Abstract

This paper reports a longitudinal study on the ontogeny of triadic cooperative interactions in a hand-reared lowland gorilla from 6 months to 36 months of age. Using the behavioural categories developed by Hubley and Trevarthen to characterize the origins of “secondary intersubjectivity” in human babies between 8–12 months of age, I chart the emergence of comparable coordinations of gestures and actions with objects and acts of dyadic communication. The findings show that the categories and concepts of secondary intersubjectivity are applicable to the gorilla, who engages with people in cooperative actions with objects. The ontogeny of triadic interaction in the gorilla was very similar to that described in human infants, but more extended in time and with some peculiarities, such as the absence of pointing and showing gestures, some of whose functions might be taken over by contact gestures which in human infants may appear later in development. The results do not support claims of human uniqueness in the development of cooperative action, but suggest a heterochrony in some aspects of the ontogeny of triadic interactions leading to a divergence between gorilla and human infants within secondary intersubjectivity. Keywords: Triadic communication; secondary intersubjectivity; shared intentionality; cooperation; gorilla