ONTARIO, CANADA—Economic historian Cornelius Christian of Brock University thinks the assassinations of Roman emperors could be linked to decreased rainfall and lack of food for the Roman military, according to a Live Science report. Christian compared ancient climate data collected in a previous study from fossilized tree rings in France and Germany—the Roman frontier—with records of mutinies and emperor assassinations.
Rainfall predicts assassinations of Ancient Roman emperors, from 27 BC to 476 AD.
When rainfall is low, Roman troops starve, and are more likely to mutiny.
Lower rainfall predicts more troop mutinies.
More mutinies predict more assassinations of Roman emperors.
A dictator relies on his military’s support; shocks to this support can threaten his rule. Motivated by this, we find that lower rainfall, along the north-eastern Roman Empire, predicts more assassinations of Roman emperors. Our proposed mechanism is as follows: lower precipitation increases the probability that Roman troops, who relied on local food supplies, starve. This pushes soldiers to mutiny, hence weakening the emperor’s support, and increasing the probability he is assassinated.