When Germ Theory Didn’t Matter

Abstract For 11,000 years since the Neolithic, acute infections spread globally across human populations like a plague of plagues. Then around the beginning of the Industrial Revolution, infectious disease mortality declined substantially in a handful of affluent nations, increasing life expectancies and population sizes along with declining fertility in urbanizing populations. These health and demographic changes constituted the Second Epidemiological Transition. This chapter examines the best documented example of this transition in England and Wales from the late eighteenth century to the early twentieth century. Although the acceptance of Germ Theory would later inform many medical breakthroughs, it only made modest contributions during this time period. Instead, health improvements were largely the result of dietary and living changes that reversed some of the ancient trends that occurred during the First Epidemiological Transition.