There are striking parallels between humans and other primates. We have many things in common with chimpanzees and bonobos, and especially with their social behaviors.
Some of these shared traits are social in nature, such as the capacity for perceiving and responding to the emotions of others. There is one important way in which humans and bonobos differ when it comes to emotional recognition, however: bonobos are more attracted to the emotions of strangers than are humans, as described in a study published in Emotion, a journal of the American Psychological Association.
The study was designed by researchers from Leiden University and the University of Amsterdam to compare human and bonobo reactions to emotionally charged and neutral images, including those of familiar and unfamiliar faces. Researches at the Apenheul Zoo in the Netherlands trained bonobos to look at a screen and press a button to toggle between two images. Both pictures were of bonobos, but one was one they would recognize and the other one they wouldn’t. There was a mix of “neutral” bonobo pictures and bonobo pictures showing emotion. The bonobos were taught to quickly choose an image from each set of images.
An analogous study was conducted on human zoogoers, who were shown two images (one of a stranger and one of someone they visited the zoo with) with expressions conveying different emotions.
Researchers found that both humans and bonobos were drawn to pictures of unfamiliar people whose expressions or actions conveyed strong emotions. Considering how similarly social humans and bonobos are, this wasn’t a huge surprise. The human and ape worlds diverged here, however. Bonobos were more drawn to the emotions of complete strangers, while humans preferred the faces of people they already knew.
The origins of human emotion and the reasons for its distinctiveness from those of our ancestors may be illuminated by these findings. Scientists speculate that it is related to the differences in the environments in which humans and bonobos evolved. There is less strife among bonobos and perhaps more curiosity about outsiders because of the greater stability of their living conditions. Humans, who had previously lived a nomadic lifestyle, have recently begun to retreat inward, towards each other, most likely to ensure their own survival.
Both Eurekalert! and Emotion are good places to start.
