Cross-taxa similarities in affect-induced changes of vocal behavior and voice in arboreal monkeys.

International audienceMeasuring the affective state of an individual across species with comparable non-invasive methods is a current challenge in animal communication research. This study aims to explore to which extent affect intensity is conveyed in the vocal behaviours of three nonhuman primate species (Campbell's monkeys, De Brazza's monkeys, red-capped mangabeys), which vary in body size, ecological niche and social system. Similarly in the three species, we experimentally induced a change in captive social groups' affect by locking all group members together in their outside enclosure. The two experimental conditions which varied in affect intensity consisted in imposing a pre-reunion 90 mn-separation by splitting up the respective group into two subgroups (High affect condition) or not (Low affect condition). We measured call rates as well as voice features at the time of reunion in both conditions. The three studied species reacted in a very similar way. Across species, call rates changed significantly between the behaviourally defined states. Furthermore, contact call duration and, to some extent, voice pitch increased. Our results suggest, for the first time in arboreal Old World monkeys, that affect intensity is conveyed reliably in vocal behaviour and specific acoustic characteristics of voice, irrespective of body size and ecological niche differences between species. Cross-taxa similarities in acoustic cues of affect intensity point to phylogenetic constraints and inheritance from a common ancestor, whereas variations in vocal behaviour and affect intensity-related acoustic cues between species may be an adaptation to specific social requirements and depend on social systems. Our findings as well as a comparison with published works on acoustic communication in other vertebrate groups support the hypothesis that affect intensity in human voice originates from precursors already found deep inside the vertebrate phylogeny

Manual laterality and strategy use for a coordinated bimanual task requiring precise and power grip in guenons and mangabeys

International audienceBimanual tasks have been repeatedly shown to elicit manual asymmetries supposed to reflect hemispheric specialization. And yet, a coordinated bimanual task, the BOX task, appears to be inefficient in detecting biases of hand preferences. The BOX task involves two sequential actions requiring a precise grip, lift the lid of a box and grasp a small item inside the box (while holding the lid). In the present study, we compared manual laterality exhibited for the classic bimanual BOX task and for a unimanual BOX task in 11 De Brazza's monkeys (Cercopithecus neglectus) and 19 red-capped mangabeys (Cercocebus torquatus). In addition, we assessed strategy use for solving the bimanual BOX task. We found that left-hand use for grasping the item was higher in the BOX-bimanual task than in the BOX-unimanual task. We propose that this increase in left-hand use for grasping the item results from both a hemispheric specialization for lifting the lid and an advantage in using a skillful strategy. Indeed, we revealed (1) group-level right biases for lifting the lid and (2) a complete differentiation between the roles of the two hands in subjects showing a left-hand preference for grasping the item. Finally, the bimanual BOX task showed age differences in the two species, either in manual laterality for grasping the item or in strategy use. This study provides additional evidence that manual laterality might be sensitive to maturational factors and characteristics of the bimanual tasks such as the order and the features of sequential actions

Which are the Features of the TUBE Task That Make it so Efficient in Detecting Manual Asymmetries? An Investigation in Two Cercopithecine Species (Cercopithecus neglectus and Cercocebus torquatus)

International audienceIn the last decade, the TUBE task has been repeatedly shown to be highly efficient in detecting manual asymmetries that are strong hand preferences reflecting hemispheric specialization, in non human primates. The TUBE task was thus classified as a high-level task, presumably because it involves bimanual coordination. However, this task also requires a precise action made by digit(s), which may also be a crucial feature in eliciting manual asymmetries. In the present study, we compared hand preferences for a new TUBE-unimanual task and the classic TUBE-bimanual task, both performed mostly by using the forefinger, in 12 guenons (De Brazza's monkey: Cercopithecus neglectus) and 18 mangabeys (red-capped mangabey: Cercocebus torquatus). We found a relationship between hand preferences exhibited for the two tasks, suggesting that precise use of the forefinger may induce the activation of a specialized hemisphere in both the TUBE-unimanual and the TUBE-bimanual task. However, we showed that the strength of manual laterality was higher in the TUBE-bimanual task than in the TUBE-unimanual task, indicating that bimanual coordination may enhance the expression of hand preferences. We propose that the TUBE-bimanual task is highly efficient in detecting hemispheric specialization because bimanual role differentiation would make precise digit use highly skillful. Finally, we revealed species differences in hand use, especially in females: the most arboreal species, De Brazza's monkeys, increased left-hand use from the TUBE-unimanual to the TUBE-bimanual task whereas the most terrestrial species, red-capped mangabeys, increased right-hand use

Effet d’audience sur la communication gestuelle des mangabés à collier (Cercocebus torquatus)

International audienc

Post-reunion minute by minute temporal evolution of the mean number of calls (all call types and callers combined) emitted by each group (C, B1, B2, M1, M2) in the High affect intensity condition.

