24 décembre 2014

La langue des singes

Oui, les singes ont une langue. Et elle est beaucoup plus sophistiquée que ce qui était cru auparavant. Absolument fascinant:

(...) They found that Campbell's monkeys in the Ivory Coast’s Tai Forest use the term krak to indicate that a leopard is nearby, and the sound “hok” to warn others that there’s an eagle circling overhead. 

(...) But then the researchers found that on Sierra Leone's Tiwai Island, where there are no leopards, the same monkey species uses krak as a general alarm call for any threat, including eagles.

"Our 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 study's lead author, Philippe Schlenker from France's National Centre for Scientific Research and New York University, said in a press release.

To work out what was going on, the researchers played recordings of different types of threats (the sound of an eagle screeching or a leopard growling), and listened to the calls that resulted in the different locations.

On the mainland, they found that the Campbell’s monkeys were using a more specific dialect - they were not only saying krak when a leopard was nearby and hok when an eagle was close, but also krak-oo and hok-oo to signify less serious ground and air threats. They also said boom when the coast was clear again.

But on the island, although the monkeys occasionally said hok when an eagle was nearby, they also said krak pretty generally across most threats.

(...) "The important thing is that in this situation, both krak-oo and hok are more informative than krak,” he says. “By logic, if you hear krak you can infer there was a reason krak-oo and hok were not uttered, so you infer the negation.” That is, when monkeys in the forest say krak, they are also implying not-hok and not-krak-oo, neither a minor threat nor an aerial threat. In the forest, monkeys understand that this must refer to a leopard - the only non-minor, non-aerial threat nearby. 

On the island, however, it remains a general alarm call. That’s because krak does not intrinsically imply negation."



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