True hunger for extremity is rare. Most animals that can temporarily survive in an extreme environment would prefer a less stressful one. Extremophiles—species that thrive in extremes—make up a much smaller percentage of life on earth, occupying places whose conditions would kill most other organisms. But beyond extremophilia, there is a second category: organisms that don’t love extremes but manage to be exceptionally resilient. For example, the tardigrade, a micro-animal that lives all across the world, from the tallest of the Himalayas to the abyssal deep. These organisms exist among us, functioning well in temperate environments, but they can also withstand many forms of harshness—freezing, aridity, toxic chemicals, radiation, lack of oxygen, salinity, pressure. Biologists refer to tardigrades as extremotolerant.
When my long-distance commute was painful, when it made me carsick enough to puke or left me stranded at Logan airport while rats cavorted through the garbage cans, I liked to think about tardigrades. Under the microscope, these animals look like eight legged bears. Most are smaller than a millimeter. In their normal, active life cycle, they are vulnerable like other animals, but when they lie dormant, they can survive for years without food or water, suspending their metabolism so that they require almost nothing. They can wait like this for the return of moisture, which makes it possible for them to once again forage and reproduce. Humans have irradiated them, tested them at subzero temperatures, and exposed them to the hard vacuum of outer space. Because of their barrel-chested shape, these creatures are also called water bears and moss piglets. They are often photographed under the microscope on slides of moisture scraped from moss, or leaf litter, or damp gutters. But these “moss piglets” are far tougher than their nicknames—they have survived all five mass extinctions and will probably survive the sixth, the one we are experiencing now. These tiny organisms may well outlast us on this planet.
After emerging from the airport terminal doors at some ungodly hour of the night, the first outdoor breath always felt like a drug, like a sheet of weather dissolving on my tongue. Even in the most human landscapes we are always invisibly outnumbered, even among highways, taxis, great swaths of concrete elevated by the pillars of civil engineering, there is always the wind blowing off the water, the clouds teeming with microbial life, the hidden biodiversity of unfiltered air.
Though they are wingless, tardigrades can also fly. When they dry out, they can be blown for great distances by the wind, only to emerge from their latent state and thrive somewhere else. If they don’t ride on the wind, they can travel as passengers, in films of water on the fur of animals or on the feet of migratory birds.
In April 2019, tardigrades crashed on the moon when the privately funded Israeli lander Beresheet (meaning “the beginning”) malfunctioned and was destroyed on impact. The payload, a disc roughly the size of a DVD, included data about life on earth, the entire contents of Wikipedia in English, human DNA samples, and dormant tardigrades incased in epoxy resin. According to the Arch Mission Foundation who designed this “lunar library,” the resin may have actually helped the disc to survive the crash. These latent-state tardigrades in their protective coating may have been flung onto the surface of the moon near the impact site, causing alarm for astrobiologists. Though it’s unlikely that these dormant tardigrades could survive for long there, scientists can’t be certain. Beresheet and the Arch Mission Foundation may have inadvertently contaminated the moon with one of earth’s toughest species. Nova Spivak, Arch Mission’s founder, told Wired that after the crash, “For the first twenty-four hours we were just in shock…We sort of expected that it would be successful. We knew there were risks but we didn’t think the risks were that significant.”
In an astounding display of human hubris, “seeding” the moon with data and DNA was actually the idea. The website tagline for the Arch Mission Foundation is “humanity’s backup plan.” They were founded in 2015 as “a non-profit organization that maintains a backup of planet Earth, designed to continuously preserve and disseminate humanity’s most important knowledge across time and space…. preserving the knowledge and biology of our planet in a solar system wide project called The Billion Year Archive.™” These trademarked (!) libraries are supposed to ensure that human civilization is never forgotten, that caches of data will be placed throughout the galaxy, wherever human technology has gone. They took the generous idea of inter-planetary communication and made it into a human-centric model of data colonization focused on the preservation of our species, the planting of data flags on distant planets. Another one of their libraries was launched by Elon Musk in 2018 and is now orbiting the sun in the glove compartment of a cherry red Tesla roadster, a hallowed piece of space trash that Musk has threatened to suspend in orbit for the next thirty million years.
Is there anything that humans can’t ruin? The question is tempting, but equally hubristic—there are still many things humans don’t have the power to ruin, including the geological processes of the earth. At the timescale of an ice age, we wouldn’t really know what ruin meant. As astrobiologist and planetary geologist Nathalie Cabrol has said, humanity may destroy the climate that supports it, but the earth itself will be fine. On future earth, be it a desert planet or a snowball, life will continue, just not for us, and not necessarily in a way most humans would recognize. As the climate changes and becomes more extreme, the species that do survive may be increasingly lonely. And the more a creature can tolerate, the more likely it is to end up alone in an increasingly hostile world.
When I met Matt, the man who would become my husband, he was giving a talk about one of his artworks: an enclosure designed to feed and house a single tardigrade. The piece looked like an orb—one side held a glass bubble for the tardigrade, and the other held a digital avatar created in its image. You could interact with the avatar like a toy, a Tamagotchi, and the orb would simultaneously feed the tardigrade by squirting moss into the habitat with a long, thin needle. Matt had named the avatar Steven, giving him a Facebook profile and an email address. The project was designed to blur the boundary between conceptions of life and artificial life, to question the way humans anthropomorphize natural processes. But to me, the single micro-animal living in his orb looked like an image of ecological loneliness, a vision in miniature of the last animal alive in a small sphere, proliferating only through the simulacrum of a digital life.
