Wild Bornean orangutans strip leaves off twigs and use them to amplify a sound they make to ward off predators, according to a new study. Scientists say the leaves allow the orangutans to alter the frequency of their ‘kiss squeak call’, making them sound bigger and more threatening.
From MSNBC:
This new finding marks the first time an animal has been known to use a tool to help it communicate, say the scientists who studied the behavior.
The bigger an orangutan is, the lower the frequency of its unaided kiss squeak, for physiological reasons, said study team member Madeleine Hardus of the University of Utrect in the Netherlands. So when smaller orangutans clasp their hand or a bunch of leaves to their mouth, they’re likely doing it to artificially lower the frequency of their call and make themselves sound bigger.
Merely sounding bigger might do the trick to scare off a predator, because the jungles where the orangutans live are thick, which makes it difficult for the predator to actually see the primate and visually size them up.
For many years, scientists thought that humans were the only species that is able to transmit cultural knowledge, passing new behaviors by social learning. But recent research has proved that this isn’t so – we are continually seeing new examples of animals, particularly primates, developing tools and teaching each other how to use them.
So, those deranged-looking cymbal monkeys that haunt your nightmares weren’t all that far off the mark. Next stop, planet of the apes.
Link [MSNBC]
Photo credit: Flickr user scragz
