Universals in nonverbal behavior represent an important issue in the study of the cross-cultural communication. Perhaps the most well-known research in nonverbal universals was conducted by Paul Ekman, who examined literate and preliterate cultures from various language groups and identified six universal facial expressions: happiness, sadness, disgust, surprise, fear and anger. Another notable researcher, Irenaus Eibl-Eibesfeldt, studied children born with sensory, mental, and physical deprivations and discovered crucial factors in the roles played by learning and inheritance in the development of expressive behavior. He also conducted important research on universals in approach-avoidance behavior. Other research has focused on the development of the human smile and two other closely related nonverbal universals: mutual gaze and the infantile eye fixation. Other nonverbal universals studied include interactional synchrony, body movement and speech rhythm, quasi-courtship behavior, and turn-taking. Researchers offer conflicting explanations of the historical development of universal human communication structures. A position supporting genetic-environmental interaction balances these explanations. The concept of survival value seems to be the most reasonable explanation of the exact origin of specific behaviors. However, the notion of opposites represents a deeper, unifying structure in cross-cultural communication that ties together theories of nonverbal behavior, linguistics and myth. (JD)