<p>Black bars represent minutes for which the number of vocalizations was significantly higher than the number of calls in the Low affect intensity condition (Mann-Whitney tests, p<0.05). Dotted lines represent mean call rates in each group in the Low affect intensity condition.</p

Red-capped mangabeys (Cercocebus torquatus) adapt their interspecific gestural communication to the recipient’s behaviour

International audienceSensitivity to recipient’s attention and responsiveness are critical markers of intentional communication. Although previous research showed that ape gestures can be intentional, few studies have yet addressed this question concerning monkeys. Here, we characterise the effect of a recipient’s presence, attentional state and responsiveness on the interspecific gestural communication of captive red-capped mangabeys (Cercocebus torquatus). Previous reports showed that they produced learnt begging gestures towards a human recipient preferentially when the latter was facing them. We used here a novel setup that allows subjects to move around an experimenter and to use different modalities (visual and acoustic) to communicate. We found that when the recipient was not facing them, mangabeys moved to a position in the visual field of their recipient rather than using attention-getters. Interestingly, unlike apes, they did not elaborate their communication visually or acoustically when the experimenter did not respond favourably to their begging. However, our results may suggest that begging gestures were goal-directed, since mangabeys inhibited them when the experimenter was not available to answer immediately (i.e. give a reward). Overall, red-capped mangabeys’ interspecific visual communication presented intentionality features, but their use of begging gestures was less flexible than that of great apes in similar situations

Sonograms of the contact calls in the three studied species.

<p>Sonograms of the contact calls in the three studied species.</p

Familiarity modulates both intra- and interspecific yawn contagion in red-capped mangabeys

International audienceYawn contagion (YC) is, compared to spontaneous yawning, an evolutionary recent phenomenon probably linked to behavioral synchronization in highly social species that is more likely when it involves familiar subjects. Here, we investigate for the first time in monkeys which factors modulate intra- and interspecific YC. Through an experimental approach, we exposed 17 red-capped mangabeys to video stimuli (Yawn vs Control) depicting familiar/unfamiliar red-capped mangabeys and humans, and unfamiliar hamadryas. We found that mangabeys yawned more often in response to Yawn than Control videos independently from the species depicted, demonstrating both intra- and interspecific YC in the tested species. Moreover, both mangabey and human familiar yawning stimuli evoked a stronger yawning response in the subjects compared to the unfamiliar counterparts. Neither the amount of time spent looking frontally at the screen (probability of stimulus perception) nor the levels of self-directed behaviors (a proxy of anxiety) accounted for the results. In conclusion, we provide the first evidence that in non-human primate familiarity modulates both intra- and inter-specific YC. Stimuli emitted by familiar faces somehow ease the mechanisms underlying YC, and this modulation can also apply to heterospecific subjects when previous shared experiences provide the prerequisites for the development of social bonds

Manuel de Paléodémographie

La paléodémographie a pour champ d’étude les populations du passé, ayant laissé peu - ou pas - de traces écrites. Fondée sur des données archéologiques, elle vise à reconstituer la dynamique des peuplements ou à estimer certains paramètres démographiques, notamment à partir de l’étude des squelettes exhumés, approche privilégiée dans cet ouvrage. Ce manuel est le fruit d’une collaboration entre historiens-démographes et anthropo-archéologues, soucieux de croiser les données ostéo-archéologiques avec des sources historiques et environnementales pour l’étude des populations anciennes, avec le concours de mathématiciens et de statisticiens. Une telle entreprise suppose donc une équipe pluridisciplinaire, mais aussi des sources en qualité et en nombre suffisants. Ce manuel est un livre pratique à l’usage des anthropologues et des archéologues désireux d’interpréter des vestiges osseux en termes démographiques, accessible au plus grand nombre, tant dans la compréhension que dans l’application de ces méthodes. Le croisement des différentes informations permet de retracer les conditions de vie des populations du passé, selon les milieux socioéconomiques, les niveaux techniques et culturels et les contextes sanitaires, conférant à la discipline une importante dimension historique et ouvrant de nouvelles perspectives de recherches

Model Life Tables for Preindustrial Populations. First Applications in Paleodemography

Contemporary model life tables cannot accurately reconstruct the mortality patterns experienced by pre-industrial populations. It has thus become essential to develop mortality models that are adapted to the populations studied by paleodemographers, and that fulfil a threefold objective: to be based on a sufficiently large set of tables representing early mortality at diverse times and places; to use entries that can be easily obtained from reliable and well-established anthropological indicators; and to take the population growth rate into account, despite the problem of calculating it from bone remains. Our models are based on linear regressions that link the logarithm of mortality probabilities to a demographic variable or to one of the paleodemographic indicators suggested by J.-P Bocquet-Appel: the juvenility index, the p ratio (the deceased aged 5 to 19 years, over the deceased aged 5 years and over), and the mean age at death of adults, all of which are used as entries in the models constructed for men, women, and both sexes combined. Different growth rates are also used, for an interval from −0.01 to +0.01, by steps of 0.0025. For each entry, the set of models represents 75 model life tables, making it possible to estimate mortality by age and, under certain assumptions, some of the demographic indicators associated with it. If we assume that the demographic behaviour of archaeological populations closely resembles that of observed pre-industrial populations, we can propose an estimate of the demographic parameters of two ancient cemeteries in western Franc