The Justinianic Plague

The Justinianic Plague was a pandemic which affected the Byzantine Empire from 541-750 CE. This plague was caused by the spread of the bacterium Yersinia pestis, mostly through fleas on rats. It is called the Justinianic Plague because it began during the reign of Justinian I.

The outbreak of this plague was most severe in the empire’s capital, Constantinople, but it spread through other ports around the Mediterranean Sea and impacted much of Western Eurasia and Europe. The death toll of this disease is still hotly debated, with different scholars suggesting estimates varying from 20% to 50% of the people around the Mediterranean Sea, though most scientists now favor a lower estimate for the death toll.

We also rely on the work of paleogeneticists, people who study the past by examining genetic material preserved on the remains of ancient living beings. Paleogeneticists use specialized techniques to collect fragments of the DNA of microscopic organisms, which they can then reassemble to try to identify what the microbe is. Paleogeneticists can examine the ancient DNA from the microbes found on the bodies of those who may have died from the Justinianic Plague and show that this disease killed them.

The Justinianic Plague severely impacted the region around the Mediterranean Sea. With so many people getting sick and dying, there was a lot of chaos in the empire, and industries such as farming and trading slowed down. The outbreak has been connected with interrupting Justinian I’s military plans and even leading to the decline of the Byzantine Empire, though recent work has argued that the impact of the plague was not a serious as previously thought.

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