Spatial cohesion of adult male chimpanzees (<i>Pan troglodytes verus</i>) in Taï National Park, Côte d'Ivoire

Eckhardt, Nadin; Polansky, Leo; Boesch, Christophe

doi:10.1002/ajp.22316

Cited by 24 publications

(21 citation statements)

References 67 publications

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“…The fact that presence of non-preferred social partners and long-distance auditory gesture networks were correlated shows not only that these gestures were used to communicate with weak social bonds but also that individuals maintain these weak social bonds over time, since the repeated proximity scans picked up the same pattern of weak social bonds as the repeated instances of long-distance auditory gestures. These results strongly suggest that the modality of communication in the current study was shaped by the strength of social bonds between chimpanzees rather than coordination of movement with spatially distant individuals 105 114 .…”

Section: Discussionsupporting

confidence: 53%

Wild chimpanzees modify modality of gestures according to the strength of social bonds and personal network size

Roberts

2016

Sci Rep

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Primates form strong and enduring social bonds with others and these bonds have important fitness consequences. However, how different types of communication are associated with different types of social bonds is poorly understood. Wild chimpanzees have a large repertoire of gestures, from visual gestures to tactile and auditory gestures. We used social network analysis to examine the association between proximity bonds (time spent in close proximity) and rates of gestural communication in pairs of chimpanzees when the intended recipient was within 10 m of the signaller. Pairs of chimpanzees with strong proximity bonds had higher rates of visual gestures, but lower rates of auditory long-range and tactile gestures. However, individual chimpanzees that had a larger number of proximity bonds had higher rates of auditory and tactile gestures and lower rates of visual gestures. These results suggest that visual gestures may be an efficient way to communicate with a small number of regular interaction partners, but that tactile and auditory gestures may be more effective at communicating with larger numbers of weaker bonds. Increasing flexibility of communication may have played an important role in managing differentiated social relationships in groups of increasing size and complexity in both primate and human evolution.

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Section: Discussionsupporting

confidence: 53%

Wild chimpanzees modify modality of gestures according to the strength of social bonds and personal network size

Roberts

2016

Sci Rep

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“…In the chimpanzee fission-fusion social system, the association patterns change by means of the fission and fusion of subunits (known as parties or sub-groups) according to both the activity (e.g., resting, feeding) and distribution of resources (Pepper et al, 1999). Individuals thus stay in close proximity with some conspecifics from the wider community at infrequent intervals, often weeks apart, but each individual can recognize members of their own community and is capable of maintaining long-term relationships with these individuals (Boesch, 1996; Barrett et al, 2003; Muller and Mitani, 2005; Amici et al, 2008; Eckhardt et al, 2015). Reciprocated social relationships are a key feature of the chimpanzee social system and are marked by increased time and energy investment in repeated and reciprocated instances of association and interaction (Watts, 2006; Mitani, 2009).…”

Section: Introductionmentioning

confidence: 99%

Social Brain Hypothesis: Vocal and Gesture Networks of Wild Chimpanzees

Roberts

2016

Front. Psychol.

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A key driver of brain evolution in primates and humans is the cognitive demands arising from managing social relationships. In primates, grooming plays a key role in maintaining these relationships, but the time that can be devoted to grooming is inherently limited. Communication may act as an additional, more time-efficient bonding mechanism to grooming, but how patterns of communication are related to patterns of sociality is still poorly understood. We used social network analysis to examine the associations between close proximity (duration of time spent within 10 m per hour spent in the same party), grooming, vocal communication, and gestural communication (duration of time and frequency of behavior per hour spent within 10 m) in wild chimpanzees. This study examined hypotheses formulated a priori and the results were not corrected for multiple testing. Chimpanzees had differentiated social relationships, with focal chimpanzees maintaining some level of proximity to almost all group members, but directing gestures at and grooming with a smaller number of preferred social partners. Pairs of chimpanzees that had high levels of close proximity had higher rates of grooming. Importantly, higher rates of gestural communication were also positively associated with levels of proximity, and specifically gestures associated with affiliation (greeting, gesture to mutually groom) were related to proximity. Synchronized low-intensity pant-hoots were also positively related to proximity in pairs of chimpanzees. Further, there were differences in the size of individual chimpanzees' proximity networks—the number of social relationships they maintained with others. Focal chimpanzees with larger proximity networks had a higher rate of both synchronized low- intensity pant-hoots and synchronized high-intensity pant-hoots. These results suggest that in addition to grooming, both gestures and synchronized vocalizations may play key roles in allowing chimpanzees to manage a large and differentiated set of social relationships. Gestures may be important in reducing the aggression arising from being in close proximity to others, allowing for proximity to be maintained for longer and facilitating grooming. Vocalizations may allow chimpanzees to communicate with a larger number of recipients than gestures and the synchronized nature of the pant-hoot calls may facilitate social bonding of more numerous social relationships. As group sizes increased through human evolution, both gestures and synchronized vocalizations may have played important roles in bonding social relationships in a more time-efficient manner than grooming.

