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Gruber, Thibaud

Nom
Gruber, Thibaud
Affiliation principale
Fonction
Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/783
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0000-0002-6766-3947

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  • Publication
    Accès libre
    Apes have culture but may not know that they do
    (2015-3-23)
    Gruber, Thibaud 
    ;
    Zuberbühler, Klaus 
    ;
    Clément, Fabrice 
    ;
    van Shaik, Carel
    There is good evidence that some ape behaviors can be transmitted socially and that this can lead to group-specific traditions. However, many consider animal traditions, including those in great apes, to be fundamentally different from human cultures, largely because of lack of evidence for cumulative processes and normative conformity, but perhaps also because current research on ape culture is usually restricted to behavioral comparisons. Here, we propose to analyze ape culture not only at the surface behavioral level but also at the underlying cognitive level. To this end, we integrate empirical findings in apes with theoretical frameworks developed in developmental psychology regarding the representation of tools and the development of metarepresentational abilities, to characterize the differences between ape and human cultures at the cognitive level. Current data are consistent with the notion of apes possessing mental representations of tools that can be accessed through re-representations: apes may reorganize their knowledge of tools in the form of categories or functional schemes. However, we find no evidence for metarepresentations of cultural knowledge: apes may not understand that they or others hold beliefs about their cultures. The resulting Jourdain Hypothesis, based on Molière’s character, argues that apes express their cultures without knowing that they are cultural beings because of cognitive limitations in their ability to represent knowledge, a determining feature of modern human cultures, allowing representing and modifying the current norms of the group. Differences in metarepresentational processes may thus explain fundamental differences between human and other animals’ cultures, notably limitations in cumulative behavior and normative conformity. Future empirical work should focus on how animals mentally represent their cultural knowledge to conclusively determine the ways by which humans are unique in their cultural behavior.
  • Publication
    Accès libre
    Social Network Analysis Shows Direct Evidence for Social Transmission of Tool Use in Wild Chimpanzees
    (2014)
    Hobaiter, Catherine
    ;
    Poisot, Timothee
    ;
    Zuberbühler, Klaus 
    ;
    Hoppitt, William
    ;
    Gruber, Thibaud 
    Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition-that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, "moss-sponging'' and "leaf-sponge re-use,'' in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most "cultural'' of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.
  • Publication
    Accès libre
    Vocal Recruitment for Joint Travel in Wild Chimpanzees
    (2013)
    Gruber, Thibaud 
    ;
    Zuberbühler, Klaus 
    Joint travel is a common social activity of many group-living animals, which requires some degree of coordination, sometimes through communication signals. Here, we studied the use of an acoustically distinct vocalisation in chimpanzees, the 'travel hoo', a signal given specifically in the travel context. We were interested in how this call type was produced to coordinate travel, whether it was aimed at specific individuals and how recipients responded. We found that 'travel hoos' were regularly given prior to impending departures and that silent travel initiations were less successful in recruiting than vocal initiations. Other behaviours associated with departure were unrelated to recruitment, suggesting that 'travel hoos' facilitated joint travel. Crucially, 'travel hoos' were more often produced in the presence of allies than other individuals, with high rates of recruitment success. We discuss these findings as evidence for how motivation to perform a specific social activity can lead to the production of a vocal signal that qualifies as 'intentional' according to most definitions, suggesting that a key psychological component of human language may have already been present in the common ancestor of chimpanzees and humans.
  • Publication
    Accès libre
    Female bonobos use copulation calls as social signals
    (2011)
    Clay, Zanna
    ;
    Pika, Simone
    ;
    Gruber, Thibaud 
    ;
    Zuberbühler, Klaus 
    During mating events, females of many primate species produce loud and distinct vocalizations known as ‘copulation calls’. The adaptive significance of these signals is considered to be in promoting the caller’s direct reproductive success. Here, we investigated copulation calling in bonobos (Pan paniscus), a species in which females produce these vocalizations during sexual interactions with partners of both sexes. Females were more likely to call when mating with males than with females. We also observed a positive relationship between the likelihood of calling and partner rank, regardless of partner sex. Sexual activity generally increased with swelling size (an indicator of reproductive state) and, during their peak swelling, females called more with male than with female partners. Female bonobos are unusual among the nonhuman primates in terms of their heightened socio-sexuality. Our results suggest that in this species, copulation calls have undergone an evolutionary transition from a purely reproductive to a more general social function, reflecting the intrinsic evolutionary links between vocal behaviour and social cognition.
  • Publication
    Accès libre
    Community-specific evaluation of tool affordances in wild chimpanzees
    (2011)
    Gruber, Thibaud 
    ;
    Muller, Martin N. N.
    ;
    Reynolds, Vernon
    ;
    Wrangham, Richard W.
    ;
    Zuberbühler, Klaus 
    The notion of animal culture, defined as socially transmitted community-specific behaviour patterns, remains controversial, notably because the definition relies on surface behaviours without addressing underlying cognitive processes. In contrast, human cultures are the product of socially acquired ideas that shape how individuals interact with their environment. We conducted field experiments with two culturally distinct chimpanzee communities in Uganda, which revealed significant differences in how individuals considered the affording parts of an experimentally provided tool to extract honey from a standardised cavity. Firstly, individuals of the two communities found different functional parts of the tool salient, suggesting that they experienced a cultural bias in their cognition. Secondly, when the alternative function was made more salient, chimpanzees were unable to learn it, suggesting that prior cultural background can interfere with new learning. Culture appears to shape how chimpanzees see the world, suggesting that a cognitive component underlies the observed behavioural patterns.
