The performance of language is multimodal, not confined to speech. Review of monkey and ape communication demonstrates greater flexibility in the use of hands and body than for vocalization. Nonetheless, the gestural repertoire of any group of nonhuman primates is small compared with the vocabulary of any human language and thus, presumably, of the transitional form called protolanguage. We argue that it was the coupling of gestural communication with enhanced capacities for imitation that made possible the emergence of protosign to provide essential scaffolding for protospeech in the evolution of protolanguage. Similarly, we argue against a direct evolutionary path from nonhuman primate vocalization to human speech. The analysis refines aspects of the mirror system hypothesis on the role of the primate brain’s mirror system for manual action in evolution of the human language‐ready brain.

Language, humans’ most distinctive trait, still remains a ‘mystery’ for evolutionary theory. It is underpinned by a universal infrastructure—cooperative turn-taking—which has been suggested as an ancient mechanism bridging the existing gap between the articulate human species and their inarticulate primate cousins. However, we know remarkably little about turn-taking systems of non-human animals, and methodological confounds have often prevented meaningful cross-species comparisons. Thus, the extent to which cooperative turn-taking is uniquely human or represents a homologous and/or analogous trait is currently unknown. The present paper draws attention to this promising research avenue by providing an overview of the state of the art of turn-taking in four animal taxa—birds, mammals, insects and anurans. It concludes with a new comparative framework to spur more research into this research domain and to test which elements of the human turn-taking system are shared across species and taxa.

A previous observational study suggested that when faced with a partner with its back turned, chimpanzees tend to move around to the front of a non-attending partner and then gesture — rather than gesturing once to attract attention and then again to convey a specific intent. We investigated this preference experimentally by presenting six orangutans, five gorillas, nine chimpanzees, and four bonobos with a food begging situation in which we varied the body orientation of an experimenter (E) with respect to the subject (front vs. back) and the location of the food (in front or behind E). These manipulations allowed us to measure whether subjects preferred to move around to face E or to use signals to attract her attention before they begged for food. Results showed that all species moved around to face E and then produced visual gestures, instead of using tactile/ auditory gestures behind E to call her attention. Species differences were apparent particularly when the food and E were in different locations. Unlike gorillas and orangutans, chimpanzees and bonobos (from genus Pan) produced their gestures in front of E in all conditions, including that in which subjects had to leave the food behind to communicate with her. Implications of these results are discussed in the context of the evolution of social cognition in great apes.