Aug. 5, 2009 -- Wild orangutans have invented a sound modification tool that makes a "kiss squeak" noise and fools listeners into thinking the individual is larger than he or she actually is, according to a new study. The study, published in the latest Proceedings of the Royal Society B, presents the first evidence concerning how and why non-human primates alter their own calls using tools and even their own hands. In this case, the researchers describe the kiss squeak call as a sharp intake of air through pursed lips. Hardly a love call, the noise is produced by orangutans when predators startle them, or they are otherwise disturbed. "As far as I and my colleagues know, no other primate emits kiss squeak sounds," lead author Madeline Hardus told Discovery News. "Male great apes can use their hands during the production of calls, such as buttress drumming in chimpanzees, chest beating in gorillas and snag crashing in orangutans, but in these examples, calls are not modified; they're added with other acoustic elements." "Only kiss squeaks are known to be modified," added Hardus, a researcher in the Behavioral Biology Group at the University of Utrecht. Related Content:
For the study, Hardus and her colleagues recorded kiss squeaks made by wild orangutans at Central Kalimantan in Borneo, Indonesia. The orangutans will make the sound themselves, make it against their hands or produce it against leaves stripped from twigs. The latter method constitutes the sound modification tool. Often orangutans will hold the leaves in one hand while making the noise, freeing the other hand to shake and throw twig "missiles," rocks and more. Detailed analysis of the digitized recordings found that the hand and leaf-modified kiss squeaks lowered the maximum frequency of the calls, with the leaf tool version producing the lowest sounds. Since larger animals tend to emit such low noises, the scientists think the orangutans are trying to make themselves sound as big and imposing as possible for approaching predators that may only hear, but not see, the tree-dwelling primates. The kiss squeak sound likely then "deters (others) by indicating that the presence of the predator has been noticed, probably leading the predator to leave the hunt faster and give up its hiding position." The researchers found that using the leaf tool didn't increase the volume of the sound or change it in respects other than reducing its frequency. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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