Assessing the reliability of an automated method for measuring dominance hierarchy in non-human primates

Among animal societies, dominance is an important social factor that influences inter-individual relationships. However, assessing dominance hierarchy can be a time-consuming activity which is potentially impeded by environmental factors, difficulties in the recognition of animals, or disturbance of animals during data collection. Here we took advantage of novel devices, machines for automated learning and testing (MALT), designed primarily to study non-human primate cognition, to additionally measure the dominance hierarchy of a semi-free-ranging primate group. When working on a MALT, an animal can be replaced by another, which could reflect an asymmetric dominance relationship. To assess the reliability of our method, we analysed a sample of the automated conflicts with video scoring and found that 74% of these replacements included genuine forms of social displacements. In 10% of the cases, we did not identify social interactions and in the remaining 16% we observed affiliative contacts between the monkeys. We analysed months of daily use of MALT by up to 26 semi-free-ranging Tonkean macaques (Macaca tonkeana) and found that dominance relationships inferred from these interactions strongly correlated with the ones derived from observations of spontaneous agonistic interactions collected during the same time period. An optional filtering procedure designed to exclude chance-driven displacements or affiliative contacts suggests that the presence of 26% of these interactions in data sets did not impair the reliability of this new method. We demonstrate that this method can be used to assess the dynamics of both individual social status, and group-wide hierarchical stability longitudinally with minimal research labour. Further, it facilitates a continuous assessment of dominance hierarchies in captive groups, even during unpredictable environmental or challenging social events, which underlines the usefulness of this method for group management purposes. Altogether, this study supports the use of MALT as a reliable tool to automatically and dynamically assess dominance hierarchy within captive groups of non-human primates, including juveniles, under conditions in which such technology can be used

The Evolution of Primate Short-Term Memory.

Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of short-term memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities.info:eu-repo/semantics/publishedVersio

The Evolution of Primate Short-Term Memory

Short-term memory is implicated in a range of cognitive abilities and is critical for understanding primate cognitive evolution. To investigate the effects of phylogeny, ecology and sociality on short-term memory, we tested the largest and most diverse primate sample to date (421 non-human primates across 41 species) in an experimental delayed-response task. Our results confirm previous findings that longer delays decrease memory performance across species and taxa. Our analyses demonstrate a considerable contribution of phylogeny over ecological and social factors on the distribution of short-term memory performance in primates; closely related species had more similar short-term memory abilities. Overall, individuals in the branch of Hominoidea performed better compared to Cercopithecoidea, who in turn performed above Platyrrhini and Strepsirrhini. Interdependencies between phylogeny and socioecology of a given species presented an obstacle to disentangling the effects of each of these factors on the evolution of short-term memory capacity. However, this study offers an important step forward in understanding the interspecies and individual variation in short-term memory ability by providing the first phylogenetic reconstruction of this trait’s evolutionary history. The dataset constitutes a unique resource for studying the evolution of primate cognition and the role of short-term memory in other cognitive abilities

ManyPrimates: an infrastructure for international collaboration in primate cognition research

Un des objectifs des recherches en cognition chez les primates est de comprendre l'histoire évolutive de leurs capacités cognitives. De grands échantillons provenant d'un large éventail d'espèces sont essentiels pour atteindre ce but. Cependant, la fiabilité des inférences évolutives résultant de ces études souffre souvent d’échantillons réduits, limités à une poignée d’individus et d'espèces. Le projet ManyPrimates propose de surmonter ces limitations en fournissant un cadre collaboratif à grande échelle à l’intention d’études comparatives sur la cognition des primates. S'appuyant sur des initiatives similaires issues d'autres domaines de la psychologie, ce consortium a déjà produit une étude pilote sur la mémoire à court terme regroupant, à ce jour, l'un des échantillons de primates le plus important, i.e. 176 individus, et le plus diversifié, i.e. douze espèces provenant de onze sites différents. D’autres projets sur la mémoire à court terme, mais aussi sur les capacités d’inhibition ou encore l’inférence par exclusion sont en cours, et représentent des opportunités prometteuses pour répondre à des questions encore ouvertes sur l’origine des capacités cognitives des primates. Cet article présente les résultats préliminaires et les perspectives de cet ambitieux projet ainsi que le fonctionnement de cette infrastructure collaborative et les différentes manières d’y contribuer.Research in primate cognition improves our understanding of the evolutionary history of these mental abilities. Large samples from a wide diversity of species are essential to achieve such objectives. However, research on primate cognition usually suffers from very small samples limited to a handful of species, which prevents reliable evolutionary inferences. The ManyPrimates project offers to overcome some of these problems by providing a large-scale collaborative framework for comparative studies on primate cognition. Building on similar initiatives in other areas of psychology, this consortium has already produced a pilot study on short-term memory gathering one of the largest, i.e. 176 individuals, and most diverse, i.e. twelve species from eleven different sites, primate samples to date. Other projects on short-term memory, inhibitory abilities and on inference by exclusion are in progress on large and diverse data sets and represent exciting opportunities to answer still open questions on the origin of the extraordinary cognitive abilities of primates. This paper describes these projects but also the coordination and communication of this collaborative infrastructure and the different ways to contribute to it