Flush: The Remarkable Science of an Unlikely Treasure

IT TURNS OUT THAT SENDING YOUR CORPSE TO A COMPOSTING facility may not be for everyone. After death, we still routinely bury or burn our dearly departed. But from a biological standpoint, we’re a fairly complete plant food once we fully decompose into rich soil: cadavers offer all of the minerals and nutrients generally deemed essential for flora, except for nickel. As author Caitlin Doughty described in From Here to Eternity, the “recomposition” movement—literally returning our remains to the earth and embracing the freedom of a “body rendered messy, chaotic, and wild”—is, well, gaining ground.

I vividly remember my visit to the Body Farm in Knoxville, Tennessee, where people had donated their corpses to science so forensic experts could learn how we decompose under a variety of natural and sinister circumstances: in the ground, on the ground, in a car trunk, in a trailer. I found the place utterly fascinating, and oddly touching. In death, donors were helping scientists learn more about the inevitable conclusion to life and helping forensic sleuths solve murders and bring killers to justice. When I wrote about it, though, a photo editor was so disgusted by the mere idea of the place that my pictures taken inside the two-and-a-half-acre compound, sans any visible bodies, were rejected as inappropriate.

Donating your newborn’s umbilical cord may not be for everyone either. After a birth, we still routinely dismiss the roughly two-foot-long tether as medical waste and throw it in the trash. But from a biological standpoint, the cord is packed with stem cells and progenitor cells that give rise to oxygen-carrying red blood cells, infection-fighting white blood cells, and clot-forming platelets that can help treat or cure more than seventy conditions ranging from leukemia to sickle cell disease. With more than 40,000 cord blood transplants performed around the world, that movement is making headway as well. For another story, I described how a leukemia patient was saved by a double cord-blood transplant. The procedure used umbilical cords from two anonymous babies (nicknamed Amelia and Olivia after their respective A and O blood types) to effectively reseed his bone marrow after his own had been obliterated by chemotherapy and radiation. Despite the lifesaving potential, many hospitals don’t even give new parents the option of donating the cord after its removal.

When I began writing this book, a question kept popping into my head: What has value? Very few people would question the value of donating blood, an organ, sperm, or eggs. Saving a life or helping to bring a new one into the world is a celebrated act of altruism. But once we’ve branded something as useless or worthless—or let’s face it, icky—it’s often hard to see it in a new light. Which brings me to donating your poop. Sure, we’re often eager to be rid of it as soon as possible. But from a biological standpoint, the normal by-product of digestion can be utterly transformative for both plant and human life. I’d like to think it’s something we can all get behind. Before you make a face or go searching for the perfect gift bag, though, there’s a good reason why we should care about this diamond in the rough that we work so hard to make from birth until death.

Poop is there at the beginning, usually as a greenish-black and tar-like but nearly odorless output that babies normally produce within a day or two of birth (though sometimes while still in utero). Meconium, its technical name, contains mucus, bile, water, shed intestinal cells, amniotic fluid, downy fetal hair, and other bits that the fetus swallowed during gestation. Its expulsion from the body christens the intestinal tract and clears the way for a newborn’s digestive system to begin disposing of the leftovers from breast milk or baby formula. Poop is often there at the end as well, when the dregs of our lower digestive system sigh out of our bodies, the inner and outer anal sphincters relaxing one last time. Between those two seminal events, an adult at the midpoint of a fairly large distribution curve defecates eight or nine times every week. One compilation of studies put the weekly yield at about two pounds, or roughly the weight of a store-bought pineapple, though a newer global model more than doubled that estimate. Given the planet’s current population of eight billion people, some back-of-the-envelope math suggests that our annual production equals, well, a crapload of pineapples.

As a former microbiologist maybe I’m biased, but it seems a bit strange that we consistently shun a natural substance that we make so much of (OK, maybe not John Waters—or Germans). As a homeowner, I was both mortified and amused when a neighbor compared the brown primer a crew had just sprayed onto our house to “an unmentionable bodily function.” Shit brown. She had meant it as an insult, and yet her sense of propriety prevented her from saying the words. As a writer working on this book, I was disturbed to discover that the transcription service I used for some interviews had trained its artificial intelligence algorithm to censor objectionable slang like “shit” and “piss” and “butthole” in the recording. In an effort to be rid of them, we have even erased the words.

