Though research has indicated that the ability to empathize and experience emotions may not be uniquely human, many questions still remain over the extent to which different species are able to "have feelings" or sympathize with others. But according to a new study in the Proceedings of the National Academy of Sciences, Bonobos are capable of recognizing and reacting to pictures of an emotional nature, revealing fascinating insights into their cognitive abilities as well as their social character.

Bonobos fall into the Hominid family, which also includes humans, chimpanzees, orangutans, and gorillas. Due to man’s close evolutionary relationship with these great apes, researchers have often tended to focus on these species when investigating the cognitive and emotional capacities of animals.

Such studies often involve a test known as the dot-probe task, which is a well-established psychological tool for measuring emotional attention, and has previously been used to reveal the ability of chimps to identify the sentimental tone of photographs. During the test, animals are presented with a series of images, some of which are deemed to be neutral while others carry emotional qualities. This picture is then removed and replaced by a simple dot, which the animal must touch in order to receive a treat.

Depending on the reaction time of the animal to the appearance of the dot, researchers can gauge how much attention the subject was paying, and subsequently determine whether emotional images attract more attention than neutral ones.

When conducting the dot-probe task using bonobos, the study authors found that reaction times were much faster when the animals were presented with emotionally charged images of other bonobos, indicating a capacity to empathize with the animals being depicted.

Unlike chimpanzees, however, the bonobos were much more reactive to images displaying "protective and affiliative behaviors," such as grooming, mating, and yawning, than to signs of aggression or distress.

Accounting for this, the researchers suggest that, since bonobos live in large groups and rely on social cohesion for their survival, such behaviors play a pivotal role in bonobo interactions and therefore arouse their emotional attention.

^{Grooming is an important social activity for bonobos. GUDKOV ANDREY/Shutterstock}

Yawning, for instance, has been found to be contagious among bonobos, just as it is for humans, and the mechanism controlling this response is thought to be controlled by the mirror neuron network. These neurons are stimulated when animals observe others performing actions that they associate with themselves, and are therefore associated with higher cognitive empathic functions.

Furthermore, yawning is thought to play an important protective role for bonobos, since it has been shown to cool the brain and thereby increase vigilance. When seeing others yawn, therefore, it is possible that bonobos’ emotional attention is aroused by a recognition of the need for collective protection.

Similarly, both grooming and sexual intercourse carry important emotional significance for bonobos, as they help to foster social ties and bring the group closer together. While sex may be merely functional for most animals, bonobos are thought to be the only species other than humans to engage in face-to-face sex and tongue kissing, suggesting a heightened emotional relevance.

Such findings are very much in keeping with bonobo neuroanatomy. For instance, bonobos have high volumes of grey matter in brain regions called the amygdala and insula, both of which are associated with emotional regulation and the ability to empathize with others. This may help to explain why bonobos appear to be less aggressive and more caring than either humans or chimpanzees, accounting for what the study authors describe as their "soft and friendly character."