Chimpanzees can learn a new sound for a common object, suggesting that the ability to acquire the building blocks of language may be more ancient than humans, according to a new study.

When a band of captive chimpanzees was transferred from the Netherlands to Scotland's Edinburgh Zoo in 2010, they used different grunts to refer to apples. Three years later, after the two groups had bonded, they had converged toward a common sound for the fruit, said a study published online in the journal Current Biology.

That acoustic convergence suggests that an important element of language cognition may have been present 7 million to 13 million years ago, in the last common ancestor of chimpanzees and humans.

Research has shown that primates can produce unique calls for things or events in their environment, such as the arrival of a predator or discovery of high-quality food. Experiments have shown that fellow members can extract valuable information from those calls, and act appropriately.

"We don't call them semantic signals like in human language — we call them functionally referential calls," said study co-author Simon Townsend, a comparative biologist at the University of Zurich.

"In animals there's always been a feeling that you can't really decouple these referential calls from the underlying emotional state that the animal is experiencing," Townsend said. "In human language, there's no link between the way that we're feeling and the word and what it sounds like."

For that reason and others, most researchers had assumed that referential calls were innate and rigid among nonhuman primates, and not flexible and socially learned as they are among Homo sapiens. "What we've demonstrated is that there is no difference, at least in chimpanzees," Townsend said.

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