Biosocial functions of grooming behavior among the common Indian langur monkey (Presbytis entellus).

An intensive study of the Indian langur monkey (Presbytis entellus) reveals an interplay between biological and social processes. This study which involved captive animals and over 1,500 observation hours suggests that grooming behavior alone cannot be used to measure status differences between the sexes, nor as a means to understand how pathogens carried by ecto-parasites are controlled. It is shown that the type of grooming exhibited in an interactional setting and the region of the body presented by one animal to another for grooming is often determined by the immediate social events and by the nature of the relationship existing between the participants. For these Colobine langur monkeys grooming behavior not only facilitates integration but it also enables an animal to manipulate a tense situation into a peaceful one. Without reference to many of the other patterns of behavior which only relatively, not absolutely differentiate age and sex classes, grooming behavior cannot be entirely understood.