Abstract: The hypothesis that the enlarged brain size of the primates was selected for by social, rather than purely ecological, factors has been strongly influential in studies of primate cognition and behaviour over the past two decades. However, the Machiavellian intelligence hypothesis, also known as the social brain hypothesis, tends to emphasize certain traits and behaviours, like exploitation and deception, at the expense of others, such as tolerance and behavioural coordination, and therefore presents only one view of how social life may shape cognition. This review outlines work from other relevant disciplines, including evolutionary economics, cognitive science and neurophysiology, to illustrate how these can be used to build a more general theoretical framework, incorporating notions of embodied and distributed cognition, in which to situate questions concerning the evolution of primate social cognition.

Abstract: Primates give alarm calls in response to the presence of predators. In some species, such as the Thomas langur (Presbytis thomasi), males only emit alarm calls if there is an audience. An unanswered question is whether the audience's behaviour influences how long the male will continue his alarm calling. We tested three hypotheses that might explain the alarm calling duration of male Thomas langurs: the fatigue, group size and group member behaviour hypotheses. Fatigue and group size did not influence male alarm calling duration. We found that males only ceased calling shortly after all individuals in his group had given at least one alarm call. This shows that males keep track of and thus remember which group members have called.

Abstract: When humans are asked to evaluate rewards or outcomes that follow unpleasant (e.g., high-effort) events, they often assign higher value to that reward. This phenomenon has been referred to as cognitive dissonance or justification of effort. There is now evidence that a similar phenomenon can be found in nonhuman animals. When demonstrated in animals, however, it has been attributed to contrast between the unpleasant high effort and the conditioned stimulus for food. In the present experiment, we asked whether an analogous effect could be found in humans under conditions similar to those found in animals. Adult humans were trained to discriminate between shapes that followed a high-effort versus a low-effort response. In test, participants were found to prefer shapes that followed the high-effort response in training. These results suggest the possibility that contrast effects of the sort extensively studied in animals may play a role in cognitive dissonance and other related phenomena in humans.

Abstract: The long-held belief that human dominance and equine submission are key to successful training and that the horse must be taught to [`]respect' the trainer infers that force is often used during training. Many horses respond by trialling unwelcome evasions, resistances and flight responses, which readily become established. When unable to cope with problem behaviours, some handlers in the past might have been encouraged to use harsh methods or devices while others may have called in a so-called [`]good horseman' or [`]horse whisperer' to remediate the horse. Frequently, the approaches such practitioners offer could not be applied by the horse's owner or trainer because of their lack of understanding or inability to apply the techniques. Often it seemed that these [`]horse-people' had magical ways with horses (e.g., they only had to whisper to them) that achieved impressive results although they had little motivation to divulge their techniques. As we begin to appreciate how to communicate with horses sensitively and consistently, misunderstandings and misinterpretations by horse and trainer should become less common. Recent studies have begun to reveal what comprises the simplest, most humane and most effective mechanisms in horse training and these advances are being matched by greater sharing of knowledge among practitioners. Indeed, various practitioners of what is referred to here as [`]natural horsemanship' now use techniques similar to the [`]whisperers' of old, but they are more open about their methods. Reputable horse trainers using natural horsemanship approaches are talented observers of horse behaviour and respond consistently and swiftly to the horse's subtle cues during training. For example, in the roundpen these trainers apply an aversive stimulus to prompt a flight response and then, when the horse slows down, moves toward them, or offers space-reducing affiliative signals, the trainer immediately modifies his/her agonistic signals, thus negatively reinforcing the desired response. Learning theory and equine ethology, the fundamentals of the emerging discipline of equitation science, can be used to explain almost all the behaviour modification that goes on in these contexts and in conventional horsemanship. By measuring and evaluating what works and what does not, equitation science has the potential to have a unifying effect on traditional practices and developing branches of equitation.

Abstract: Planning for future needs, not just current ones, is one of the most formidable human cognitive achievements. Whether this skill is a uniquely human adaptation is a controversial issue. In a study we conducted, bonobos and orangutans selected, transported, and saved appropriate tools above baseline levels to use them 1 hour later (experiment 1). Experiment 2 extended these results to a 14-hour delay between collecting and using the tools. Experiment 3 showed that seeing the apparatus during tool selection was not necessary to succeed. These findings suggest that the precursor skills for planning for the future evolved in great apes before 14 million years ago, when all extant great ape species shared a common ancestor.