Chimps and bonobos don't need a translator

Chimps and bonobos used hand gestures to communicate to one another in a variety of social situations. Previous studies have shown the two species to deploy similar gestures, but the latest study is the first to show the degree to which the shared gestures have similar meanings.

As part of the new research, scientists observed the use of shared hand gestures among chimps and bonobos, paying close attention to the reaction elicited by each gesture.

For example, researchers watched bonobos regularly extend an arm in front of another. The gesture causes the bonobos on the receiving end to climb onto the back of the gesturer. Once in piggyback position, the first bonobos ceased gesturing, satisfied that his or her gesture had been properly interpreted.

Scientists also closely analyzed the many gestures deployed during grooming interactions.

Observing the responses to various gestures helped researchers confirm the meaning of 33 bonobo gesture types. By comparing the hand gestures and their meanings to each group of chimpanzees, scientists showed the two ape species use a surprisingly similar symbolic language.

Researchers shared their results in the journal PLOS Biology.

"The overlap in gesture meanings between bonobos and chimpanzees is quite substantial and may indicate that the gestures are biologically inherited," Kirsty Graham, a research psychologist at the University of York in England, said in a news release.

Graham and her colleagues believe similar gestures with similar meanings were likely used by the two species last common ancestor.

"In future, we hope to learn more about how gestures develop through the apes' lifetimes," Graham said. "We are also starting to examine whether humans share any of these great ape gestures and understand the gesture meanings."