The Great Digestion
Our clothes had started to melt.
There were numerous theories about why this had started to happen, many of which bore resemblance to the Biblical interdiction against wearing clothes made of two different fibers — but the scientific enterprise is less interested in the why than in the how, and some basic microscopy indicated the presence of acrylotropha on our clothes.
In fact, the acrylotropha were everywhere.
The number of theories exploded, a number of possibilities greater than the number of viewpoints that could spawn them, with many outlandish and downright conspiratorial exemplars. Did acrylotropha come to Earth as stowaway microorganisms, hitchhiking on a cargo vessel from the Martian settlements? Carbon, fluorine, chlorine, and nitrogen were precious on Mars, so the Reds used genetic engineering and directed evolution to develop strains of microorganisms to break down complex plastics and polymers to simple compounds as a critical part of their recycling infrastructure.
Could these microorganisms have also been bred, by these same techniques, by one of the rising ecofascist cults right here on Earth? These groups had already kidnapped politicians and journalists, and rendered their bodies down to a monomer soup as part of a ghoulish terror campaign. They had fed them to the forests on their sprawling, verdant compounds. It wasn’t hard to believe that these same groups would let loose a microorganism to disrupt the world’s supply chain, bringing governments to their knees. Neither was it hard to believe that this same group might, in their ideological zeal, simply lose control of their creation in one of their labs.
Could these acrylotropha have simply emerged from the pressures of random mutation, natural selection and the sheer abundance of microplastics in the sea, soil, and the bodies of all Earth’s creatures? Prominent scholars proposed the idea of a critical mass of plastic, at which the odds of the mutation that would turn that waste into a substrate would become a virtual inevitability. There were, after all, extremophiles living on the still-hot reactor core in Pripyat.
We’ll never know where the microbiota originated, and while the governments of earth scrambled to blame each other, the Reds, the Dark Greens, and any other group they could identify, our clothes continued to melt — and so did our electronics, medical devices, optical equipment, building materials, many types of resin, and almost all packaging.
There was a brief arms race between engineers and Nature, whereby the former sought to develop more resistant plastics. That effort surely bought some time for humanity to prepare for the violent change to come, but the complex molecules that made up so many objects vital to human systems had turned into a thin chemical slime in just under thirty years; the pale yellow slick coated the ground, floated on the surface of bodies of water, and covered our bodies. It was everywhere.
The simple plastics were the first to go. PETase was likely present in the first acrylotropha to appear, and before long, a series of random mutations spawned new species able to break multiple carbon rings, liberate chlorine, and survive — even thrive — in the high concentrations of resulting compounds. Facultative anaerobes appeared within a decade of the first observations of polyester degradation, and without a need for O2 as an electron acceptor, acrylotropha variants could burrow deeper into the earth and dive further underwater, able to transform substrates in the most oxygen-rare environments. That was the inflection point, as the treasure hoard of microplastic on the sea floor, with its staggering surface-area-to-mass ratio, finally became available for fermentation. There was no going back.
As soon as the acrylotropha had begun breaking down the plastics into monomers, other microscopic members of the trophic web had found a new food source in their waste products. More pedestrian varieties of aerobic bacteria set to work on the new substrates, while the more volatile product compounds simply dissipated into the atmosphere. The pale yellow of the slick gave way before long to a rich-smelling algae-green paste. Earth’s plastic, now food for aerobes, had become the basis for a transformation in Earth’s ecology not seen since the Great Oxidation.
All the gigatons of carbon-containing compounds, once locked below the earth’s surface, suddenly became bioavailable. Symbiotic communities of acrylotroph-fungus lichen became omnipresent. Soil was enriched by the new microorganisms, quickly counteracting decades of soil depletion. The rhizosphere was as productive as it had ever been, as the nitrogen bound up in the microplastics in the earth were suddenly accessible as fertilizer for plants. New species of photosynthetic, plastic-eating biota took a collective breath of carbon dioxide, and exhaled rich and glorious oxygen, all while horizontal gene transfer continued to broaden the scope of what was becoming a new genus. Climate change and plastic pollution vanished in tandem.
Billions died, either due to economic shock, political upheaval, or simple lack of access to basic goods in a ravaged global supply chain.
Those who survived inherited a transformed world, reset to the condition at the dawn of the Bakelite era. Humanity names its ages by materials: stone, bronze, and iron; the plastic age had ended, but what knowledge we retained on paper remained, and the terror of the Great Digestion we emerged into a new age of high-performance ceramics, foamed aluminum, doped glass, and all manner of bioengineered wood, cotton, linen, wool, latex, silk, and chitin. What territory wasn’t claimed by the Dark Greens came to be governed by either eco-kibbutzim or technocratic feudalism. Democracy was abandoned in the mad scramble for survival during the dark ages of the GD.
It took more than a century.
Plastic had been absorbed into the ecosystem in one enormous metabolic convulsion, and we didn’t know whether the acrylotropha were persistent enough to survive after having devoured all its substrate. Was it still present on Earth, hidden at some depth? The Reds wondered the same of possible relic specie of an earlier Martian era, even as the terraforming operations on Mars thickened the atmosphere and warmed the sterile surface.
Terran immigration to Mars, Titan, Enceladus, and Europa may never return for fear of acrylotroph contamination, on the basis of concerns that the microorganisms are now part of Terran gut microbiome. We still don’t know whether humanity will have a second chance at plastic and, given the cost of our dependency and the pain of our withdrawal, we still don’t know if we want one. Earth’s ecosystem is stronger than ever and, for the sin of plastic, we shall never leave her garden: microscopic seraphim guard her gates.
Author’s Note: I’m not in favour of this vision for humanity, and I don’t think it will happen either. Also, I’m not a biologist, so please don’t @ me with attacks on my scientific accuracy. This writing is a thought experiment, as is much sci-fi, but I figured I’d make my views explicit in this note anyway. This was an idea rattling around in my head for a few months now, and I’m glad to have finally written it out. Thanks for reading this far.
Stay safe.