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“…Thus within a 'single' call, the pant-hoot, almost every call type within the chimpanzee repertoire can be included. A further quandary is that pant-hoots, as mentioned above, can be emitted in any number of contexts, the apparent goal is to maintain contact or recruit individuals hundreds of meters away (Eckhardt et al 2015).…”

Section: Call Combinations and Context Fluiditymentioning

confidence: 99%

Why does the chimpanzee vocal repertoire remain poorly understood and what can be done about it?

Crockford

2019

The Chimpanzees of the Taï Forest

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After decades of research, the origins of human speech remain little understood. One potential problem is that the vocal repertoires of humans' closest living relatives, the apes, remain poorly described. Given that the evolution of language has left few fossils, many researchers interested in this question adopt a comparative approach, examining differences and consistencies between human and animal communication. However, comparisons will remain limited in the absence of a comprehensive analysis of the vocal repertoires of the other extant apes, especially of our two closest living relatives, the chimpanzee and bonobo. After years of observing and conducting field experiments with both western chimpanzees in the Taï Forest, Ivory Coast, and eastern chimpanzees in the Budongo Forest, Uganda, I posit several reasons why a comprehensive analysis of the chimpanzee vocal repertoire has not yet been completed, in spite of 45 years of research, and what can be done to remedy this situation. I raise four main problems and later present potential solutions: a) How do we categorise graded calls into information-specific units? b) Why are most call types emitted in most contexts? c) If different call types are combined flexibly within the same context, can calls be tied to emotional states? d) The constraintsand advantagesimposed by dense forest habitat. I also tabulate cross-site consensus in call categorisation, associated contexts of usage, and potential call functions. I also note cross-site variation in presence and absence of vocalisations. Anecodote After an intense three years observing Taïi chimpanzees and listening to their vocalisations for my PhD, I was not to return to the Taï Forest for 17 years. On my first day back with the North Group, after walking through the forest in the dark, I arrived at a group of females as dawn was breaking. I heard through the forest a pant-hoot so familiar, a shiver of pleasure ran down my spine. This was the voice of Narcisse, one of the youngest mothers in the North Group 17 years earlier. Three minutes later, Narcisse walked into view with a baby on her back, and with her adult daughter, granddaughter, and adult son close behind her. This whole remarkable family had survived the devastating epidemics that had ravaged the group in the intervening years. The pattern of her distinctive pant-hoot had not changed in 17 years, likewise those of the other three adult females I had known 17 years earlier, Mystere, Perla, and Belle. Even though the pant-hoot is emitted in a number of contexts, shows greater within than between individual variability, and shows group and population differences, something in the quality and the rhythm of the call is retained year in and year out and as with human voices, is a robust marker of individual identity. This begs the question, why do chimpanzees have such a robust marker of individual identity? Why do they, nonetheless, express thisand other calls-with such extensive acoustic and contextual variability?

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Spatial cohesion of adult male chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d'Ivoire

Cited by 24 publications

References 67 publications

Wild chimpanzees modify modality of gestures according to the strength of social bonds and personal network size

Wild chimpanzees modify modality of gestures according to the strength of social bonds and personal network size

Social Brain Hypothesis: Vocal and Gesture Networks of Wild Chimpanzees

Why does the chimpanzee vocal repertoire remain poorly understood and what can be done about it?

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