Voici les éléments 1 - 9 sur 9
  • Publication
    Métadonnées seulement
    Female bonds and kinship in forest guenons
    (2015-4-1)
    Candiotti, Agnes
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    Coye, Camille
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    Ouattara, Karim
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    Petit, Eric
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    Vallet, D
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  • Publication
    Métadonnées seulement
    Suffixation influences receivers' behaviour in non-human primates
    (2015)
    Coye, Camille
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    Ouattara, Karim
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    Lemasson, Alban
    Compared to humans, non-human primates have very little control over their vocal production. Nonetheless, some primates produce various call combinations, which may partially offset their lack of acoustic flexibility. A relevant example is male Campbell's monkeys (Cercopithecus campbelli), which give one call type ('Krak') to leopards, while the suffixed version of the same call stem ('Krak-oo') is given to unspecific danger. To test whether recipients attend to this suffixation pattern, we carried out a playback experiment inwhichwe broadcast naturally and artificially modified suffixed and unsuffixed 'Krak' calls of male Campbell's monkeys to 42 wild groups of Diana monkeys (Cercopithecus diana diana). The two species form mixed-species groups and respond to each other's vocalizations. We analysed the vocal response of male and female Diana monkeys and overall found significantly stronger vocal responses to unsuffixed (leopard) than suffixed (unspecific danger) calls. Although the acoustic structure of the 'Krak' stem of the calls has some additional effects, subject responses were mainly determined by the presence or the absence of the suffix. This study indicates that suffixation is an evolved function in primate communication in contexts where adaptive responses are particularly important.
  • Publication
    Métadonnées seulement
    Monkey semantics: two 'dialects' of Campbell's monkey alarm calls
    (2014)
    Schlenker, Philippe
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    Chemla, Emmanuel
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    Arnold, Kate
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    Lemasson, Alban
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    Ouattara, Karim
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    Keenan, Sumir
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    Ryder, Robin
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    We develop a formal semantic analysis of the alarm calls used by Campbell's monkeys in the Tai forest (Ivory Coast) and on Tiwai island (Sierra Leone)-two sites that differ in the main predators that the monkeys are exposed to (eagles on Tiwai vs. eagles and leopards in Tai). Building on data discussed in Ouattara et al. (PLoS ONE 4(11):e7808, 2009a; PNAS 106(51): 22026-22031, 2009b and Arnold et al. (Population differences in wild Campbell's monkeys alarm call use, 2013), we argue that on both sites alarm calls include the roots krak and hok, which can optionally be affixed with -oo, a kind of attenuating suffix; in addition, sentences can start with boom boom, which indicates that the context is not one of predation. In line with Arnold et al., we show that the meaning of the roots is not quite the same in Tai and on Tiwai: krak often functions as a leopard alarm call in Tai, but as a general alarm call on Tiwai. We develop models based on a compositional semantics in which concatenation is interpreted as conjunction, roots have lexical meanings, -oo is an attenuating suffix, and an all-purpose alarm parameter is raised with each individual call. The first model accounts for the difference between Tai and Tiwai by way of different lexical entries for krak. The second model gives the same underspecified entry to krak in both locations (= general alarm call), but it makes use of a competition mechanism akin to scalar implicatures. In Tai, strengthening yields a meaning equivalent to non-aerial dangerous predator and turns out to single out leopards. On Tiwai, strengthening yields a nearly contradictory meaning due to the absence of ground predators, and only the unstrengthened meaning is used.
  • Publication
    Accès libre
    Anti-predator strategies of free-ranging Campbell's monkeys
    Ouattara, Karim
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    Lemasson, Alban
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    Habitat type, predation pressure and reproductive interests are all thought to determine the anti-predator behaviour of non-primates, but only few systematic studies exist. Here, we experimentally elicited anti-predator behaviour in six different groups of forest-living Campbell’s monkeys, using visual and acoustic models of leopards, crowned eagles, and snakes. Individuals produced a variety of anti-predator behaviours, depending on the type of predator and whether or not it was visible. Adult males generally behaved conspicuously, either by attacking eagles or producing threat behaviours at a distance to leopards. Adult females remained cryptic to eagles, but joined their male in approaching leopards. To snakes, both males and females responded strongly to familiar Gaboon vipers, but far less to unfamiliar black mambas. Finally, if a predator could only be heard, both males and females produced fewer alarm calls and often changed their vertical position in the canopy (upwards for leopards; downwards for eagles), despite all predator vocalisations being presented from the ground. We concluded that Campbell’s monkeys display sex-specific anti- predator behaviours, which are largely driven by the predators’ hunting techniques, mode of predator detection and the forest habitat structure.
