A key theme in Harper’s story is that the collapse of Roman civilisation could not have been avoided by greater sagacity. When they built their grand edifice the Romans could not have known that they were also creating an environment in which diseases could spread as never before, and they had no understanding of the climate changes that were under way. Still less could they have known that a conjunction of the two would lead to the destruction of their world. It is hardly surprising that by the time of Gregory, the Roman mind was unhinged by eschatological fears and apocalyptic religions.
Historians have long been fascinated by “the single greatest regression in all of human history”. Using data from “natural archives” such as ice cores and genomic evidence, Harper offers a compelling new take on Rome’s fate, arguing that it was “the triumph of nature over human ambitions”. Pandemics and natural changes in the climate caused by volcanic eruptions sent Italy reeling backwards. Infectious diseases such as smallpox spread rapidly through the urbanised empire thanks partly to its famed roads. AD536-45 was “the coldest decade of the last 2,000 years”, causing food shortages. Plague, climate change and war reversed a millennium of material advances. A work of remarkable erudition and synthesis, Harper’s timely study offers a chilling warning from history of “the awesome, uncanny power of nature”.