastgate Centre in Zimbabwe’s capital city of Harare that, at 55,000 square meters, would be the country’s largest commercial building. What Old Mutual didn’t wish to do was pay the high cost of air-conditioning such a massive space. Could Pearce, working with the Arup construction firm, devise a design that relied solely on passive, natural climate control?
Pondering the problem, Pearce found inspiration in the termite mounds that dotted the savannas across his country. The largest mounds could reach several meters in height, dwarfing the legions of termites who built them just as a modern skyscraper towers over an individual construction worker. Each funneled air underground through networks of channels into a spherical nest that housed termites by the millions, and even larger numbers of fungi and bacteria. In all, a typical nest contained about a small cow’s worth of hot, breathing biomass. Based on the ideas of the Swiss entomologist Martin Lüscher, many researchers believed the mounds acted as air conditioners, maintaining a nest’s pleasant temperature, humidity, and oxygenation by continuously exchanging hot air rising from deep inside a colony with cooler drafts diffusing down from the surface. According to Lüscher, the mounds’ towering height allowed the “hot breath” of the colony’s biomass to drive this convective exchange. Lüscher’s theory came to prominence in 1961, reaching a wide audience through an article in Scientific American.
Imagining the mounds as air conditioners, Pearce drew up plans for a masonry-insulated building of large, open spaces shot through with elaborate ductwork and clusters of tall heat-exchanging chimneys. The ducts would channel air through the building, while the chimneys would siphon heat from the bustling occupants and machinery during the day, venting it up and out to cool the building after dark. To get the design and engineering just right, Pearce ultimately became a bit like a termite himself, descending from his lofty architect’s perch to personally labor at the construction site, helping to cast and install some of the masonry blocks with his own two hands. The Eastgate Centre debuted in 1996, achieving world renown for its pioneering “biomimetic” design that regulated its temperature at a fraction of the cost and energy of conventional buildings of comparable size.
Pearce ultimately became a bit like a termite himself, descending from his lofty architect’s perch to personally labor at the construction site with his own two hands.
There was just one problem. While the Eastgate Centre did work as planned, the mounds on which it was based functioned in an entirely different manner. Around the same time that the Eastgate Centre opened its doors, the American scientist Scott Turner was using propane pumps and arrays of tiny electronic sensors to painstakingly measure gas exchange throughout nearly 50 South African termite mounds. He found that the mounds didn’t regulate temperature so much as push oxygen and carbon dioxide into and out of the nest. This mixing of air was powered not by the colony’s internal heat but by external air pressure: The termites built their mounds tall to catch the wind, not to promote convection. A mound’s porous, permeable outer surface allowed air to suffuse into and through the colony, rather like the alveoli in a human lung. The mounds weren’t crude air conditioners so much as a wildly complicated external respiratory system.
Though it was partially inspired by a flawed understanding of termite mounds, Pearce’s biomimetic design for Eastgate Centre had ironically worked so well because it unintentionally mimicked the termites’ true temperature-regulating solution, which was the mound’s permeable outer surface paired with the simple thermal capacity of surrounding soil. In addition to its duct-laced atriums and soaring chimneys, the building relied on massive foundational concrete slabs as heat sinks to store thermal energy during warmer daylight hours before releasing it during the cooler nights. “Eastgate Centre succeeded because Pearce was a very good architect rather than a crude imitator of nature,” Turner says. “And being so, he managed to converge on a lot of the same functionality the mounds actually have. It’s really pretty remarkable.”
The Eastgate Centre is one of many stories of people looking to nature for both inspiration and justification—and getting it wrong. But getting it right is no easy task. The more we try to draw inspiration from natural architecture, the more we understand that even the simplest structure is deeply entangled with the character and identity of its builder, making it difficult to interpret. Our first reaction is often to use concepts from our own world as a Rosetta Stone. Termite mounds look like cooling towers, after all. The elegance and simplicity of this equivalence made it easy to believe Lüscher’s model. Even today, descriptions of Pearce’s design in the architectural literature reference Lüscher’s model as correct, and many scientists still colloquially describe termite mounds as “air conditioners.” But the early waves of biomimicry, which were driven by simple qualitative comparison, are now giving way to a more sophisticated and complex understanding of animal homes.
