Abstract: Understanding cooperation between unrelated individuals remains a central problem in animal behaviour; evolutionary mechanisms are debated, and the importance of reciprocity has been questioned. Biological market theory makes specific predictions about the occurrence of reciprocity in social groups; applied to the social grooming of mammals, it predicts reciprocity in the absence of other benefits for which grooming can be exchanged. Considerable effort has been made to test this grooming trade model in nonhuman primates; such studies show mixed results, but may be confounded by kin effects. We examined patterns of reciprocity within and across bouts, and tested predictions of the grooming trade model, among wild male chimpanzees, Pan troglodytes: a system with negligible kin effects. In accord with the model's expectations, we found that some grooming was directed by lower- to higher-ranked individuals, and that, on average, higher-ranked individuals groomed more reciprocally. We found no support, however, for a prediction that more reciprocity should occur between individuals close in rank. For most dyads, reciprocity of effort occurred through unbalanced participation in grooming bouts, but reciprocity varied considerably between dyads and only a small proportion showed strongly reciprocal grooming. Despite this, each male had at least one reciprocal grooming relationship. In bouts where both individuals groomed, effort was matched through mutual grooming, not alternating roles. Our results provide mixed support for the current grooming trade, biological market model, and suggest that it needs to incorporate risks of currency inflation and cheating for species where reciprocity can be achieved through repeated dyadic interactions.

Abstract: We hypothesized that in an open environment, horses cope with a series of challenges in
their interactions with human beings. If the horse is not physically constrained and is free to move
in a small enclosure, it has additional options regarding its behavioral response to the trainer. The
aim of our study was to evaluate the influence of 2 different training strategies on the horse’s behavioral
response to human stimuli. In all, 12 female ponies were randomly divided into the following 2
groups: group A, wherein horses were trained in a small enclosure (where indicators of the level of
attention and behavioral response were used to modulate the training pace and the horse’s control over
its response to the stimuli provided by the trainer) and group B, wherein horses were trained in a closed
environment (in which the trainer’s actions left no room for any behavioral response except for the one
that was requested). Horses’ behavior toward the human subject and their heart rate during 2 standardized
behavioral tests were used to compare the responses of the 2 groups. Results indicated that the
horses in group A appeared to associate human actions with a positive experience, as highlighted by
the greater degree of explorative behavior toward human beings shown by these horses during the tests.
The experience of the horses during training may have resulted in different evaluations of the person, as
a consequence of the human’s actions during training; therefore, it seems that horses evaluate human
beings on daily relationship experiences.

Abstract: Living in complex social systems requires perceptual and cognitive capacities for the recognition of group membership and individual competitors. Olfaction is one means by which this can be achieved. Many animals can identify individual proteins in urine, skin secretions, or saliva by scent. Additionally, marking behaviour in several mammals and especially in horses indicates the importance of sniffing conspecifics’ faeces for olfactory recognition. To test this hypothesis, we conducted two separate experiments: Experiment 1 addressed the question of whether horses can recognise the group membership of other horses by sniffing their faeces. The horses were presented with four faecal samples: (1) their own, (2) those of other members of their own group, (3) those of unfamiliar mares, and (4) those of unfamiliar geldings. Experiment two was designed to assess whether horses can identify the group member from whom a faecal sample came. Here, we presented two groups of horses with faecal samples from their group mates in random distribution. As controls, soil heaps and sheep faecal samples were used. In experiment one, horses distinguished their own from their conspecifics’ faeces, but did not differentiate between familiarity and sex. In experiment two, the horses from both groups paid most attention to the faeces of the horses from which they received the highest amount of aggressive behaviours. We therefore suggest that horses of both sexes can distinguish individual competitors among their group mates by the smell of their faeces.

Abstract: Chimpanzees at Budongo, Uganda, regularly gesture in series, including ‘bouts’ of gesturing that include response waiting and ‘sequences’ of rapid-fire gesturing without pauses. We examined the distribution and correlates of 723 sequences and 504 bouts for clues to the function of multigesture series. Gesturing by older chimpanzees was more likely to be successful, but the success rate of any particular gesture did not vary with signaller age. Rather, older individuals were more likely to choose successful gestures, and these highly successful gestures were more often used singly. These patterns explain why bouts were recorded most in younger animals, whereas older chimpanzees relied more on single gestures: bouts are best interpreted as a consequence of persistence in the face of failure. When at least one gesture of a successful type occurred in a sequence, that sequence was more likely to be successful; overall, however, sequences were less successful than single gestures. We suggest that young chimpanzees use sequences as a ‘fail-safe’ strategy: because they have the innate potential to produce a large and redundant repertoire of gestures but lack knowledge of which of them would be most efficient. Using sequences increases the chance of giving one effective gesture and also allows users to learn the most effective types. As they do so, they need to use sequences less; sequences may remain important for subtle interpersonal adjustment, especially in play. This ‘Repertoire Tuning’ hypothesis explains a number of results previously reported from chimpanzee gesturing.

Abstract: A previously described (Windschnurer et al., 2009) avoidance distance test was used to assess animals’ fear of humans in order to quantify the human–animal relationship (HAR). This study investigated the influence of the dominant and flightiest animals within a group on the responsiveness of animals during the avoidance distance test. Eighty-eight pregnant heifers comprised of four different genotypes were used (22 animals per genotype): Limousin × Holstein-Friesian, Limousin × Simmental, Charolais × Limousin, and Charolais × Simmental. Sixty of the 88 heifers were group housed (n = 5) into 12 pens with 3 pens per breed, while 28 heifers were singly housed (seven heifers per breed). A reactivity test was performed on days 10, 18, 25 and 30 post-housing on the singly housed heifers, and then on the group housed heifers, on the same days, to calculate a reactivity score. On days 33 and 37 flight and dominance tests, respectively, were performed to identify the flightiest and the dominant animal within each group. On day 41, an avoidance test, measuring both the avoidance distance towards a familiar and an unfamiliar human, was performed on all heifers. No difference (P > 0.05) in reactivity scores was found between the genotypes, between pens for the group housed heifers or between singly housed and group housed heifers (P = 0.28). The avoidance distance (AD) of singly (S) housed heifers towards a familiar (F) (ADSF) human was shorter (P < 0.001) than the avoidance distance of group (G) housed heifers towards an unfamiliar human (ADSU). The ADSF and ADGF were correlated with the ADSU and ADGU (R = 0.87 for singly housed heifers; R = 0.61 for group housed heifers, P < 0.001). For the singly housed heifers, no correlation was observed between reactivity score and ADSF (R = 0.36, P = 0.18), whereas the reactivity score and ADSU were correlated (R = 0.68, P = 0.004). For the group housed heifers no significant correlation was detected between the reactivity score and ADGF (R = 0.18, P = 0.22) or ADGU (R = &#8722;0.11, P = 0.39). No influence of the most dominant animal and the flightiest animals was found on the behaviour of the group in term of avoidance distance and reactivity (P > 0.05). It is concluded that the assessment of the fear of the animals towards humans using the avoidance test at the feed bunk may be useful for singly and group housed heifers and that the leaders of a group such as the flightiest animal or the dominant animal did not influence the avoidance distance test.