Great ape communication as contextual social inference: a computational modeling perspective

Human communication has been described as a contextual social inference process. Research into great ape communication has been inspired by this view to look for the evolutionary roots of the social, cognitive, and interactional processes involved in human communication. This approach has been highly productive, yet it is often compromised by a too-narrow focus on how great apes use and understand individual signals. In this paper, we introduce a computational model that formalizes great ape communication as a multi-faceted social inference process that relies on information contained in the signal, the relationship between communicative partners, and the social context. This model makes accurate qualitative and quantitative predictions about real-world communicative interactions between semi-wild-living chimpanzees. When enriched with a pragmatic reasoning process, the model explains repeatedly reported differences between humans and great apes in the interpretation of ambiguous signals (e.g. pointing gestures). This approach has direct implications for observational and experimental studies of great ape communication and provides a new tool for theorizing about the evolution of uniquely human communication.

Pantomimic fossils in modern human communication

Bodily mimesis, the capacity to use the body representationally, was one of the key innovations that allowed early humans to go beyond the ‘baseline’ of generalized ape communication and cognition. We argue that the original human-specific communication afforded by bodily mimesis was based on signs that involve three entities: an expression that represents an object (i.e. communicated content) for an interpreter . We further propose that the core component of this communication, pantomime, was able to transmit referential information that was not limited to select semantic domains or the ‘here-and-now’, by means of motivated—most importantly iconic—signs. Pressures for expressivity and economy then led to conventionalization of signs and a growth of linguistic characteristics: semiotic systematicity and combinatorial expression. Despite these developments, both naturalistic and experimental data suggest that the system of pantomime did not disappear and is actively used by modern humans. Its contemporary manifestations, or pantomimic fossils , emerge when language cannot be used, for instance when people do not share a common language, or in situations where the use of (spoken) language is difficult, impossible or forbidden. Under such circumstances, people bootstrap communication by means of pantomime and, when these circumstances persist, newly emergent pantomimic communication becomes increasingly language-like. This article is part of the theme issue ‘Reconstructing prehistoric languages’.

Origins and complexities of infant communication and social cognition

This chapter investigates how infants communicate before they have acquired a language; the underlying social cognition and motivation; and the evolutionary and ontogenetic origins of human communication. Evidence is reviewed that by 12 months of age, infants’ production and comprehension of the human pointing gesture involves several interwoven layers of communicative intentions, and pertains in complexity to unique forms of human communication. Limits of infant communication pertain to representational gesture use, particularly the spontaneous creation of pantomimic iconic gestures, and to the expression of referential intentions in early infancy. Commonalities and differences to ape communication are identified at different developmental ages regarding the use of reaching gestures and communication about distal and absent referents. Recent evidence is presented for the role of social interaction in the early ontogenetic emergence of uniquely human forms of gestural communication.

Orangutan pantomime: elaborating the message

We present an exploratory study of forest-living orangutan pantomiming, i.e. gesturing in which they act out their meaning, focusing on its occurrence, communicative functions, and complexities. Studies show that captive great apes may elaborate messages if communication fails, and isolated reports suggest that great apes occasionally pantomime. We predicted forest-living orangutans would pantomime spontaneously to communicate, especially to elaborate after communication failures. Mining existing databases on free-ranging rehabilitant orangutans' behaviour identified 18 salient pantomimes. These pantomimes most often functioned as elaborations of failed requests, but also as deceptions and declaratives. Complexities identified include multimodality, re-enactments of past events and several features of language (productivity, compositionality, systematicity). These findings confirm that free-ranging rehabilitant orangutans pantomime and use pantomime to elaborate on their messages. Further, they use pantomime for multiple functions and create complex pantomimes that can express propositionally structured content. Thus, orangutan pantomime serves as a medium for communication, not a particular function. Mining cases of complex great ape communication originally reported in functional terms may then yield more evidence of pantomime.

Great ape communication: Cognitive and evolutionary approaches

There are good arguments for examining great ape communicative achievements for what they contribute to our understanding of great ape cognition and its evolution (Russon & Begun, in press a). Our concern is whether Shanker & King's (S&K's) thesis advances communication studies from a broader cognitive and evolutionary perspective.