Our nomadic ancestors had it easy. They answered their calls of nature whenever and wherever they felt like it—exactly as any other nonhuman animal on earth does. The early humans had no privacy issues and no preferences regarding toilet paper. They simply relieved themselves where they wanted and wandered away from their droppings, leaving them for Mother Nature to process, converting it back to soil. They went on to chase gazelles and forage for berries, and once their bodies extracted the nutrients from all that food, more deposits would fall onto the earth, keeping the cycle going.

As humans kept wandering, they fertilized places along the way—especially those “rest stops” where their clans chose to stay for a while. Some of these early humans may have even noticed that plants tended to grow bigger, better, and tastier in such rest stops. So, tribes made a point of coming back to those spots the next season, or even several years in a row—and then, one year some decided to just settle at those convenient spots.

These early settlers brought us to the advent of farming. They were the ones who began cultivating land and domesticating animals, who switched from a nomadic lifestyle to husbandry. They are the ones we credit with the establishment of modern civilization. They are also the ones we must credit—or blame, depending on the point of view—for leaving humankind forever stuck dealing with its waste. Once humans settled, they could no longer walk away from their shit. And sure enough, shit began to pile up.

If there’s one thing we have in common with our ancestors, it’s that they were just as dismayed with their excrement as we are with ours. Even our Neolithic ancestors wanted nothing to do with their shit. Some dug pits away from their dwellings or in the middle of their fields. Some designated “bathroom spaces” outside the village, or behind the bushes, or underneath the trees. Some went out to the riverbanks, letting the excrement get carried away by water—possibly to the dismay of the villagers living downstream. For as long as the settlements were small, those methods worked. But as the little villages burgeoned into cities and their populations grew, while the surrounding fields and forests shrank, all that shit really began to stink. So, as humanity grew, the sewage systems began to grow, too.

The Bronze Age Plumbers

The Minoan civilization, which flourished on Crete and other Aegean islands from about 2600 to 1100 BCE, pre-dating ancient Greece, had more than 100 cities. Knossos, the Minoans’ largest city, counted 80,000–100,000 inhabitants in its heyday. An average adult produces about a pound of poo a day, and an average child a little less, so the Minoans likely generated some 50 tons of feces daily, all deposited within a relatively limited physical space and accumulating week after week. Part of it probably ended up fertilizing some vegetable patches nearby, but 50 tons a day is more than city gardens can handle. What does one do with all that shit? And what does one use as an easy and readily available force to purge it from yards and homes?

The engineering answer was water. Every human civilization has been located next to some water source—a lake, a sea, or a glacier-fed river—because without water, life, food, and daily human activities don’t really work. A few smart Minoans, frustrated by the daily battle with their excrement, turned to water as a solution. And they were the ones to credit—or blame, again, depending on your point of view—for teaching humankind to dump its sewage into the water. They were the first to set the precedent of discarding our unwanted excrement into aquatic basins. They were the ones who started flushing waste out into the deep blue, rather than keeping it on land.

This new step in excrement history was very important, not only because it led to the creation of sewage systems as we know them, but also because it began to alter the existing nutritional balance of land and water ecosystems, which left us grappling with many of the environmental problems we are experiencing today.

The health of soil ecosystems has always depended on their having sufficient concentrations of nitrogen, potassium, phosphorus, and carbon, as well as some other nutrients like iron, magnesium, and sulfur. Without these elements, the plants can’t build their cell walls or convert carbon dioxide into oxygen. The richest soils, coveted by farmers and gardeners worldwide, have always been high in these basic nutrients. By contrast, aquatic and marine environments have evolved to be low on these elements. And that’s fine. For aquatic ecosystems, an overabundance of these elements isn’t a good thing. Many water-based sewage systems we use today continuously over-enrich waterways, contributing to toxic algal blooms and coastal marshes’ decay.

But for the Minoans and those who came after them, water was what kept the city clean. They built the first ever, simple yet functioning, version of a flushing toilet and a sewage system. Four thousand years ago, the Palace of Minos in Knossos had a cleaning system in which rainwater from the roof was gathered and used to flush the sewage from three bathrooms in the east wing. A sophisticated water system directed different sources of wastewater into pipes underneath the floors, which then joined together to form a large underground channel that also disposed of toilet contents. The Minoans commonly used ceramic pipes, shaping the pipe ends so that the pieces fit tightly into each other. The pipes’ upper parts had openings covered by ceramic lids, allowing for cleaning. Just like our modern plumbing, the Minoan pipes occasionally clogged, so the underground sewers came equipped with manholes for cleaning, maintenance, and ventilation and were built large enough for service workers to enter them.

The Harappan civilization that flourished in the Indus Valley, also built an impressive sewage system for its time. At its height, between 2600 and 1900 BCE, the city of Harappa—which sits in Punjab Province, Pakistan—counted more than 23,000 residents and occupied about 370 acres. Mohenjo-daro was another well-developed city of the Indus Valley civilizations. More than 2,000 years before the Roman Empire would become famous for its feats of engineering, the Harappans built clay brick houses equipped with private toilet facilities that emptied into a sewage structure—a system of covered outside drains.

