A brief history of models of carcinogenesis
Since its origin in the 19th century, epidemiology has faced an internal tension between an approach oriented toward biology and the study of mechanisms, and an approach oriented toward populations and their interactions with the environment. Initially, this tension took the form of an opposition between microbiology and statistics. I describe the early roots of the quantitative approach to health and disease and several historical examples of the above tension, with particular emphasis on cancer. The tension between mechanistic and population-based studies is still present within epidemiology and is in fact essential for the success of the discipline.