What makes a cry a cry? A review of infant distress vocalizations

Abstract

In contrast to the cries of human infants, sounds made by non-human infants in different stressful behavioral contexts (hunger or physical discomfort, isolation, capture by humans or predators) are usually treated as distinct types of vocalizations. However, if distress vocalizations produced by different species and in different contexts share a common motivational state and associated neurochemical pathways, we can expect them to share a common acoustic structure and adaptive function, showing only limited variation that corresponds to the infant’s level of arousal. Based on this premise, we review the acoustic structure and adaptive function of two types of distress calls, those given when infants were isolated from their mothers (isolation calls) or captured by humans (capture calls). We conducted a within-context comparison examining the two call types across a diverse selection of mammalian species and other vertebrate groups, followed by a comparison of how acoustic structure and function differs between these contexts. In addition, we assessed acoustic traits that are critical to the response of caregivers. Across vertebrate species, distress vocalizations produced in these two behavioral contexts tend to be tonal with a simple chevron, flat or descending pattern of frequency modulation. Reports that both isolation and capture calls of vertebrate infants serve to attract care-givers are universal, and the fundamental frequency of infant vocalizations is often critical to this response. The results of our review are consistent with the hypothesis that differences in the acoustic structure of isolation and capture distress vocalizations reflect differences in arousal, and not discrete functions. The similarity in acoustic structure and caregiver response observed across vertebrates adds support to the hypothesis that the production and processing of distress vocalizations are part of a highly-conserved system of social vocal behaviour in vertebrates. Bioacoustic research may move forward by recognizing the commonality among different forms of infant solicitations that attract caregivers, and the commonality of these solicitations with vocalizations that attract conspecifics in still other behavioral contexts.

Neurobiology of culturally common maternal responses to infant cry

“…From the moment of birth, certain signals from babies effectively influence parenting: Infant cries motivate adults to approach and to act (7,8). That is, infant cries and caregiver responses to them constitute an integrated dyadic system that encompasses the infant production of cries as well as the adult anatomy (9-12), physiology (5, 13), and perception, processing, and response apparatus to cries (2,4,5,(14)(15)(16)(17). Cries put both infant and caregiver in states of strong mutual nervous system activation and increase the probability of behavioral attunement (18).…”

“…In observations of maternal behavior in situ in 11 countries, we hypothesized preferred and common patterns of new mothers' responses to their own infants' cries. In three independent companion fMRI experiments in three countries, we sought to identify neurobiological underpinnings of the same behavioral responses in new mothers in the United States to their own young infants' cries, in experienced mothers in China to infant cries in comparison with noninfant cry emotional sounds, and in experienced mothers and inexperienced nonmothers in Italy to generic infant cries.Care-soliciting vocalizations are common in the young of many species (2,6,16,20,21) and constitute a signal system that has been conserved throughout mammalian evolution (2,22). Human infants effectively elicit parental attention, proximity, and solicitude by crying (23-29); in times of famine, for example, crying…”

“…of course sucking and screaming, were well performed by my infant" (1). Human infants command precious few means of agency, and so their faces and voices serve signaling functions essential to their survival (2)(3)(4). The acoustic structure of infant distress vocalizations (cries) and caregiver responses appear to be conserved among mammals, including humans (2,5).…”

Tennis grunts communicate acoustic cues to sex and contest outcome

“…In fact, aside from laughter (see Bryant et al, 2016;Scott, Lavan, Chen, & McGettigan, 2014) and infant cries (Lingle, Wyman, Kotrba, Teichroeb, & Romanow, 2012 for review), human nonverbal vocalisations (such as moans, sighs, roars, screams, and grunts) have received little attention, especially from a functional and evolutionary perspective.…”

“…Human nonverbal vocalisations likely predate language, and appear homologous in structure and function with nonhuman vocalisations (e.g. laughter Davila-Ross, Owren, & Zimmermann, 2010;Pisanski, Cartei, McGettigan, Raine, & Reby, 2016; infant distress vocalisations Lingle et al, 2012). As such, they may constitute a relatively direct link between animal and human vocal systems.…”