Preterm and full term infant vocalization and the origin of language (original) (raw)
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Functional flexibility of infant vocalization and the emergence of language
We report on the emergence of functional flexibility in vocalizations of human infants. This vastly underappreciated capability becomes apparent when prelinguistic vocalizations express a full range of emotional content-positive, neutral, and negative. The data show that at least three types of infant vocalizations (squeals, vowel-like sounds, and growls) occur with this full range of expression by 3-4 mo of age. In contrast, infant cry and laughter, which are speciesspecific signals apparently homologous to vocal calls in other primates, show functional stability, with cry overwhelmingly expressing negative and laughter positive emotional states. Functional flexibility is a sine qua non in spoken language, because all words or sentences can be produced as expressions of varying emotional states and because learning conventional "meanings" requires the ability to produce sounds that are free of any predetermined function. Functional flexibility is a defining characteristic of language, and empirically it appears before syntax, word learning, and even earlier-developing features presumed to be critical to language (e.g., joint attention, syllable imitation, and canonical babbling). The appearance of functional flexibility early in the first year of human life is a critical step in the development of vocal language and may have been a critical step in the evolution of human language, preceding protosyntax and even primitive single words. Such flexible affect expression of vocalizations has not yet been reported for any nonhuman primate but if found to occur would suggest deep roots for functional flexibility of vocalization in our primate heritage. evolution of language | infant communication | flexibility in communication | language development | primate communication R esearch on evolution and development of language has been devoted primarily to syntax, the uniquely human capacity to produce well-formed complex sentences (1-4). Additional work has targeted the emergence of simpler communicative structures and thus has shifted attention back in evolutionary time to an earlier possible split of hominins from the primate background. For example, research has considered the presumably earlier evolution of simple sentences or "protosyntax" (5). Other work influenced by recent trends in evolutionary developmental biology (evo-devo) (6, 7) has focused on infrastructure for language, invoking capabilities logically more foundational even than protosyntax and presumably moving the communicative differentiation of hominins from other primates much farther back. For example, symbolic expression in single words beginning in modern human development at about 12 mo is a precursor to even the simplest syntax (8). Moving the evolutionary focus even farther back in time, joint attention-infant pointing with gaze alternation between an object and an adult interactor, occurring before the end of the first year-is deemed a critical precursor to words (9). 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 .
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.
Language Origins Viewed in Spontaneous and Interactive Vocal Rates of Human and Bonobo Infants
Frontiers in Psychology, 2019
From the first months of life, human infants produce "protophones," speech-like, non-cry sounds, presumed absent, or only minimally present in other apes. But there have been no direct quantitative comparisons to support this presumption. In addition, by 2 months, human infants show sustained face-to-face interaction using protophones, a pattern thought also absent or very limited in other apes, but again, without quantitative comparison. Such comparison should provide evidence relevant to determining foundations of language, since substantially flexible vocalization, the inclination to explore vocalization, and the ability to interact socially by means of vocalization are foundations for language. Here we quantitatively compare data on vocalization rates in three captive bonobo (Pan paniscus) mother-infant pairs with various sources of data from our laboratories on human infant vocalization. Both humans and bonobos produced distress sounds (cries/screams) and laughter. The bonobo infants also produced sounds that were neither screams nor laughs and that showed acoustic similarities to the human protophones. These protophone-like sounds confirm that bonobo infants share with humans the capacity to produce vocalizations that appear foundational for language. Still, there were dramatic differences between the species in both quantity and function of the protophone and protophone-like sounds. The bonobo protophone-like sounds were far less frequent than the human protophones, and the human protophones were far less likely to be interpreted as complaints and more likely as vocal play. Moreover, we found extensive vocal interaction between human infants and mothers, but no vocal interaction in the bonobo motherinfant pairs-while bonobo mothers were physically responsive to their infants, we observed no case of a bonobo mother vocalization directed to her infant. Our crossspecies comparison focuses on low-and moderate-arousal circumstances because we reason the roots of language entail vocalization not triggered by excitement, for example, during fighting or intense play. Language appears to be founded in flexible vocalization, used to regulate comfortable social interaction, to share variable affective states at various levels of arousal, and to explore vocalization itself.