  • Publication
    Accès libre
    A comparison of bonobo and chimpanzee tool use: evidence for a female bias in the Pan lineage
    (2010)
    Gruber, Thibaud 
    ;
    Clay, Zanna
    ;
    Zuberbühler, Klaus 
    Chimpanzees, Pan troglodytes, are the most sophisticated tool-users among all nonhumanprimates. From an evolutionary perspective, it is therefore puzzling that the tool use behaviour of their closest living primate relative, the bonobo, Pan paniscus, has been described as particularly poor. However, only a small number of bonobo groups have been studied in the wild and only over comparably short periods. Here, we show that captive bonobos and chimpanzees are equally diverse tool-users in most contexts. Our observations illustrate that tool use in bonobos can be highly complex and no different from what has been described for chimpanzees. The only major difference in the chimpanzee and bonobo data was that bonobos of all age-sex classes used tools in a play context, a possible manifestation of their neotenous nature.We also found that female bonobos displayed a larger range of tool use behaviours than males, a pattern previously described for chimpanzees but not for other great apes. Our results are consistent with the hypothesis that the female-biased tool use evolved prior to the split between bonobos and chimpanzees.
  • Publication
    Accès libre
    Wild Chimpanzees Rely on Cultural Knowledge to Solve an Experimental Honey Acquisition Task
    (2009)
    Gruber, Thibaud 
    ;
    Muller, Martin N
    ;
    Strimling, Pontus
    ;
    Wrangham, Richard
    ;
    Zuberbühler, Klaus 
    Population and group-specific behavioral differences have been taken as evidence for animal cultures [1–10], a notion that remains controversial. Skeptics argue that ecological or genetic factors, rather than social learning, provide a more parsimonious explanation [11–14]. Work with captive chimpanzees has addressed this criticism by showing that experimentally created traditions can be transmitted through social learning [15–17]. Recent fieldwork further suggests that ecological and genetic factors are insufficient to explain the behavioral differences seen between communities, but the data are only observational [18, 19]. Here, we present the results of a field experiment [20, 21] that compared the performance of chimpanzees (P. t. schweinfurthii) from two Ugandan communities, Kanyawara and Sonso, on an identical task in the physical domain—extracting honey from holes drilled into horizontal logs. Kanyawara chimpanzees, who occasionally use sticks to acquire honey [4], spontaneously manufactured sticks to extract the experimentally provided honey. In contrast, Sonso chimpanzees, who possess a considerable leaf technology but no foodrelated stick use [4, 22], relied on their fingers, but some also produced leaf sponges to access the honey. Our results indicate that, when genetic and environmental factors are controlled, wild chimpanzees rely on their cultural knowledge to solve a novel task.
  • Publication
    Accès libre
    Community-specific evaluation of tool affordances in wild chimpanzees
    Gruber, Thibaud 
    ;
    Muller, Martin N
    ;
    Reynolds, Vernon
    ;
    Zuberbühler, Klaus 
    The notion of animal culture, defined as socially transmitted community-specific behaviour patterns, remains controversial, notably because the definition relies on surface behaviours without addressing underlying cognitive processes. In contrast, human cultures are the product of socially acquired ideas that shape how individuals interact with their environment. We conducted field experiments with two culturally distinct chimpanzee communities in Uganda, which revealed significant differences in how individuals considered the affording parts of an experimentally provided tool to extract honey from a standardised cavity. Firstly, individuals of the two communities found different functional parts of the tool salient, suggesting that they experienced a cultural bias in their cognition. Secondly, when the alternative function was made more salient, chimpanzees were unable to learn it, suggesting that prior cultural background can interfere with new learning. Culture appears to shape how chimpanzees see the world, suggesting that a cognitive component underlies the observed behavioural patterns.
  • Publication
    Accès libre
    The influence of ecology on chimpanzee (Pan troglodytes) cultural behavior: a case study of five Ugandan chimpanzee communities
    Gruber, Thibaud 
    ;
    Potts, Kevin B
    ;
    Krupenye, Christopher
    ;
    Zuberbühler, Klaus 
    The influence of ecology on the development of behavioral traditions in animals is controversial, particularly for chimpanzees (Pan troglodytes), for which it is difficult to rule out environmental influences as a cause of widely observed community-specific behavioral differences. Here, we investigated 3 potential scenarios that could explain the natural variation in a key extractive tool behavior, "fluid-dip," among several communities of chimpanzees of the Pan troglodytes schweinfurthii subspecies in Uganda. We compared data from previous behavioral ecological studies, field experiments, and long-term records of chimpanzee tool-using behavior. We focused on the quality of the available food, dietary preferences, and tool sets of 5 different communities, and carried out a standardized field experiment to test systematically for the presence of fluid-dip in 4 of these communities. Our results revealed major differences in habitat, available diet, and tool use behavior between geographically close communities. However, these differences in ecology and feeding behavior failed to explain the differences in tool use across communities. We conclude that ecological variables may lead both to innovation and loss of behavioral traditions, while contributing little to their transmission within the community. Instead, as soon as a behavioral tradition is established, sociocognitive factors likely play a key maintenance role as long as the ecological conditions do not change sufficiently for the tradition to be abandoned.