Language and life history: A new perspective on the development and evolution of human language

Abstract

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.

Middle Childhood: An Evolutionary-Developmental Synthesis

“…Indeed, managing the balance between prosocial and coercive tactics is an important part of developing social skills (Hawley 2014). More broadly, competition shapes many aspects of cognitive and behavioral development in middle childhood; for example, increased pragmatic abilities allow children to gossip, joke, tease, and engage in verbal duels-all forms of social competition mediated by language (Locke and Bogin 2006). Intensifying social competition also contributes to explain the early peak of psychopathology onset observed in middle childhood, characterized by increasing rates of externalizing disorders (e.g., conduct disorder), anxiety disorders (including social phobia), and attention deficit hyperactivity disorder (ADHD; Del ).…”

Functional flexibility of infant vocalization and the emergence of language

“…Similarly, canonical babbling (onset at about 7 mo) is a crucial step toward verbal vocabulary because development and imitation of canonical syllables (e.g., "baba") is required for extensive word learning (10, 11). Recent reasoning influenced by evo-devo converges on the contention that the evolution of language in hominins and the development of language in modern infants are guided by a common set of infrastructural principles, with similar foundational steps (such as canonical babbling, joint attention, and so on) being required in both cases for subsequent languagerelated advancement (12)(13)(14).We continue to be influenced by evo-devo logic and seek the deepest foundations in our communicative phylogenetic history and the earliest points of departure in evolution and development between humans and other animals, especially our closest primate relatives. Our report focuses on a capability appearing earlier in human development than any of those listed above, one that scarcely has been considered in work on origins of language.…”

Aeschylus : Prometheus Bound

“…Sexual selection and sexual conflicts within local groups suffuse adolescence and young adulthood; the former has been postulated as a driving force in the evolution of language (Locke and Bogin 2006), and both processes should contribute to the well-documented sex differences in verbal abilities, with females superior. Alexander (1989) describes evidence for the pervasiveness of group against group conflicts in human evolution, Bowles (2006) lends population-genetic rigor to the efficacy of this level of selection in humans, and Lahti & Weinstein (2005) explain how the tension between within-group cooperation and within-group conflict should shift in relation to the strength of external threats.…”