Behaviour 2019
How do wild infant bearded capuchin monkeys (Sapajus libidinosus) react towards lipsmacking?
Ana Clara Varella, Natalia Albuquerque, Marina Belli, Patrícia Izar. University of São Paulo, São Paulo, São Paulo, Brazil

Lipsmacking (LS) is believed to be a face-to-face interaction that facilitates social bonding. However, evidence that infants actually engage with the emitter’s face during LS is still lacking. Here we investigated if LS is maintained only by face-to-face interactions or if other factors may be also involved. We analyzed the responses of four wild infant monkeys in their 2nd month of life by investigating 94 randomized LS bouts from focal videos. We used two categories of infants behavior towards the emitter: physical contact (touching, grabbing, others, self-directed, with others, no contact) and head orientation (face, head, other parts, out). We found that infants spent a similar amount of time engaged with the emitter’s face (mean=0,270,04sec) and with other features of their surroundings (out=0,360,04sec). In addition, LS bouts when the infants were in No contact lasted significantly longer (0,350,04sec) than other contact categories (touching:p=0.011; others:p=0.002; grabbing, self, with others:p>0.001). The results suggest a relevant role of other mechanisms besides face-to-face interaction in the maintenance of LS and points to further investigation of the function of LS.