Abstracts EFP-GfP 2021 Seminar Series

Charlotte Canteloup (Université de Lausanne) - 

From whom to learn? Social learning biases in wild vervet monkeys

Social learning is crucial for behavioural traditions to arise. Humans and various animal species biasedly learn particular behaviours from specific demonstrators. Such selectivity in learning is considered to facilitate cultural transmission of information. While social learning biases have been mostly studied in isolation, their interaction and the interplay between individual and social learning is less understood. To fill this gap in understanding, I conducted two open diffusion experiments in two groups of wild vervet monkeys in South Africa: a novel two-action puzzle box task and a novel food (unshelled peanuts) presentation task. Data of the field experiments have been analysed with modelling approaches allowing to simultaneously test for multiple biases. Results show that vervets monkeys socially learn the boxes opening and peanuts processing techniques. We documented how the two boxes and three different peanut opening techniques spread within the groups. We found evidence of a rank transmission bias favouring learning from higher-ranked individuals, with no evidence for age, sex or kin bias in both experiments and that vervets preferentially used the technique yielding the highest observed payoff. These results suggest that traditions may arise when individuals integrate information about the efficiency of a behaviour alongside cues related to the rank of a demonstrator in wild vervet monkeys. 

Daria Valente (Università di Torino) - 

Similarities and differences in lemur vocal behaviour: a comparative approach

Vocal signals represent a great source of information and diversity and investigating such an extraordinary form of communication can enlighten different aspects of species' biology. For instance, we can derive information about the morphological factors underlying production and perception mechanisms, or the influence of social dynamics and evolutionary pressures in shaping the vocal capacities of a species. Despite a continually growing number of studies dedicated to the investigation of vocal repertoires, this discipline still suffers from a vast diversity in the methodological approach undermining the assessment of vocal repertoire size. Moreover, some of the current methods often rely on human perceptual and cognitive biases, limiting the feasibility to perform comparative analyses. Using as model the vocal repertoires of three Strepsirrhine primate species, I tested computational methodologies recently proven able to perform acoustic features extraction and analysis. I will discuss weaknesses and strengths of several data treatment strategies characterising peculiarities and divergences across vocal signals and species, as well as the power of each technique in the quantification of vocal repertoires, crucial to supporting cross-species comparisons.

Dietmar Crailsheim (Universitat de Girona) - 

Assessing the sociability of former pet and entertainment chimpanzees (Pan troglodytes) by using a monolayer and a multiplex social network approach

The detrimental long-term effects of early life adversities on social functioning are well studied in wild-caught ex-laboratory chimpanzees, while former pet and entertainment chimpanzees have received less attention to date. Therefore, we investigated the long-term effects of early life adversities on sociability in former pet and entertainment chimpanzees by analysing their allogrooming networks based on data collected over a 12-year period and by analysing 4-layered multiplex networks consisting of the interaction types stationary vicinity, affiliative behaviour, allogrooming and passive close proximity. We found that wild-caught former pet and entertainment chimpanzees were more selective regarding their grooming partners and spent less time grooming, compared to captive born chimpanzees. Individuals predominantly housed solitary during infancy spent less time grooming compared to those predominantly housed socially during infancy. The multiplex approach enabled a broader view on sociability as four social interaction types were considered simultaneously. While we found some social interaction types to be more similar than other ones, each interaction type did impart different information. It also became apparent that individuals might score different in the different interaction types. These individual differences were partially attributable to early life experiences, which affected not only allogrooming but also the affiliative behaviour. We conclude that long-term observations and the application of a multiplex approach provide a more realistic framework to assess the sociability and can function as a tool to support care management decisions, rehabilitation efforts and help to improve the chimpanzees´ quality of life.

Vedrana Šlipogor (Universität Wien) - 

Unique, just like everyone else? Integrative approach to the study of personality in common marmosets (Callithrix jacchus)

Consistent inter-individual differences, i.e. animal personalities, are defined as behaviours that are stable within an individual throughout time, contexts and situations. Evolutionary bases and socio-ecological consequences of personality have been explored in many animal taxa, and particularly in non-human primates. In my presentation, I will give an overview of our studies on personality in common marmosets (Callithrix jacchus), a gregarious neotropical primate species. Conceptually, we have evaluated different personality assessment methods; empirically, we have investigated social and non-social personality traits under both controlled laboratory and ecologically relevant field conditions, and we have explored possible links among personality traits, marmosets’ social environment and their individual learning capabilities. By using an integrative approach, we have applied various experimental and observational designs in social and solitary set-ups. My presentation will thus shed light on whether i) different assessment methods reliably capture personality variation and agree in their evaluations, ii) personality traits are stable both short-term and long-term and specific to the solitary or social context, or captive and natural circumstances, and iii) certain personality traits and animals’ social environment are linked to the individuals’ variation in learning. The latter findings have already laid the path for exciting future studies. Exploring further aspects of inter-individual behavioural and cognitive variation in the social domain; both on a behavioural and physiological level, could be a particularly promising research endeavour in the years to come. Eventually, studying personality in highly social non-human primates may contribute to understanding the complexity of personality in our own species better. 

