Colwyn Trevarthen is Professor (Emeritus) of Child Psychology and Psychobiology in the Department of Psychology of the University of Edinburgh. He was trained as a biologist and psychologist, and pioneered research on infant communication in the 1960s with Jerome Bruner, T. Berry Brazelton and Martin Richards. He has published widely on brain development, the development of communication in infants and toddlers, musical and gestural communication, parent-infant interaction, and the interpersonal foundations of language and meaning. He has co-authored and edited Brain Circuits and Functions of the Mind: Essays in Honor of Roger Sperry; Children with Autism: Diagnosis and Interventions to Meet Their Needs; and Communicative Musicality: Exploring the Basis of Human Companionship.