A new linguistic research has revealed that the same species of monkeys located in separate geographic regions use their alarm calls differently to warn of approaching predators.
Lead author Philippe Schlenker said that their findings show that Campbell's monkeys have a distinction between roots and suffixes, and that their combination allows the monkeys to describe both the nature of a threat and its degree of danger.
The combined team of linguists and primatologists at New York University analyzed alarm calls of Campbell's monkeys on two sites, the Tai forest in Ivory Coast and Tiwai Island in Sierra Leone, and notably, monkey predators on the two sites differ: the primates are threatened by eagles on Tiwai Island and by eagles and leopards in the Tai Forest.
Using transcriptions of these monkey calls gathered in field experiments involving playbacks of predator calls (e.g. eagle shrieks and leopard growls), the researchers found greater complexity in expression than previously understood as well as differences in alarm calls between the two locations.
Confirming with linguistic means some hypotheses initially made by primatologists, theiranalysis showed that these calls make a distinction between roots (especially "hok" and "krak") and suffixes (-oo), and that their combination allows the monkeys to describe both the nature of a threat and its degree of danger.
For instance, "hok" warns of serious aerial threats, usually eagles, whereas "hok-oo" can be used for a variety of general aerial disturbances; in effect the suffix -oo serves as a kind of attenuator.
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