Pandemics That Brought Down Ancient Civilizations

The standard story of civilizational collapse reads like a military briefing. Armies mass. Borders break. Empires fall to the sword, or to drought, or to the slow metabolic failure of overextension. It is a tidy narrative, and it is probably wrong — or at least incomplete — for most of the cases we care about.

The more interesting story is smaller. It lives in teeth.

Ancient DNA extraction has done more to rewrite the history of human catastrophe in the last two decades than any amount of archival work. When researchers pull bacterial genetic material from the molars of people dead for three or four millennia, they are reaching past every chronicle, every inscription, every royal claim about why things fell apart — and finding something that left no monument and gave no speeches. What they keep finding, with uncomfortable regularity, is disease.

The silence at Cahokia

Start with the most complete silence on this continent. According to History.com's coverage of pre-Columbian urban centers, Cahokia, the great Mississippian city in what is now southern Illinois, held somewhere between 10,000 and 20,000 people at its height — making it the largest urban settlement north of Mexico. Its central earthwork, Monks Mound, rose a hundred feet and covered more ground at its base than the Great Pyramid of Giza. The trade network radiating out from it reached the Great Lakes, the Gulf Coast, the Appalachian foothills.

By 1400 CE, the city was empty. Columbus would not sail for another ninety years.

For most of the twentieth century, the explanations leaned environmental: drought, soil exhaustion, deforestation. These factors were almost certainly part of the story. But bioarchaeological analysis of late Mississippian burials tells a different story through the bones themselves — rising rates of tuberculosis, vertebral and rib lesions, malnutrition signatures in children and young adults who should have been the demographic engine of the city. The same trade routes that carried copper from Lake Superior and shell from the Florida coast carried pathogens. Population density and long-distance contact are the twin engines of urban civilization. They are also the twin engines of every pandemic.

What makes Cahokia particularly hard to sit with is the total absence of testimony. No chronicles. No prayers. No names of the lost. "Whatever swept through the wooden longhouses beneath Monks Mound left no testimony except a falling birth rate, a rising death rate, and an abandoned skyline of earthen pyramids facing the sun." The civilization that built one of the ancient world's great cities vanished before history arrived to record what it had been.

The Hittites and the weaponized donkey

The Hittites, unlike the Mound Builders, left us writing — and what they wrote is genuinely unsettling. According to the World History Encyclopedia's documentation of Suppiluliuma I's reign (c. 1350–1322 BCE), the Hittite New Kingdom plague texts from Hattusa constitute some of the earliest sustained written accounts of epidemic disease anywhere in the human record. The tablets describe a sickness moving through the population and livestock simultaneously: skin ulcers, swollen lymph nodes, people dying alongside the donkeys that carried their grain. Modern researchers examining the symptom descriptions have proposed Francisella tularensis — tularemia, rabbit fever — as the likely culprit.

But the tablets do not only describe the outbreak. They describe what the Hittites did with it. During a period of conflict with the neighboring kingdom of Arzawa, the cuneiform records indicate that sick, dying donkeys were driven across the border into enemy territory. The Arzawans fell ill. No germ theory. No microscope. No scientific vocabulary for transmission. And yet, operationally, lethally, the Hittites had identified the vector and deployed it against an enemy — and then recorded the entire operation in clay for their gods and their kings and, accidentally, for us.

This is the earliest documented act of biological warfare in the human record. What it implies about the centuries before writing existed to capture it is a question nobody can answer.

The plague prayers of Mursili II, Suppiluliuma's eventual successor, add a theological dimension that is almost as disturbing. Mursili watched two kings — his father and his brother — die of the same invisible disease within a year of each other. He then wrote, across two decades, a series of prayers to the gods demanding to know what his people had done to deserve this. He confessed sins he was not sure he had committed. He confessed sins committed before he was born. The empire that had weaponized plague against its neighbors could not stop it from hollowing out its own foundations. When the Late Bronze Age Collapse arrived a century later, the Hittites were among the first great powers to disintegrate.

Athens, and the general who survived to write it down

The plague of Athens in 430 BCE is the ancient pandemic with the best primary witness. Thucydides was infected, recovered, and described what he had seen with the clinical precision he applied to military campaigns: violent fever, throats and tongues turning bloody, skin darkening into pustules and ulcers, victims throwing themselves into rainwater cisterns to cool the burning. Most were dead within seven to nine days. Between 75,000 and 100,000 Athenians died across four years — perhaps a quarter of the city's population. Pericles, the statesman whose defensive strategy had packed the rural population behind the city walls, contracted the disease in 429 BCE and did not survive it.

