Provine, R. R., Fischer, K.R (1989) Laughing, Smiling and Talking: Relation to sleeping and social context in humans. Ethology, 83(1989) 295-305 Provine, R. R., Fischer, K.R (1989) Laughing, Smiling and Talking: Relation to sleeping and social context in humans. Ethology, 83(1989) 295-305