ABSTRACT
Comparative perspectives are crucial in the study of human development, yet longitudinal comparisons of humans and other primates are still relatively uncommon. Here, we combined theoretical frameworks from cross-cultural and comparative psychology, to study maternal style in 10 mother-infant pairs of German urban humans (Homo sapiens) and 10 mother-infant pairs of captive chimpanzees (Pan troglodytes), during the first year of infants' development. We conducted focal observations of different behaviours (i.e. nursing, carrying, body contact, touching, grooming, restraining, approaching, leaving, rejection, aggression, mutual gaze, object stimulation), during natural interactions. Analyses revealed a more distal maternal style in WEIRD humans than in captive chimpanzees, with different behaviours being generally more common in one of the two species throughout development. For other behaviours (i.e. nursing), developmental trajectories differed between WEIRD humans and captive chimpanzees, although differences generally decreased through infants' development. Overall, our study confirms functional approaches as a valid tool for comparative longitudinal studies.
Subject(s)
Maternal Behavior , Pan troglodytes , Animals , Female , Infant , Humans , Pan troglodytes/physiology , Mothers , Aggression , Child DevelopmentABSTRACT
Human mothers interact with their infants in different ways. In Western, educated, industrialized, rich and democratic (WEIRD) societies, face-to-face interactions and mutual gazes are especially frequent, yet little is known about their developmental trajectories and if they differ from those of other primates. Using a cross-species developmental approach, we compared mother-infant interactions in 10 dyads of urban humans from a WEIRD society (Homo sapiens) and 10 dyads of captive zoo-based chimpanzees (Pan troglodytes), when infants were one, six and 12 months old. Results showed that face-to-face interactions with mutual gaze events were common in both groups throughout the infant's first year of life. The developmental trajectories of maternal and infants' looks partially differed between species, but mutual gaze events were overall longer in humans than in chimpanzees. Mutual gazes were also more frequent in humans, peaking at six months in humans, while increasing with age in chimpanzees. The duration and frequency of mutual gazes varied across contexts in both groups, with mutual gazes being longer during caring/grooming and feeding contexts. These findings confirm that some aspects of early socio-cognitive development are shared by humans and other primates, and highlight the importance of combining developmental and cross-species approaches to better understand the evolutionary roots of parenting behaviour. This article is part of a discussion meeting issue 'Face2face: advancing the science of social interaction'.
