The Thief in the Mirror

The few animals capable of recognizing themselves in a mirror have advanced social cognition related to adopting the perspective of someone else

With a Little Help from a Friend

In humans, the most commonly assumed motivation behind altruism is empathy. Might this also apply to other animals or are they indifferent to each other's welfare

Peace Lessons from an Unlikely Source

How much is the aggression we observe in nonhuman primates the result of culture, and will the answer provide insights into our own violent behaviour

Cebus Apella Tolerate Intermittent Unreliability in Human Experimenters

Monkeys form expectations for outcomes based on interactions with human experimenters. Not only do they anticipate receiving rewards which the experimenter indicates, but capuchin monkeys, a cooperative new world monkey species, apparently anticipate rewards based on what the experimenter has given to their partner. However, this could be due to subjects responding to either outcomes or experimenters. Here we examine whether capuchin monkeys will continue to interact with human experimenters who are occasionally unreliable. We tested ten monkeys with a series of familiar human experimenters using an exchange task. The experimenters had never before participated in exchange studies with these monkeys, hence the monkeys learned about their behavior during the course of testing. Occasionally experimenters were unreliable, failing to give a reward after the monkey returned the token. We found that monkeys did recognize these interactions as different, responding much more quickly in trials following those which were non-rewarded than in other situations with the same experimenter. However, subjects did not change their preference for experimenters when given the opportunity to choose between the unreliable exchanger and another exchanger, nor did subjects learn to prefer reliable experimenters from watching other monkeys’ interactions. Instead, subjects returned the tokens to the same location from which they received it. These results indicate that capuchin monkeys may not be sensitive to isolated instances in which experimenters are unreliable, possibly because of a strong bias to returning the token to the location from which it was donated

Fairness in Animals: Where to from Here?

In the last decade, there has been an explosion of work investigating non-human species’ behavior as it relates to the human sense of fairness and justice. This work has provided a much-needed evolutionary perspective on humans, and highlighted ways in which humans’ behavior is both similar to and different from that of other species. In this concluding paper, we outline the major threads of the work highlighted in this and the previous special issues of Social Justice Research and provide thoughts on future directions for the field. This is a very exciting time in our exploration of the evolution of human justice and fairness, and we eagerly await the developments of the next decade

Situating the study of jealousy in the context of social relationships

Whereas the feelings of other beings are private and may always remain so, emotions are simultaneously manifested in behavior, physiology, and other observables. Nonetheless, uncertainty about whether emotions can be studied adequately across species has promoted skepticism about their very presence in other parts of the animal kingdom. Studying social emotions like jealousy in the context of the social relationships in which they arise, as has been done in the case of animal empathy, may help dispel this skepticism. Empathy in other species came to be accepted partly because of the behavioral similarities between its expression in nonhuman animals and humans, and partly because of the neurological parallels. Non-invasive brain imaging results like those reported in the target article can thus help integrate human and animal emotions within an evolutionary framework — but the social context underlies precise definitions of the phenomenon

Ingroup-Outgroup Bias in Contagious Yawning by Chimpanzees Supports Link to Empathy

Humans favor others seen as similar to themselves (ingroup) over people seen as different (outgroup), even without explicitly stated bias. Ingroup-outgroup bias extends to involuntary responses, such as empathy for pain. However, empathy biases have not been tested in our close primate relatives. Contagious yawning has been theoretically and empirically linked to empathy. If empathy underlies contagious yawning, we predict that subjects should show an ingroup-outgroup bias by yawning more in response to watching ingroup members yawn than outgroup. Twenty-three chimpanzees (Pan troglodytes) from two separate groups watched videos of familiar and unfamiliar individuals yawning or at rest (control). The chimpanzees yawned more when watching the familiar yawns than the familiar control or the unfamiliar yawns, demonstrating an ingroup-outgroup bias in contagious yawning. These results provide further empirical support that contagious yawning is a measure of empathy, which may be useful for evolutionary biology and mental health