Speech, verbally mediated consciousness, and culture most evidently differentiate people from animals. Moreover, verbal communication has historically been viewed as a human attribute. Yet, the biological precursors to verbal communication exist in animal communication: obvious links have been found between human and animal nonverbal vocal communication. Knowledge of these links contribute to our understanding of three major theoretical and clinical issues: the evolution of vocal communication; the process of speech acquisition during infancy; and the pathways of disorders in communicative development. In Nonverbal Vocal Communication specialists from several disciplines review the present knowledge on neural substrates of vocal communication, on primate vocal communication, and on precursors and prerequisites of human speech. Among other points, the book illustrates that animal vocal signals, particularly in primates, appear to be much more complex than mere expressions of effective states. The nonverbal communication data is complemented by comparative and developmental research of the preverbal period of human vocal communication. Studies of speech acquisition, biological adaptation and environmental support to speech yield a complex picture of interrelations between biogenetic and environmental factors. The new evidence that parents--without knowing--are well-fitted for supporting infant communicative development is astonishing. Their capacities represent a primary, biological model of didactic educational support.