Alex Mielke (University of Oxford) - 

Replicability and reproducibility in primate sociality studies

Primatology as comparative science is dependent on successful replication: to make statements about evolutionary patterns, we must ensure that studies of different species measure the same thing. Local variation and group dynamics mean that studies of social behaviour often arrive at different results for different species or even the same species. We tend to interpret differences in results as biologically meaningful – however, is that really justified? Sampling and measurement error are inevitable in the messy business of collecting interactional data. Also, researchers have to choose how to collect, process, and analyse data, with a bewildering number of options available at all steps. We do not currently know how these choices affect results. In contrast to adjacent fields, observational primatology has yet to see an open dialogue of replicability and ways to ensure the quality of our studies. In this talk, I will demonstrate how unchecked researcher degrees of freedom can skew results of primate sociality studies, and will lay out some ways to increase credibility of our scientific work: multiverse analysis and increased data transparency. 

Jaimie Morris (Canterbury Christ Church University) - 

Genetic and morphological analyses of historic and contemporary populations of western lowland gorilla: A multidisciplinary approach for the conservation of a critically endangered primate

This study investigates the morphology and genetic diversity of the critically endangered sub-species, the western lowland gorilla. Regional variation of an historic wild population was assessed morphologically and genetically, and genetic comparisons between this and a contemporary UK captive population were made to assess the genetic fitness of the contemporary population, with the aim of assisting future conservation planning.
Geometric morphometric analyses were applied to skulls and mandibles of both sexes in the historic population to assess regional variation in relation to size and shape. No significant difference was found for regional size comparisons but shape variation between regions did find significant variation in skull morphology.
MtDNA and nuclear markers were employed to detect regional differentiation in the historic population, and to compare genetic diversity between historic and contemporary populations. The mtDNA results were hindered by nuclear insertions (numts) yet 30 sequences of the mitochondrial hypervariable region I (HVI) were obtained and haplogroups identified, which revealed potential differences in the historic distribution of haplogroups than current literature reports.
Genetic analyses confirmed that all the gorillas used in this study were western lowland gorillas. Nuclear analysis based on microsatellites confirmed the paternity of individuals in the contemporary population. Comparisons between the historical population and the captive US population showed that genetic diversity of the UK captive population had been retained at similar levels to historic wild populations and the US captive population, thus concluding that the UK captive population investigated in this research is genetically sustainable for the foreseeable future.


Iván García-Nisa (Durham University) - 

Investigating the contribution of communication to social learning opportunities in Barbary macaques

Social learning refers to the spread of novel behaviours between individuals, often resulting in group-level behavioural traditions, and is important for individual survival. Visual attention is generally biased towards close affiliates and/or dominant individuals in social animals. Therefore, studies on social learning can use affiliative interactions to represent the patterns through which social information may be transmitted. Communication interactions may also represent inadvertent social learning opportunities since they are often described as acts where the receiver extracts information that the sender had no intention to provide. However, the role of communication in social learning studies has been neglected. Here, I used social network analysis, network-based diffusion analysis and permutation-based regression models to explore the role of communication networks in the diffusion of social information. In the first study, three extractive foraging tasks of increasing difficulty were presented to a group of Barbary macaques to investigate social learning. Evidence of social transmission was found only for the most difficult tasks. In a second study, communication networks based on vocalizations produced in affiliative and agonistic contexts were compared to networks based on who observed whom during presentations of the difficult foraging task. Affiliative and observation networks predicted social learning. Communication networks predicted affiliative interactions. Only communication networks based on vocalizations produced in affiliative contexts predicted who observed whom during task introductions. The results suggest that communication networks, which mirror social bonds, may represent social learning opportunities. Integration of communication networks into studies of social learning is a fruitful avenue for further research.

Cécile Sarabian (Kyoto University) - 

From cognition & behavior to infection: primate responses to parasitic threat

Intense selection pressure from parasites on free-living animals results in behavioral adaptations helping potential hosts to avoid sources of infection. In primates, such ‘behavioral immunity’ is expressed in different contexts through a so-called ‘adaptive system of disgust’, and may vary according to the ecology of the host, the nature of the infectious agent, and the individual itself. Taking an interdisciplinary and cross-species perspective, I describe primate responses to parasitic threat through three main questions: (1) which parasite cues do individuals avoid? (2) how may parasitic threats affect cognition? (3) how does variability in the disgust response modulate parasite infection? Using field and lab experiments, behavioral observations and parasitological investigations, our work is revealing that primates avoid biological contaminants through multiple sensory modalities, that the nature of the threat (e.g. disgust-related images of invertebrates, carcasses, and food) impacts cognitive performance differently, and that variation in disgust sensitivity tends to be correlated with parasite infection. Here, I discuss these disparities in light of the ecology of the species but also of individual trade-offs. Finally, I propose a new framework linking the adaptive system of disgust in both people and non-human primates to possible solutions for crop-raiding issues, wildlife tourism practices, and animal entertainment industry-related concerns.

