Orangutans spontaneous whistling sheds light on evolution of speech

December 12th, 2008 - 1:20 pm ICT by ANI  

Washington, Dec 12 (ANI): An orangutans spontaneous whistling is offering researchers at Great Ape Trust of Iowa new insights into the evolution of speech and learning.

Dr. Serge Wich and his colleagues at Great Ape Trust have provided the first-ever documentation of a primate mimicking a sound from another species without being specifically trained to do so.

Bonnie, a 30-year-old female orangutan living at the Smithsonian National Zoological Park in Washington, D.C., started whistling a sound that is in a humans, but not an orangutans, repertoire after hearing an animal caretaker make the sound.

This is important because it provides a mechanism to explain documented between-population variation in sounds for wild orangutans, Wich said.

In addition, it counters a long-held assumption that non-human primates have fairly fixed sound repertoires that are not under voluntary control. Being able to learn new sounds and use these voluntarily are also two important aspects of human speech and these findings open up new avenues to study certain aspects of human speech evolution in our closest relatives, Wich added.

Wich said that scientists have long known that orangutans copy physical movements of humans, but Bonnies whistling indicates that the learning capacities of orangutans and other great apes in the auditory domain might be more flexible than previously believed.

The behaviour goes against the argument that orangutans have no control over their vocalizations and the sounds are purely emotional that is, an involuntary response to stimuli such as predators.

Bonnie seems to whistle for the sake of making a sound rather than to receive a food reward or some other incentive. If asked to whistle, she is likely to oblige, another indication to scientists that she makes the sound voluntarily.

The findings will be presented on Dec. 18 at a scientific symposium on orangutan genetics at the University of Zurich, Switzerland.

The study is published this month in Primates. (ANI)

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