Posts Tagged ‘symbiosis’
“Bacteria represent the world’s greatest success story”*…
But as Stephen Jay Gould goes on to observe (in his 1996 book, Full House: The Spread of Excellence from Plato to Darwin), “They are today and have always been the modal organisms on earth; they cannot be nuked to oblivion and will outlive us all. This time is their time, not the ‘age of mammals’ as our textbooks chauvinistically proclaim. But their price for such success is permanent relegation to a microworld, and they cannot know the joy and pain of consciousness. We live in a universe of trade-offs; complexity and persistence do not work well as partners.”
Still, we (more complex) humans have recognized– and accommodated– bacteria for millennia. As We Make Money Not Art explains in a review of a recent book– We The Bacteria. Notes Toward Biotic Architecture by architectural historians Beatriz Colomina and Mark Wigley— that’s fascinatingly apparent in the history of architecture…
This “alternative history of architecture from the point of view of microbes” compiles the research that led to the exhibition We the Bacteria: Notes Toward Biotic Architecture at the 24th Milan Triennale last year. Curated by Colomina and Wigley, the show investigated how microbial ecosystems relate to spatial design and health inequality.
The book argues that microbes have not only built the whole planetary biosphere but they have also been the real architects of our homes and cities throughout the ages. Or rather, it’s the fear and diseases they cause that have shaped our spaces and the ways we move through them.
About ten thousand years ago, humans began retreating into spaces increasingly cut off from the exterior world. Plants, soil and insects could be left outside. But microbes, including pathogenic ones, followed humans inside their homes, where they adapted, mutated and generated new diseases. As our shelters expanded into villages, cities and sprawling empires, so too did the microbial ecosystems.
The authors narrate how buildings and bodies exist in a constant microbial exchange, co-evolving into a single, dynamic ecosystem. The microbiome of a home is highly specific to its inhabitants. Even the microbiome of a frequently cleaned hospital room resembles the microbiome of the previous patient, but starts to resemble that of a new occupant after twenty-four hours.
Architecture cannot exist without microbes, and, by extension, without disease. While scrubbing, spraying and disinfecting may eliminate most microorganisms, these practices also breed extremophiles, species so resistant that they can take over the space.
Throughout history, the book reveals, health crises have dictated architectural and urban design. From toilets to fumigation systems, from the plague hospitals, aka lazarettos, to the sanatoriums for tuberculosis patients; from sewage systems to urban parks, cities have been continually reshaped in response to the threats they sought to contain. Architecture became the first line of defence against microbes…
[More of the intertwined history of bacteria and our reponse to them, with lots of fascinating photos…]
… Given the important role that microbes play for our immune systems and the environments we inhabit, the authors call for a biotic architecture. Biotic architecture is less human-centric than traditional architecture. It learns from microbes rather than resists them. It does, of course, maintain some antimicrobial protocols against pathogens remain crucial. Water, sewage systems, toilets and food preparation areas still need to be cleansed, but cleaning routines should also embrace controlled exposure to microbial diversity. During COVID-19, for example, microbiologist Elisabetta Caselli and her colleagues replaced conventional disinfectants with probiotic-based sanitation in six Italian public hospitals. The result was a decrease in surface pathogens by up to 90% compared to conventional chemical cleaning and lower rates of healthcare-associated infections and antibiotic resistances… For once, here is a book that presents a vision where humans can actively contribute to microbial diversity, collaborate with the unseen world around us and build in ways that nurture rather than harm the environment…
More– and more fascinating images– at: “We The Bacteria. Notes Toward Biotic Architecture.”
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As we coexist, we might recall that it was on this date in 2012 that Rebekah Speight of Dakota City, Nebraska sold a McDonald’s Chicken McNugget that resembled President George Washington for $8,100 on eBay (the third most expensive McNugget ever sold). She had kept the McNugget in her freezer for 3 years before deciding to sell it…. because bacteria.
“Over the long term, symbiosis is more useful than parasitism. More fun, too.”*…
There are many more varieties of minerals on earth than previously believed– and about half of them formed as parts or byproducts of living things…
The impact of Earth’s geology on life is easy to see, with organisms adapting to environments as different as deserts, mountains, forests, and oceans. The full impact of life on geology, however, can be easy to miss.
A comprehensive new survey of our planet’s minerals now corrects that omission. Among its findings is evidence that about half of all mineral diversity is the direct or indirect result of living things and their byproducts. It’s a discovery that could provide valuable insights to scientists piecing together Earth’s complex geological history—and also to those searching for evidence of life beyond this world.
In a pair of papers published on July 1, 2022 in American Mineralogist, researchers Robert Hazen, Shaunna Morrison and their collaborators outline a new taxonomic system for classifying minerals, one that places importance on precisely how minerals form, not just how they look. In so doing, their system acknowledges how Earth’s geological development and the evolution of life influence each other.
Their new taxonomy, based on an algorithmic analysis of thousands of scientific papers, recognizes more than 10,500 different types of minerals. That’s almost twice as many as the roughly 5,800 mineral “species” in the classic taxonomy of the International Mineralogical Association, which focuses strictly on a mineral’s crystalline structure and chemical makeup.
