Origins of epidemiology.

In this paper we trace the history of epidemiology from 1800 to the present time. The history is highly selective because our purpose is to illuminate the evolving relationship of epidemiology with demography. We first describe the common "prehistory" of these two disciplines in the early nineteenth century, and then describe their divergence during three successive eras of epidemiology up to the end of the twentieth century. In the final section, we draw attention to exceptional individuals who bridged the two disciplines despite the historical trend in the other direction, and express our hope that recent signs of convergence in the face of globalization and the AIDS pandemic will be borne out during the coming decades.