Scientists have collected the largest dataset of chimpanzee “conversations” and discovered that chimpanzees communicate through gestures in a rapid back-and-forth pattern, similar to the way people speak and interrupt during conversations. The findings, published on July 22 in the journal Current Biology, shed light on the fascinating communication patterns of our closest relatives.
“While human languages are incredibly diverse, a hallmark we all share is that our conversations are structured with fast-paced turns of just 200 milliseconds on average,” said Catherine Hobaiter at the University of St Andrews, UK. “But it was an open question whether this was uniquely human or if other animals share this structure.”
“We found that the timing of chimpanzee gesture and human conversational turn-taking is similar and very fast, which suggests that similar evolutionary mechanisms are driving these social, communicative interactions,” says Gal Badihi, the study’s first author.
The researchers found that chimpanzee “conversations” follow a similar communicative structure to human conversations despite using gestures instead of speech. They collected data from five wild chimpanzee communities in East Africa, gathering information on over 8,500 gestures from 252 individuals. The timing of turn-taking and conversational patterns were measured, revealing that 14% of communicative interactions involved an exchange of gestures.
The data showed that the timing of chimpanzee conversations resembled human conversations, with short pauses between a gesture and a gestural response lasting about 120 milliseconds.
The delayed behavioral reactions to gestures indicate that these interactions truly resemble human conversations. The researchers state that the gestures produced in response depend on those in the previous turn, emphasizing the genuine nature of these gestural exchanges.
“We did see a little variation among different chimp communities, which again matches what we see in people where there are slight cultural variations in conversation pace: some cultures have slower or faster talkers,” Badihi says.
“Fascinatingly, they seem to share both our universal timing and subtle cultural differences,” says Hobaiter. “In humans, it is the Danish who are ‘slower’ responders, and in Eastern chimpanzees, that’s the Sonso community in Uganda.”
The similarity in face-to-face communication between humans and chimpanzees indicates shared underlying rules in communication, pointing towards common ancestral mechanisms. This suggests that human communication may not be as unique as previously thought. Additionally, the findings hint at similar strategies adopted by chimpanzees and humans to improve coordinated interactions and navigate competition for communicative “space.”
“It shows that other social species don’t need language to engage in close-range communicative exchanges with quick response time,” Badihi says. “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.”
In future studies, the researchers aim to investigate the reasons behind chimpanzees engaging in these conversations in future studies. It is their belief that chimpanzees frequently use gestures to request things from each other.
“We still don’t know when these conversational structures evolved or why!” Hobaiter says. “To get at that question, we need to explore communication in more distantly related species—so that we can work out if these are ape-characteristic or ones that we share with other highly social species, such as elephants or ravens.”
Journal reference:
- Gal Badihi, Kirsty E. Graham, Charlotte Grund, Alexandra Safryghin, Adrian Soldati, Ed Donnellan, Chie Hashimoto, Joseph G. Mine, Alex K. Piel, Fiona Stewart, Katie E. Slocombe, Claudia Wilke, Simon W. Townsend, Klaus Zuberbühler, Chiara Zulberti, Catherine Hobaiter. Chimpanzee gestural exchanges share temporal structure with human language. Current Biology, 2024; DOI: 10.1016/j.cub.2024.06.009
