Chimps can change grunts to match local norms

Just as humans can learn the local language after migrating to a new place, chimpanzees too can change their grunts over time to make them sound more like those of new peers, new research says.

"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 Britain.

After a group of adult chimpanzees from the Netherlanders was introduced to their new companion at the Edinburgh Zoo in 2010, the Dutch individuals changed their referential call for apple to match those used by Edinburgh individuals by 2013.

"We think it is 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," Stuart Watson, also from University of York, said.

That acoustic convergence had nothing to do with individual food preferences, either, the researches said.

The findings suggest that human language is not as unique as we thought in its ability to reference external objects with socially learned symbols.

The researchers used audio analysis to demonstrate the convergence of structure, but they could also hear the difference.

The findings "represent the first evidence of non-human animals actively modifying and socially learning the structure of a meaningful referential vocalisation" from other members of their species, the researchers said.

The findings appeared in the journal Current Biology.