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Morrison and Hazen also identified 57 processes that individually or in combination created all known minerals. These processes included various types of weathering, chemical precipitations, metamorphic transformation inside the mantle, lightning strikes, radiation, oxidation, massive impacts during Earth’s formation, and even condensations in interstellar space before the planet formed. They confirmed that the biggest single factor in mineral diversity on Earth is water, which through a variety of chemical and physical processes helps to generate more than 80 percent of minerals.
But they also found that life is a key player: One-third of all mineral kinds form exclusively as parts or byproducts of living things—such as bits of bones, teeth, coral, and kidney stones (which are all rich in mineral content) or feces, wood, microbial mats, and other organic materials that over geologic time can absorb elements from their surroundings and transform into something more like rock. Thousands of minerals are shaped by life’s activity in other ways, such as germanium compounds that form in industrial coal fires. Including substances created through interactions with byproducts of life, such as the oxygen produced in photosynthesis, life’s fingerprints are on about half of all minerals.
But they also found that life is a key player: One-third of all mineral kinds form exclusively as parts or byproducts of living things—such as bits of bones, teeth, coral, and kidney stones (which are all rich in mineral content) or feces, wood, microbial mats, and other organic materials that over geologic time can absorb elements from their surroundings and transform into something more like rock. Thousands of minerals are shaped by life’s activity in other ways, such as germanium compounds that form in industrial coal fires. Including substances created through interactions with byproducts of life, such as the oxygen produced in photosynthesis, life’s fingerprints are on about half of all minerals.
Historically, scientists “have artificially drawn a line between what is geochemistry and what is biochemistry,” said Nita Sahai, a biomineralization specialist at the University of Akron in Ohio who was not involved in the new research. In reality, the boundary between animal, vegetable, and mineral is much more fluid.
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A new origins-based system for classifying minerals reveals the huge geochemical imprint that life has left on Earth. It could help us identify other worlds with life too: “Life Helps Make Almost Half of All Minerals on Earth,” from @jojofoshosho0 in @QuantaMagazine.
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As we muse on minerals, we might send systemic birthday greetings to Thomas Samuel Kuhn; he was born on this date in 1922. A physicist, historian, and philosopher of science, Kuhn believed that scientific knowledge didn’t advance in a linear, continuous way, but via periodic “paradigm shifts.” Karl Popper had approached the same territory in his development of the principle of “falsification” (to paraphrase, a theory isn’t false until it’s proven true; it’s true until it’s proven false). But while Popper worked as a logician, Kuhn worked as a historian. His 1962 book The Structure of Scientific Revolutions made his case; and while he had– and has— his detractors, Kuhn’s work has been deeply influential in both academic and popular circles (indeed, the phrase “paradigm shift” has become an English-language staple).
“What man sees depends both upon what he looks at and also upon what his previous visual-conception experience has taught him to see.”
Thomas S. Kuhn, The Structure of Scientific Revolutions
“They swore by concrete. They built for eternity”*…
Understanding how the materials we use work– and don’t work– together…
For most of a red swamp crayfish’s life, cambarincola barbarae are a welcome sight. Barbarae – whitish, leech-like worms, each a couple of millimeters long – eat the swamp scum off the crayfish’s shells and gills, and in most cases improve the crayfish’s health and life expectancy. Together, barbarae and crayfish form a mutualistic symbiotic relationship. Both species benefit from their cohabitation, and barbarae have evolved to the point where their entire life cycle, from egg to adult, occurs while attached to a crayfish.
But their symbiosis is contextual – a tentative truce. Young crayfish (who molt their shells more frequently and therefore accumulate less scum) don’t need much cleaning, and will take pains to remove barbarae from their shells. And even when molting has slowed and a crayfish has allowed the symbiosis to flourish, there are limits to barbarae’s loyalty: If there isn’t enough food for them to survive, they’ll turn parasitic, devouring their host’s gills and eventually killing them.
Like symbioses, composite materials can be incredibly productive: two things coming together to create something stronger. But like crayfish and barbarae, their outcomes can also be tragic. Rarely are two materials a perfect match for each other, and as the environment changes their relationship can turn destructive. And when composites turn destructive – as was evident in the reinforced concrete when the Champlain Towers North were inspected back in 2018 – the fallout can be catastrophic.
The history of what we now call composite materials goes back many thousands of years. For modern consumers, the most common composites are fiber-reinforced plastics (the colloquial “carbon fiber” and “fiberglass”), but perhaps the first composites in history were reinforced mud bricks. The Mesopotamians learned to temper their bricks by mixing straw into them at least as early as 2254 BC, increasing their tensile strength and preventing them from cracking as they dried. This method continues around the world today.
But by far the most commonly used composite material in history is steel-reinforced concrete. Roman concrete usage started as early as 200 BCE, and almost three centuries later Pliny the Elder included a note about what appears to be high quality hydraulic concrete in his Naturalis Historiae. These recipes were subsequently forgotten, and the material largely disappeared between the Pantheon and the mid nineteenth century. Modern concrete involves some legitimate process control: limestone and other materials are heated to around 900° C to create portland cement, which is then pulverized and mixed with water (and aggregate) to create an exothermic reaction resulting in a hard and durable object. The entire process consumes vast amounts of power and produces vast amounts of carbon dioxide, and the industry supporting it today is estimated to be worth about a half a trillion dollars.
