scholarly journals Uniting against a common enemy: Perceived outgroup threat elicits ingroup cohesion in chimpanzees

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246869
Author(s):  
James Brooks ◽  
Ena Onishi ◽  
Isabelle R. Clark ◽  
Manuel Bohn ◽  
Shinya Yamamoto
Keyword(s):  
Pan Troglodytes ◽  
Group Cohesion ◽  
Behavioral Pattern ◽  
Feeding Competition ◽  
Evolutionary Origin ◽  
Group Coordination ◽  
Common Enemy ◽  
In The Wild ◽  
Group Hunting

Outgroup threat has been identified as an important driver of ingroup cohesion in humans, but the evolutionary origin of such a relationship is unclear. Chimpanzees (Pan troglodytes) in the wild are notably aggressive towards outgroup members but coordinate complex behaviors with many individuals in group hunting and border patrols. One hypothesis claims that these behaviors evolve alongside one another, where outgroup threat selects for ingroup cohesion and group coordination. To test this hypothesis, 5 groups of chimpanzees (N = 29 individuals) were observed after hearing either pant-hoots of unfamiliar wild chimpanzees or control crow vocalizations both in their typical daily environment and in a context of induced feeding competition. We observed a behavioral pattern that was consistent both with increased stress and vigilance (self-directed behaviors increased, play decreased, rest decreased) and increased ingroup cohesion (interindividual proximity decreased, aggression over food decreased, and play during feeding competition increased). These results support the hypothesis that outgroup threat elicits ingroup tolerance in chimpanzees. This suggests that in chimpanzees, like humans, competition between groups fosters group cohesion.

Colour preferences in relation to diet in chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and mandrills (Mandrillus sphinx)

2021 ◽  
Author(s):  
M. Carmen Hernández ◽  
Sandra González-Campos ◽  
Isabel Barja
Keyword(s):  
Color Vision ◽  
Pan Troglodytes ◽  
Gorilla Gorilla ◽  
Black And White ◽  
Mandrillus Sphinx ◽  
In The Wild ◽  
Sampling Intervals ◽  
Colour Preferences ◽  
Two Phases ◽  
Zero Group

Although trichromatic color vision has been extensively studied as it grants significant advantages for Old World primates, it is unknown which selective pressures were behind trait’s evolution. The leading hypothesis would be that colour vision arose as a foraging adaptation because it allowed individuals to spot food more efficiently. To test this, we exposed three chimpanzees (Pan troglodytes), five gorillas (Gorilla gorilla) and three mandrills (Mandrillus sphinx) to colour cardboard plates to assess if colours related to diet were the most preferred. Experimental setting was divided in two phases. During the first one, animals were provided with colour cardboard plates of only one colour per data collection session. The order of colour presentation was randomly determined: white, black, yellow, green and red. In phase two, primates were simultaneously provided with cardboard plates of all colours. Behavioural interactions with plates were measured using a one-zero group focal sampling (10 s sampling intervals and 20 m observation periods). Results showed that when animals were exposed to only one colour at a time, they exhibited different colour preferences depending on the species considered. Chimpanzees preferred red and yellow, the colours linked to fruits, while gorillas selected red and white. Mandrills exhibited fewer differences between colours preference, being red the most selected. Furthermore, when all colours were simultaneously provided, individuals chose colours related to diet over black and white. Although there were clear individual differences, our results support that trichromatic color vision is an advantage in detecting and selecting red items. In the wild, it could be important in the detection of reddish fruits and leaves.

Why not chimpanzees, lions, and hyenas too?

2005 ◽  
Vol 28 (5) ◽  
pp. 716-717 ◽  
Author(s):  
Richard Schuster
Keyword(s):  
Shared Intentionality ◽  
In The Wild ◽  
Group Hunting ◽  
Intelligent Action

Examples are cited of group hunting in chimpanzees, lions, and hyenas consistent with evidence for intentionality, organization, and coordination. These challenge the claim for shared intentionality as uniquely human. Even when rarely performed in this way, the significance of such behaviors should not be minimized, especially if this level of “intelligent” action emerges spontaneously in the wild.

Feeding Competition and Patch Size in the Chimpanzee Species Pan Paniscus and Pan Troglodytes

Behaviour ◽  
1988 ◽  
Vol 105 (1-2) ◽  
pp. 148-164 ◽  
Author(s):  
Richard W. Wrangham ◽  
Frances J. White
Keyword(s):  
Social Organization ◽  
Pan Troglodytes ◽  
Patch Size ◽  
Pan Paniscus ◽  
Feeding Competition ◽  
Feeding Time ◽  
Pan Troglodytes Schweinfurthii ◽  
Relative Importance ◽  
Party Size ◽  
Ecological Basis

AbstractThe relative importance of feeding competition in Pan paniscus and Pan troglodytes schweinfurthii is examined in an attempt to understand the major differences in social organization of the two species. P. paniscus at Lomako is characterized by a stronger tendency for association among females than among female P. troglodytes at Gombe. Party size in P. paniscus is dependent on patch size. Feeding competition was more important in small patches than in large patches. The total amount of feeding time by a party in a patch (chimp-minutes) was a measure of patch size that was available for both chimpanzee species. P. paniscus was found to have larger party sizes and to use larger food patches than P. troglodytes. The importance of dispersed ground foods for each species of chimpanzee was compared and, although the results are not conclusive, they indicate that this type of food was equally important in the diets of both populations. Two hypotheses of the ecological basis for differences in social structure are compared in light of this evidence.

