Abduction and potential case of predation of an infant howler monkey (Alouatta guariba clamitans) by a tufted capuchin monkey (Sapajus nigritus)

The likelihood of interspecific interactions between wild primates is particularly high for species with overlapping territories. The sharing of the same or similar ecological niches can result in competition for space or resources, which can lead to agonistic encounters such as predator-prey interactions. Here, we report the observation of an abduction and potential case of predation of an infant howler monkey (Alouatta guariba clamitans) by an adult male capuchin monkey (Sapajus nigritus) in Minas Gerais, Brazil. Evidence of capuchin monkeys' predation of other smaller sympatric primate species has already been reported, as well as description of agonistic interactions between capuchin and howler monkeys, but none as drastic as the case described here. Although we were not able to collect evidence after the abduction, we discuss the events leading up to it and present arguments in favour of the case of interspecific predation or infanticid

Complex patterns of signalling to convey different social goals of sex in bonobos, Pan paniscus

This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 283871.Sexual behaviour in bonobos (Pan paniscus) functions beyond mere reproduction to mediate social interactions and relationships. In this study, we assessed the signalling behaviour in relation to four social goals of sex in this species: appeasement after conflict, tension reduction, social bonding and reproduction. Overall, sexual behaviour was strongly decoupled from its ancestral reproductive function with habitual use in the social domain, which was accompanied by a corresponding complexity in communication behaviour. We found that signalling behaviour varied systematically depending on the initiator's goals and gender. Although all gestures and vocalisations were part of the species-typical communication repertoire, they were often combined and produced flexibly. Generally, gestures and multi-modal combinations were more flexibly used to communicate a goal than vocalisations. There was no clear relation between signalling behaviour and success of sexual initiations, suggesting that communication was primarily used to indicate the signaller's intention, and not to influence a recipient's willingness to interact sexually. We discuss these findings in light of the larger question of what may have caused, in humans, the evolutionary transition from primate-like communication to language.Publisher PDFPeer reviewe

Bonobos modify communication signals according to recipient familiarity

This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 283871.Human and nonhuman primate communication differs in various ways. In particular, humans base communicative efforts on mutual knowledge and conventions shared between interlocutors. In this study, we experimentally tested whether bonobos (Pan paniscus), a close relative to humans, are able to take into account the familiarity, i.e. the shared interaction history, when communicating with a human partner. In five experimental conditions we found that subjects took the recipients' attentional state and their own communicative effectiveness into account by adjusting signal production accordingly. More importantly, in case of communicative failure, subjects repeated previously successful signals more often with a familiar than unfamiliar recipient, with whom they had no previous interactions, and elaborated by switching to new signals more with the unfamiliar than the familiar one, similar to what has previously been found in two year-old children. We discuss these findings in relation to the human capacity to establish common ground between interlocutors, a crucial aspect of human cooperative communication.Publisher PDFPeer reviewe

Bonobos assign meaning to food calls based on caller food preferences

Funding: The study was funded by an ERC starting grant PRILANG 283871 to KZ (https://erc.europa.eu/funding/starting-grants) and by the Swiss National Science Foundation (NCCR Evolving Language, grant agreement 51NF40_180888.Human communication relies heavily on pragmatic competence. Speech utterances are often ambiguous requiring listeners to use interaction history, shared knowledge, presumed intention and other contextual variables to make inferences about a speaker’s meaning. To probe the evolutionary origins of pragmatic competence we tested whether bonobos (Pan paniscus) can make inferences about the type of food available from listening to other group members’ food calls. We trained two group members to either prefer blue or pink chow and demonstrated these preferences to observers. A third group member served as an untrained control. In playback experiments, we broadcast the food calls of a trained demonstrator and the untrained group member to investigate whether subjects were able to infer which coloured chow was most likely available, based on the callers’ trained food preferences or lack thereof. As predicted, when hearing the untrained group member’s calls, subjects did not exhibit a bias, whereas they responded with a significant foraging bias when hearing a trained group member’s calls. These findings suggest that bonobos may take into account the idiosyncratic food preferences of others, although subjects probably differed in what they remembered.Publisher PDFPeer reviewe

Investigating self-recognition in bonobos : mirror exposure reduces looking time to self but not unfamiliar conspecifics

