The Four Horsemen – War, Famine, Pestilence and Death* – tend to work as a team. War brings famine (and famine, or at least land shortage, brings war). Hunger makes people vulnerable to infectious diseases – and pestilence, famine and war all bring death.
But sometimes a new disease turns up unexpectedly, like Ebola in West Africa right now, or smallpox in the Aztec Empire in the 16th century, or the Plague of Justinian in 541AD, the first recorded pandemic caused by the bacterium Yersinia pestis, better known from its second appearance in 1347 as the Black Death.
Historians are good are looking back and finding explanations, and epidemic diseases are most deadly when certain preconditions exist: poverty, poor hygiene, poor nutrition and over-population all make things worse. But sometimes, there are no preconditions, and it doesn’t do to blame the victims: the Aztecs were doing just fine until the Spanish arrived, bringing smallpox to a population that had no immunity to the disease. Continue reading