Nowhere is the relationship between builder and home as clear as with social insects. Small, collaborative creatures such as wasps, bees, ants, and termites are nature’s greatest builders, despite the fact that their homes are made by following elegantly simple rules. “The animals that make the most intricate and orderly structures tend to be ones with more limited intelligence,” says John Wenzel, an entomologist and expert on wasp nests at the Carnegie Museum of Natural History in Pennsylvania. “Instead of starting at zero and learning everything each generation, they have a baseline of innate, instinctive behavior that can be polished up relatively quickly through successive generations of natural selection.” Larger and more intelligent creatures are restricted in what they can build both by their brains and their brawn. Other than humans, if big animals build at all, they usually just dig holes or pile up sticks.
These hard-coded behaviors in all their diversity can be seen as extensions of an insect’s genes’ influence beyond the confines of its body, forming a blurred boundary between physiology and environment in what the biologist Richard Dawkins has dubbed the “extended phenotype.” Where Pearce interpreted the termite mound directly in terms of functional units familiar to humans, other researchers use insect architecture primarily to gain insight into its inscrutable residents. “You don’t have to even see the animal in order to have an excellent record of its behavior,” says Wenzel. “You just examine the structure and figure out how it was built.”
Almost inevitably, Wenzel says, those examinations yield surprises not only about the animal being observed, but also the observer. A telling example is the comparative architecture of orb-weaver versus tangle-web spiders. Imagine a spider web, and chances are you summon an orb-weaver’s work in your mind: A branch-hung mesh of silk spiraling around a central hub so orderly and symmetrical you would consider it beautiful, and certainly superior to the irregular skein of strands of a tangle web in a wood pile. An orb web’s beauty comes from the simple algorithm the spider follows to construct it within a single plane. By comparison, a tangle web is the result of a significantly more dynamic behavioral process of trial-and-error construction, methodically stringing and testing silk between any available surfaces until an ideal prey-trapping tension is reached. It looks messy, and primitive.
But the tangle web is actually derived from the more primitive orb web. A tangle web can be built almost anywhere, and it doesn’t require airflow to catch prey. Its marvelous, asymmetric design allowed the spiders that developed it to begin a great radiation into thousands of new species. “Humans like symmetry and order, I think because symmetry and order help us recognize patterns, and we like to think we understand things,” says Wenzel. “A tangle web shows where this can go wrong.”
The Eastgate Centre is one of many stories of people looking to nature for both inspiration and justification—and getting it wrong.
A more subtle structural lesson lay at the root of a mystery Wenzel repeatedly encountered as a student at The University of Kansas in the late 1980s. He was studying the nest-building of Polistes annularis, a common North American paper wasp that builds large, curved nests beneath the eaves of houses. He watched, day after day, as workers labeled with dabs of paint laid down row after row of hexagonal paper cells. Very rarely, he’d notice a worker place a pentagon instead, and the array’s perfection would seemingly be spoiled. Following their simple rules, other workers would tear out the aberrant cell and replace it with a hexagon, only to have their efforts undone by the very same first worker, who would again lay down a pentagon. A back-and-forth tug-of-war would ensue until one side or the other gave up. Often the pentagon would remain. One day, Wenzel made the mistake of mentioning these “errors” within earshot of his professor, the distinguished animal behaviorist Rudolf Jander, who scolded him mercilessly.
“Are you in the mind of the wasp?” Jander had asked. “Do you know what an ‘error’ is? You can’t say, can you? You can only measure. Just measure. The wasps will tell you what this is about; you don’t tell them anything.”
Chastened, Wenzel returned to his studies, measuring and counting the pentagons until a pattern formed. The placement of the pentagons wasn’t random; instead, they appeared at points of anticipated structural stress, where subsequent layers of the nest would be built with curvature. The aberrant pentagons—and the rare wasps who placed them—proved to be strengthening the nest’s structure in the same way a tailor takes in pleats in pants.
“In my studies I’ve seen things many times that I think are anomalies, pathologies, almost like mutations,” Wenzel says. But what seem like pathologies can cross an adaptive valley and reach a peak of fitness in the landscape of selection. In other words, they can become useful, even essential. And difficult to understand.
Later, I catch up with Turner, now a professor at The State University of New York College of Environmental Science and Forestry in Syracuse. He has just flown back from an urban-planning conference in Holland, where he discussed termite mounds and other animal architectures as possible inspirations for future biomimetic “organic cities.” I ask him if there are biomimetic lessons to be learned from termite mounds.
“Sure,” he says. “We sometimes look to nature to validate our own solutions. If the unsentimental natural world has settled on something similar, that makes us feel good. But you simply can’t make great explicit leaps between the societies of humans and social insects like termites. There are different value systems at play.”
