Chimps vocally adapt to new neighbors

Feb 05, 2015, 4:54 PM EST
A chimpanzee tastes an ice cream bar received from a zookeeper to help endure the intense summer heat at the Zoo in Rio de Janeiro, Brazil, on January 13, 2015.

Researchers have published findings about the ways in which chimpanzees change the sound of their grunts depending on their surroundings and their neighbors. The findings show that chimps adapt their vocal sounds to different locales. The BBC reports:

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 is the first evidence of chimps re-learning such "referential calls".
The findings, reported in the journal Current Biology, suggest that when chimp grunts refer to objects, they can function in a surprisingly similar way to human words - instead of simply being governed by how the chimp feels about the object.
The key to the switchover wasn't simply being exposed to the different call in a new environment. Instead, the researchers said the change took hold only after "strong social relationships had formed" between the two groups.
So why did the Dutch chimps change to accommodate the Scottish chimps, rather than vice versa? Were the Dutch chimps merely following the lead of the combined groups' dominant male, an Edinburgher? The researchers say previous studies of wild vervet monkeys point to a different reason.
"An alternative is that conformity mechanisms may have motivated the immigrants to adopt the vocal norms of the host group," they wrote.
More studies will be needed to nail down the full explanation. "It would be really exciting to try and find out why chimpanzees are motivated to sound more similar to their group mates," the University of Zurich's Simon Townsend, another one of the study's co-authors, said in a news release. "Is it so that they can be better understood? Or is it just to sound more similar to their friends?"