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Zuberbühler, Klaus

Nom
Zuberbühler, Klaus
Affiliation principale
Fonction
Professeur ordinaire
Email
klaus.zuberbuehler@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/670
_
0000-0001-8378-088X

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  • Publication
    Métadonnées seulement
  • Publication
    Métadonnées seulement
    How Intentional Are Chimpanzee Vocalizations?
    (2015)
    Crockford, Catherine
    ;
    Wittig, Roman
    ;
    Zuberbühler, Klaus 
  • Publication
    Accès libre
    Single Aggressive Interactions Increase Urinary Glucocorticoid Levels in Wild Male Chimpanzees
    (2015)
    Wittig, Roman M.
    ;
    Crockford, Catherine
    ;
    Weltring, Anja
    ;
    Deschner, Tobias
    ;
    Zuberbühler, Klaus 
    A basic premise in behavioural ecology is the cost-benefit arithmetic, which determines both behavioural decisions and evolutionary processes. Aggressive interactions can be costly on an energetic level, demanding increased energy or causing injuries, and on a psychological level, in the form of increased anxiety and damaged relationships between opponents. Here we used urinary glucocorticoid (uGC) levels to assess the costs of aggression in wild chimpanzees of Budongo Forest, Uganda. We collected 169 urine samples from nine adult male chimpanzees following 14 aggressive interactions (test condition) and 10 resting events (control condition). Subjects showed significantly higher uGC levels after single aggressive interactions compared to control conditions, likely for aggressors as well as victims. Higher ranking males had greater increases of uGC levels after aggression than lower ranking males. In contrast, uGC levels showed no significant change in relation to aggression length or intensity, indicating that psychological factors might have played a larger role than mere energetic expenditure. We concluded that aggressive behaviour is costly for both aggressors and victims and that costs seem poorly explained by energetic demands of the interaction. Our findings are relevant for studies of post-conflict interactions, since we provide evidence that both aggressors and victims experience a stress response to conflict.
  • Publication
    Accès libre
    An intentional vocalization draws others' attention: A playback experiment with wild chimpanzees
    (2015)
    Crockford, Catherine
    ;
    Wittig, Roman M.
    ;
    Zuberbühler, Klaus 
    A vital step in the evolution of language is likely to have been when signalers explicitly intended to direct recipients' attention to external objects with the use of referential signals. Although animal signals can direct the attention of others to external events, such as in monkey predator alarm calls, there is little evidence that this is the result of an intention to inform the recipient. Two recent studies, however, indicate that the production of chimpanzee quiet alarm calls, given to snakes, complies with some standard behavioral markers of intentional signaling, such as gaze alternation. But it is currently unknown whether the calls alone direct receivers' attention to the threat. To address this, we carried out a playback experiment with free-ranging chimpanzees in Budongo Forest, Uganda, using a within-subjects design. From a hidden speaker, we broadcast either quiet alarm 'hoos' ('alert hoos') or acoustically distinguishable hoos produced while resting ('rest hoos') and found a significant increase in search behavior after 'alert' compared with 'rest' hoos, with subjects monitoring either the call provider or the area near the call provider. In sum, chimpanzee 'alert hoos' represent a plausible case of an intentionally produced animal vocalization (other studies) that refers recipients to signalers and/or to an external event (this study).
  • Publication
    Accès libre
    Triadic social interactions operate across time: a field experiment with wild chimpanzees
    (2014)
    Wittig, Roman M.
    ;
    Crockford, Catherine
    ;
    Langergraber, Kevin E.
    ;
    Zuberbühler, Klaus 
    Social animals cooperate with bonding partners to outcompete others. Predicting a competitor's supporter is likely to be beneficial, regardless of whether the supporting relationship is stable or transient, or whether the support happens immediately or later. Although humans make such predictions frequently, it is unclear to what extent animals have the cognitive abilities to recognize others' transient bond partners and to predict others' coalitions that extend beyond the immediate present. We conducted playback experiments with wild chimpanzees to test this. About 2 h after fighting, subjects heard recordings of aggressive barks of a bystander, who was or was not a bond partner of the former opponent. Subjects looked longer and moved away more often from barks of the former opponents' bond partners than non-bond partners. In an additional experiment, subjects moved away more from barks than socially benign calls of the same bond partner. These effects were present despite differences in genetic relatedness and considerable time delays between the two events. Chimpanzees, it appears, integrate memories of social interactions from different sources to make inferences about current interactions. This ability is crucial for connecting triadic social interactions across time, a requirement for predicting aggressive support even after a time delay.
  • Publication
    Métadonnées seulement
    Food sharing is linked to urinary oxytocin levels and bonding in related and unrelated wild chimpanzees
    (2014)
    Wittig, Roman M.
    ;
    Crockford, Catherine
    ;
    Deschner, Tobias
    ;
    Langergraber, Kevin E.
    ;
    Ziegler, Toni E.
