Like humans, wild chimpanzees engage in impetuous, turn-taking conversations, waiting a fraction of a second for them to ‘speak’.
Animals often communicate through gestures, including hand movements and facial expressions.
Scientists who studied their chats in detail found that they took “rapid turns” as they exchanged information and occasionally interrupted each other.
This expression suggests “profound evolutionary similarities”. [with humans] How face-to-face conversations are structured,” Professor Kate Hobiter from the University of St Andrews told BBC News.
This rapid turn-taking is a hallmark of human conversation, explains Professor Hobiter, who studies primary communication. “We all take about 200 milliseconds between turns and show some interesting little cultural variations. Some cultures are ‘fast talkers’.”
A millisecond is one thousandth of a second.
A 2009 linguistics study found these differences in timing—on average, Japanese speakers took seven milliseconds to respond, while Danish speakers took 470 milliseconds to intervene.
By examining thousands of instances of wild chimpanzees interacting with each other, Professor Hobiter and his colleagues were able to time the animals’ conversations.
“It’s amazing to see how close the chimpanzee and human times were,” he said.
Chimps had a large range in their conversation times. “Intervals ranged from interrupting the signaler for 1,600 milliseconds before completing their gesture to taking 8,600 milliseconds to respond,” explained Professor Hobeiter.
“This may be because chimps were in a natural setting, so they could exhibit a wide range of behavior – sometimes interrupting each other and other times taking longer to respond.”
As part of an investigation into the evolutionary origins of communication, researchers observed and recorded the behavior of five communities of wild chimpanzees in the forests of Uganda and Tanzania over decades.
They have recorded and translated more than 8,000 gestures from more than 250 individual animals.
Lead researcher Dr Gale Padihy from the University of St Andrews explained that the gestures allowed the chimpanzees to avoid conflict and coordinate with each other.
“So one chimpanzee can signal to another that they want food, and the other can give them food, or if they’re feeling less generous, signal them to go away.
“They can come to an agreement about how or where to get married. It’s attractive and done in a few small gestural exchanges.”
He said future studies looking at the relationship of other primate species more distant to us could give us a more complete evolutionary picture of why we adopted this fast turn-taking chatter.
“It’s a great way to better understand when and why our conversational rules evolved,” he said.