This chapter argues that (1) explosive population growth is a major factor in the transition to the Anthropocene and (2) the control of infectious disease was the proximate cause of modern population growth. Thus, the changing patterns of mortality should be integrated into narratives of humanity’s takeover of planet earth. It also argues that human expansion (in both pre-modern and modern times) creates the ecological conditions for the emergence of new infectious diseases, and therefore the evolution of novel threats is likely to remain a dimension of life in the Anthropocene for the planet’s dominant species.