Mapping variation in orangutan gestural communication using multilayer social networks

Gestures are a fundamental component of primate communication. Here, we used social network analyses to assess how similarities in socio-demographic and contextual profiles (proximity, kinship, age similarity, sex combination, contextual similarity) related to patterns of gestural communication (repertoire similarity, gestural frequency and responsiveness), at the individual, dyadic and group levels. We recorded gestures in two captive groups of Sumatran orangutans ( Pongo abelii ) ( N = 16). Principal component analyses revealed two main dimensions explaining variance in gestural profiles, reflecting spatial proximity, contextual similarity and partially kinship and sex combination. At the dyadic level, spatial proximity predicted higher gestural frequency, whereas communities were mainly described by kinship, age and contextual similarity. These findings suggest that while spatial proximity and contextual similarity consistently shaped gestural communication at the individual level, demographic variables became more influential at the community level, where gestural communities may rather reflect enduring demographic and contextual characteristics.