Emotions are defi ned as dynamic episodes characterized by a high degree of coordination between several organismic subsystems in the interest of optimal adaptation to relevant events. We argue that the constitutive feature of emotions—synchronization of response channels—is linked to the evolutionary origin of emotional expressions by suggesting that it is an essential aspect of spontaneous affect expressions in animals and humans. The signifi cance of this mechanism to the signaling function in emotional expression communication is explored. In particular, the importance of the perception of a sender’s authenticity in speech communication and music is highlighted. These theoretical notions are then exemplifi ed with a concrete illustration from ongoing research.