Journal of Phonetics, 2007
opening of the larynx into the pharynx is in high position in Neanderthal. (Lieberman, 1972; Lieberman & Crelin, 1971, p. 77) (2) This characteristic would make it impossible to produce the complete range of speech sounds, notably the three extreme ''point'' or ''quantal'' vowels [i a u] found in almost all the world's spoken languages. A lowered larynx and so a large pharynx is thus considered by Lieberman and Crelin to be a key anatomical prerequisite for modern human speech. Apes and human newborns do not have and Neanderthals did not have the anatomical prerequisites for producing the full range of human speech: Even if [Neanderthal] were able to make optimum use of his speech-producing apparatus, the constraints of his supralaryngeal vocal tract would make it impossible to produce 'articulate' human speech, i.e. the full range of phonetic contrasts employed by modern man. (Lieberman, 1972; Lieberman & Crelin, 1971, p. 92-93) Thus, according to Lieberman, Neanderthals therefore could not produce ''human speech'', and this was probably one of the causes for their extinction: Thus I propose that the extinction of Neanderthal Hominids was due to the competition of modern human beings who were better adapted for speech and language. (Lieberman, 1984, p. 329) The extinction of Neanderthal hominids may derive from their having lacked human speech. (Lieberman, 1991, p. 76) This theory is attractive for explaining the lack of speech in apes and the (relatively) slow appearance of a well-formed vowel system in human babies, and it is widespread (Boe¨, 2001), having been adopted by many
Introduction to the Special Issue on Nonverbal Vocal Communication in Development
Journal of Nonverbal Behavior
Nonverbal vocal aspects of communication, often related to affective states, are crucial to social interactions not only for animals but also for humans during early infancy, as well as being one of the pillars of human language development and acquisition. The thread that binds together the contributions to this Special Issue is the analysis of nonverbal vocal communication during development, both from ontogenetic and phylogenetic perspectives. This introduction presents the multiple viewpoints emerging from this Special Issue and delineates future research directions for investigating the nonverbal aspects of vocal communication in early development.
The Role of Prelinguistic Vocalizations in Infancy
1971
This paper deals with three areas conc.!erning early vocal development: (1) review and critique of existino experimental evidence suggesting that early vocal behavior has the properties of an operant response, (2) speculations concerning the role of non-verhal vocal behavior in early psychological development, and (3) suggestions for future research. Skinner's "Verbal Behavior" takes the position that verbal behaviOr could be analy2ed within operant conditioning frameworks. Chomsky argues that the system which Skinner proposes is too simplistic to account for the intricacieA of human speech. Other work reviewed covers conditioned vocal responses, conditioned response differentiation, reinforcer effectiveness, and the relationship between age and conditionability. Speculation about the role of early vocal responses includes a discussion of Watson's hypothesis that the human infant is structured from birth for the processing of response-contingent information and that at least two response-contingent sequences must occur within the infant's memory span in order for him to develop an initial awareness that his responses resulted in the change in external stimulation. It is suggested that the role of response-contingent stimulation on vocal development and its long-term consequences on vocal behavior warrants further investigation. (Cx)
Very young infants' responses to human and nonhuman primate vocalizations
Behavioral and Brain Sciences, 2014
Any account of "what is special about the human brain" (Passingham 2008) must specify the neural basis of our unique ability to produce speech and delineate how these remarkable motor capabilities could have emerged in our hominin ancestors. Clinical data suggest that the basal ganglia provide a platform for the integration of primate-general mechanisms of acoustic communication with the faculty of articulate speech in humans. Furthermore, neurobiological and paleoanthropological data point at a two-stage model of the phylogenetic evolution of this crucial prerequisite of spoken language: (i) monosynaptic refinement of the projections of motor cortex to the brainstem nuclei that steer laryngeal muscles, presumably, as part of a "phylogenetic trend" associated with increasing brain size during hominin evolution; (ii) subsequent vocal-laryngeal elaboration of cortico-basal ganglia circuitries, driven by human-specific FOXP2 mutations. This concept implies vocal continuity of spoken language evolution at the motor level, elucidating the deep entrenchment of articulate speech into a "nonverbal matrix" (Ingold 1994), which is not accounted for by gestural-origin theories. Moreover, it provides a solution to the question for the adaptive value of the "first word" (Bickerton 2009) since even the earliest and most simple verbal utterances must have increased the versatility of vocal displays afforded by the preceding elaboration of monosynaptic corticobulbar tracts, giving rise to enhanced social cooperation and prestige. At the ontogenetic level, the proposed model assumes age-dependent interactions between the basal ganglia and their cortical targets, similar to vocal learning in some songbirds. In this view, the emergence of articulate speech builds on the "renaissance" of an ancient organizational principle and, hence, may represent an example of "evolutionary tinkering" (Jacob 1977).