Chimpanzees can change their grunts to communicate better with new companions, according to a study of two groups that were housed together in Edinburgh.
In 2010, nine new arrivals from a Dutch safari park used an excited, high-pitched call for apples, while the locals used a disinterested grunt.
By 2013, the Dutch chimps had switched to a similar low grunt, despite an undiminished passion for apples.
This was the first evidence of chimps re-learning such "referential calls".
The findings, reported in the journal Current Biology, suggested that when chimp grunts referred to objects, they could function in a surprisingly similar way to human words, instead of simply being governed by how the chimp felt about the object.
Our ability to learn new "words" from our peers might date back to a shared ancestor with chimpanzees, some six million years ago, the paper's senior author Katie Slocombe said.
"One really powerful way to try and understand how language evolved is to look at the communication systems of animals that are closely related to us," Dr Slocombe said.
"What kind of basic communication skills were in that common ancestor? And what really is unique in humans, and has evolved since?"
The reason for the change, Dr Slocombe conceded, was difficult to pin down precisely.
The Dutch chimps might have changed their grunt purely in order to communicate better - rather like learning a new word.
Or they might have made the adjustment for social reasons: "If you tend to mimic someone's accent, they tend to get on better with you and they like you more. So it could be something similar to that, that we're seeing in the chimps."
Whether the change was in vocabulary, accent, or a little of both, it appeared to be a striking example of vocal learning, she said.