In History of Shit, French psychoanalyst Dominique Laporte’s irreverent smackdown of the Western world’s delusions of grandeur, he observes, “We dare not speak about shit. But, since the beginning of time, no other subject—not even sex—has caused us to speak so much.” Consider for a minute how often parents (and pet owners) obsess over poop and what it might mean. We share vivid recollections of the colors, sounds, smells, or freakishly large volumes from a diaper-changing episode. We revel in the satisfied or even joyful exclamations of a properly pooping tot (not to mention the relieved parents). These moments are often remembered as celebrated steps in a child’s development: The first poop! The first poop that isn’t weirdly black or green! The first mostly solid poop! The first poop in a toilet!

Later in life, we often obsess over its absence and what it might mean, especially after an accident, illness, or surgery. Its reappearance can elicit joyful exclamations from the properly pooping patient and loved ones alike: the body’s systems are recovering and life is getting back up to speed. My first normal bowel movement after a surgeon removed my gallbladder and a gallstone the size of a grape definitely sparked joy.

The loss of my gallbladder was a timely reminder that there’s still much to learn about what body parts like the squishy pear-shaped organ actually do. Many doctors call it “expendable,” by which they generally mean that you can live a normal life without it despite its role in concentrating, storing, and distributing fat-dissolving bile made by the liver. I reluctantly agreed to have mine removed after six years of dithering over sporadic episodes of punch-to-the-chest pain that initially felt like a heart attack. I wasn’t particularly sad to see the organ whisked away in pieces like green wet wipes through a hole in my belly button. (OK, I didn’t really see that happening, but it’s a fun mental image along with the tan, multifaceted stone that had exceeded an inch in diameter by then and had to be popped out through the same portal and would have been a rather nice addition to the Ball jar of antique marbles that I keep on a bookcase in my office except that surgical centers are apparently unaccustomed to such requests for souvenirs.)

The surgeon, anesthesiologist, and nurses, unfortunately, all neglected to explain just how much the routine outpatient procedure and multiple accompanying drugs can wreak havoc on a person’s indoor plumbing. (To be clear, there are many, many ways to muck up your intestinal tract.) In the post-surgery recovery room, a discharge nurse warned me against straining too hard while on the pot, lest the effort cause some serious collateral damage; in rare cases, severe constipation even kills. Death by bowel movement can happen through a defecation-associated pulmonary embolism when a blood clot in a deep leg or pelvic vein suddenly breaks free and blocks blood flow in an artery within the lungs. Alternatively, excessive strain can send a patient’s blood pressure soaring. That pressure buildup can cause blood vessels in the brain or abdomen to bulge and rupture, leading to a life-threatening stroke, aneurysm, or heart attack. Elvis Presley, in fact, likely died on the toilet (poor Elvis). Due to a long-standing addiction to opiates, he had become severely and chronically constipated and developed a dramatically enlarged colon. The medical condition is called megacolon, and yes, it’s pretty much what you’d imagine. One plausible hypothesis suggests that Elvis strained too hard and keeled over from a massive heart attack. So severe constipation may have dethroned the King.

In the end, my own Great Poop Vigil only lasted fifty-two hours after the surgery—far earlier than many other poor souls have reported. As a middle-aged man, I still felt a bit odd celebrating and telling my parents about my toilet triumph. But that first splashdown was a moment of pure relief that suggested things were on the mend. My surgery and recovery forced me to pay far more attention to how my body works and what goes in and comes out of it. The episode also brought home how much we still have to learn about the push and pull of the teeming masses that call the intestinal tract home. We’re still accustomed to thinking that we live apart from the rest of nature, but an entire world in miniature is literally inside of us: we can’t escape the fact that its fate is closely intertwined with ours. Understanding what it is and what it does may help us appreciate our own inner power and learn how to live in better sync with a remarkable ecosystem that has coevolved with us. By extension, that mental shift may help us understand how working with nature instead of trying to overwhelm or dominate it can help us avoid a lot of pain.

