Innovation is the ability to solve novel problems or find novel solutions to familiar problems, and it is known to affect fitness in both human and non-human animals. In primates, innovation has been mostly studied in captivity, although differences in living conditions may affect individuals' ability to innovate. Here, we tested innovation in a wild group of Barbary macaques (Macaca sylvanus). In four different conditions, we presented the group with several identical foraging boxes containing food. To understand which individual characteristics and behavioural strategies best predicted innovation rate, we measured the identity of the individuals manipulating the boxes and retrieving the food, and their behaviour during the task. Our results showed that success in the novel task was mainly affected by the experimental contingencies and the behavioural strategies used during the task. Individuals were more successful in the 1-step conditions, if they participated in more trials, showed little latency to approach the boxes and mainly manipulated functional parts of the box. In contrast, we found no effect of inhibition, social facilitation and individual characteristics like sex, age, rank, centrality, neophobia and reaction to humans, on the individuals' ability to innovate. Innovation has been defined as the solution to a novel problem, or the novel solution to a familiar problem 1,2. In humans, the ability to innovate and socially transmit innovations has been crucial through evolution, allowing us to reach a unique level of behavioural and cultural complexity 3,4. However, innovation also provides a variety of benefits to other animals, allowing them to develop novel responses against predators, exploit novel resources and invade new niches 1,5-15. By allowing individuals to better cope with novel socio-ecological challenges, innovation is thought to provide direct fitness benefits, especially in dynamic environments 1,2,9,10,12,13,16,17 The ability to innovate is therefore widespread across taxa. Several species of birds, fish, carnivores and rodents, just to name a few, show evidence of innovation 2,18,19 for reviews. Studies in captivity have also shown that some primate species are excellent problem-solvers 20-27. Great apes, for instance, can use several new solutions to extract food from a container, inhibiting old strategies when they become inefficient 24. When presented with a novel foraging task, great apes could successfully move food through a maze, planning up to two steps ahead to avoid food falling into traps 28. Even lemurs (Varecia spp.) and callitrichid monkeys (Leontopithecus spp., Saguinus spp., Callithrix spp.), who are phylogenetically more distant from humans and have relatively small brain sizes 29 , can solve novel foraging tasks by retrieving food from different containers 21. Apart from inter-specific differences, there are also several intra-specific differences in terms of innovation. Traditionally, these differences have been explained by the Innovation by Necessity and the Free T...

Neophobia (the fearful reaction to novel stimuli or situations) has a crucial effect on individual fitness and can vary within and across species. However, the factors predicting this variation are still unclear. In this study, we assessed whether individual characteristics (rank, social integration, sex) and species socio-ecological characteristics (dietary breadth, group size, domestication) predicted variation in neophobia. For this purpose, we conducted behavioral observations and experimental tests on 78 captive individuals belonging to 10 different ungulate species—an ideal taxon to study inter-specific variation in neophobia given their variety in socio-ecological characteristics. Individuals were tested in their social groups by providing them with familiar food, half of which had been positioned close to a novel object. We monitored the individual latency to approach and eat food and the proportion of time spent in its proximity. Using a phylogenetic approach and social network analyses, we showed that across ungulate species neophobia was higher in socially more integrated individuals, as compared to less integrated ones. In contrast, rank and sex did not predict inter-individual differences in neophobia. Moreover, species differed in their levels of neophobia, with Barbary sheep being on average less neophobic than all the other study species. As group size in Barbary sheep was larger than in all the other study species, these results support the hypothesis that larger group size predicts lower levels of neophobia, and confirm ungulates as a highly promising taxon to study animal behavior and cognition with a comparative perspective. Significance statement In several species, individuals may respond fearfully to novel stimuli, therefore reducing the risks they may face. However, it is yet unclear if certain individuals or species respond more fearfully to novelty. Here, we provided food to 78 individual ungulates with different characteristics (e.g., sex, rank, social integration, group size, domestication, dietary breadth) in different controlled conditions (e.g., when food was close to novel or to familiar objects). Across species, we found that socially integrated individuals responded more fearfully in all species. Moreover, being in larger groups decreased the probability of fearfully responding to novelty.

