An experimental examination of female responses to infant face coloration in rhesus macaques

In many primates, infants possess distinctive coloration that changes as a function of age. This colour is thought to serve the purpose of eliciting caretaking behaviour from the mother as well as other conspecifics. The present study investigated the responses of adult female rhesus macaques (Macaca mulatta) to pictures of infant faces in relation to infant age and facial coloration. Study animals were shown digitized images of neonates and 5-6-month-old infants displaying either unaltered facial colour, pink neonatal colour, or novel (green) facial colour. While infant and neonate faces of all colours elicited the attention of adult females, pink neonatal facial coloration did not appear to be especially attractive to subjects in contrast with the findings from an earlier study [Higley, J.D., Hopkins, W.D., Hirsch, R.M. Marra, L.M. Suomi S.J., 1987. Preferences of female rhesus monkeys (Macaca mulatta) for infantile coloration. Dev. Psychobiol. 20, 7-18]. The results suggest that infant facial colour is not particularly important in mediating infant attractiveness to rhesus macaque females as previously suggested or that other infantile facial characteristics might be more important than colour in eliciting caretaking behaviours amongst females.