A convergent interaction engine: vocal communication among marmoset monkeys

Abstract

To understand the primate origins of the human interaction engine, it is worthwhile to focus not only on great apes but also on callitrichid monkeys (marmosets and tamarins). Like humans, but unlike great apes, callitrichids are cooperative breeders, and thus habitually engage in coordinated joint actions, for instance when an infant is handed over from one group member to another. We first explore the hypothesis that these habitual cooperative interactions, the marmoset interactional ethology, are supported by the same key elements as found in the human interaction engine: mutual gaze (during joint action), turn-taking, volubility, as well as group-wide prosociality and trust. Marmosets show clear evidence of these features. We next examine the prediction that, if such an interaction engine can indeed give rise to more flexible communication, callitrichids may also possess elaborate communicative skills. A review of marmoset vocal communication confirms unusual abilities in these small primates: high volubility and large vocal repertoires, vocal learning and babbling in immatures, and voluntary usage and control. We end by discussing how the adoption of cooperative breeding during human evolution may have catalysed language evolution by adding these convergent consequences to the great ape-like cognitive system of our hominin ancestors. This article is part of the theme issue ‘Revisiting the human ‘interaction engine’: comparative approaches to social action coordination’.

Revisiting the human ‘interaction engine’: comparative approaches to social action coordination

“…In scrutinizing repetition and elaboration in gesture use, the authors find that the research setting predicts elaborated gestural redoings in Bornean orangutans (the less socially tolerant species in the wild), insofar as elaboration is more frequent in captive compared with wild individuals and more successful in captivity. This confirms the idea that both the immediate and developmental environments shape a species' interactional ethology, emphasizing how social and environmental factors can trigger the emergence of certain interaction engine capacities (see also [ 11 ]).…”

“…Although an exhaustive list of the interaction engine's elements seems to be missing, most researchers would probably agree that they relate to four major components [ 1 – 3 , 11 ]: multimodality (here summarized as the ability to communicate through different sensory channels (visual, auditory, acoustic) and organs (e.g. hands or mouth), [ 6 , 12 ]), sequence organization (communicative acts that have a contingent relationship with the previous and following act, presuming a normative obligation to deliver appropriate responses at the next best occasion, [ 13 , 14 ]), turn-taking (rapid turns at talking with minimal response gaps between conversational turns, [ 15 , 16 ]) and intentionality (the ability to communicate and respond to intentions not behaviours, [ 1 , 3 ]).…”

“…Looking beyond phylogenetic origins, Judith Burkart and her colleagues [ 11 ] discuss the role of convergent evolution in the emergence of specific interaction engine features. They point to a double legacy in humans, with a powerful cognitive apparatus inherited from ape-like ancestors on the one hand, and novel motivational components added as result of convergent evolution on the other (e.g.…”

“…shared levels of prosociality linked to the cooperative breeding systems of callitrichid monkeys and humans). According to the authors, it is the combination between phylogenetic and convergent components that must have shaped our unique set of socio-cognitive skills [ 11 ]. Nonetheless, it requires further scientific scrutiny to understand which elements were shaped by environments or social systems like cooperative breeding, and which were phylogenetically inherited from our ape-like ancestors.…”

“…Studies from recent years have already compiled an interesting set of evidence, warranting an update of the interaction engine hypothesis. Some species of nonhuman primates were shown to engage in communicative turn-taking [11,21,22], exhibit communication that is apparently organized in sequences, or 'adjacency pairs' [21,23,24], engage in latent forms of self-initiated, communicative repair [25,26], and communicate and behave in ways suggestive of joint commitment [23,[27][28][29][30]. But if many of our socio-cognitive abilities are not uniquely derived, what made language evolution possible?…”