Ewald, Paul W.

Paul W. Ewald (born c. 1953) is an American evolutionary biologist, specializing in the evolutionary ecology of parasitism, evolutionary medicine, agonistic behavior, and pollination biology. He is the author of Evolution of Infectious Disease (1994) and Plague Time: The New Germ Theory of Disease (2002), and is currently director of the program in Evolutionary Medicine at the Biology Department of the University of Louisville. Ewald is known for his theories on the evolution of virulence and his theory that many common diseases of unknown origin are likely the result of chronic low-level infections from viruses, bacteria or protozoa. Ewald contended with the conventional wisdom that a "well-adapted parasite is a benign parasite," pointing out that this idea relies on group selection, and instead suggested that low virulence is only selected for if the pathogen relies on host mobility for transmission.