Pooja Dongre (Université de Lausanne)- 

Immigrants trigger novel food acquisition in a wild primate

The entry into and spread of information within social groups is critical for the establishment of population level cultures. We exposed five groups of wild vervet monkeys to a novel food, unshelled peanuts, to investigate who would innovate shelling them and subsequently consume them, and whether this new foraging technique would spread quickly in the groups. We report that, in three of five groups, the innovator was a new immigrant male during these group’ first exposures to peanuts, one of whom had previously acquired the feeding habit in his natal group. In these groups, other individuals, particularly juveniles and low rankers, were significantly more likely to adopt the practice. Moreover, the continued presence of the immigrant across four exposures was necessary for fast transmission of this information to a large proportion of the group. In the other two groups with no new immigrant males, no one innovated at the first exposure. In one of these groups, an infant innovated at the third exposure but the behavior did not spread to many others. This report, on wild primates, of information entering and spreading rapidly in a social group via new immigrants extends our understanding of the potential role of immigrants in transmitting cultural innovations among natural populations. 

Eva Gazagne (L'Université de Liège) 

From the ground to the sky: Habituation, surveys, and areal monitoring technologies in primatological fieldwork

Methods in which we monitor threatened primate populations with minimal human disturbance, resources, manpower, and reduced risk of disease transmission are becoming outstanding requirements for the near future of wildlife research. Although habituation to human observer is widely accepted as the first step toward conducting field research to collect a wide range of eco-ethological data, the process is still poorly documented. We analyzed the habituation process over time in a wild troop of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment of the Sakaerat Biosphere Reserve, Thailand. Based on the number of encounters, contact duration, and behavioral responses to the observer, we found statistical evidence of habituation progress over five stages. The complete habituation process took 13 months and allowed us to assess ranging patterns, foraging strategies, and seed dispersal effectiveness of this vulnerable species. Our study provided an effective methodology to analyze the habituation process across a wide range of primate species and highlighted the pros and cons of habituation. The next step is to discuss alternative monitoring methods with cutting-edge technologies. I will present my postdoctoral project on the description of community structure and spatial organization of seven diurnal endangered primate species which occur in Cat Tien National Park, Vietnam. We will use a combination of systematic thermal imaging drone surveys and standard ground surveys with the aim of comparing detection rates for each primate species and to present a potentially reliable methodology to monitor primate communities in remote or disturbed tropical forests.

Francesca De Petrillo (Institute for Advanced Study of Toulouse) - 

Ecological variation in primate decision-making

Both human and non-human animals face a myriad of choices every day: what food to eat, where to spend their time, and with whom to mate or to interact with. Comparative studies of decision-making have revealed important variability across different species’ decision-making strategies. What governs the variation in decision-making strategies seen across the natural world? To answer this question, I will present a series of comparative studies examining decision-making under risk, probabilistic reasoning, logical inferences and cognitive control in tufted capuchin monkeys, rhesus macaques and lemurs, respectively. The results of these studies suggest that ecological complexity consistently predicts differences across species’ decision strategies and cognitive abilities, thereby highlighting how comparative studies can provide critical insights into the evolutionary contexts that favor some kinds of decision-making strategies over others.

Grégoire Boulinguez-Ambroise (Center for Research and Interdisciplinarity, Paris) - 

Infant-holding: The forgotten behavior in primate developmental and evolutionary studies

Many primate juveniles rely on parental care after birth, namely infant-holding. Actively clinging on the parental fur is often their first main motor experience. Some are carried on the belly, supporting their whole weight, some on the back, other are cradled in the parental arms allowing a strong visual contact with the parent. We can then expect a plural effect of infant-holding on the juvenile: on its prehensile system, on sociality, and brain development. In our study, we compared two primates: the early independent (i.e., not carried) Microcebus murinus and the carried Papio anubis juvenile. We found significant differences regarding their limb motor systems’ ontogenies. Juvenile baboons have very wide phalanges, which can be explained by the fur-grasping grip, involving a close contact between phalanges. Associated to these morphological features, we reported a much higher relative grasping performance than in mouse lemurs. We even found the way young baboons are cradled to strongly induce the lateralization of their limb motor system. When cradled, the infant holds onto the mother’s side with one hand, while the other is free from clinging, receiving different motor and neurological stimulations. Maternal cradling-side bias influences offspring handedness during at least the period juveniles are carried. Furthermore, we found cradling behavior to be left-lateralized at population-level, being related to the right-hemispheric specialization for emotions, thus improving maternal infant’s monitoring (and potentially survival), also promoting social stimulation. Infant holding has been an often-neglected feature when discussing primate evolution, but it requires our full attention for future research.  

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