Intentional communication between wild bonnet macaques and humans

Abstract

Comparative studies of nonhuman communication systems could provide insights into the origins and evolution of a distinct dimension of human language: intentionality. Recent studies have provided evidence for intentional communication in different species but generally in captive settings. We report here a novel behaviour of food requesting from humans displayed by wild bonnet macaques Macaca radiata, an Old World cercopithecine primate, in the Bandipur National Park of southern India. Using both natural observations and field experiments, we examined four different behavioural components—coo-calls, hand-extension gesture, orientation, and monitoring behaviour—of food requesting for their conformity with the established criteria of intentional communication. Our results suggest that food requesting by bonnet macaques is potentially an intentionally produced behavioural strategy as all the food requesting behaviours except coo-calls qualify the criteria for intentionality. We comment on plausible hypotheses for the origin and spread of this novel behavioural strategy in the study macaque population and speculate that the cognitive precursors for language production may be manifest in the usage of combination of signals of different modalities in communication, which could have emerged in simians earlier than in the anthropoid apes.

Gestural communication of wild bonnet macaques in the Bandipur National Park, Southern India

“…It is worth mentioning here that individuals from this same population of bonnet macaques are capable of intentional signalling through gestures and vocalisations in a unique context of requesting food from humans (Deshpande, Gupta, and Sinha 2018).…”

The origins of gestures and language: history, current advances and proposed theories

“…For the signaller's gesture to be considered as intentional it must ( i ) have a social goal, ( ii ) be directed towards a particular recipient as evidenced by body orientation, gaze alternation and/or physical contact with the recipient, and ( iii ) elicit a voluntary response from the recipient indicated by gazing at the recipient (signaller waits for the recipient's response), and/or communication persistence when the recipient does not react or the recipient's response does not match the signaller's goal [e.g. bonobos (Pika, Liebal & Tomasello, ; Genty, Neumann & Zuberbühler, ; Fröhlich et al ., ); chimpanzees (Tomasello, Gust & Frost, ; Leavens, Hopkins & Thomas, ; Hobaiter & Byrne, ); gorillas (Pika, Liebal & Tomasello, ; Genty et al ., ); orangutans (Cartmill & Byrne, ); bonnet macaques Macaca radiata (Deshpande, Gupta & Sinha, ); Campbell's monkeys and red‐capped mangabeys (Maille et al ., ); olive baboons (Meguerditchian & Vauclair, ; Meunier, Prieur & Vauclair, ); Tonkean macaques, Macaca tonkeana (Meunier, Fizet & Vauclair, ); see also Pollick & de Waal, and Call & Tomasello, ]. As documented by many authors, diverse criteria have been proposed to differentiate intentionally produced gestures from innate and/or conditioned gestures (i.e.…”

“…gestures associated with vocalisations or facial expressions) to convey informative content (e.g. Crockford et al ., ; Schel et al ., ; Fischer & Price, ; Hobaiter, Byrne & Zuberbühler, ; Deshpande, Gupta & Sinha, ; Oña, Sandler & Liebal, ). In addition, very little is known about meaningful combinations or intentional use of facial expressions (Waller, Caeiro & Davila‐Ross, ; Scheider et al ., ).…”

Changing ecologies, shifting behaviours: Behavioural responses of a rainforest primate, the lion-tailed macaque Macaca silenus, to a matrix of anthropogenic habitats in southern India

“…Human-nonhuman primate conflict can result in heavy costs to both parties, even, in certain cases, threatening the persistence of the species in a human-dominated landscape [ 55 ]. Troops of certain primate species can quickly learn to recognise humans as a potential source of food, even without the actual presence of provisioned foods [ 25 , 56 ]. In the Forest Edge, during our study, for example, tourists would often stop their vehicles to observe the lion-tailed macaques, subsequently, the macaques learnt to reduced their Active Foraging and Food Search when tourists were within a distance of 10m.…”