For socialized animals,such as primates,emotions are the expres-sion of internal states,which may be recognized by others to adjust an individual's potential actions(Girard and Bellone 2020).Facial expressions are therefore important signals in communication(e.g.,happy or in pain)and can help individuals understand potential meanings between each other(Dolensek et al.2020).Facial expres-sions can be expressed and processed freely and are useful in social interactions and bonding(Waller et al.2016).