The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 283871 and the Swiss National Science Foundation (Social learning in primate communication: 31003A_166458 / Coordinating joint action in apes: Testing the boundaries of the human interaction engine: CR31I3_159655).The question of whether animals have some sort ofself-awareness is a topic of continued debate. A necessary precondition forself-awareness is the ability to visually discriminate the self from others,which has traditionally been investigated through mirror self-recognition experiments.Although great apes generally pass such experiments, interpretations of resultshave remained controversial. The aim of this study was to investigate howbonobos (Pan paniscus) respond todifferent types of images of themselves and others, both before and afterprolonged mirror exposure. We first presented presumably mirror-naive subjectswith representations of themselves in three different ways (mirror image,contingent and non-contingent video footage) as well as representations ofothers (video footage of known and unknown conspecifics). We found thatsubjects paid significantly less attention to contingent images of themselves(mirror image, video footage) than to non-contingent images of themselves andunfamiliar individuals, suggesting they perceived the non-contingent self-imageas novel. We then provided subjects with three months of access to a largemirror centrally positioned in the enclosure. Following this manipulation,subjects showed significantly reduced interest in the non-contingentself-images, while interest in unknown individuals remained unchanged,suggesting that the mirror experience has led to a fuller understanding oftheir own self. We discuss implications of this preliminary investigation forthe on-going debate on self-awareness in animals.Publisher PDFPeer reviewe

How apes get into and out of joint actions : shared intentionality as an interactional achievement

Compared to other animals, humans appear to have a special motivation to share experiences and mental states with others (Clark, 2006; Grice, 1975), which enables them to enter a condition of ‘we’ or shared intentionality (Tomasello & Carpenter, 2005). Shared intentionality has been suggested to be an evolutionary response to unique problems faced in complex joint action coordination (Levinson, 2006; Tomasello, Carpenter, Call, Behne, & Moll, 2005) and to be unique to humans (Tomasello, 2014). The theoretical and empirical bases for this claim, however, present several issues and inconsistencies. Here, we suggest that shared intentionality can be approached as an interactional achievement, and that by studying how our closest relatives, the great apes, coordinate joint action with conspecifics, we might demonstrate some correlate abilities of shared intentionality, such as the appreciation of joint commitment. We provide seven examples from bonobo joint activities to illustrate our framework.PostprintPeer reviewe

Characteristics of Suicide Attempts in Anorexia and Bulimia Nervosa: A Case–Control Study

Objective: Compared to other eating disorders, anorexia nervosa (AN) has the highest rates of completed suicide whereas suicide attempt rates are similar or lower than in bulimia nervosa (BN). Attempted suicide is a key predictor of suicide, thus this mismatch is intriguing. We sought to explore whether the clinical characteristics of suicidal acts differ between suicide attempters with AN, BN or without an eating disorders (ED). Method: Case-control study in a cohort of suicide attempters (n = 1563). Forty-four patients with AN and 71 with BN were compared with 235 non-ED attempters matched for sex, age and education, using interview measures of suicidal intent and severity. Results: AN patients were more likely to have made a serious attempt (OR = 3.4, 95 % CI 1.4–7.9), with a higher expectation of dying (OR = 3.7,95 % CI 1.1–13.5), and an increased risk of severity (OR = 3.4,95 % CI 1.2–9.6). BN patients did not differ from the control group. Clinical markers of the severity of ED were associated with the seriousness of the attempt. Conclusion: There are distinct features of suicide attempts in AN. This may explain the higher suicide rates in AN. Higher completed suicide rates in AN may be partially explained by AN patients ’ higher desire to die and their more severe and lethal attempts

Gestural communication of the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins

