Visual and tactile communication in Macaca arctoides and its ontogenetic development

This film is based on a 500-hour observational study of a laboratory social group of stump-tailed macaques. It demonstrates the visual and tactile adult communicative repertoire of the species and shows how the adult communication system develops in infants. The neonate produces only a small communicative repertoire of reflexive tactile behaviors that function primarily in clinging to the mother's fur (grasping) and nursing (rooting and sucking); their communicative function is secondary. As the infant develops, its repertoire becomes larger. The stereotyped, reflexive, tactile behaviors drop out of the repertoire; and more complex behaviors, which are mainly communicative in function and occur in response to complex environmental situations, appear. Most adult behaviors develop slowly. Behaviors present in one developmental stage often change gradually, both in form and in function as the infant matures; after modification, they appear as new behaviors in later stages. For example, the neonatal tactile sucking behavior gradually develops into the lipsmacking expression, a strictly communicative expression in the adult.