We humans are impatient talkers. We quickly take turns in exchanging information and frequently interrupt each other. Chimpanzees do the same, according to a new British study.
The scientists have collected the largest dataset ever of chimpanzee conversations in different locations in East Africa. They found that the communication between the animals is bizarrely similar to our way of speaking. “Although human languages are incredibly diverse, one common feature is that our conversations are structured around rapid transitions, lasting on average just 200 milliseconds,” says researcher Catherine Hobaiter from the University of St Andrews. “The big question was whether this is something unique to humans or whether other animals use this communication structure too.”
The evolution of communication
“We found that the timing of the ‘conversations’ of chimpanzees and humans is similar. In both species, the reaction time is very fast. This strongly suggests that there are similar evolutionary mechanisms driving these social interactions,” says lead researcher Gal Badihi.
Previous studies have shown that human conversations have a similar structure all over the world. The team now wanted to find out whether the same communicative patterns also exist in chimpanzees, even though they communicate through gestures instead of speech. The biologists went on a trip to East Africa to collect a wealth of data from five different chimpanzee groups in the wild.
Data and gestures
In total, the researchers collected data from 252 chimpanzees, who made more than 8,500 gestures. They carefully monitored the timing of turn-taking and the structure of the conversation, and found that 14 percent of the conversations were an exchange of gestures between two chimpanzees. Most of the “conversations” consisted of two parts, but in some communicative interactions, the researchers counted up to seven gesture combinations back and forth.
The apes’ timing was similar to that of humans, with short pauses of about 120 milliseconds between a gesture and its response. Behavioral responses to the gestures were slightly slower. “The similarities with human conversations paint a clear picture: the interactions between the wild chimpanzees are true gestural exchanges, with responses dependent on the gestures of their conversation partners in the preceding turn,” the researchers write.
Slome Denen
“We saw some subtle differences in conversational rhythm between the five chimpanzee communities. That’s something we see in humans too: some cultures have slower or faster talkers,” Badihi explains. “What’s fascinating is that we seem to share both our universal timing and subtle cultural differences with our distant cousins. For example, in humans, it’s the Danes who are quite slow to respond, and in eastern chimpanzees, it’s the Sonso community in Uganda.”
These similarities between human interaction and chimpanzee face-to-face communication, the researchers say, point to shared underlying communication rules that originate from our ancestors. Human communication is therefore not as unique as we previously thought.
Widespread
“This shows that other social species do not need language to exchange information at short distances from each other,” Badihi said. “Human conversations share their evolutionary history with other species. This type of communication is not unique to humans, but appears to be widespread among social animals.”
In future studies, the researchers hope to understand why chimpanzees engage in these conversations in the first place. They believe the animals primarily use gestures to ask each other for things. “We still don’t know when these conversational structures evolved, or why,” Hobaiter says. “To answer that question, we need to study communication in more distantly related species, so we can figure out whether this is a trait of great apes, or something we share with other highly social species, like elephants or ravens.”