Social groups of gorillas were observed in three captive facilities and one African field site. Cases of potential gesture use, totalling 9,540, were filtered by strict criteria for intentionality, giving a corpus of 5,250 instances of intentional gesture use. This indicated a repertoire of 102 gesture types. Most repertoire differences between individuals and sites were explicable as a consequence of environmental affordances and sampling effects: overall gesture frequency was a good predictor of universality of occurrence. Only one gesture was idiosyncratic to a single individual, and was given only to humans. Indications of cultural learning were few, though not absent. Six gestures appeared to be traditions within single social groups, but overall concordance in repertoires was almost as high between as within social groups. No support was found for the ontogenetic ritualization hypothesis as the chief means of acquisition of gestures. Many gestures whose form ruled out such an origin, i.e. gestures derived from species-typical displays, were used as intentionally and almost as flexibly as gestures whose form was consistent with learning by ritualization. When using both classes of gesture, gorillas paid specific attention to the attentional state of their audience. Thus, it would be unwarranted to divide ape gestural repertoires into ‘innate, species-typical, inflexible reactions’ and ‘individually learned, intentional, flexible communication’. We conclude that gorilla gestural communication is based on a species-typical repertoire, like those of most other mammalian species but very much larger. Gorilla gestures are not, however, inflexible signals but are employed for intentional communication to specific individuals

A study of lemurs' cognitive abilities,Behavioural inhibition in brown lemurs (Eulemur Fulvus) and in black lemurs (Eulemur Macaco)

La présente étude a eu pour but d'étudier l'inhibition comportementale chez deux espèces de lémuriens: le lémur brun (Eulemur fulvus) et le lémur noir (Eulemur macaco).Dans une première série d'expériences, leur faculté de self-control a été étudiée dans une tâche de choix alimentaire utilisant une procédure de renforcement inversé (qui consiste à récompenser le sujet par la quantité opposée à celle qu'il a choisie). Comme la majorité des primates, les lémuriens ont initialement présenté une préférence significative et impulsive pour la plus grande quantité de nourriture. L'application d'un apprentissage approprié a permis aux sujets d'inhiber leur impulsivité et d'apprendre à sélectionner la plus petite quantité de nourriture pour obtenir la plus grande. Leurs performances ont été maintenues lors du retour à la procédure de renforcement inversé, et plusieurs mois après la fin de l'expérience. Les sujets ont généralisé leur performance lors de la présentation de nouvelles combinaisons de quantités, mettant ainsi en évidence certaines capacités numériques. Les sujets ont spontanément transféré leur faculté de self-control dans une tâche de choix entre deux aliments différant par leur valeur qualitative. Ils ont également été capables d'apprendre à sélectionner le symbole numérique associé à la plus petite quantité de nourriture pour obtenir la plus grande. Dans une deuxième série d'expériences, nous avons testé leur habileté à manipuler l'information afin d'induire en erreur un expérimentateur humain. Les lémuriens ont été entraînés à indiquer l'emplacement d'une récompense cachée à un expérimentateur coopérateur. Lors de l'intervention d'un expérimentateur compétiteur, les sujets devaient ajuster leurs comportements de manière adaptée au nouveau contexte. Bien que les lémuriens n'aient pas intentionnellement trompé le compétiteur, ils ont été capables de toujours communiquer l'emplacement de la récompense au coopérateur et d'ajuster individuellement leurs comportements face au compétiteur : certains sujets refusaient de participer en sa présence, d'autres ne communiquaient pas l'emplacement de la récompense, et un sujet a efficacement augmenté son choix de l'emplacement non appâté pour induire le compétiteur en erreur.The present work assessed the inhibition of action in two species of lemurs: brown lemurs (Eulemur fulvus) and black lemurs (Eulemur macaco). In a first study, their self control ability was assessed in a food-choice task using a reverse-reward contingency (that consisted in reinforcing the subject with the quantity of food it did not select). As other primates, lemurs initially showed an significant and impulsive bias toward the larger quantity of food. The application of an appropriate training permitted the lemurs to overcome their impulsivity and to learn to reliably select the smaller quantity of food to receive the larger one. Their performances were maintained when the original reverse-reward contingency was rerun, even several months later. They were able to transpose their acquired ability to novel array-size combinations, thus revealing some numerical skills. They spontaneously transferred their self-control ability to arrays of food varying in their qualitative value and learned to reliably select the numeric symbol associated with the smaller quantity of food to obtain the larger one. In a second study, we asked whether lemurs could learn to deceive a human experimenter. The subjects were trained to communicate about the location of a hidden reward to a cooperative trainer. When a competitive trainer was introduced, they were able to maintain their performance with the cooperative trainer, and showed individual behavioural adjustments in the competitive context: some subjects refused to participate, others withheld information about the location of the reward, and one subject reliably increased his choices of the unbaited location to mislead this trainer