The plague, smallpox, scurvy, and yellow fever no longer have widespread prevalence today. But in their heyday, they each had profound influences on human history which far outlasted them. This course will look at the biological and medical basis of each of these diseases and then see what social, political, and economic roles each played in influencing historical developments and events. The four talks in the series are entitled How the Plague Revitalized Europe, How Scurvy Saved Britain, How Smallpox Invaded the New World, and How Yellow Fever Doubled the Size of the U.S.