Thermal Temperatures and Social Network Position in Bonobos

In a variety of species, the maintenance of stable social connections is associated with lower levels of stress in individuals. Understanding how physiological stress responses interact reciprocally with social connections in bonobos, humans closest living relative, can provide useful information about both the emergence of social connections in our own species, as well as provide guidance for animal welfare procedures. Infrared thermography (IRT) has been shown to be a reliable non-invasive measure of stress response in some species, specifically non-human primates. The current study examines the relationship between baseline facial temperatures, social network position, and demographic variables in a population of bonobos at the Jacksonville Zoo and Gardens. Behavioral observations and IRT were used in combination with exponential random graph models and permutation-based approaches to examine the degree to which thermal temperatures are both predictive and reflective of variables such as age, sex, and position in the social network. The results of the ERGM indicated the sex was a significant predictor of the structure of the network, but age and thermal temperature were not. An analysis of variance was conducted to further explore the relationship between sex and thermal temperature, which showed that males had on average a significantly higher thermal temperature than females. These results have implications both in animal welfare, and in understanding the evolutionary origins of social networks