It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility (...) to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language. (shrink)

Although all natural languages are spoken, there is no accepted account of the evolution of a skill prerequisite to language—control of the movements of speech. If selection applied at sexual maturity, individuals achieving some command of articulate vocal behavior in previous stages would have enjoyed unusual advantages in adulthood. I offer a parental selection hypothesis, according to which hominin parents apportioned care, in part, on the basis of their infants’ vocal behavior. Specifically, it is suggested that persistent or noxious crying (...) reduced care to individuals who would have had difficulty learning complex behaviors, and that cooing and babbling increased social interaction and care as well as control over complex oralmotor activity of the sort required by spoken language. Several different tests of the hypothesis are suggested. (shrink)