The truth is that we’re out of step with the rest of the planet at an “Oh, shit!” moment in history. Climate scientists are telling us that we must act now to avert the worst outcomes of rising sea levels and air temperatures linked to our reliance on fossil fuels. A wholesale shift to other energy sources will require some creative reimagining of postindustrial society, of what is most important and meaningful in life. There’s no single cure-all for what ails us, but one of the best places to start creating solutions is with our own humble number two.

If we understand that we are intrinsic members of the natural world, that we are literal conduits between the inner ecosystems within our guts and the larger ones all around us, it may help us embrace our essential roles as caretakers of both. Becoming better stewards may require new ways of thinking about conventional regulations and infrastructure that no longer fit the changing landscape. It also may require re-thinking how we measure and talk about value and progress.

Multiple cultures have long told creation stories and folktales that emphasize the essential nature of regenerative cycles in which one creature’s body or by-products give rise to others. One tale from the Chukchi people of Siberia and recorded in the Chukchi Bible by Yuri Rytkheu describes how the world was created from the stomach and bladder of a raven, the First Bird. “A raven, flying over an expanse. From time to time he slowed his flight and scattered his droppings. Wherever solid matter fell, a land mass appeared; wherever liquid fell became rivers and lakes, puddles and rivulets. Sometimes First Bird’s excrements mingled together, and this created the tundra marshes. The hardest of the Raven’s droppings served as the building blocks for scree slopes, mountains, and craggy cliffs.”

These traditional narratives act as counterweights to our contemporary tales, which are more likely to feature polluted waterways, preventable diseases, and shit going where it shouldn’t. In our words, in our images, in the very architecture of our spaces, “we’re not taught to attach any meaning to what’s thrown away,” Shawn Shafner, a Washington, DC–based artist, educator, and activist, told me. To help break the taboo of what we’ve deemed unmentionable or insignificant, Shafner founded The POOP Project—short for People’s Own Organic Power. Through art, theater, and humor (one of his songs includes the words, “I’m a pooper. Yes, I doo”), he disarms audiences into having more serious discussions about how to have healthier relationships with their bodies and the planet.

Despite our protestations that it’s someone else’s problem, we could all use a reality check. Towns and cities from Norway to Canada still pump their wastewater directly into the sea. New York City’s famously dysfunctional combined sewer system regularly dumps raw sewage into canals and waterways after heavy rains. Cities in Florida, Texas, and other states have likewise been inundated with raw sewage after hurricanes. Even in my own city, Seattle, the enviable wastewater treatment infrastructure still occasionally fails, like when a January 2021 power outage at a pump station not far from my house dumped 2.2 million gallons of storm water and sewage—likely including some of my own—into Lake Washington.

We will always be vulnerable to natural disasters. But our inattention to the fate of a “useless” product is disproportionately harming the most vulnerable and increasing the risk to all. “Our shit is pointing to a place where we’ve rejected that regenerative cycle for a myth of waste, and we’ve rejected our own body’s capacity to be a regenerative agent in that cycling,” Shafner told me. Our very existence depends upon reclaiming that responsibility, writes author Jenny Odell in How to Do Nothing. “Even if you cared only about human survival, you’d still have to acknowledge that this survival is beholden not to efficient exploitation but to the maintenance of a delicate web of relationships. Beyond the life of individual beings, there is the life of a place, and it depends on more than what we can see, more than just the charismatic animals or the iconic trees. While we may have fooled ourselves into thinking we can live cut off from that life, to do so is physically unsustainable, not to mention impoverished in still other ways.”

Like it or not, we are linked to this web and bound to our own less-than-charismatic crap. It’s true that our complicated antihero can raise a stink and reveal only glimpses of potential amid the peril, kernels of Jekyll amid the Hyde. But if we take more than a passing look, we spy a veritable cornucopia of possibilities for human protection, innovation, and transformation. We see lifesaving medicine and sustainable power. We see compost and fertilizer we can use to restore eroded, depleted, or otherwise degraded land. We see a time capsule of evidence for understanding past lives and murderous ends. We see ways of measuring human health from the cradle to the grave, early warnings of community outbreaks like COVID-19, and urgent indicators of environmental harm.

