Emily June Bethell, Caralyn Kemp, Harriet Thatcher, Julia Schroeder, Kevin Arbuckle, David Farningham, Claire Witham, Amanda Holmes, Ann MacLarnon, Stuart Semple

Social attention is fundamental to a wide range of behaviours in non-human primates. However, we know very little about the heritability of social attention in non-human primates, and the heritability of attention to social threat has not been assessed. Here, we provide data to begin to fill this gap in knowledge. We tested 67 female rhesus macaques, Macaca mulatta, on an attention bias preferential looking task in which they viewed threat-neutral face pairs. We recorded a number of looking time measures of social attention to conspecific faces, and attention to conspecific threat faces specifically. In addition, we recorded levels of vigilant scanning in the social group. We quantified heritability and maternal effects using pedigree information. Repeatabilities for social attention ranged from 11% - 25%. Repeatability for attention to threat faces was 16%, with zero repeatability for attention bias, calculated by subtracting duration of looking towards the neutral face from duration of looking towards the threat face (a common practice in the literature). Heritabilities for social attention were 8% - 14%, with maternal effects 6% - 11%. Heritability for attention to threat was 10%, with maternal effect 4%. This is the first study that we are aware of to test the heritability of attention to threat in a non-human primate. We discuss these findings in light of understanding mechanisms underlying social behaviour in primates, evolutionary pathways of social attention in humans, epidemiology of mental health issues such as anxiety, and potential for improving markers of animal emotion and wellbeing in captivity.