Alba Motes-Rodrigo

Early life experiences have important fitness consequences across animals, with maternal environments playing a crucial role in some species’ survival and reproduction during adulthood. A potential pathway linking maternal behaviour with individual fitness is dominance rank, which in some primates – like cercopithecines – is maternally inherited during the juvenile period and strongly linked to individual social behaviour and reproductive success. While females of these species maintain their rank for life in their natal group, males disperse and must integrate into new dominance hierarchies. In this context, the long-term effects of maternal characteristics on male rank post-dispersal and the potential of males’ social behaviour in mediating this relationship remains unexplored. Using 16 years of data from a wild vervet monkey population ( Chlorocebus pygerythrus ), we tested the effects of maternal rank, grooming and proximity on the rank males acquired their first year post-dispersal. In addition, we measured the extent to which the males’ own social behaviour both pre– and post-dispersal mediate this relationship combining Bayesian social networks with mediation analyses. We did not find support for a mediating effect of males’ social behaviour on the relationship between maternal characteristics and male rank post-dispersal. Instead, we found that maternal characteristics influence males’ social behaviour during the juvenile period and that males’ own social behaviour post-dispersal (grooming out-degree) is related to their rank when they integrate into a new group. In addition, we found that consistency in males’ social behaviour pre-to post-dispersal is restricted to grooming behaviour, highlighting the different roles of proximity and grooming relationships in vervet societies. Taken together these results reveal very limited long-term effects of maternal characteristics on male behaviour during the heavily underexplored process of dispersal and the flexibility of male vervet social behaviour following a change in social environment.

Traditionally, primates have been considered primarily visual animals. However, studies across a variety of taxa suggest that, in the context of food evaluation, reliance on this sense might be more nuanced that previously thought, with dietary specialization and food item properties leading to differences in sensory prioritization. We assessed the use of sensory cues during food evaluation and food-related behaviors such as muzzle contact in two mixed-sex groups of wild vervet monkeys ( Chrorocebus pygerythrus ) over 5 months (N _monkeys = 44). Using 18,868 food evaluation observations collected during 44 hr of focal samples, we found that vervets mainly used their sense of vision when evaluating food (96.8% of all instances). However, the relative usage of each sense varied with food category, and we observed that males used smell for bark inspection more frequently than females. We also found that juveniles used tactile inspection more often than adults. Performance of most food-related behaviors investigated (preparation and rejection) differed significantly according to food type but not between age classes or sexes. In addition, juveniles initiated muzzle contact more often than adults and females received muzzle contact more often than males did. We found overall low rejection rates of food items, suggesting that most food items were familiar to the vervets regardless of age and sex. These findings are in line with optimal foraging theory, according to which the food evaluation process should be adapted to the familiarity of food items, allowing individuals to maximize their intake of energy and critical nutrients, while minimizing the time and effort spent in food evaluation.

In social animals, open wounds pose a risk not only for the injured individual but also for its wider social context, especially when the probability of infection transmission is high. To mitigate this danger, different strategies have evolved across species, with ants representing one of the few taxa beyond humans that engage in social wound care. Yet, who provides this care and what drives care provision remains unexplored. To answer these questions, we combined controlled injury experiments with automated behavioral tracking and simulations across six colonies of the ant Camponotus fellah . Our results demonstrate that caregivers are workers in a transitional state between nursing and foraging roles, characterized by elevated activity and broad nest coverage. Being in this transitional state, however, is required but not sufficient to explain the temporal dynamics of individual care provision. Instead, care provisioning is best explained by preinjury spatial overlap, encounter rates, and social interactions, which together constitute an affinity index that predicts both the frequency and duration of subsequent wound care events. We further show that the treatment of open wounds is not the result of a generalized increase in social behaviors directed to the injured ants but part of a care response toward injuries that also involves an increase in allogrooming. Taken together, our findings reveal the necessary conditions for an individual to act as a caregiver and highlight affinity-driven dyadic interactions as an underexplored mechanism for the behavioral coordination of social immunity strategies in decentralized caste-based insect societies.

Traditionally, primates have been considered primarily visual animals. However, studies across a variety of taxa suggest that, in the context of food evaluation, the reliance on this sense might be more nuanced that previously thought, with dietary specialization and food item properties leading to differences in sensory prioritization. We performed a field-based study assessing the use of sensory cues during food evaluation as well as food-related behaviours such as muzzle contact in two mixed-sex groups of wild vervet monkeys including three age classes over a period of five months (nmonkeys = 44). Using a total of 18868 food evaluation observations collected over 44 hours of focal follows, we found that vervets mainly relied on their sense of vision when evaluating food (96.8% of all instances). Sensory usage varied according to food category and sex differences were only observed in the use of smell for a subset of these. Juveniles initiated muzzle contact and used tactile inspection more often than adults whereas females received muzzle contact more often than males. In addition, the low rejection rates suggest that most food items were familiar to the vervets regardless of age and sex. These findings are in line with optimal foraging theory according to which the food evaluation process should be adapted to the familiarity of food items and allows individuals to maximize their intake of energy and critical nutrients, while minimizing the time and effort in food evaluation.

