The pitch of babies’ cries predicts their voice pitch at age five

Voice pitch (fundamental frequency, F0) is a key dimension of our voice that varies Voice pitch (fundamental frequency, F0) is a key dimension of our voice that varies before and after puberty. While a recent longitudinal study indicates that inter-individual differences in voice pitch remain stable in men during adulthood and may even be determined before puberty [1], whether these differences emerge in infancy remains unknown. Here, using a longitudinal study design, we investigate the hypothesis that inter-individual differences in F0 are already present in the cries of pre-verbal babies. While based on a small sample (n = 15), our results indicate that the F0 of babies’ cries at 4 months of age may predict the F0 of their speech utterances at 5 years of age, explaining 41% of the inter-individual variance in voice pitch at that age in our sample. We also found that the right-hand ratio of the length of their index to ring finger (2D:4D digit ratio), which has been proposed to constitute an index of prenatal testosterone exposure, was positively correlated with F0 at both 4 months and 5 years of age. These findings suggest that a substantial proportion of between-individual differences in voice pitch, which convey important biosocial information about speakers, may partly originate in utero and thus already be present soon after birth

Structure d'une population de gorilles (Gorilla g. gorilla) visitant une clairière forestière (nature et rôle des rencontres intergroupes dans sa dynamique)

Ce travail de thèse apporte de nouvelles données sur la structure et la dynamique sociales du gorille de plaine de l'Ouest (G. g. gorilla) et, sur les relations intergroupes et leur influence sur la dynamique des groupes. Il repose sur l'observation, pendant 17 mois, d'une population de gorilles visitant une clairière forestière naturelle en République du Congo. Les 377 gorilles identifiés étaient organisés en 37 groupes reproducteurs (GR), 8 groupes non reproducteurs (GNR) dépourvus de femelles adultes et 31 mâles solitaires. Notre étude confirme la structure des populations observées sur d'autres sites et met notamment l'accent sur la prédominance des GR uni-mâle. Par ailleurs, elle met en évidence la présence non négligeable de GNR et leur importance dans la dynamique de la population. L'étude de la dynamique des groupes révèle que les femelles adultes effectuent préférentiellement des transferts entre GR et choisissent les mâles en fonction de leur qualité. L'étude de la fréquentation de la clairière par les gorilles montre que les modalités de visites diffèrent selon les unités. Le taux et la nature des interactions varient selon les enjeux des rencontres en terme de femelles mais ne dépendent pas de l'apparentement qui lie les mâles adultes. Enfin, les rencontres semblent avoir un effet sur la dynamique sociale en facilitant les transferts entre les unités, notamment des immatures. L'ensemble des résultats est confronté aux études réalisées en forêt sur des groupes habitués ou sur des clairières.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Temporal calling patterns of a captive group of chimpanzees (Pan troglodytes)

International audienceUnlike the acoustic features of calls, the temporal patterns of call usage in nonhuman primates are highly flexible. Our recent studies suggest that vocal patterns and species social needs coevolved. Different patterns, for example calling alone by producing one or several calls in a sequence or interacting vocally with more or less call overlap, may serve different functions. Vocal turn-taking in particular may be key to understanding the possible link between vocal behavior and social life. Turn-taking is used flexibly in many primate species, notably during affiliative encounters, and follows social and temporal rules that evoke similarities with human conversations. We tested the influence of caller characteristics and production context on the vocal behavior of a captive group of 15 chimpanzees using 48h30 of scan and focal sampling. 84% of the 516 recorded utterances were isolated calls. When there were vocal interactions, overlapping calls prevailed (63%), mostly involving adult males pant-hooting. Chimpanzees mostly produced calls in series, and the higher-ranked the caller, the faster the speed of call delivery. The social importance of consecutive calling was supported by a higher rate of audience reaction when the number of calls increased, suggesting strategic use of message redundancy. However, social integration, age, and sex weakly influenced call rates and interaction patterns. Although this study concerns a single study group, the rarity of turn-taking supports findings for wild chimpanzees. Why chimpanzees do not display this vocal behavior, which is commonly observed in primates, including other apes, is still puzzling

A pilot study of calling patterns and vocal turn-taking in wild bonobos Pan paniscus

International audienceIn several species of non-human primates, non-agonistic vocal exchanges can be seen as a primitive form of conversation, as they respect basic temporal rules (i.e. turn-taking, overlap avoidance), the same as those that guide human conversations. Conversational rules have recently been suggested in captive great ape species, yet the only study investigating vocal turn-taking in wild great apes did not find any evidence of such vocal roles. Whether the environmental conditions (captivity versus free ranging) or the social organisation of a given species shape temporally ruled vocal exchanges remain open questions. Here, we investigated general calling patterns of peaceful vocal exchanges in a wild bonobo community. This pilot study revealed that wild bonobos respect the fundamental temporal rules of vocal turn-taking, namely the avoidance of overlapping and the presence of short call-intervals between interlocutors on the order of 2 sec, corroborating findings from captive bonobos. Despite the limited sample size, our finding suggests that vocal exchanges appear context-dependent but neither age nor sex seem to influence their occurrence. While further studies are needed to confirm these observations, this study helps to fill a major gap in research on the vocal communication of wild great apes, paving the way for more extensive comparative studies, representing a further step towards a better understanding of how vocal turn-taking arose in humans