Abstract: The value of age is well recognized in human societies, where older individuals often emerge as leaders in tasks requiring specialized knowledge, but what part do such individuals play in other social species? Despite growing interest in how effective leadership might be achieved in animal social systems, the specific role that older leaders may play in decision-making has rarely been experimentally investigated. Here, we use a novel playback paradigm to demonstrate that in African elephants (Loxodonta africana), age affects the ability of matriarchs to make ecologically relevant decisions in a domain critical to survival—the assessment of predatory threat. While groups consistently adjust their defensive behaviour to the greater threat of three roaring lions versus one, families with younger matriarchs typically under-react to roars from male lions despite the severe danger they represent. Sensitivity to this key threat increases with matriarch age and is greatest for the oldest matriarchs, who are likely to have accumulated the most experience. Our study provides the first empirical evidence that individuals within a social group may derive significant benefits from the influence of an older leader because of their enhanced ability to make crucial decisions about predatory threat, generating important insights into selection for longevity in cognitively advanced social mammals.

Abstract: Chimpanzees (Pan troglodytes) sometimes help both humans and conspecifics in experimental situations in which immediate selfish benefits can be ruled out. However, in several experiments, chimpanzees have not provided food to a conspecific even when it would cost them nothing, leading to the hypothesis that prosociality in the food-provisioning context is a derived trait in humans. Here, we show that chimpanzees help conspecifics obtain both food and non-food items—given that the donor cannot get the food herself. Furthermore, we show that the key factor eliciting chimpanzees' targeted helping is the recipients' attempts to either get the food or get the attention of the potential donor. The current findings add to the accumulating body of evidence that humans and chimpanzees share the motivation and skills necessary to help others in situations in which they cannot selfishly benefit. Humans, however, show prosocial motives more readily and in a wider range of contexts.

Abstract: Even though the term “stress” is widely used, a precise definition is notoriously difficult. Notwithstanding this difficulty, stress continues to be an important concept in biology because it attempts to describe how animals cope with environmental change under emergency conditions. Without a precise definition, however, it becomes nearly impossible to make testable a priori predictions about how physiological and hormonal systems will respond to emergency conditions and what the ultimate impact on the animal will be. The reactive scope model is a recent attempt to formulate testable predictions. This model provides a physiological basis to explain why corticosterone negative feedback, but not baseline corticosterone concentrations, corticosterone responses to acute stress, or the interrenal capacity to secrete corticosterone, is correlated with survival during famine conditions in Galápagos marine iguanas. Reactive scope thus provides a foundation for interpreting and predicting physiological stress responses.

Abstract: Current definitions of horse personality traits are rather vague, lacking clear, universally accepted guidelines for evaluation in performance tests. Therefore, the aim of the present study was to screen behavioural and physiological measurements taken during riding for potential links with scores the same horses received in the official stallion performance test for rideability and personality traits. Behaviour, heart rate (HR) and HR variability from thirty-six stallions participating in a performance test were recorded repeatedly during their performance test training. Using the coefficient of determination, regression analysis revealed that about 1/3 of variation (ranging between r = 0.26 (“constitution” (i.e. fitness, health)) and r = 0.46 (rideability)) in the personality trait scores could be explained by selecting the three most influential behaviour patterns per trait. These behaviour patterns included stumbling (with all traits except character), head-tossing (temperament, rideability), tail-swishing (willingness to work), involuntary change in gait (character) and the rider's use of her/his hands (constitution, rideability), voice (temperament) or whip (constitution). Subsequent mixed model analysis revealed a significant (P < 0.05) influence of the behaviour pattern “horse-induced change in gait” on character (-0.98 ± 0.31 scores per additional occurrence of change in gaits), of head-tossing (-0.25 ± 0.08 scores) and rider's use of voice (-0.51 ± 0.25; P = 0.0594) on temperament, and of stumbling on each of the following: willingness to work (-2.5 ± 1.2), constitution (-2.5 ± 1.2 scores; P = 0.0516) and rideability scores (-3.3 ± 1.4). In addition, constitution scores tended (P = 0.0889) to increase with higher low frequency/high frequency heart rate variation ratios (LF/HF), indicating a shift towards sympathetic dominance and thus a higher stress load in horses with higher scores for constitution. Rideability scores from the training phase were also significantly influenced by head-tossing (-0.5 ± 0.1), and in addition rideability scores from the final test were influenced by the training rider, ranging between average estimated rideability scores of 6.8 ± 0.4 for one training rider and 8.36 ± 0.3 scores for another training rider. Horses ridden with their nose-line predominantly behind the vertical received higher scores for rideability (8.3 ± 0.3) than horses ridden with their nose-line at the vertical (7.7 ± 0.2). These findings indicate that either judges perceive horses to have a better rideability when they readily offer a more extreme poll flexion, or that riders make use of horses’ better rideability by imposing a more extreme poll flexion. Several of the above described associations, but also of the non-existing links (e.g. no association between shying or heart rate and temperament) between behaviour patterns and scores for personality traits are rather surprising, warranting further investigation regarding the underlying causes of these relationships. Some of these behaviour patterns should be considered when redesigning the current guidelines for evaluation of personality traits during breeding horse performance tests, ultimately leading to improved genetic selection for equine personality traits. However, ethical implication of defining aversive behaviour such as head-tossing as an indicator of, for example, poor temperament, should not be neglected when devising new guidelines: such aversive behaviour may in fact be an indication of inadequate training techniques rather than poor horse personality.