  • Publication
    Accès libre
    Campbell's Monkeys Use Affixation to Alter Call Meaning
    Ouattara, Karim
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    Lemasson, Alban
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    Human language has evolved on a biological substrate with phylogenetic roots deep in the primate lineage. Here, we describe a functional analogy to a common morphological process in human speech, affixation, in the alarm calls of free-ranging adult Campbell's monkeys (Cercopithecus campbelli campbelli). We found that male alarm calls are composed of an acoustically variable stem, which can be followed by an acoustically invariable suffix. Using long-term observations and predator simulation experiments, we show that suffixation in this species functions to broaden the calls' meaning by transforming a highly specific eagle alarm to a general arboreal disturbance call or by transforming a highly specific leopard alarm call to a general alert call. We concluded that, when referring to specific external events, non-human primates can generate meaningful acoustic variation during call production that is functionally equivalent to suffixation in human language.
  • Publication
    Accès libre
    The alarm call system of female Campbell's monkeys
    Ouattara, Karim
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    N'Goran, Koffi J.-N
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    Gombert, Jean-Emile
    Field studies on male forest guenon alarm-calling behaviour have revealed a number of intricacies about how these primates use vocalizations to protect themselves from predation. In these species, the vocal behaviour of adult females is often different from that of the males, but little systematic work has been done. Here, we describe the alarm call system of female Campbell's monkeys, Cercopithecus campbelli, in their natural forest habitat in western Ivory Coast. We found that in response to disturbing events, females produced three basic alarm call types, ‘wak-oos’, ‘hoks’ and acoustically variable ‘trill’ calls, consisting of repeated and rapidly ascending (RRA) pulses, which varied systematically in the temporal and frequency domains. Using observational and experimental data we were able to demonstrate that the RRA calls consisted of four acoustic variants, which could be associated with specific contexts, allowing listeners to draw inferences about the type of disturbance experienced by the caller. We also compared the alarm call behaviour of free-ranging individuals with published results from captivity. As predicted, captive individuals failed to produce predator-specific alarm calls, but they also produced an RRA variant in response to humans that was absent in the wild. We discuss the relevance of these findings in terms of their broader potential impact on evolutionary theories of primate communication.
  • Publication
    Accès libre
    Speed of call delivery is related to context and caller identity in Campbell’s monkey males
    Lemasson, Alban
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    Ouattara, Karim
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    Bouchet, Hélène
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    Call rate can be a salient feature in animal communication. Depending on the species, different psychological variables appear to influence call rates but the exact nature of these relationships remains poorly explored. Here, we demonstrate for free-ranging Campbell's monkeys that the call rates of four different alarm series (termed H, K, K+, and B series) vary systematically as a function of context, associated behaviour, and identity of the caller. K+ series were given more rapidly to predation than non- predation events, K+ and K series more rapidly to visual than auditory predator detection, and H series more rapidly while counterattacking an eagle than staying put. Finally, there were individual differences in B series, suggesting that call rate potentially provides listeners with cues about the caller's anti-predator behaviour, event type experienced, and his identity.
  • Publication
    Accès libre
    Campbell's monkeys concatenate vocalizations into context-specific call sequences
    Ouattara, Karim
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    Lemasson, Alban
    ;
    Primate vocal behavior is often considered irrelevant in modeling human language evolution, mainly because of the caller's limited vocal control and apparent lack of intentional signaling. Here, we present the results of a long-term study on Campbell's monkeys, which has revealed an unrivaled degree of vocal complexity. Adult males produced six different loud call types, which they combined into various sequences in highly context-specific ways. We found stereotyped sequences that were strongly associated with cohesion and travel, falling trees, neighboring groups, nonpredatory animals, unspecific predatory threat, and specific predator classes. Within the responses to predators, we found that crowned eagles triggered four and leopards three different sequences, depending on how the caller learned about their presence. Callers followed a number of principles when concatenating sequences, such as nonrandom transition probabilities of call types, addition of specific calls into an existing sequence to form a different one, or recombination of two sequences to form a third one. We conclude that these primates have overcome some of the constraints of limited vocal control by combinatorial organization. As the different sequences were so tightly linked to specific external events, the Campbell's monkey call system may be the most complex example of ‘proto-syntax’ in animal communication known to date.
  • Publication
    Accès libre
    Social learning of vocal structure in a nonhuman primate?
    Lemasson, Alban
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    Ouattara, Karim
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    Petit, Eric J
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    Non-human primate communication is thought to be fundamentally different from human speech, mainly due to vast differences in vocal control. The lack of these abilities in non-human primates is especially striking if compared to some marine mammals and bird species, which has generated somewhat of an evolutionary conundrum. What are the biological roots and underlying evolutionary pressures of the human ability to voluntarily control sound production and learn the vocal utterances of others? One hypothesis is that this capacity has evolved gradually in humans from an ancestral stage that resembled the vocal behavior of modern primates. Support for this has come from studies that have documented limited vocal flexibility and convergence in different primate species, typically in calls used during social interactions. The mechanisms underlying these patterns, however, are currently unknown. Specifically, it has been difficult to rule out explanations based on genetic relatedness, suggesting that such vocal flexibility may not be the result of social learning.