The ability to discriminate between sets that differ in the number of elements can be useful in different contexts and may have survival and fitness consequences. As such, numerical/quantity discrimination has been demonstrated in a diversity of animal species. In the laboratory, this ability has been analyzed, for example, using binary choice tests. Furthermore, when the different number of items first presented to the subjects are subsequently obscured, i.e., are not visible at the moment of making a choice, the task requires memory for the size of the sets. In previous work, angelfish (Pterophyllum scalare) have been found to be able to discriminate shoals differing in the number of shoal members both in the small (less than 4) and the large (4 or more) number range, and they were able to perform well even when a short memory retention interval (2-15 s) was imposed. In the current study, we increased the retention interval to 30 s during which the shoals to choose between were obscured, and investigated whether angelfish could show preference for the larger shoal they saw before this interval. Subjects were faced with a discrimination between numerically small shoals (≤4 fish) and also between numerically large (≥4 fish) shoals of conspecifics. We found angelfish not to be able to remember the location of larger versus smaller shoals in the small number range, but to exhibit significant memory for the larger shoal in the large number range as long as the ratio between these shoals was at least 2:1. These results, together with prior findings, suggest the existence of two separate quantity estimation systems, the object file system for small number of items that does not work with the longer retention interval and the analogue magnitude system for larger number of items that does.

Primates live in complex social systems with social structures ranging from more to less despotic. In less despotic species, dominance might impose fewer constraints on social choices, tolerance is greater than in despotic species and subordinates may have little need to include novel food items in the diet (i.e. neophilia), as contest food competition is lower and resources more equally distributed across group members. Here, we used macaques as a model to assess whether different dominance styles predict differences in neophilia and social tolerance over food. We provided familiar and novel food to 4 groups of wild macaques (N = 131) with different dominance styles (Macaca fuscata, M. fascicularis, M. sylvanus, M. maura). Our study revealed inter- and intra-specific differences in individuals’ access to food, which only partially reflected the dominance styles of the study subjects. Contrary to our prediction, social tolerance over food was higher in more despotic species than in less despotic species. Individuals with a higher dominance rank and being better socially integrated (i.e. higher Eigenvector centrality) were more likely to retrieve food in all species, regardless of their dominance style. Partially in line with our predictions, less integrated individuals more likely overcame neophobia (as compared to more integrated ones), but only in species with more tolerance over food. Our study suggests that individual characteristics (e.g. social integration or personality) other than dominance rank may have a stronger effect on an individual’s access to resources.

Although behavior, biology, and ecology of giraffes have been widely studied, little is known about their cognition. Giraffes' feeding ecology and their fission-fusion social dynamics are comparable with those of chimpanzees (Pan troglodytes), suggesting that they might have complex cognitive abilities. To assess this, we tested 6 captive giraffes on their object permanence, short-term memory, and ability to use acoustic cues to locate food. First, we tested whether giraffes understand that objects continue to exist even when they are out of sight. Giraffes saw one of two opaque containers containing food, then containers were closed, and 2 s later giraffes could choose one. Second, we measured giraffes' memory repeating the procedure but with a delay of 30 s, 60 s, or 2 min between closing the containers and subjects' choice. Finally, we investigated whether giraffes could locate food inside one of two identical opaque containers, when the only cue provided was the sound made by food when shaking the baited container, or the lack of sound when shaking the empty container. Our results show that giraffes form mental representations of completely hidden objects, but may not store them for longer than 30 s. Moreover, they rely on stimulus enhancement rather than acoustic cues to locate food, when no visual cues are provided. Finally, we argue that giraffes and other ungulates might be a suitable model to investigate the evolution of complex cognitive abilities from a comparative perspective.