Communication in chimpanzees is given new perspective

Chimpanzee vocalization article image
Image: Getty Images

Humans have an uncanny ability to view the world from each other’s perspectives. The fact that we often choose not to is irrelevant for the sake of this article. While this ability is considered to be a uniquely human characteristic, a new study on chimpanzees shows that may not be the case.

A paper published in the journal Science Advances reveals that chimpanzees change how they communicate depending on each other’s perspectives. In particular, the chimpanzees studied would change how they alerted others of a potential threat depending on the others’ awareness of the threat. This marks the first time an animal other than humans has been observed adjusting how they communicate based on another’s perspective.

Previous studies have shown how advanced chimpanzee communication can be. For example, if there is a potential threat a chimpanzee may send out an alert call, warning the other chimpanzees to retreat to safety. Upon noticing that the others are out of danger, the chimpanzee making the alert call will stop.

These previous studies, however, were unable to control for behavioral cues which left an unanswered question; did the chimpanzee stop alerting the others because they had climbed to safety or because it assumed the others had recognized the threat? These two possibilities may seem similar, but they have very different implications. While the former is reactionary, based on behavioral cues, the latter would imply that chimpanzees are capable of taking on another’s perception of the world around them.

To control for behavioral clues in this new study, Catherine Crockford and her team at the Max Planck Institute for Evolutionary Anthropology came up with an ingenious experimental design.

The researchers hid a taxidermy snake model on a path that was frequently traveled by chimpanzees. As a chimpanzee approached the snake model, a nearby speaker would mimic a “second chimpanzee” by emitting either an alert call or rest call. The researchers would then see how the chimpanzee reacted upon seeing the snake model.

experimental design chimp vocalization
The experimental design used for the study. The thicker the arrow, the more attention the chimpanzee directed towards that stimulus. The speech bubbles represent the frequency of the chimpanzee call. Image: Crockford et. al.

Remarkably, when the alert call was used the chimpanzees spent less time warning the speaker than when the rest call was emitted. Therefore, the chimpanzees were able to assess the threat that the snake model posed to the “second chimpanzee” and react accordingly.

While chimpanzee communication is still far simpler than that of humans, this study shows it is much more complex than previously thought. Furthermore, these results imply that the ability to view the world from one another’s perspectives may have started well before humans evolved. It seems like this uniquely human trait may not be so unique after all.