Charles Nunn is a research scientist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and an Assistant Professor in the Department of Integrative Biology at the University of California in Berkeley, USA. His research interests include primate behaviour, disease ecology and comparative biology.

Sonia Altizer is an Assistant Professor at the Institute of Ecology of the University of Georgia. Her research focuses on the ecology and evolution of host-pathogen interactions in wild animal populations.

In combination with predation and competition for resources, infectious disease is a key ecological factor that influences the evolution of animal mating and social systems. Although recent studies have begun to illuminate the central role that infectious disease plays in the lives of some mammals, surprisingly little is yet known or has been written about its influence on the complex mating and social systems of primates, including humans.