At the time, Matt and I were at an artist residency in January, and everything in the landscape was snowblind white. We walked down the paths between cabins as the drifts slowly got taller, narrowing the gap between the pine trees and the ground. Matt lived in Michigan and I lived in New York City. He was the youngest tenured professor in his department; I was a recent MFA graduate with three roommates and psychopathic landlord. My relief at being in the woods, at escaping my apartment, was intense and more than a little tinged with grief. Most of my waking hours were spent missing people—my father, who had died seven years earlier, my best friend, who had fallen into a deep depression, and my boyfriend, who had moved to the West Coast and was being steadily consumed by the philosophies of Ayn Rand. In the atmosphere of the residency, I felt like a twenty-seven-year old impostor, like at any moment the threadbare fabric of my life would rub away to reveal the skin. Or maybe there had never been any fabric on the loom at all, and I had simply been shuttling back and forth across one set of threads until they broke.
Matt complicated all that. He made me pencil drawings of Oculotrema hippopotami, a tiny parasite that lives in hippopotamus eyes. Instead of art films, he invited all the residents to watch cartoons at the end of the day, making cones for popcorn from sheets of drawing paper. He brought me to his studio where he was running high-voltage electrical current through a flame to turn it into a speaker. I watched the flame wobble as it talked, the tinny notes of voices expanding the flicker of the torch. Before we had thought too much about it, we were close. We set up our laptops across from one another and worked in the library while the snow fell outside.
One afternoon, we sat there listening to clips from the Space Record, the golden, two-disk set sent into space with Voyager 1 and 2. The record was designed in 1977 to communicate with any extraterrestrial life it encountered. Its tracks include music from around the world, greetings from children in different languages, and brainwaves from the EEG of Ann Druyan, one of the researchers in charge of the project.
Before she recorded her brainwaves, Druyan carefully planned a thought itinerary to include the ideas and mental images she wanted to send into space. But she had also just fallen in love, and two days before the recording, she and Carl Sagan had decided to get married over the course of a single phone call, without ever going on a date or even spending time alone. Druyan’s hour-long EEG was compressed into a minute and put on the record, a minute that, according to NASA’s website, sounds like “a string of exploding firecrackers.” Druyan later said, “My feelings as a twenty-seven year old woman, madly fallen in love, they’re on that record… It’s forever. It’ll be true one-hundred million years from now. For me Voyager is a kind of joy so powerful, it robs you of your fear of death.”
I had the opposite reaction to falling in love at twenty-seven. Before I met Matt, I was more sanguine about dying, but our time together seemed, and still seems, so short. Fifty years? Sixty? It feels like earth time—only slow from an individual scale, an illusion of suspension that belies our status as an eyeblink in the geological history of the planet. We would argue about the benefits of endurance, of immortality. Matt wanted to escape death like a character in a movie, an ice zombie rescued from the deep freeze by intrepid scientists from the future. I had always laughed at this argument, but for the first time, I wanted to linger, too. Love set the fear of death loose on me.
When tardigrades enter their dormant state, it’s called cryptobiosis. In this state, their metabolism shuts down, their cells dry out, and they don’t experience their normal processes of aging. In a favorable environment, some species of tardigrade can live anywhere from three months to two years, but they can survive in cryptobiosis for three decades. When tardigrades are exposed to harsh conditions like radiation, a newly discovered protein called a damage suppressor may help to shield their DNA, preventing it from fracturing at high levels of radiation. These creatures might seem passive in their toughness, but at the cellular level, they are fighting to survive.
One of the lessons of Tardigotchi is that data alone isn’t proof of life, or rather, it can only be proof that life once existed. The avatar of a tardigrade doesn’t replace the need for the unique future of the living creature’s proteins. The world around the data ages into the oblivion of relentless change. Or as the poet Susan Howe put it, “facts are perceptions of surfaces. Words are widows of thought.” We catch just a partial story of the living world. But that doesn’t make it any less profound to imagine the fossilized brainwaves of a person deeply in love, banking slowly around the shadow side of a distant planet.
When the residency ended, I waited to see if Matt would go back to his old life. He waited to see if I would go back to mine. But it never really felt like a choice. We started commuting to see one another, booking flights on Spirit Airlines, one of the most godforsaken, dilapidated carriers. Our first spring, we walked in Prospect Park as the paths of packed snow slowly turned into a flood that reflected the sky. We had no idea what our life together would look like if it wasn’t at a distance, but when we were apart the waiting was like a hollow under my collarbone, a constant hunger for the smallest details of another human’s life.
What doesn’t kill you makes you stronger is one of the stupidest American expressions. Even at the level of the tardigrade, withstanding damage has its consequences. In one experiment, most of the tardigrades exposed to the hard vacuum of space survived and even reproduced, but their mortality rate afterwards was higher than the control. Having a damage-suppressing protein that protects your DNA is not a ticket to immortality, but rather a way to exist with extreme conditions for longer, to enter an altered state so that living doesn’t kill you. For humans, tolerance is dangerous because you can passively persist in it while you wait for the world to change. Living in an air-conditioned apartment is a way of tolerating summers that get progressively hotter, distancing yourself from the physical effects of the heat, waiting for things to improve. And all the while, the ecosystem around you (your ecosystem) is facing the full force of those changes, year after year. While you enact your form of resilience and wait, other living things are becoming more stressed, and scarcer. In the middle of the sixth extinction, biodiversity as we know it is diminishing. It would be better to say what doesn’t kill us makes us lonelier.
Neither Ann Druyan nor Carl Sagan believed in an afterlife. In 2003, she told an interviewer that people sometimes ask her if Sagan changed his mind when he was dying, if he ever abandoned his atheism to entertain the idea that they might see one another again. She said the answer is no. All told, they had about twenty years. Twenty years of collaboration, activism, parenthood. And she is a widow now, engaged in the most intimate of long-distance relationships—the interaction between a living mind and the memory of the dead.