ABSTRACT
Allogrooming behaviour between adult mammals in non-sexual and non-parental contexts appears, on the whole, to be less common than in birds. It has been observed in a wide variety of ungulate and artiodactyl species in zoos, but the individuals may have been paired in most cases. Species which have evolved allogrooming or allopreening behaviour have ritualized invitation behaviour which often immediately precedes the partner starting to allogroom or allopreen. Allogrooming is accompanied by fixation on the area receiving attention, and this gives the impression that the grooming monkey is exercising extreme concentration. Under natural conditions, allogrooming may be important in the removal of ecto-parasites from the pelage. Many allogrooming bouts are initiated by invitation of the dominant animal. On comparative grounds, it would seem reasonable that higher-status individuals should allogroom those of lower status. There is a correlation between the rigidity of the hierarchy and the amount of allogrooming behaviour.