This hasn’t stopped classical biomimicry from its myriad successes. Japanese bullet trains blast through tunnels with barely a whisper thanks to aerodynamic shells inspired by the beaks of diving birds. Olympic swimmers shatter world records by wearing suits coated with a drag-reducing texture resembling sharkskin. Rising energy and materials costs have led to a new generation of skyscrapers and
“smart buildings” in cities around the world with bio-inspired passive cooling systems and lightweight structural supports.
But, according to Rupert Soar, an engineer and entrepreneur who has studied termite mounds in collaboration with Turner, most of today’s biomimicry barely mimics biology at all. It would be better described as an expression of “biophilia,” an instinctive human tendency to seek connections with other living things. To Soar, true biomimicry is more of a process than a product, and, like the sophisticated chaos of a tangle web, it’s not always pretty.
“Architects are still looking at this in terms of designing specific structures, shapes, and forms for specific functions,” Soar says. “But in nature that’s not how we see solutions and innovations emerge! We just see organisms following very simple sets of rules, algorithms playing out again and again as related to some objective.”
“Are you in the mind of the wasp? Do you know what an ‘error’ is? You can only measure. Just measure.”
A truer biomimicry, Soar believes, would abandon simple biophilia and its crude design metaphors—bullet trains as bird beaks, sharkskins as swimsuits, or termite mounds as skyscrapers. Instead, architects and designers would begin building things as nature builds them. That is, iteratively and algorithmically, with each form sculpted by many optimized functions, each of which acts as its own independent agent. Soar and many others have experimented with simulating insects and insect homes using “agent modeling systems” in which thousands, millions, even billions of individual programs— each a very primitive “virtual insect” with its own objective—compete over limited resources within some carefully arranged digital domain. Following the “right” set of rules in their virtual world, the agents can replicate the structures and morphologies actual insects create in reality. These systems are not limited to replication, however—they can also be used for innovation. Sometimes, complex optimizations can emerge that bear little resemblance to anything produced by the minds of insects or of humans.
“For architectural problems, one agent may want to resolve a door, another a window, another the flow of water or of heat, and collectively they negotiate a solution,” Soar says. “This is possible now because computers can handle the massive amounts of information required.”
This agent-based approach suggests that we needn’t fully understand the minds and societies of insects or their home-building habits to leverage their power. Yet integrating these techniques into human architecture can be risky. An agent modeling system may arrive at a highly-optimized solution for any given problem, but it can never tell you how it got there, or if the resulting solution is truly the best. The organic constructs that emerge may be wondrously optimized and ornate, but they still develop through an inefficient, sometimes brutal process. Such structures are typically closer to instability and collapse than would be tolerable in modern architecture. Perhaps worst of all, because the products of an agent modeling system often embody so many functions within one form, they can be asymmetric, chaotic, and unappealing to the human eye.
And so we recoil, retreating to something orderly, symmetrical, and sturdy, some simple shape of concrete and steel—and something we can control, which does not involve yielding top-down influence over a building’s design and construction.
A truer biomimicry would abandon simple biophilia and its crude design metaphors.
Nevertheless, Soar suspects architecture will eventually enter a more biomimetic phase as the need grows for more energy-efficient buildings. Agent-based optimizations could become commonplace, along with new construction technologies such as 3D printing, which would allow unprecedented architectural experimentation and innovation. A revolution may occur in how humans construct and live within their homes. Boxy, self-similar houses and office buildings could give way to a wild profusion of easily produced and altered organic forms. Everyday people might then interact with architecture almost like insects, forming social swarms that rely on bio-inspired environmental cues to build and maintain their homes—their hives.
In this strange future, biomimicry could become less a fashionable conceit and more a basic mode of interaction—a building’s occupants would collectively work from the bottom-up to maintain its structure, each individual’s actions attuned to the needs of the many in new ways. “[These environments] will be smelly, noisy, flashy, and textural, full of attention-catching sensory inputs that people will feed off to decide what they do next,” Soar says.
These far-out possibilities and deep connectivities between habitat and inhabitants do sound bizarre, perhaps because they ask us to jettison some of what seems to make us human. Would we ever choose the dynamic chaos of a tangle web over the simplicity of an orb weaver’s web, or a van der Rohe home? Aren’t we more comfortable in static, sturdy structures of stone, glass, and steel than we would be in any flexible biomimetic confection? Perhaps we are. But it is also true that we have continually made our cities and our economies increasingly complex, interconnected, and responsive—organic, in one sense of the word. For better or worse, we are already more similar to nature’s greatest builders than we realize. And, as our understanding of animal homes becomes more sophisticated and we transition more completely from biophilia to biomimicry, this convergence can only accelerate.
Freelance writer Lee Billings is the author of Five Billion Years of Solitude: The Search for Life Among the Stars.