Peter M. Kappeler is the head of the Department of Behavior and Ecology at the German Primate Center in Göttingen. He is editor of Primate Males: Causes and Consequences of Variation in Group Composition and coeditor of Lemur Social Systems and Their Ecological Basis.

Michael E. Pereira is a research associate at the Lincoln Park Zoo and a science teacher at the Latin School of Chicago. He is coeditor of Juvenile Primates: Life History, Development, and Behavior, also published by the University of Chicago Press.