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Early communicative gestures in human and chimpanzee 1-year-olds observed across diverse socioecological settings. Learn Behav 2023; 51:15-33. [PMID: 36441398 PMCID: PMC9971150 DOI: 10.3758/s13420-022-00553-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2022] [Indexed: 11/29/2022]
Abstract
We investigated the communicative gestures used by chimpanzee and human infants. In contrast to previous studies, we compared the species at the same age (12-14 months) and used multiple groups living in diverse socioecological settings for both species. We recorded gestures produced by infants and those produce by others and directed toward infants. We classified the gestures into the following types: human-usual, chimpanzee-usual, and species-common; and searched for within species and between species differences. We found no significant differences between groups or species in overall rates of infant-produced or infant-received gestures, suggesting that all of these infants produced and received gestures at similar levels. We did find significant differences, however, when we considered the three types of gesture. Chimpanzee infants produced significantly higher rates of chimpanzee-usual gestures, and human infants produced significantly higher rates of human-usual gestures, but there was no significant species difference in the species-common gestures. Reports of species differences in gesturing in young infants, therefore, could be influenced by investigators' choice of gesture type. Interestingly, we found that 1-year-old infants produced the gesture of "hold mutual gaze" and that the chimpanzee infants had a significantly higher rate than the human infants. We did not find strong evidence that the specific types of gestural environment experienced by young infants influenced the types of gestures that infants produce. We suggest that at this point in development (before human infants use lots of speech), nonverbal communicative gestures may be equally important for human and chimpanzee infants.
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Goldsborough Z, Schel AM, van Leeuwen EJC. Chimpanzees communicate to coordinate a cultural practice. Proc Biol Sci 2023; 290:20221754. [PMID: 36651045 PMCID: PMC9845976 DOI: 10.1098/rspb.2022.1754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Human culture thrives by virtue of communication, yet whether communication plays an influential role in the cultural lives of other animals remains understudied. Here, we investigated whether chimpanzees use communication to engage in a cultural practice by analysing grooming handclasp (GHC) interactions-a socio-cultural behaviour requiring interindividual coordination for successful execution. Previous accounts attributed GHC initiations to behavioural shaping, whereby the initiator physically moulds the partner's arm into the desired GHC posture. Using frame-by-frame analysis and matched-control methodology, we find that chimpanzees do not only shape their partner's posture (22%), but also use gestural communication to initiate GHC (44%), which requires an active and synchronized response from the partner. Moreover, in a third (34%) of the GHC initiations, the requisite coordination was achieved by seemingly effortless synchrony. Lastly, using a longitudinal approach, we find that for GHC initiations, communication occurs more frequently than shaping in experienced dyads and less in mother-offspring dyads. These findings are consistent with ontogenetic ritualization, thereby reflecting first documentation of chimpanzees communicating to coordinate a cultural practice. We conclude that chimpanzees show interactional flexibility in the socio-cultural domain, opening the possibility that the interplay between communication and culture is rooted in our deep evolutionary history.
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Affiliation(s)
- Zoë Goldsborough
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Bücklestraße 5a, Konstanz, 78467, Germany,Animal Behaviour and Cognition, Department of Biology, Utrecht University, Padualaan 8, Utrecht, CA 3584, The Netherlands,Department of Biology, University of Konstanz, Universitätsstraße 10, Konstanz 78464, Germany
| | - Anne Marijke Schel
- Animal Behaviour and Cognition, Department of Biology, Utrecht University, Padualaan 8, Utrecht, CA 3584, The Netherlands
| | - Edwin J. C. van Leeuwen
- Animal Behaviour and Cognition, Department of Biology, Utrecht University, Padualaan 8, Utrecht, CA 3584, The Netherlands,Behavioral Ecology and Ecophysiology Group, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium,Centre for Research and Conservation, Royal Zoological Society of Antwerp, K. Astridplein 26, B 2018 Antwerp, Belgium
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Wilke C, Lahiff NJ, Sabbi KH, Watts DP, Townsend SW, Slocombe KE. Declarative referential gesturing in a wild chimpanzee ( Pan troglodytes). Proc Natl Acad Sci U S A 2022; 119:e2206486119. [PMID: 36375066 PMCID: PMC9704713 DOI: 10.1073/pnas.2206486119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/07/2022] [Indexed: 03/27/2024] Open
Abstract
Humans are argued to be unique in their ability and motivation to share attention with others about external entities-sharing attention for sharing's sake. Indeed, in humans, using referential gestures declaratively to direct the attention of others toward external objects and events emerges in the first year of life. In contrast, wild great apes seldom use referential gestures, and when they do, it seems to be exclusively for imperative purposes. This apparent species difference has fueled the argument that the motivation and ability to share attention with others is a human-specific trait with important downstream consequences for the evolution of our complex cognition [M. Tomasello, Becoming Human (2019)]. Here, we report evidence of a wild ape showing a conspecific an item of interest. We provide video evidence of an adult female chimpanzee, Fiona, showing a leaf to her mother, Sutherland, in the context of leaf grooming in Kibale Forest, Uganda. We use a dataset of 84 similar leaf-grooming events to explore alternative explanations for the behavior, including food sharing and initiating dyadic grooming or playing. Our observations suggest that in highly specific social conditions, wild chimpanzees, like humans, may use referential showing gestures to direct others' attention to objects simply for the sake of sharing. The difference between humans and our closest living relatives in this regard may be quantitative rather than qualitative, with ramifications for our understanding of the evolution of human social cognition.
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Affiliation(s)
- Claudia Wilke
- Department of Psychology, University of York, York, YO10 5DD, United Kingdom
- Department of Comparative Language Science, University of Zurich, CH-8050 Zurich, Switzerland
- Centre for the Interdisciplinary Study of Language Evolution, University of Zurich, CH-8050 Zurich, Switzerland
| | - Nicole J. Lahiff
- Department of Psychology, University of York, York, YO10 5DD, United Kingdom
- Department of Comparative Language Science, University of Zurich, CH-8050 Zurich, Switzerland
- Centre for the Interdisciplinary Study of Language Evolution, University of Zurich, CH-8050 Zurich, Switzerland
| | - Kris H. Sabbi
- Department of Anthropology, Tufts University, Medford, MA 02155
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131
| | - David P. Watts
- Department of Anthropology, Yale University, New Haven, CT 06511
| | - Simon W. Townsend
- Department of Comparative Language Science, University of Zurich, CH-8050 Zurich, Switzerland
- Centre for the Interdisciplinary Study of Language Evolution, University of Zurich, CH-8050 Zurich, Switzerland
- Department of Psychology, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Katie E. Slocombe
- Department of Psychology, University of York, York, YO10 5DD, United Kingdom
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