Chimps chat like humans: Rapid fire gestures reveal early language

During socialization, chimpanzees exchange gestures at a rapid rate, which is similar to the human conversation style based on the "question-answer" model. This discovery comes from analyzing five wild communities of common chimpanzees (Pan troglodytes) living in East Africa.

Researchers considered 8,559 gestures made by 252 chimpanzees, making it one of the largest studies of its kind. They recorded face-to-face interactions among the animals and noted the time that elapsed between the execution of one gesture and the response to it.

The analysis of chimpanzee "conversations" showed that the time between the signals sent by chimpanzees closely matches the time between signals in human interactions—sometimes even 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 characterized all the studied chimpanzee communities, the exact reaction time differed depending on the group. For example, 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 instance, 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 percent of the team's interactions among chimpanzees could be described as "extended." Most communication was based on single gestures signaling "go away" or "come with me," to which the other participant responded by fleeing or following. However, when the topic of communication was food or grooming, 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.