Differential effects of multiplex and uniplex affiliative relationships on biomarkers of inflammation

Abstract

Social relationships profoundly impact health in social species. Much of what we know regarding the impact of affiliative social relationships on health in nonhuman primates (NHPs) has focused on the structure of connections or the quality of relationships. The influence of relationship dimensionality (e.g., the breadth of affiliative behaviors used) on health and fitness outcomes remains unknown. Here we explored how social networks containing dyads with either multiplex (dyads both groom and huddle) or uniplex (dyads only groom) affiliative relationships differ in their structure and association with biomarkers of inflammation, an indicator of individual health risk. Being strongly embedded in multiplex affiliative networks, which were more modular and kin biased, was associated with lower inflammation (IL-6, TNF-alpha). In contrast, being well connected in uniplex networks, which were more strongly linked with social status, was associated with greater inflammation. Results suggest that multiplex affiliative relationships may function as supportive relationships that promote health. In contrast, the function of uniplex affiliative relationships may be more transactional and may incur physiological costs. This complexity is important to consider for understanding the mechanisms underlying the association of social relationships on human and animal health.

Intragroup sociality drives individual participation in intergroup competition in an urban-dwelling nonhuman primate

“…Multilayer analysis can help us understand an individual’s role in a group by uncovering how an individual’s actions across various contexts can scale up to group-level consequences such as maintaining group cohesion [100], as well as health outcomes. In fact, a recent study on rhesus macaques found that individuals central in a uniplex (grooming) network had higher measures of inflammation compared to individuals central in a multiplex (grooming and huddling) network [116]. The effect of such seemingly subtle behavioural differences on health outcomes underlies the need to consider such complexities in animal socioecology.…”

“…Specifically, we predicted that such individuals would show greater propensities to participate in IGC if they receive more (compared to less) coalitionary support from their group members in the context of intra-group conflicts. Moreover, given that the strength of individuals’ ties across multiple (rather than just single) forms of affiliation may be especially advantageous for resource access, health and fitness [115,116], we also predicted that individuals’ centrality in their multilayer affiliative networks would have a particularly strong, positive influence on their likelihood of participation in IGC.…”