The reason for the fall of the mighty Roman Empire remains one of the most hotly-debated historical questions of all time. Although the Eastern “Byzantine” portion of the Empire lasted until roughly A.D. 1453, the Western part fell around A.D. 476. More than 200 explanations have been proposed for the fall of the latter, ranging from intruders and plagues to corruption, civil wars and climate change.
Researchers still disagree about the primary catalyst, as well as the extent to which the break-up was an economic and social collapse, as opposed to a political event in which Germanic-speaking invaders overtook chunks of the former Empire. Now, a growing faction of researchers maintains that clues to this lost world lie hidden in an unexpected place: the genomes of ancient rats.
While the downfall of a complex human society doesn’t come down to a single cause, getting a clearer picture of ancient human migration, settlements and trade networks would help researchers gauge how other factors — like urban living and the economy — were affected by the Western Roman Empire's fall. And given their reliance on humans for food and shelter, rats serve as excellent proxies for these historical processes.
