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 The discovery represents the first evidence that animals besides
humans can replace the vocal sounds their native group uses for
specific objects - in the chimps' case, apples - with those of their
new community.
One expert on chimp vocalizations, Bill Hopkins of Yerkes National
Primate Research Center in Atlanta, who was not involved in the
study, questioned some of its methodology, such as how the
scientists elicited and recorded the chimps' calls, but called it
"interesting work."
Chimps have specific grunts, barks, hoots and other vocalizations
for particular foods, for predators and for requests such as "look
at me," which members of their troop understand.
Earlier studies had shown that these primates, humans' closest
living relatives, can learn totally new calls in research settings
through intensive training. And a 2012 study led by Yerkes' Hopkins
showed that young chimps are able to pick up sounds meaning "human,
pay attention to me," from their mothers.
But no previous research had shown that chimps can replace a call
they had used for years with one used by another troop. Instead,
primatologists had thought that sounds referring to objects in the
environment were learned at a young age and essentially permanent,
with any variations reflecting nuances such as how excited the
animal is about, say, a banana.
In the new research, scientists studied adult chimpanzees that in
2010 had been moved from a safari park in the Netherlands to
Scotland's Edinburgh Zoo, to live with nine other adults in a huge
new enclosure.
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It took three years, and the formation of strong social bonds among
the animals, but the grunt that the seven Dutch chimps used for
"apple" (a favorite food) changed from a high-pitched eow-eow-eow to
the lower-pitched udh-udh-udh used by the six Scots, said co-author
Simon Townsend of the University of Zurich. The change was apparent
even to non-chimp-speakers (scientists).
"We showed that, through social learning, the chimps could change
their vocalizations," Townsend said in an interview. That suggests
human language isn't unique in using socially-learned sounds to
signify objects.
Unanswered is what motivated the Dutch chimps to sound more like the
Scots: to be better understood, or to fit in by adopting the reining
patois?
(Reporting by Sharon Begley; Editing by Nick Zieminski)
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