Eat, Poop, Die, by Joe Roman (Little, Brown Spark, 253 pages)
One of the most fascinating and underrated places on the planet is Surtsey, an island off the southern coast of Iceland born in the 1960s. This land mass, the product of a volcanic eruption, was hoisted above water as if offered on a platter by Poseiden himself, offering scientists the chance to study how life develops on an inhospitable slab of rock.
It turns out that despite the grandest theories of theologians and biologists, life — on this rock, anyway — needed something humble, and kind of gross, for it to emerge and take root. It needed excrement. It was nitrogen deposited on Surtsey via the waste of visiting seabirds that began the alchemy that led to vegetation growing on the island, leading to more animals colonizing the virgin island.
The story of Surtsey and its remarkable development over the past half century begins Eat, Poop, Die, Joe Roman’s surprisingly engaging study of how the most basic of functions contributes to the world’s ecology. The book’s crude title and attendant jokes (“Perfect bathroom reading” reads one commendation on Roman’s website) detract from the seriousness of the work, and its elegance. That said, it takes some work to get the average reader interested in how excrement and rotting corpses power the planet, so perhaps a little levity (including a sideways photo of the author on the book jacket) was necessary.
Roman, a scholar at the Gund Institute for Environment at the University of Vermont, can tell you more about whale poop than you want to know: for example, “In addition to being rich in nitrogen and phosphorus, the concentration of iron in whale poop is more than ten million times greater than in the surrounding seawater in the Southern Ocean.”
Whales’ nutrient-rich excrement helps nourish microscopic animals, and when whales die and their carcasses sink to the ocean floor, they create a habitat called “whale fall” which is ecologically important because, as Roman writes, “The abyssal seafloor is a vast nutrient-poor desert.” When whales are hunted to near extinction, or stranded on beaches and their corpses blown up with explosives, the natural order is disrupted in a way that is no less destructive because it is invisible to humans.
Similarly, Roman looks at the surprising connection between salmon and forest growth in Alaska and the Pacific Northwest. What do fish have to do with trees? A lot, it turns out, when the fish are the favorite meal of bears who live in those forests, as well as other creatures that eat salmon, such as eagles, mink, coyotes and wolves.
Scientists are able to determine where nitrogen in plant life originates by a chemical signature that varies by flora and fauna. And there are researchers whose jobs involve comparing the trees next to streams full of salmon with trees that grow next to salmon-less rivers. Spoiler alert: The salmon-adjacent trees “grew faster and taller — which was good for the salmon, as more shade and large woody debris provided cooler summer temperatures and river structure that aided in salmon reproduction and growth.”
The reason, scientists speculate, is the marine-derived nitrogen in the fish gets distributed in the forest through bear excrement. “The salmon life cycle and the massive pulse of nutrients the fish deliver are crucial aspects of forest ecosystems. The trees, streams, and salmon are all connected.”
Roman writes not just from a desk but from deep in the field. For his chapter on salmon he visits a salmon research station in Alaska; he travels to Surtsey, and to Yellowstone National Park to observe how the reintroduction of wolves changed the ecosystem there. As one sign in the park explains it, “Although wolves do not directly affect all life around them, their effects possibly tumble down the entire food chain. This hypothesis is called a ‘trophic cascade.’”
And don’t count the buffalo out — they have roles as groundskeepers, with their excrement depositing nitrogen and phosphorus into the soil. As bison disappeared on the prairies, so did their natural fertilization. Roman interviews a Native American who calls bison “eco-engineers” because in addition to the nutrients they leave behind, they plow the fields with their hooves. This is not a book for reading while you’re eating lunch, as I learned when coming across something called the Bristol Stool Chart, an illustrated scale of the variety of human feces, used by medical practitioners. And of course, human excrement is addressed here; mammals defecate about 1 percent of their body weight every day, with humans making about two trillion pounds of waste each year, much of which is not contributing in a positive way to the planet’s ecology. But some is — I learned, with some dismay, that some people fertilize their gardens with their own urine. (It’s called “pee-cycling,” and yes, Roman tried it, although fist bump to his family who wouldn’t let him set up the system at home or use it in their garden. Instead his urine went to a pee-cycling center in Brattleboro, Vermont.)
But the bulk of the book is about non-human animals and the largely unnoticed role their bodily functions serve in our world. While Roman is careful to note that some of the theories he writes about are unproven, he makes a convincing case that when animal populations shrink, we’d best pay attention, because there are costs other than not being able to see a certain species anymore. In centuries past, for example, John James Audubon famously described migrating pigeons as blocking out the sun; others have described rivers so dense with salmon that you could walk across the water on top of the fish.
Roman believes that replenishing depleted populations is “one of the best nature-based tools we have to face the climate crisis. Wild animals, through their movements and behaviors — their eating, pooping and dying — can help rebuild ecosystems, recycle and redistribute nutrients, keep the planet a little cooler, and address the biodiversity crisis.” We need to “rewild the world,” he says, in a conclusion that is more of an op-ed than a science book. Having established himself as an authority on poop, who are we to argue? It’s a fine book for animal lovers, climate warriors and science geeks, but otherwise may struggle to find an audience. B
