Federico Rossano: Max Planck Institute for Evolutionary Anthropology

In this talk I address two crucial aspects of gestural communication in non-human primates: how gestures are acquired/developed and how similar is their use when compared to human behavior (in particular with respect to issues such as communicative intentions and recipient design).
There is general agreement among researchers that nonhuman primates gesture in sophisticated ways (Tomasello & Call, 2007; Pollick & de Waal, 2007). However, the process by which apes acquire gestures is an issue of debate. One of the central questions in this debate is whether apes acquire species-typical gestural repertoires, with little individual innovation (the “biological inheritance” hypothesis) (e.g., Genty et al., 2009), or whether they develop gestures individually through the ritualization of particular social acts (the “ontogenetic ritualization” hypothesis) (e.g., Tomasello, 1996). In the first part of the talk, I address this question by examining the relationship between the structure of a particular social interaction and the form of the gestures used to elicit that interaction. I present data on nine mother-infant Bonobo pairs as they engage in a particular social interaction: co-locomotion via a ventral or dorsal carry and I show how ontogenetic ritualization is the best account for the development of their gestural repertoire.

In the second part of the talk I present an ongoing study on food sharing in great apes, with particular focus on how they perform offers and requests and how other group members recognize and respond to these intentional actions. The main focus will be on Orang-Utangs and Chimpanzees.

In this work I start from actions (functions) and their sequential unfolding, rather than on specific gestural forms investigated out of context.

Genty, E., Breuer, T., Hobaiter, C. & Byrne, R. W. (2009). Gestural communication of
the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins. Animal Cognition, 12, 527-546.

Pollick, A. S. & de Waal, F. B. M. (2007). Ape gestures and language evolution.
Proceedings of the National Academy of Sciences, 104(19), 8184-8189.

Tomasello, M. (1996). Do apes ape? In B. G. Galef & C. M. Heyes (Eds.), Social
Learning in Animals: The Roots of Culture (pp. 319-346). San Diego: Academic
Press.

Tomasello, M. & Call. J. (2007). Comparing the gestures of apes and monkeys. In J. Call
& M. Tomasello (Eds.), The gestural communication of apes and monkeys (pp. 197-220). London: Lawrence Erlbaum Publishers.