Abstract: Summary
Many animals are lateralized when using sensory organs such as the eyes, ears or nostrils. Sensory laterality is not, as previously believed, caused by adjustment to motor laterality, but rather by one sided information processing in the particular brain hemi-spheres. While the right hemisphere predominantly analyses emotional information, the left hemisphere governs controlled rational, cognitive decisions. Since the brain hemi-spheres are largely connected with contralateral sensory organs, it is possible to infer how the information may be being interpreted by the side of preferred eye, ear or nostril used. The left eye usually dominates in emotional situations, i.e. fear or positive ex-citement, and the right eye in rational situations. Moreover, laterality increases when animals are stressed, e.g. when animals are confronted with anthropogenic or natural factors they can not handle, such as unsuitable housing or training conditions or un-avoidable predation pressure and social competition. A strong or increasing laterality could therefore potentially indicate welfare issues.
Zusammenfassung
Viele Tiere zeigen eine eindeutige sensorische Lateralität, sprich sie benutzen bevor-zugt ein Auge, ein Ohr, oder eine Nüster zur Aufnahme von Sinneseindrücken. Dies korreliert in den meisten Fällen nicht mit der motorischen Lateralität, sondern wird viel mehr durch die einseitige Verarbeitung von Informationen in den jeweiligen Gehirnhe-misphären bedingt. So werden emotionale Reaktionen von der rechten, reaktiven Ge-hirnhemisphäre und rationale Reaktionen von der linken, kognitiven Gehirnhemisphäre gesteuert. Da die Gehirnhälften zum Großen Teil mit den kontrolateralen Sinnesorga-nen verbunden sind lässt die Seite mit welcher Sinneseindrücke aufgenommen werden Schlüsse auf deren Informationsgehalt zu. So zeigen Tiere bei linksseitiger Aufnahme von Sinneseindrücken vermehrt reaktive, emotionalen Reaktionen, wie etwa bei Angst oder freudige Erregung, und bei rechtsseitig aufgenommene Sinneseindrücke eher rationales, gesteuertes Verhalten. Zudem verstärkt sich die sensorische Lateralität wenn Tiere Stress erfahren, sprich wenn sie wiederholt mit Situationen anthropogenen oder natürlichen Ursprungs konfrontiert werden denen sie nicht gewachsen sind, wie etwa bei unpassenden Haltungs- und Trainingsbedingungen, oder bei unausweichli-chem Raubtierdruck und sozialer Konkurrenz. Eine stark ausgeprägte, zunehmende sensorische Lateralität kann daher auf ein beeinträchtigtes Wohlergehen der Tiere hinweisen.