scholarly journals Food hardness and stone tool weight in wild primate nut-cracking

2018 ◽  
Author(s):  
Michael Haslam
Keyword(s):  
Pan Troglodytes ◽  
Macaca Fascicularis ◽  
Primate Species ◽  
Stone Tool ◽  
Pan Troglodytes Verus ◽  
Crack Open ◽  
Hardness Curve ◽  
Species Overlap ◽  
In The Wild ◽  
Nut Cracking

AbstractThis study presents data on average stone tool weights and the hardness of foods processed by the three known stone-tool-using primate species: Burmese long-tailed macaques (Macaca fascicularis aurea), bearded capuchins (Sapajus libidinosus) and Western chimpanzees (Pan troglodytes verus). Each of these primates uses stone hammers to crack open nuts in the wild, making them suitable for inter-species behavioural comparison. This work draws on published results to identify a distinct difference in the tool weight/food hardness curve between chimpanzees and the two monkey taxa, with the latter reaching an asymptote in mean tool weight of just over 1 kg regardless of increasing food hardness. In contrast, chimpanzees rapidly increase their tool weight in response to increasing hardness, selecting average masses over 5 kg to process the hardest nuts. Species overlap in their preference for tools of 0.8-1 kg for opening foods of hardness 2-3 kN, suggesting that this conjunction may represent a primate stone-tool-use optimum.

scholarly journals Play-solicitation gestures in chimpanzees in the wild: flexible adjustment to social circumstances and individual matrices

2016 ◽  
Vol 3 (8) ◽  
pp. 160278 ◽  
Author(s):  
Marlen Fröhlich ◽  
Roman M. Wittig ◽  
Simone Pika
Keyword(s):  
Pan Troglodytes ◽  
Systematic Study ◽  
Demographic Factors ◽  
Social Play ◽  
Great Apes ◽  
Play Interactions ◽  
In The Wild ◽  
Communicative Exchange

Social play is a frequent behaviour in great apes and involves sophisticated forms of communicative exchange. While it is well established that great apes test and practise the majority of their gestural signals during play interactions, the influence of demographic factors and kin relationships between the interactants on the form and variability of gestures are relatively little understood. We thus carried out the first systematic study on the exchange of play-soliciting gestures in two chimpanzee ( Pan troglodytes ) communities of different subspecies. We examined the influence of age, sex and kin relationships of the play partners on gestural play solicitations, including object-associated and self-handicapping gestures. Our results demonstrated that the usage of (i) audible and visual gestures increased significantly with infant age, (ii) tactile gestures differed between the sexes, and (iii) audible and visual gestures were higher in interactions with conspecifics than with mothers. Object-associated and self-handicapping gestures were frequently used to initiate play with same-aged and younger play partners, respectively. Our study thus strengthens the view that gestures are mutually constructed communicative means, which are flexibly adjusted to social circumstances and individual matrices of interactants.

scholarly journals Communication styles in bonobos and chimpanzees: Same same but different?

2016 ◽  
Author(s):  
Marlen Fröhlich ◽  
Paul H Kuchenbuch ◽  
Gudrun Müller ◽  
Barbara Fruth ◽  
Takeshi Furuichi ◽  
...  
Keyword(s):  
Pan Troglodytes ◽  
Pan Paniscus ◽  
Quantitative Comparison ◽  
Communication Styles ◽  
Special Focus ◽  
Communicative Behavior ◽  
Temporal Relationships ◽  
In The Wild ◽  
Communicative Abilities ◽  
Species Variability

Comparative studies in relation to language origins have mainly focused on our closest living relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). Direct comparisons however are still lacking and/or concerned individuals living in captive environments only. Here, we carried out a systematic, quantitative comparison of communicative abilities of bonobos and chimpanzees living in four different communities in the wild with a special focus on within- and between-species variability. The analyses focused on communicative exchanges between mother-infant dyads to initiate joint travel. The communicative behavior of twelve bonobo (LuiKotale, Wamba; DRC) and thirteen chimpanzee mother-infant dyads (Taï South, Côte d’Ivoire; Kanyawara, Uganda) was filmed during a total of 1033 (bonobos) and 1189 (chimpanzees) hours of observation. We analyzed ‘signal-response’ structures (e.g. response waiting, gestural sequences, temporal relationships) in 316 bonobo and 415 chimpanzee carry initiations, while taking into account dyadic role, infant age and site. Differences in behavior could not be attributed to within-species variability. Bonobos solicited carries more frequently from shorter distances and via coordinated responses. Chimpanzees used a higher frequency of response waiting and sequences, showing overall more persistence. Our findings suggest that interactional intelligence paved the way to language with communication styles being influenced by social matrices.

Begging and social tolerance: Food solicitation tactics in young chimpanzees (Pan troglodytes) in the wild

2020 ◽  
Vol 41 (2) ◽  
pp. 126-135
Author(s):  
Marlen Fröhlich ◽  
Gudrun Müller ◽  
Claudia Zeiträg ◽  
Roman M. Wittig ◽  
Simone Pika
Keyword(s):  
Pan Troglodytes ◽  
Social Tolerance ◽  
In The Wild
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