To route the filth out of their homes, Harappan engineers dug 20-inch-deep gutters. They lined them with clay bricks and covered them with wooden boards and loose stones. The covers helped keep filth from escaping but could be easily opened at any moment to clean clogged passageways. The gutters were sloped so that the water could flow, and they joined drains from other houses along the way—much like our sewer pipes do today. Wherever a drain ran a longer distance, or where several drain routes met, the Harappans installed a brick-lined cesspool to avoid overflowing or clogging. Naturally, such cesspools needed to be periodically emptied, so the ancient engineers equipped their shafts with steps leading down into the pits.

The Harappans and the Minoans were probably the first people who really flushed, albeit without metal levers attached to gleaming white bowls. This approach worked for twenty-something-thousand inhabitants pooping on some 300 acres, but cities were going to grow much bigger than that.

The Romans and the Cloaca Massima

Unlike the Minoans and the Harappans, the city of Rome had to clean up after about a million people, so small, wood-covered gutters wouldn’t do. With 10 times more inhabitants than Knossos had at its height, and thus producing 10 times more waste, totaling 500 tons a day, the Romans had to construct a truly colossal sewer system. They built the Greatest Sewer, or Cloaca Massima, named after the Roman goddess Cloacina—the Cleanser, from the Latin verb cluo, meaning “to clean.” The Cloaca Massima moved millions of gallons of water and flushed about a million pounds of crap a day. It was so immense that Greek geographer and historian Strabo wrote that Roman sewers were big enough “for wagons loaded with hay to pass” and for “veritable rivers” to flow through them. Despite many earthquakes, floods, collapsed buildings, and other cataclysms, the Roman sewers stood strong over centuries.

The Romans were also famous for building their toilets—in their private homes and for public use. But these facilities, while seemingly looking very advanced for an ancient civilization, were, in reality, far from glamorous, especially the public ones. The Romans very much differentiated between the two—they even had different names for them, explains Ann Olga Koloski-Ostrow, an anthropologist and author of The Archaeology of Sanitation in Roman Italy: Toilets, Sewers, and Water Systems. The name “latrine,” or latrina in Latin, was used to describe a private toilet in someone’s home, usually erected over a cesspit. Public toilets, constructed in the middle of the city for everyone to use, were called foricae. They were often attached to public baths, the water from which was used to flush down the filth. Built from marble, some of these ancient public toilets survived to this day, including the one in Ephesus, an ancient Roman city, whose well-preserved ruins reside in modern-day Turkey. They look like long marble benches with a row of holes in them, with no dividers in between—the ancient toilet-goers clearly had far fewer inhibitions than we do today—although the elaborate folds of the toga afforded some seclusion. “The clothes they wore would provide a barricade so you actually could do your business in relative privacy, get up, and go. And hopefully your toga wasn’t too dirty after that,” Koloski-Ostrow says.

The white, polished marble bench seats with a row of holes in them, foricae remains may look beautiful and clean to us today, but that was hardly the case when these facilities were operational, Koloski-Ostrow says. They had low roofs and tiny windows that let in little light. People sometimes missed the holes, so the floors and seats were often soiled and the air surely stunk. Overall Koloski-Ostrow thinks the facilities were so unwelcoming that the Roman elite would use them only under great duress. The upper-class Romans, who sometimes paid for the foricae to be erected, generally wouldn’t set foot in these places.

Neither were the public toilets built to accommodate women. “By the second century CE, I don’t think women used them,” Koloski-Ostrow says. “It was mostly the men’s world. The public latrines were constructed in the areas of the city where men had business to do. Maybe a slave girl who was sent to the market would venture in, out of necessity, although she would fear being mugged or raped. But an elite Roman woman wouldn’t be caught dead in there.” Back at their comfortable villas, the wealthy citizens had their own personal latrines constructed over cesspools, but even they may have preferred to use the more comfortable and less smelly chamber pots, which they made their slaves empty onto the garden patches. They didn’t even want to connect their cesspools to the sewer pipes, because that would be likely to bring the vermin and the stink into the house. Instead, they hired stercorraii—manure removers—to empty their pits. Koloski-Ostrow writes that in one case, “11 asses may have been paid for the removal of manure.”

One thing, however, the Romans did was wipe—even despite their lack of toilet paper. They Roans cleaned their behinds with sea sponges attached to a stick, and the gutter supplied clean flowing water to dip the sponges in. This soft and gentle tool was called a tersorium, which literally meant “a wiping thing.” Whether they washed their hands after that is another story. Maybe they dipped their fingers into an amphora by the door. Maybe they did not. Maybe they did it in some parts of the empire, but not in others. Worse, the tersoria were probably reused and shared by all the fellow butt-wipers who came and went throughout the day. So, if one of the forica visitors had intestinal worms, all the others would carry them home, too. Without any knowledge of how diseases spread, the overall Roman toilet setup could hardly be called hygienic by our standards.

So overall, while the Cloaca Massima solved Rome’s sewage removal problems, it didn’t solve the city’s health issues. It carried the filth out of the city and dumped it into the Tiber, polluting the very water some citizens depended on for irrigation, bathing, and drinking. And so, while the Romans no longer had to see, or smell, their excrement, they hadn’t done much to eliminate its hazardous nature. Through the next several centuries, as humankind kept concentrating in cities, it would find itself in a bitter battle with its own waste, seemingly with no way to win.

Adapted from The Other Dark Matter: The Science and Business of Turning Waste into Wealth and Health by Lina Zeldovich, to be published by the University of Chicago on November 19, 2021. Copyright © 2021 by Lina Zeldovich.

Editors’ Note: This article has been updated to reflect the fact that the city of Harappa is located in Pakistan, not India.

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