Why do gorillas make sequences of gestures?

Great ape gestures have attracted considerable research interest in recent years, prompted by their flexible and intentional pattern of use; but almost all studies have focused on single gestures. Here, we report the first quantitative analysis of sequential gesture use in western gorillas (Gorilla gorilla gorilla), using data from three captive groups and one African study site. We found no evidence that gesture sequences were given for reasons of increased communicative efficiency over single gestures. Longer sequences of repeated gestures did not increase the likelihood of response, and using a sequence was seldom in reaction to communicative failure. Sequential combination of two gestures with similar meanings did not generally increase effectiveness, and sometimes reduced it. Gesture sequences were closely associated with play contexts. Markov transition analysis showed two networks of frequently co-occurring gestures, both consisting of gestures used to regulate play. One network comprised only tactile gestures, the other a mix of silent, audible and tactile gestures; apparently, these clusters resulted from gesture use in play with proximal or distal contact, respectively. No evidence was found for syntactic effects of sequential combination: meanings changed little or not at all. Semantically, many gestures overlapped massively with others in their core information (i.e. message), and gesture messages spanned relatively few functions. We suggest that the underlying semantics of gorilla gestures is highly simplified compared to that of human words. Gesture sequences allow continual adjustment of the tempo and nature of social interactions, rather than generally conveying semantically referential information or syntactic structures.

[1]  M. Tomasello,et al.  A longitudinal investigation of gestural communication in young chimpanzees , 2006, Primates.

[2]  Michael Tomasello,et al.  Gestural communication in young gorillas (Gorilla gorilla): Gestural repertoire, learning, and use , 2003, American journal of primatology.

[3]  T. Breuer,et al.  Physical maturation, life‐history classes and age estimates of free‐ranging western gorillas—insights from Mbeli Bai, Republic of Congo , 2009, American journal of primatology.

[4]  R. Byrne,et al.  Gestural communication of the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins , 2009, Animal Cognition.

[5]  P. Slater,et al.  Bird Song: Biological Themes and Variations , 1995 .

[6]  John R. Buck,et al.  The use of Zipf's law in animal communication analysis , 2005, Animal Behaviour.

[7]  H. Montgomery.  Comparative Perspective , 2020, Encyclopedia of Personality and Individual Differences.

[8]  David A. Leavens,et al.  Chimpanzees differentially produce novel vocalizations to capture the attention of a human , 2007, Animal Behaviour.

[9]  Regina Pustet.  Zipf and his heirs , 2004 .

[10]  R. Byrne,et al.  The Mentalities of Gorillas and Orangutans: The development of spontaneous gestural communication in a group of zoo-living lowland gorillas , 1998 .

[11]  K. Zuberbühler,et al.  The Syntax and Meaning of Wild Gibbon Songs , 2006, PloS one.

[12]  Ruud van den Bos,et al.  The Mentalities of Gorillas and Orangutans , 2000, Animal Behaviour.

[13]  P. Greenfield,et al.  “Language” and intelligence in monkeys and apes: Grammatical combination in Pan paniscus : Processes of learning and invention in the evolution and development of language , 1990 .

[14]  George Kingsley Zipf,et al.  Human behavior and the principle of least effort , 1949 .

[15]  Richard W. Byrne,et al.  Orangutans Modify Their Gestural Signaling According to Their Audience's Comprehension , 2007, Current Biology.

[16]  S. Pika.  Gestures in Subadult Bonobos (Pan paniscus) , 2007 .

[17]  D. Gardner,et al.  Teaching Sign Language to Cross-Fostered Chimpanzees , 1990 .

[18]  J. Tanner.  Gestural phrases and gestural exchanges by a pair of zoo-living lowland gorillas , 2004 .

[19]  Richard W. Byrne,et al.  Representation of Action Through Iconic Gesture in a Captive Lowland Gorilla , 1996, Current Anthropology.

[20]  Michael Tomasello,et al.  To move or not to move: How apes adjust to the attentional state of others , 2004 .

[21]  David A. Leavens,et al.  Intentionality as measured in the persistence and elaboration of communication by chimpanzees (Pan troglodytes). , 2005, Child development.

[22]  A. Jansson,et al.  Laboratory observations on the reproductive behaviour of the pigeon (Columba livia) during the pre-incubation phase of the breeding cycle ☆ , 1963 .

[23]  Charles T. Snowdon,et al.  Language capacities of nonhuman animals , 1990 .

[24]  R. Byrne,et al.  Concealing facial evidence of mood: Perspective-taking in a captive gorilla? , 1993, Primates.

[25]  K. Zuberbühler.  A syntactic rule in forest monkey communication , 2002, Animal Behaviour.

[26]  David A. Leavens,et al.  Tactical use of unimodal and bimodal communication by chimpanzees, Pan troglodytes , 2004, Animal Behaviour.

[27]  M. E. Laidre,et al.  The Gestural Communication of Apes and Monkeys, Josep Call, Michael Tomasello (Eds.). Erlbaum, Mahwah, New Jersey (2007), Pp. viii + 256. Price $34.95. , 2009 .

[28]  Michael Tomasello,et al.  Gestural communication of orangutans (Pongo pygmaeus) , 2006 .

[29]  R. Parnell,et al.  Group size and structure in western lowland gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Republic of Congo , 2002, American journal of primatology.

[30]  S. Parker,et al.  The Mentalities of Gorillas and Orangutans: Comparative Perspectives , 2006 .

[31]  Michael Tomasello,et al.  Introduction: Intentional Communication in Nonhuman Primates , 2007 .

[32]  LAURANCE R. DOYLE,et al.  Quantitative tools for comparing animal communication systems: information theory applied to bottlenose dolphin whistle repertoires , 1999, Animal Behaviour.

[33]  W. J. Smith,et al.  Message, Meaning, and Context in Ethology , 1965, The American Naturalist.

[34]  W. Hopkins.  The Dynamic Dance: Nonvocal Communication in African Great Apes , 2005, International Journal of Primatology.

[35]  R. Gardner,et al.  Teaching sign language to a chimpanzee. , 1969, Science.

[36]  S. Pika.  Gestures in Subadult Gorillas (Gorilla gorilla) , 2007 .

[37]  Michael Tomasello,et al.  Use of gesture sequences in chimpanzees , 2004, American journal of primatology.