for National Geographic News
Bonnie's whistling isn't so surprising to her caregivers. The 140-pound (63.5-kilogram) orangutan at the National Zoo in Washington, D.C., has been whistling for about two decades.
Now a new study suggests that the sounds she makes could hold clues about the origins of human language.
"The assumption is that someone was whistling and she probably picked it up from them," said animal keeper and study co-auther Erin Stromberg.
Lisa Stevens, the zoo's curator for great apes and giant pandas, said the key point is that the orangutan was not trained to whistle.
While orangutans can be taught new sounds with extensive training, Bonnie is the first indication that the animals can independently pick up the sounds from other species.
"It's something she spontaneously developed," Stevens said. "It wasn't a trick."
Orangutans are known to imitate humans. Bonnie, for instance, sometimes sweeps up after herself, just as her caretakers do, even though the zookeepers don't encourage this behavior.
Lead author Serge Wich of the Great Ape Trust of Iowa, said orangutans in Indonesia have been seen pretending to wash clothes.
"We know they are capable of imitating these motor skills, but we never had any good indication of sounds for vocalization," said Wich, who presented his research on December 18 during a symposium at the University of Zurich, Switzerland.
Bonnie the Orangutan Whistling
"Now at least we have an indication that they can imitate sounds" without being trained, he said.
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