Scientists already knew that chimpanzees have special grunts that refer to different types of foods, but a new study revealed that these grunts can change if a chimp is introduced to a new social group. 

A team of researchers studied the changes of two separate groups of chimpanzees who moved in together at Edinburgh Zoo in Scotland. When the groups started interacting, they changed the sounds of their grunts over time to sound more like their peers. 

"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," researcher Katie Slocombe, of the University of York, told Psy Post. 

Before this study scientists generally thought that the sounds emitted by chimpanzees were fixed and never changed, reported Psy Post. 

These findings "represent the first evidence of non-human animals actively modifying and socially learning the structure of a meaningful referential vocalization" from other members of their species, the researchers told Psy Post. 

"It would be really exciting to try and find out why chimpanzees are motivated to sound more similar to their group mates," researcher Simon Townsend, of the University of Zurich, told Psy Post. "Is it so that they can be better understood? Or is it just to sound more similar to their friends?" 

The study was published in the journal Current Biology on Feb. 5.