Chimpanzee chats: Surprising speed and parallels to human speech

Chimpanzees communicate at a pace similar to humans. A new study published in "Current Biology" suggests that the fundamental principles of language could have evolved earlier than previously thought.

During socialisation, chimpanzees exchange gestures rapidly, akin to the human conversation style based on the "question-answer" model. This discovery comes from analysing five wild communities of common chimpanzees (Pan troglodytes) living in East Africa.

Researchers studied 8,559 gestures by 252 chimpanzees, making it one of the most extensive studies. They recorded face-to-face interactions among chimpanzees, noting the time elapsed between the execution of one gesture and the response to it.

The analysis of chimpanzee "conversations" revealed that the time between signals sent by chimpanzees was remarkably close to the time between signals in human interactions—and even slightly shorter. "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 from the University of St Andrews in the United Kingdom, as quoted by "New Scientist".

Although quick responses characterised all the studied chimpanzee communities, the exact reaction time differed depending on the group. For instance, the chimpanzee community in Uganda needed a few milliseconds more to respond than other observed communities.

Reaction time differences are also observed in humans, depending on their language. For example, Japanese speakers typically have a faster exchange style than Danish speakers. "We don't know whether this is a cultural difference, something we learn over time, or a response to the environment," Badihi pondered.

Only 14% of the interactions the team observed among chimpanzees could be described as "extended." Most communication was based on single gestures signalling "go away" or "come with me," and the other participant responded by fleeing or following. However, when the topic of communication was food or grooming each other, the exchange of "questions and answers" lasted longer.

"It shows that other social species don’t need language to engage in close-range communicative exchanges with quick response time. 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," Badihi concluded.