Clever prospectors have created extraordinary opportunities to plumb its depths for water, fuel, and minerals. It can grant mobility and independence. Poop is the ultimate multitasker and could even help sustain and protect astronauts while fueling their way to Mars. Human feces, in short, is the shit, and it’s high time we break the taboo and talk about its many merits. Our vastly underrated output contains a crystal ball of narratives about the past and future, about our pitfalls and possibilities. What we see within it reflects our own prejudices and mistakes, as well as the power to learn and change our fate.

Let’s revel for a moment in the great leveler, the democratic reminder that, as Japanese author Tarō Gomi famously illustrated, everyone poops. There is humor and delight and optimism in that childlike wonder, a welcome reminder of our link to whales and elephants and the rest of the animal kingdom. There are also far bigger stories to tell. Not only warnings of damage to our bodies and the world around us, but also hopeful tales of our untapped potential to rebuild and restore. We’ve heard far too little about the intricate factories in our guts, the ingenious applications for their products, and the innovators who are connecting the dots. This book aims to change that: consider it your reintroduction to a universal if unloved companion and an invitation to discuss something that’s both unmentionable and a common fixation.

Elevating the status of our number two may help us reconnect with the world. It may also create a new dilemma that will require us to reexamine our values and morals: How do we prevent it from becoming a commodity that perpetuates decades of forcible extraction from exploited communities and further concentrates the wealth in others? How do we ensure that the benefits are distributed responsibly and equitably and that the risks aren’t disproportionately shouldered by those who are most vulnerable to the potential harm?

As one of our most underrated and complicated resources, it’s clear that poop has given us plenty to talk about. So think of this deep dive into the world’s most squandered and misplaced natural asset as a cri de coeur (or cri de colon?) for the vast, hidden potential in the “waste” and the common, obvious, and ugly things that we overlook every day. Beyond our umbilical cords after birth and our bodies after death, we have vast scientific and economic potential rumbling under our belly buttons throughout life, just waiting to toot out into the open air (sorry, gallbladder, not you). But the why and how of taking poop seriously are just as important to the future of our species as the what of its considerable contents.

Unlocking poop’s enormous potential will require us to overcome our shame, disgust, and indifference, embracing our role as both the physical producers and the moral architects of a more just and habitable planet. More than that, to become the standard-bearers our feces deserve, we will need to change our collective Western mind-set about what has worth, what moves us forward, and what it means to live in balance. A world that values and elevates the importance of our everyday output is one that no longer prioritizes the new and shiny as default options to solve climate change and other daunting challenges. It’s one that resists the siren song of disruptive, exploitative, and proprietary innovation and embraces a future of progress through imaginative retrofitting and reinvention. It is a world where we no longer require simple or pretty answers, but ones that offer more lasting solutions. Our poop is substance, not style. Form, not flash. But there is undeniable strength in its numbers, and the whole of our ample product is greater than the sum of its many parts.

First a splash. Then ripples. Then waves. This book is a series of interconnected stories highlighting the momentum that can grow from unexpected sources and help us transition to a more circular economy in which we discard nothing and abandon the fantasy that we exist outside of ancient cycles of life and death, growth and decay. It is a book about how to stop wasting and stop pretending that there’s anything left to waste. To maximize poop’s power, we’ll need to come to better grips with an agent of change that can elicit strong reactions. It is nurturing and noxious, funny and temperamental, benevolent and explosive—and it’s only beginning to reveal its many mysteries. As one researcher aptly told me, We don’t know shit.

It’s high time we did. Come, let’s get more acquainted with our inner champion. Locked within us is a medicine cabinet, a mound of fuel briquettes, a bag of fertilizer, and a biogas pipeline. Because of us—and what comes out of us—a dying mother recovers. The lights come on. The crops grow. A bus accelerates. Sometimes hope arrives in surprising packages.