Plagues Upon the Earth: Disease and the Course of Human History

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Plaques Upon the Earth by Kyle Harper

Like a conquering army, the Black Death swept across the Near East and Europe in the 1300s and remained for another 350 years as infections dipped and spiked, declined and rose again. It was the second plague to emerge from the uplands of Central Asia and reach the Atlantic shore—the first came in the 500s and lingered for two centuries. Although some cities instituted quarantines against the Black Death, there was no medication, no vaccine and little anyone could do. The human population fell by more than 50 percent in some places.

Kyle Harper may have been thinking about the past when he began work on his massive tome but the present infected Plagues Upon the Earth in the form of COVID-19. The Black Death proves a good model for how new diseases can jump species and travel widely through trade and travel. We know that plague bacteria were carried by fleas clinging to black rats, a species that thrived as civilizations grew and humans congregated in increasing number. Sorting out the origins of COVID is a task for future researchers.

Among Harper’s themes is how environmental change can lead to disease and death. The catastrophic indigenous population plunge after Europeans arrived in the New World had multiple causes (Harper is careful not to overstate or oversimplify). One cause was the transformation of many regions into plantation economies that provided fertile ground for pathogen-carrying mosquitos.

Although many human sicknesses are transmitted to us by animals, infection is a two-way street. We can make animals sick. However, humans are a species at great risk, providing abundance and mobility for parasites through our large numbers and our presence throughout the world. COVID? Harper quotes Anthony Fauci: it was “a perfect storm,” “highly transmissible, difficult to control and aggravated by human failure.”