Chimpanzees exchange gestures as rapidly as human conversations

When people are talking, they take turns talking and sometimes they interrupt. Now, researchers who have collected the largest ever dataset of chimpanzee “conversations” have found that they communicate back and forth using gestures following the same rapid-fire pattern. The findings are reported July 22 in the journal Current Biology.

“While human languages ​​are incredibly diverse, one hallmark we all share is that our conversations are structured with quick turns of just 200 milliseconds on average,” said Catherine Hobaiter.@NakedPrimate) at the University of St Andrews, UK. “But it was an open question whether this was uniquely human, or whether other animals share this structure.”

“We found that chimpanzee gesture and human conversational turn times are similar and very fast, suggesting that similar evolutionary mechanisms are driving these social, communicative interactions,” says Gal Badihi (@Gal_Badihi), author of first of the study.

Researchers knew that human conversations follow a similar pattern among people living in countries and cultures around the world. They wanted to know if the same communication structure exists in chimpanzees even though they communicate through gestures rather than speech. To find out, they collected data on chimpanzee “conversations” in five wild communities in East Africa.

In total, they collected data on more than 8,500 gestures for 252 individuals. They measured turn-taking times and conversational patterns. They found that 14% of communicative interactions involved an exchange of gestures between two interacting individuals. Most exchanges involved a two-part exchange, but some involved up to seven parts.

Overall, the data reveals a timing similar to human conversation, with short pauses between a gesture and a gestural response at around 120 milliseconds. Behavioral responses to gestures were slower. “The similarities to human conversations reinforce the description of these interactions as true gestural exchanges, in which the gestures produced in response are dependent on those of the previous sequence,” the researchers write.

“We saw little variation between different chimpanzee communities, which again matches what we see in humans where there are small cultural differences in the pace of conversation: some cultures have slower or faster speakers,” says Badihi.

“Fascinatingly, they seem to share our universal time and subtle cultural differences,” says Hobaiter. “In humans, it’s the Danes who respond ‘slowest’, and in eastern chimpanzees it’s the Sonso community in Uganda.”

This correspondence between human and chimpanzee face-to-face communication points to shared basic rules in communication, the researchers say. They note that these structures can be traced back to common ancestral mechanisms. It is also possible that chimpanzees and humans have evolved similar strategies to improve coordinated interactions and manage competition for communicative “space.” The findings suggest that human communication may not be as unique as one might think.

“This shows that other social species do not need language to engage in close communicative exchanges with fast reaction times,” says Badihi. “Human conversations may share similar evolutionary histories or trajectories with the communication systems of other species, suggesting that this type of communication is not unique to humans, but more widespread in social animals.”

In future studies, the researchers say they want to explore why chimpanzees have these conversations in the first place. They think that chimpanzees often rely on gestures to ask for something from each other.

“We still don’t know when these conversational structures evolved, or why!” Hobaiter says. “To get at this question, we need to explore communication in more closely related species – so we can understand whether these are a characteristic of apes, or ones we share with other highly social species, such as elephants or ravens. “