Male-male social bonding, coalitionary support and reproductive success in wild Guinea baboons

Evolutionary biology of social expertise

There is increasing evidence that competent handling of social interactions among conspecifics has positive effects on individual fitness. While individual variation in social competence has been appreciated, the role of long-term experience in the acquisition of superior social skills has received less attention. With the goal of promoting further research, we integrate knowledge across disciplines to assess social expertise, defined as the characteristics, skills and knowledge allowing individuals with extensive social experience to perform significantly better than novices on a given social task. We focus on three categories of social behaviour. First, animals can gain from adjusting social behaviour towards individually recognised conspecifics that they interact with on a regular basis. For example, there is evidence that some territorial animals individually recognise their neighbours and modify their social interactions based on experience with each neighbour. Similarly, individuals in group-living species learn to associate with specific group members based on their expected benefits from such social connections. Individuals have also been found to devote considerable time and effort to learning about the spatial location and timing of sexual receptivity of opposite-sex neighbours to optimise reproduction. Second, signallers can enhance their signals, and receivers can refine their response to signals with experience. In many birds and insects, individuals can produce more consistent signals with experience, and females across a wide taxonomic range can adaptively adjust mating preferences after perceiving distinct male signals. Third, in many species, individuals that succeed in reproducing encounter the novel, complex task of caring for vulnerable offspring. Evidence from a few species of mammals indicates that mothers improve in providing for and protecting their young over successive broods. Finally, for social expertise to evolve, heritable variation in social expertise has to be positively associated with fitness. Heritable variation has been shown in traits contributing to social expertise including social attention, empathy, individual recognition and maternal care. There are currently limited data associating social expertise with fitness, most likely owing to sparse research effort. Exceptions include maternal care, signal refinement, and familiarity with neighbours and group members. Overall, there is evidence that individuals in many species keep refining their social skills with experience throughout life. Hence we propose promising lines of research that can quantify more thoroughly the development of social expertise and its effects on fitness.

Compromise or choose: shared movement decisions in wild vulturine guineafowl

Shared-decision making is beneficial for the maintenance of group-living. However, little is known about whether consensus decision-making follows similar processes across different species. Addressing this question requires robust quantification of how individuals move relative to each other. Here we use high-resolution GPS-tracking of two vulturine guineafowl (Acryllium vulturinum) groups to test the predictions from a classic theoretical model of collective motion. We show that, in both groups, all individuals can successfully initiate directional movements, although males are more likely to be followed than females. When multiple group members initiate simultaneously, follower decisions depend on directional agreement, with followers compromising directions if the difference between them is small or choosing the majority direction if the difference is large. By aligning with model predictions and replicating the findings of a previous field study on olive baboons (Papio anubis), our results suggest that a common process governs collective decision-making in moving animal groups.