In the past, there has been some anecdotal evidence that our closest relative, the chimpanzee, can communicate by combining sounds, and now researchers have been able to confirm it by observing chimpanzees in the wild.
When chimpanzees are surprised, they alert their mates by making “huu” sounds. When they want to gather their relatives, a barking “waa” is used.
The researchers from the University of Zurich traveled to Uganda and tested there a pretend snake. Then the chimpanzees combined the two sounds, which indicates that they both warn of the threat and want to gather group members.
When the combination of the sounds was played to other chimpanzees, they reacted more strongly than when the respective sounds were played separately.
“That makes sense, because a threat that requires recruitment is a time-critical threat and it suggests that chimpanzees hearing them are indeed combining the meaning of the individual sounds,” says Professor Simon Townsend in a press release.
Humans and chimpanzees had a common relative six million years ago. The ability to understand the combination of sounds is probably at least that old, and can provide insights into how language developed, according to the researchers.
The study has been published in the scientific journal Nature Communications.