Network analysis highlights socio-demographic patterns of stone tool-using primates

While the nutritional benefits and social learning of tool use in primates have been widely studied, far less is known about how tool use is associated with social life. We investigated the social aspects of tool use in a hybrid population of long-tailed macaques (Macaca fascicularis aurea × M. f. fascicularis) on Koram Island, Thailand, comprising both stone tool users and non-users. To assess potential socio-demographic patterns, we examined whether tool use differed between sexes and whether it was related to variation in dominance rank. Using social network analyses, we assessed whether tool users differed in their associations outside foraging contexts by analyzing their grooming interactions and positions within the grooming network. Males were more likely to use tools than females, whereas rank was unrelated to tool use. Tool users and non-users showed similar social connectivity, grooming rates, and numbers of grooming partners. However, grooming networks indicated that non-tool users preferentially associated with other non-users, whereas tool users showed no affiliative bias. By integrating individual characteristics with social network data, this study provides insight into how tool-use behavior integrates into primate social systems, particularly in populations with substantial variation in technological behavior.