But in spite of the fortunes that have been invested in the portland cement process (as well as in a wide range of concrete admixtures, which are used to tune both the wet mixture and the finished product), the true magic of contemporary concrete is the fact that it is so often reinforced with steel – dramatically increasing its tensile strength and making it suitable for a wide range of structural applications. This innovation arose in the mid-nineteenth century, when between 1848 and 1867 it was developed by three successive Frenchmen. In the late 1870s, around the time that the first reinforced concrete building was built in New York City, the American inventor Thaddeus Hyatt noted a critical quality of the material: through some fantastic luck, the coefficients of thermal expansion of steel and concrete are strikingly similar, allowing a composite steel-concrete structure to withstand warm/cool cycles without fracturing. This quality opened up the floodgates, and in the 1880s the pioneering architect-engineer Ernest Ransome built a string of reinforced concrete structures around the San Francisco Bay Area. From there it was history.
More than any other physical technology, it is reinforced concrete that defines the 20th century. Versatile, strong, and (relatively) durable, the material is critical to life and industry as we know it. Reinforced concrete was the material of choice of Albert Kahn, who with Henry Ford defined 20th century industrial architecture; reinforced concrete is a key part of nearly every type of logistical infrastructure, from roads to bridges to container terminals; reinforced concrete makes up the literal launch pads for human space travel. It’s a critical component of power plants, dams, wind turbines, and the vast majority of mid- to late-twentieth century homes and apartment buildings. Its high compressive strength makes it ideally suited for footings and foundations; its high tensile strength lets it cantilever and span great distances easily.
But reinforced concrete is really only 140 years old – the blink of an eye, as far as the infrastructure of old is concerned. The Pantheon was built around 125 CE, by which time the Romans had been experimenting with concrete construction for well over 300 years. When we see the Pantheon, we’re seeing a mature method – a technology with full readiness, being used in an architectural style that’s tuned for its physical properties.
By contrast, even our most iconic steel-reinforced concrete buildings are prototypes…
Early on in the history of steel-reinforced concrete, it was known that the high alkalinity of concrete helped to inhibit the rebar from rusting. The steel was said to be sealed within a monolithic block, safe from the elements and passivated by its high pH surroundings; it would ostensibly last a thousand years. But atmospheric carbon dioxide inevitably penetrates concrete, reacting with lime to produce calcium carbonate – and lowering its pH. At that point, the inevitable cracks and fissures allow the rebar inside to rust, whereupon it expands dramatically, cracking the concrete further and eventually breaking the entire structure apart.
This process – carbonatation, followed by corrosion and failure – was often visible but largely ignored into the late twentieth century. Failures in reinforced concrete structures were often blamed on shoddy construction, but the reality is that like the crayfish and the barbarae, the truce between concrete and steel is tentative. What protection concrete offers steel is slowly eaten away by carbonatation, and once it’s gone the steel splits the concrete apart from the inside…
There are of course many potential innovations to come in reinforced concrete. Concrete mixtures made with fly ash and slag produce high strength and durable structures. Rebar rust can be mitigated by using sacrificial anodes or impressed current. Rebar can be made of more weather resistant materials like aluminum bronze and fiberglass. Or the entire project could be scrapped – after all, the CO2 emitted by the cement industry is nothing to thumb your nose at. Whatever we do, we should remember that the materials we work with are under no obligation to get along with one another – and that a symbiotic truce today doesn’t necessarily mean structural integrity tomorrow.
On composites, crayfish, and reinforced concrete’s tentative alkalinity: “A Symbiotic Truce,” from Spencer Wright (@pencerw), whose newsletter, “The Prepared” (@the_prepared), is always an education.
* Gunter Grass
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As we delve into durability, we might recall that it was on this date in 315 that the Arch of Constantine officially opened. A triumphal arch in Rome dedicated to the emperor Constantine the Great, it was constructed of Roman concrete, faced with brick, and reveted in marble.
Roman concrete, like any concrete, consists of an aggregate and hydraulic mortar – a binder mixed with water (often sea water) that hardens over time. The aggregate varied, and included pieces of rock, ceramic tile, and brick rubble from the remains of previously demolished buildings. Gypsum and quicklime were used as binders, but volcanic dusts, called pozzolana or “pit sand”, were favored where they could be obtained. Pozzolana makes the concrete more resistant to salt water than modern-day concrete.
The strength and longevity of Roman marine concrete is understood to benefit from a reaction of seawater with a mixture of volcanic ash and quicklime to create a rare crystal called tobermorite, which may resist fracturing. As seawater percolated within the tiny cracks in the Roman concrete, it reacted with phillipsite naturally found in the volcanic rock and created aluminous tobermorite crystals. The result is a candidate for “the most durable building material in human history.” In contrast, as Wright notes above, modern concrete exposed to saltwater deteriorates within decades.
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