In group-living animals, open wounds pose a risk not only for the injured individual but also for the entire group, especially when the risk of infection transmission is high. To mitigate this danger, different species have developed diverse strategies – with ants representing one of the few taxa beyond humans that engage in social wound care. Yet, who provides this care and what determines its allocation remains unclear. To answer these questions, we combined controlled injury experiments with automated behavioral tracking across six colonies of the ant Camponotus fellah . Our results reveal that wound care is primarily provided by a non-specialized subset of individuals whose behavioral traits align with a transitional phase between the nurse and forager roles. Among these transitioning ants, care provision was best predicted by their prior spatial and social proximity to the injured individuals in the hours before the injury, indicating that pre-existing social affinity influences caregiving behavior. These findings offer the first empirical evidence of how caregivers are integrated into the colony’s social structure and highlight the role of social interactions in shaping the organization of wound care in ants.

Reliability assessments are a quality control protocol commonly employed in fields of research that deal with video-recorded behavioural data. During these assessments, the same sample of videos is coded (at least) twice by the same researcher (intrarater reliability), or - more often - by two different researchers independently (interrater reliability). Next, levels of agreement are quantified to assess how reliable the behavioural classification is. In this manuscript, we concentrate on interrater reliability, though our points hold generally true for both cases. Despite the importance of interrater reliability assessments to ensure research quality, to the best of our knowledge there is no guideline to date specifying how they should be conducted to avoid potentially detrimental effects of ‘coders’ degrees of freedom’ (CDF) and ‘questionable coder practices’ (QCP). For instance, there is no consensus regarding how large the sample of behaviours evaluated should be, the sample composition, the inclusion of negative controls or what statistical measures should be used to compare the raters’ classifications. To begin to fill this methodological gap, we provide a list of best practices to conduct reliability tests, which we term the BRAVO (Balanced Reliability Assessment of Video Observations) workflow. We complement these recommendations with a series of simulations highlighting the properties of BRAVO and its use-cases. BRAVO represents the first step in creating a methodological gold-standard that researchers can use to perform valid reliability assessments. Given the widespread use of behavioural data across fields, we hope that the BRAVO workflow will be implemented by researchers from a variety of disciplines such as psychology, ethology, behavioural economics, and anthropology to increase quality control and scientific transparency.

The ecological success of social insects makes their colony organization fascinating to scientists studying collective systems. In recent years, the combination of automated behavioural tracking and social network analysis has deepened our understanding of many aspects of colony organization. However, because studies have typically worked with single species, we know little about interspecific variation in network structure. Here, we conduct a comparative network analysis across five ant species from five subfamilies, separated by more than 100 Myr of evolution. We find that social network structure is highly conserved across subfamilies. All species studied form modular networks, with two social communities, a similar distribution of individuals between the two communities, and equivalent mapping of task performance onto the communities. Against this backdrop of organizational similarity, queens of the different species occupied qualitatively distinct network positions. The deep conservation of the two community structure implies that the most fundamental behavioural division of labour in social insects is between workers that stay in the nest to rear brood, and those that leave the nest to forage. This division has parallels across the animal kingdom in systems of biparental care and probably represents the most readily evolvable form of behavioural division of labour.

Humans are one of the most successful species in the planet as we inhabit almost every ecosystem on Earth. This success has been attributed to our cultural proficiency, which allows us to store in the collective minds of our populations complex knowledge that no single individual could innovate on its own. In this way, we acquire most of our behavioural repertoire from experts in our communities and, contrary to any other species, we build upon this collectively-stored information to create novel solutions to face ever-more-challenging problems. This ratcheting of behavioural complexity has led to our culture being coined cumulative. The fact that not even our closest living relatives, the great apes, possess this type of culture begs the question of when did cumulative culture evolve in our lineage. In this piece, I discuss how the field of experimental primate archaeology has contributed to this question by describing several stone-tool experiments conducted with great apes.

Ape knapping experiments complement human knapping experiments as a source of behavioral data to build hypotheses about the learning mechanisms underlying the…

Ant workers are often specialized in specific tasks, and it is well‐established that the main task an ant performs in the colony can be used to predict its sensitivity and responses to task‐associated stimuli. An often‐overlooked aspect of ants' task specialization is that individuals often switch tasks throughout the day and are not always engaged in functional tasks. Furthermore, the tasks individuals engage in are often correlated with other context‐specific factors, such as worker density, which can independently influence individuals' behaviour. Given this intra‐individual variation in task engagement and its correlation with density, it is currently unknown how these two factors interact to modulate ants' sensitivity and responses to stimuli. To address this question, we built a robotic manipulation system that allowed us to teleoperate a dummy inside ant colonies and to provide simulated antennations to ants when performing different tasks in areas with different worker densities. We coupled this manipulation system with a custom‐built automated tracking system (FORT) that allowed us to track individual identities and locations as well as to record the ants' responses to the dummy stimulation. We found independent effects of task and worker density on ants' responsiveness and alarm towards the dummy. Ants were less likely to respond and be alarmed by the dummy when stimulated in areas with high worker density. Responsiveness but not alarm was further influenced by the task being performed, with ants doing broodcare being the least responsive. Our results suggest that ants' behaviour is density‐dependent and that ants experience a process of habituation to tactile stimulation. Additionally, ants' responsiveness is modulated by the task they are performing at a given time, showing that sensitivity to stimuli is context‐dependent. Our robotic set‐up constitutes a valuable tool to systematically investigate social insect behaviour under unprecedented experimental control to unravel the individual‐level behavioural rules that underpin the organization of social insect colonies. The integrated system presented here opens new research avenues to empirically investigate the effects of more complex stimuli on social insect behaviour and has the potential to significantly further our understanding of decentralized collective systems.