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February 05, 2015

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Chimps found to learn grunt for “apple” from each other

Feb. 5, 2015
Courtesy of the Universities of Zurich and York
and World Science staff

Cap­tive chimps can learn grunts from each oth­er that re­fer to spe­cif­ic foods, a study has found. 

Chim­panzees pro­duce dif­fer­ent grunts when find­ing dif­fer­ent food items, the re­search­ers not­ed, but it has been hard to tell wheth­er such grunts are an ex­pres­sion of ex­cite­ment, or spe­cif­ic re­ferences to the ob­jects.

The new study found that chimps can change the grunts as a re­sult of con­tacts with oth­er groups of chimps, similar to what humans do with words.

“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 co-re­search­er Katie Slo­combe of the Uni­vers­ity of York in the U.K.

In 2010 the re­search­ers got a chance to test wheth­er chimps are ca­pa­ble of chang­ing the calls when a group of adult chimps from Beekse Ber­gen Sa­fa­ri Park in the Neth­er­lands moved in with a group of chim­pan­zees in Ed­in­burgh Zoo.

Ac­cord­ing to the re­search­ers, be­fore the merg­er, both groups of chimps pro­duced grunts that ap­par­ently re­ferred to ap­ples. Over time, though, the new chimps at the zoo changed their grunts for “ap­ple” to match the oth­er chimps’ grunts for “ap­ple.”

“The fact, that not only hu­mans, but al­so chim­pan­zees learn object-spe­cif­ic calls sug­gests that our com­mon an­ces­tor that lived more than sev­en mil­lion years ago al­so pos­sessed this abil­ity,” said re­search­er Si­mon Townsend from the Uni­vers­ity of Zu­rich, one of the in­ves­ti­ga­tors.

The change in the call hap­pened af­ter the chimps formed friend­ships, the sci­en­tists ob­served. They added that the find­ings, re­ported in the jour­nal Cur­rent Bi­ol­o­gy on Feb. 5, sug­gest that hu­man lan­guage is­n’t as un­ique as pre­vi­ously thought in its abil­ity to re­fer to ex­ter­nal ob­jects with so­cially learn­ed sym­bols.


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Captive chimps can learn grunts from each other that refer to specific foods, a study has found. Chimpanzees produce different grunts when finding different food items, the researchers noted, but it has been hard to tell whether such grunts are an expression of excitement, or specific references to the objects. The new study found that chimps can change the grunts as a result of contacts with other groups of chimps, an ability common to human language. “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 co-researcher Katie Slocombe of the University of York in the U.K. In 2010 the researchers got a chance to test whether chimps are capable of changing the calls when a group of adult chimps from Beekse Bergen Safari Park in the Netherlands moved in with a group of chimpanzees in Edinburgh Zoo. According to the researchers, before the merger, both groups of chimps produced grunts that apparently referred to apples. Over time, though, the new chimps at the zoo changed their grunts for “apple” to match the other chimps’ grunts for “apple.” “The fact, that not only humans, but also chimpanzees learn object-specific calls suggests that our common ancestor that lived more than seven million years ago also possessed this ability,” said researcher Simon Townsend from the University of Zurich, one of the investigators. The change in the call happened after the chimps formed friendships, the scientists observed. They added that the findings, reported in the journal Current Biology on February 5, suggest that human language isn’t as unique as previously thought in its ability to refer to external objects with socially learned symbols.