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Part of what’s so unnerving about the coronavirus outbreak is the uncertainty. Medical experts, policymakers and politicians are all focused on the same set of questions: How far will it spread? How long will it last? How many people will it kill?

From its apparent point of origin in Wuhan, China, the virus has reached more than 100 countries, with the total number of cases now about 100,000. More than 3,000 people have already died. Around the world, there are roughly 300 million children who are facing school closures. That number is likely to grow. Some 16 million people are now living under lockdown in northern Italy.

Airlines are cutting flights amid growing fears over contagion and travel bans. The cruise industry is in crisis. Stock market jitters show few signs of abating, while governments plot emergency stimulus funding to reckon with the mounting economic pain born of snarled supply chains and lost business. Major sporting events have been called off or will be held behind closed doors. Worshipers hoping to pray for better times have been barred from some of the world’s holiest sites.

There’s nothing new about this scale of disruption. “There’s not a major area of human life that epidemic diseases haven’t touched profoundly,” Frank Snowden, a professor emeritus of the history of medicine at Yale University, said in an interview with the New Yorker. Epidemics, he said, “have tremendous effects on social and political stability. They’ve determined the outcomes of wars, and they also are likely to be part of the start of wars sometimes.”

It’s a macabre way of recasting how you think about human history: not as a succession of ages and epochs, but of apocalyptic death rattles and societal collapses.

In the 6th century, a plague that swept through the Roman Empire killed an estimated 30 million to 50 million people — perhaps as much as half the world’s population at the time. Ancient sources described one hideous scene in what was then Constantinople, where the bodies of thousands were tightly piled in a mass grave, “and in the little space between them the young and infants were pressed down, trodden with the feet and trampled down like spoilt grapes.” The waves of epidemics that rocked the empire over the span of 400 years played a significant role in its ultimate demise.

The Black Death in the 14th century led to the deaths of as many as 200 million people in North Africa, Asia and Europe (some 30 to 60 percent of Europe’s population perished). “Such was the multitude of those who died in the city by day and by night that it was an astonishment to hear tell thereof,” Italian author Giovanni Boccaccio, who survived the era of pestilence, wrote in his book of tales, the Decameron. The effects of such a catastrophe were vast and far-reaching: It hollowed out cities, halted wars, reversed the evolution of languages and jolted the stultifying control of landowning noble elites, who were forced to reckon with massive shortages in labor.

European colonization killed so many people in the 16th and early 17th centuries — largely because of the spread of diseases to which the indigenous populations of the Americas had no immunity — that the reduced human footprint in one hemisphere of the planet may have actually led to temperatures dropping in a period of global cooling, according to a study published last year.

Epidemics are shared experiences that imprint themselves indelibly on societies. We are arguably still living in the shadow of the 1918 influenza pandemic, which killed about 50 million people worldwide and reduced the average life expectancy in the United States by about 12 years. Scholars hold up the bungled, secretive management of the crisis then by the U.S. government as evidence of the necessity of transparency and truth-telling in the face of an outbreak. As my colleague Gillian Brockell wrote, it’s not clear to some historians if the Trump administration has heeded that lesson.

“Epidemics are a category of disease that seem to hold up the mirror to human beings as to who we really are,” Snowden told the New Yorker. “That is to say, they obviously have everything to do with our relationship to our mortality, to death, to our lives. … They show the moral relationships that we have toward each other as people, and we’re seeing that today.”

Indeed, in the course of the coronavirus epidemic, we’ve already seen countless troubling incidents of xenophobia directed often toward people of East Asian origin. There’s nothing new about that tendency. Outbreaks and plagues in the past often led to the victimization of the poor and vulnerable.

“We should be on guard against the ways that outbreaks of disease have historically led to the persecutions of marginalized people,” Hannah Marcus, a historian of science at Harvard University, wrote in the New York Times. “One of the best documented social outcomes of the plague in late-medieval Europe was the violence, often directed at Jews, who were accused of causing plague by poisoning wells.”

And then there’s the overwhelming impact on daily life. Social media platforms are swollen with videos of people around the world trying to amuse themselves while in quarantine, dancing and joking their way through the dread and dullness of it all — much like the characters in Boccaccio’s Decameron, who hole up in a villa to ride out the Black Death and entertain one another with tales.

In an essay on the impact of a 17th-century plague in northern Italy — where the word “quarantine” originates — historian Erin Maglaque sifted through accounts of bored commoners and nobles stuck in the limbo of life under lockdown.

“Early modern historians used to be interested in the idea of the ‘world turned upside down’: in moments of inversion during carnival when a pauper king was crowned and the pressures of a deeply unequal society released,” wrote Maglaque. “But what emerges … is a sense that for many the world stood still.”

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