Chimpanzees, our closest living relatives, have been found to communicate with each other in a rapid back-and-forth manner similar to human conversation. A study published in the journal Current Biology analyzed over 8,500 gestures from 252 chimpanzees across five wild communities in East Africa and found that chimpanzees take turns gesturing to each other with pauses averaging around 120 milliseconds, which is faster than the average human conversational reaction time of 200 milliseconds. This suggests that similar evolutionary mechanisms may be driving these social, communicative interactions in both humans and chimpanzees.
The study found that while all chimpanzee communities used quick responses, the exact timing varied from group to group. For example, the Sonso community of chimps in Uganda took a few milliseconds longer to return a gesture than the other chimpanzee communities in the study. This variation is also seen in human languages, with people who speak Japanese generally having a quicker turn-taking conversation style than those who speak Danish.
Most of the interactions were brief, but some extended up to seven different types of gesturing. Only 14% of the interactions observed between chimps included some exchange, while most interactions included a single gesture such as 'get away' or 'come with me'. However, when the chimps were negotiating for food or grooming, back-and-forth exchanges were more common.
The shared traits between human and chimp communication could be traced back to shared ancestral mechanisms. Human conversations may share similar evolutionary history or trajectories to the communication systems of other species, suggesting that this type of communication is not unique to humans but more widespread in social animals.
While there are still many questions to be answered, such as when these conversational structures evolved and why, the study provides evidence that humans and chimpanzees share fundamental features of communication. This suggests that similar evolutionary mechanisms may be driving these social, communicative interactions in both humans and chimpanzees.
