Humans use a wide range of different cues, both verbal and non-verbal, to communicate different emotions. But vocalizing some positive emotions may be a socially learned behavior, as opposed to a product of evolution, according to a new study published in PNAS. For the study, University College London researchers  compared the responses of 51 Westerners to those of 58 remote and culturally isolated semi-nomadic Himba people of Namibia. Nine emotions - achievement, amusement, anger, disgust, fear, sensual pleasure, relief, sadness, and surprise - were recorded from vocal signals of speakers belonging to both groups and used to test the study participants. read more