Groups of chimpanzees have their own "languages" of grunts, and new research suggests they can learn to be bilingual.

Chimps have different grunts they use for particular types of food, and scientists observed what happened when two groups that had different vocabularies moved in together, Cell Press reported. The found the primates gradually changed their grunts over time to make them sound more like their new neighbors.

"Our study shows that chimpanzee referential food calls are not fixed in their structure and that, when exposed to a new social group, chimpanzees can change their calls to sound more like their group mates," said Katie Slocombe of the University of York.

In the past, researchers have believed the acoustic structure of chimpanzee calls was fixed, but these new finding suggest quite the opposite. The fact that the two groups of chimpanzees' grunts converged over the course of three years suggests their calls are much closer to human language than we thought.

"We think it's quite easy to hear how the two groups called in different ways for apples in 2010, and how by 2013 the Dutch individuals changed their grunts to sound more like Edinburgh individuals," said Stuart Watson, also from the University of York.

The findings are the first to show that non-human animals can modify and learn the structure of a referential vocalization and share the basic "building blocks" of language with humans.

"It would be really exciting to try and find out why chimpanzees are motivated to sound more similar to their group mates," said Simon Townsend of the University of Zurich, who was also involved in the study. "Is it so that they can be better understood? Or is it just to sound more similar to their friends?"

The findings were reported recently in the Cell Press journal Current Biology.