Abstract: Variation in methods and measures, resulting in past dispute over the existence of population handedness in nonhuman great apes, has impeded progress into the origins of human right-handedness and how it relates to the human hallmark of language. Pooling evidence from behavioral studies, neuroimaging and neuroanatomy, we evaluate data on manual and cerebral laterality in humans and other apes engaged in a range of manipulative tasks and in gestural communication. A simplistic human/animal partition is no longer tenable, and we review four (nonexclusive) possible drivers for the origin of population-level right-handedness: skilled manipulative activity, as in tool use; communicative gestures; organizational complexity of action, in particular hierarchical structure; and the role of intentionality in goal-directed action. Fully testing these hypotheses will require developmental and evolutionary evidence as well as modern neuroimaging data.

Abstract: The present study investigated the influence of temperament on long-term recall and extinction of 2 instrumental tasks in 26 horses. In the first task (backward task), horses learned to walk backward, using commands given by an experimenter, in order to obtain a food reward. In the second task (active avoidance task), horses had to cross an obstacle after a bell rang in order to avoid emission of an air puff. Twenty-two months after acquisition, horses exhibited perfect recall performance in both tasks. Accordingly, no influence of temperament on recall performance could be observed for either task. In contrast, in the absence of positive or negative outcomes, the horses’ ability to extinguish their response to either task was highly variable. Resistance to extinction was related to some indicators of temperament: The most fearful horses tended to be the most resistant to extinction in the backward task, while the least sensitive horses tended to be the most resistant to extinction in the active avoidance task. These findings reveal extensive long-term memory abilities in horses and suggest an influence of temperament on learning processes other than acquisition.

Abstract: Despite the importance of individual problem solvers for group- and individual-level fitness, the correlates of individual problem-solving success are still an open topic of investigation. In addition to demographic factors, such as age or sex, certain personality dimensions have also been revealed as reliable correlates of problem-solving by animals. Such correlates, however, have been little-studied in chimpanzees. To empirically test the influence of age, sex, estrous state, and different personality factors on chimpanzee problem-solving, we individually tested 36 captive chimpanzees with two novel foraging puzzles. We included both female (N = 24) and male (N = 12) adult chimpanzees (aged 14–47 years) in our sample. We also controlled for the females’ estrous state—a potential influence on cognitive reasoning—by testing cycling females both when their sexual swelling was maximally tumescent (associated with the luteinizing hormone surge of a female’s estrous cycle) and again when it was detumescent. Although we found no correlation between the chimpanzees’ success with either puzzle and their age or sex, the chimpanzees’ personality ratings did correlate with responses to the novel foraging puzzles. Specifically, male chimpanzees that were rated highly on the factors Methodical, Openness (to experience), and Dominance spent longer interacting with the puzzles. There was also a positive relationship between the latency of females to begin interacting with the two tasks and their rating on the factor Reactivity/Undependability. No other significant correlations were found, but we report tentative evidence for increased problem-solving success by the females when they had detumescent estrous swellings.

Abstract: Pair and social bonding has been documented in various taxa, where pair formations are often described as being driven by kinship or sexual motivation. However, pair-bonding between unrelated individuals where sexual motivation is not a factor is not well documented. Many social relationships and pair-bonds between members of a dyad are facilitated by each individual's ability to recognise their partner using cues which are characteristic of that particular individual. The aims of this study were i) to investigate the existence of pair-bonding in domestic donkeys and ii) to determine whether members of a dyad could recognise their companion during a Y-maze recognition test. Subjects were 55 unrelated donkeys (38 gelded males, 15 females) in seven groups of mixed or same sex, comprising 4?14 individuals. Spatial proximity (nearest-neighbour) was observed three times a day over a 22-day period. Using a simulation approach based on observed data to generate randomised nearest-neighbour matrices, the statistical significance of social relationships was estimated. Of these, 42 (79.2%) were involved in significantly (p<0.05) non-random nearest-neighbour relationships, most of which were reciprocal pair relationships. Based on the spatial data, 24 of the donkeys which had shown significant reciprocal nearest-neighbour preferences for one individual (companion) were then used in a Y-maze recognition test in which they were presented with a choice of their companion and either a familiar donkey from the same group or an unfamiliar donkey from a different group. Donkeys? spatial location in the Y-maze demonstrated a preference for their companion versus familiar (one sample Wilcoxon signed rank test, W=239, p=0.002) or unfamiliar donkeys (W=222, p=0.041). These results verify anecdotal evidence from donkey handlers that donkeys often form pair-bonds, and show that reciprocal social preference and recognition are the basis of these. Pair-bond formation and companionship among donkeys have potential implications for their management, husbandry and welfare.

Abstract: Childhood trauma, abuse or neglect impacts the function and structure of the brain of affected children. Attunement with other beings as well as an enriched environment can contribute to normal brain development. The enriched environment of a barn and attunement with an animal may contribute to reductions in stress for traumatised children. A pilot study, using a multiple base line, single case design included four children with post-traumatic stress syndrome (aged eight to ten years) and four therapy riding horses. This study hypothesised that cortisol would correlate between each child?horse pair, using a 12-day intervention that included six consecutive days of riding and grooming. A meta-analysis was completed of correlation levels of four child?horse pairs The weighted mean cross-correlation, controlling for autocorrelation, was 0.23, Z?=?3.03, approximate 95% confidence interval 0.23?±?(1.96???0.076) or 0.08 to 0.38. The data suggest a need for further research.