Territoriality, tolerance and testosterone in wild chimpanzees

► We investigated the effects of testosterone (T) on different forms of male chimpanzee aggression. ► Male chimpanzee T levels increased before and during territorial patrols. ► In contrast, T concentrations decreased when males hunted and shared meat with others. ► The relationship between T and territorial behaviour is consistent with the challenge hypothesis. ► We hypothesize that the tolerance engendered while meat sharing explains the low T levels during hunts.