Our guest is Kyle Harper, a professor of classics and letters at the University of Oklahoma, whose books include "The Fate of Rome: Climate, Disease, and the End of an Empire" and "From Shame to Sin: The Christian Transformation of Sexual Morality in Late Antiquity." He joins us to discuss his hefty and fascinating new book, "Plagues upon the Earth: Disease and the Course of Human History." It offers a meticulously detailed "germ's-eye view" of human life on this planet -- from the origins of disease among our earliest hunter-gatherers to the current COVID-19 pandemic. Per Kirkus Reviews: "Well-conceived.... 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.... A welcome addition to the spate of recent books on epidemic disease."