The cruel irony is architectural. Pericles's strategy was rational. Keep the population safe behind walls while the fleet harassed the Spartan coast. It was exactly the right response to a conventional military threat. It was exactly the wrong response to a waterborne pathogen in a city already straining its sanitation infrastructure. The strategy that was supposed to preserve Athenian power engineered the conditions for its destruction.

For 2,400 years, the pathogen's identity remained contested. In 2006, a team led by Manolis Papagrigorakis at the University of Athens — with the finding subsequently reported by the European Union of Science Journalists Associations — published analysis of dental pulp from a mass grave at the Kerameikos. The DNA pointed to Salmonella enterica serovar Typhi. Typhoid fever. A bacterium that thrives in contaminated water and crowded conditions. The golden age of Athens ended not on a battlefield but in the epidemiological consequences of its own defensive genius.

The Roman sequence

Rome managed to acquire two civilization-threatening pandemics within a century of each other. The Antonine Plague (165–180 CE), almost certainly smallpox imported from Mesopotamia via returning legions and documented by Galen in clinical detail, killed an estimated 5 to 10 million people across an empire of roughly 75 million. Many historians mark this — not the sack of Rome in 410, not the fall of the Western Empire in 476 — as the true beginning of Rome's long decline. The Pax Romana was still in force. The frontier legions held. And then, in a single decade, the foundation cracked.

The Plague of Cyprian (249–262 CE) arrived while Rome was still metabolizing that wound. The bishop of Carthage, writing pastoral letters to console the dying, produced one of the most clinically terrifying descriptions of mass death in the ancient record. "The infected," Cyprian wrote, "walked the streets of Carthage looking like corpses that had not yet been told to lie down." Contemporary sources reported thousands of deaths per day in Rome alone at the outbreak's peak. The pathogen remains unidentified — proposals range from a hemorrhagic fever to a virulent strain of smallpox distinct from the Antonine strain — because no mass grave from this plague has yet yielded usable ancient DNA. The organism that brought the empire to within sight of collapse two centuries before its formal end walked off the historical stage without leaving a name.

What the teeth keep telling us

The largest reorientation in this whole story comes from the work of Simon Rasmussen and colleagues at the Center for GeoGenetics, University of Copenhagen, published in Cell in 2015. By sequencing ancient DNA from Eurasian skeletons, the team identified Yersinia pestis — the Black Death bacterium — in human remains dating to roughly 3000 BCE. Plague was already circulating among Stone Age humans five millennia ago, two millennia before anyone invented writing to record it.

The early strain lacked the specific genetic adaptation that would later allow the bacterium to colonize the gut of a flea and explode through rat-and-flea transmission networks. It spread pneumonically instead — person to person, on the breath, in the close quarters of the densest human settlements that had ever existed. Those settlements were the Trypillia mega-sites of what is now Ukraine and Moldova: proto-cities housing up to 15,000 people in concentric rings of timber and clay, the largest concentrations of human population on Earth at that time. They were burned — not by invaders, but by their own inhabitants, repeatedly, across dozens of sites — and then abandoned. For over a century, archaeologists proposed ritual renewal, climate stress, soil exhaustion as explanations. The ancient DNA suggests something more urgent. The burnings begin to look like containment. The abandonments begin to look like flight.

The Neolithic plague did not arrive at the end of a great civilization. It arrived at the beginning, before the concept of civilization had formed. "It was killing humans before humans had cities to lose. Before they had writing to mourn the dead. Before they had the concept of history within which to place a catastrophe."

Every named plague on this list — Athens, Rome, Constantinople, colonial Mexico — is downstream of that moment. Disease was shaping human settlement patterns before humans had any framework for understanding what disease was. The architects of our earliest cities were never only the priests and the planners. They were also the organisms in the lungs of the people who built them.

The skeletons are still in the ground. The bacterium is still in their teeth. The question of how much of our deep prehistory it wrote remains, for now, unanswered — which is not a reason to stop asking it.

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By Helen Papadopoulos, Ancient World Correspondent