Acquiring a systemic perspective on epidemic events is mandatory in an age in which such events are rapidly growing in both number and spatial distribution. In this work we describe the human/virus interaction through the ‘deep time’ of evolution. We show how ancient epidemics shaped animal and human biology influencing basic traits like multi-cellularity, immunity and cancer. Furthermore, on a much shorter time scale, we focus on the role played by globalization and anthropogenic environmental deterioration in the growing menace of recurring pandemics.