The Network Structure of Social Play: Insights into Group Cohesion and Dynamics from Mantled Howler Monkeys (Alouatta palliata)

Abstract Social networks formed via play interactions offer a powerful framework for investigating the social dynamics of animals and the functions of play behavior. Using this framework in mantled howler monkeys ( Alouatta palliata ), we examined whether social play might fulfil some of the affiliative and bonding functions typically addressed to allogrooming. We analyzed play networks in seven groups of mantled howler monkeys (89 individuals), analyzing group and individual-level patterns based on 1774 observation hours collected over approximately 3 years. We examined the relationship between group size and network complexity using edge density (the proportion of connections), modularity (the degree to which the network is subdivided into clusters), and average path lengths (the number of steps required to reach others in the network). We analyzed centrality across age-sex classes using betweenness, closeness, and eigenvector metrics. We tested which centrality measure best predicted play evenness, defined as the degree to which individuals distributed their playtime across partners. We found that network interconnectivity generally declined with group size, though average path lengths were not significantly different from those of random networks. Immatures showed the highest centrality values, while adult females exhibited the highest play evenness. However, centrality measures did not significantly predict play evenness. These patterns suggest age-specific functions of social play: immatures may benefit from frequent play to support development, while adult females may use evenly distributed play to navigate social competition. Our findings support the hypothesis that social play serves similar functions to allogrooming, contributing to social bonding.