Short-term costs and benefits of grooming in Japanese macaques.

This study investigated the short-term consequences of giving grooming in Japanese macaques (Macaca fuscata) in order to obtain information on its immediate costs and benefits. Giving grooming was associated with increased aggression received from groomees and decreased aggression received from third parties (but only as long as the groomer maintained proximity to the groomee). Grooming was also associated with decreased scratching rates. These results emphasize the unpredictable outcome of individual grooming interactions and the difficulties of social decision-making for monkeys living in despotic societies.