PLAGUES UPON THE EARTH

A survey of infectious disease as an agent in shaping human history.

In a well-conceived, somewhat overlong example of what the renowned biologist E.O. Wilson calls consilience, classics professor Harper combs through the literature of history, economics, epidemiology, and other disciplines to deliver a solid study of the role of infectious disease in the human story. “The dominance of Homo sapiens over its microbial enemies is astonishingly recent,” he writes. Until the 19th century, most people died of microbial diseases such as the bubonic plague and cholera, and only when societies set aside other priorities and performed such collective enterprises as draining swamps and installing sewers did the death toll fall and human life extend past 35 or so. Those mortality patterns, Harper writes, have a chicken-and-egg aspect. By enhancing human capital with workers who don’t die before they’ve mastered their trades, they add wealth to society, and adding wealth provides the wherewithal to combat diseases and augment human capital. Harper writes appreciatively of what has been called the “Great Escape,” by which human societies have thus unhooked themselves from the devastating effects of plague—though plague always manages to sneak back into the picture, as the recent pandemic has demonstrated. The author turns up intriguing tidbits in his travels through the literature, such as the fact that humans are unusually susceptible to viruses that seem to have evolved specifically to target us. “Our chimpanzee cousins,” he writes, “who live in the jungle, eat raw monkey for breakfast, never bathe, and make a habit of chewing on their own feces, endure only a fraction of the viral diversity that we do.” Harper ventures that we may in fact be weaker by virtue of having tamed so many epidemic diseases. Interestingly, he also locates the origins of many public health practices of today in the Middle Ages through institutions that grew as urban centers did.

Harper’s long-view study is a welcome addition to the spate of recent books on epidemic disease.