Why Rome actually fell: plagues, slavery, & ice age — Kyle Harper

Harper frames Rome's transformation through the interaction of disease and climate, while acknowledging that ancient mortality must be reconstructed from fragmentary evidence rather than modern vital statistics. He says plague episodes such as the sixth-century Plague of Justinian could cause death rates far above ordinary levels; in the fourteenth-century Black Death, some regions lost roughly half or more of their population. The interview presents the scale as historically exceptional, but does not claim that the entire Roman world experienced a uniform 60 percent mortality rate. By the end of the period Harper studies, Rome's population had fallen from its imperial-era scale to an estimated 50,000–100,000, and he argues environmental pressures contributed to this change.

Asked whether Rome might have continued without the plague and extreme cold, Harper says a more durable Mediterranean-centered empire is a plausible counterfactual. He points to Justinian's reconquests in Africa and much of Italy before the outbreak. The eastern Roman Empire did survive, but Harper imagines a stronger polity retaining Italy, North Africa, and perhaps Spain. He stresses that this is a reasonable alternative, not a certainty. Firsthand accounts show how contemporaries interpreted catastrophe through religious and apocalyptic ideas because they lacked germ theory and climate science. The historical question is therefore not only what happened, but how people made sense of events they could not explain mechanistically.