    ;
    Zuberbühler, Klaus 
    Humans excel in cooperative exchanges between unrelated individuals. Although this trait is fundamental to the success of our species, its evolution and mechanisms are poorly understood. Other social mammals also build long-term cooperative relationships between non-kin, and recent evidence shows that oxytocin, a hormone involved in parent-offspring bonding, is likely to facilitate non-kin as well as kin bonds. In a population of wild chimpanzees, we measured urinary oxytocin levels following a rare cooperative event-food sharing. Subjects showed higher urinary oxytocin levels after single food-sharing events compared with other types of social feeding, irrespective of previous social bond levels. Also, urinary oxytocin levels following food sharing were higher than following grooming, another cooperative behaviour. Therefore, food sharing in chimpanzees may play a key role in social bonding under the influence of oxytocin. We propose that food-sharing events co-opt neurobiological mechanisms evolved to support mother-infant bonding during lactation bouts, and may act as facilitators of bonding and cooperation between unrelated individuals via the oxytocinergic system across social mammals.
  • Publication
    Métadonnées seulement
    Genetic analyses suggest no immigration of adult females and their offspring into the Sonso community of chimpanzees in the Budongo Forest Reserve, Uganda
    (2014)
    Langergraber, Kevin E.
    ;
    Rowney, Carolyn
    ;
    Crockford, Catherine
    ;
    Wittig, Roman
    ;
    Zuberbühler, Klaus 
    ;
    Vigilant, Linda
    Chimpanzees are frequently used to illustrate the relationship between sex differences in dispersal and sex differences in cooperation in primates and other group-living mammals. Male chimpanzees are highly philopatric, typically remaining in their natal communities for their entire lives to cooperate with related males in competition against less related males from other groups, whereas females typically disperse once at adolescence and cooperate with each other less frequently. However, there have been a few reports of dependent male offspring joining groups when their mothers transferred between communities as adults. Although such events are difficult to document, determining how often they actually occur is important for elucidating the links between philopatry, kinship, and cooperation in both chimpanzees and group-living animals more generally. Here we use genetic analyses to investigate a previous report of a large-scale transfer of many females and their offspring into the Sonso community of chimpanzees in the Budongo Forest Reserve, Uganda. Using autosomal microsatellite genotypes, we assigned a Sonso father to ten of the fourteen putative immigrants, and found that the four putative immigrants for whom we could not assign a Sonso father (perhaps due to incomplete sampling of all Sonso candidate fathers) nevertheless had Y-chromosome microsatellite haplotypes that were common in Sonso males but absent in males from four other chimpanzee communities at Budongo. These results suggest that these putative immigrant females and their offspring were probably actually long-term residents of Sonso whose identifications were delayed by their peripheral or unhabituated status. These results are consistent with other genetic and behavioral evidence showing that male between-community gene flow is exceedingly rare in east African chimpanzees. Am. J. Primatol. 76:640-648, 2014. (c) 2014 Wiley Periodicals, Inc.
  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Urinary oxytocin and social bonding in related and unrelated wild chimpanzees
    (2013)
    Crockford, Catherine
    ;
    Wittig, Roman M.
    ;
    Langergraber, Kevin E.
    ;
    Ziegler, T. E.
    ;
    Zuberbühler, Klaus 
    ;
    Deschner, Tobias
    Animals that maintain cooperative relationships show gains in longevity and offspring survival. However, little is known about the cognitive or hormonal mechanisms involved in cooperation. Indeed, there is little support for a main hypothesis that non-human animals have the cognitive capacities required for bookkeeping of cooperative exchanges. We tested an alternative hypothesis that cooperative relationships are facilitated by an endocrinological mechanism involving oxytocin, a hormone required for bonding in parental and sexual relationships across mammals. We measured urinary oxytocin after single bouts of grooming in wild chimpanzees. Oxytocin levels were higher after grooming with bond partners compared with non-bond partners or after no grooming, regardless of genetic relatedness or sexual interest. We ruled out other possible confounds, such as grooming duration, grooming direction or sampling regime issues, indicating that changes in oxytocin levels were mediated by social bond strength. Oxytocin, which is thought to act directly on neural reward and social memory systems, is likely to play a key role in keeping track of social interactions with multiple individuals over time. The evolutionary linkage of an ancestral hormonal system with complex social cognition may be the primary mechanism through which long-term cooperative relationships develop between both kin and non-kin in mammals.
  • Publication
    Métadonnées seulement
    Wild Chimpanzees Inform Ignorant Group Members of Danger
    (2012)
    Crockford, Catherine
    ;
    Wittig, Roman M.
    ;
    Mundry, Roger
    ;
    Zuberbühler, Klaus 
    The ability to recognize other individuals' mental states their knowledge and beliefs, for example is a fundamental part of human cognition and may be unique to our species. Tests of a "theory of mind" in animals have yielded conflicting results [1-3]. Some nonhuman primates can read others' intentions and know what others see, but they may not understand that, in others, perception can lead to knowledge [1-3]. Using an alarm-call-based field experiment, we show that chimpanzees were more likely to alarm call in response to a snake in the presence of unaware group members than in the presence of aware group members, suggesting that they recognize knowledge and ignorance in others. We monitored the behavior of 33 individuals to a model viper placed on their projected travel path. Alarm calls were significantly more common if the caller was with group members who had either not seen the snake or had not been present when alarm calls were emitted. Other factors, such as own arousal, perceived risk, or risk to receivers, did not significantly explain the likelihood of calling, although they did affect the call rates. Our results suggest that chimpanzees monitor the information available to other chimpanzees and control vocal production to selectively inform them.