In a landmark study, researchers have found that chimpanzees have fast-paced, back-to-back gestural exchanges that mirror the rapid conversational give-and-take typical of humans. The implication is now published in Current Biology, thus offering the first inklings to unravel the intricate communication systems that chimpanzees developed as our closest evolutionary cousins.
“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,” explained Catherine Hobaiter of the University of St Andrews, UK. It wanted to determine if this conversational structure in humans was unique to the species, or if it was something that the entire species would resonate with.
To explore this, Hobaiter and her team collected data from five communities of wild chimpanzees in East Africa, consisting of over 8,500 gestures from 252 individual chimpanzees. They found that 14% of communicative interactions contained rapid back-and-forth exchanges of gestures between individuals, and some exchanges went up to seven parts.
The timing of the gestural exchanges was somewhat uncannily like human conversational turn-taking; the pauses were typically around 120 milliseconds. This was coupled with a somewhat slower behavioral responsiveness; again, this further cemented the sense that what was happening was a gestural exchange, one that was contingent on the turn that had just been taken.
“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,” said Gal Badihi, who was the first author of the research.
There were also slight differences among various communities of chimpanzees, similar to cultural in the human conversation rate. For example, the Sonso community of chimpanzees in Uganda took longer to get back, and they are also like the Danish tabled in the human culture.
Interactional parallels between chimpanzees and human communication could entail rule-governed similarities for either common ancestry or the independent evolution of similar strategies to better cope with the pressures of increased coordination and competition over communicative space.
“It shows that other social species don’t need language to engage in close-range communicative exchanges with quick response time,” Badihi noted. This finding has implications in the sense that human communication might take common evolutionary trajectories with other species, confirming that these fast exchanges between the participants are not only limited to humans but are quite common among social animals.
In future work, the researchers will try to determine why the chimpanzees are having these gestural conversations. They suspect that often the intent behind the interactions is to ask each other for something. “We still don’t know when these conversational structures evolved, or why!” Hobaiter said. Future work will examine whether communication in more distantly related species, for example, elephants or ravens, also exhibits these structures.
At the same time, knowledge of the specifics of chimpanzee communication may provide important insight for the researchers into the essential features of social cognition, such as empathy, awareness, and cooperative exchanges. That knowledge would help to fill in certain blanks in the division between human and animal minds, indicating the evolution of language itself.
The implications of the study not only help to increase our understanding of non-human communicative systems but also stimulate reflections on the intricately interwoven tapestries of social interactions that bind both humans and their primate relatives. You might well feel a warm relationship with a chimpanzee the next time you are in conversation at a machine-gun pace.