[youtube]http://www.youtube.com/watch?v=WakZWm4xXv0[/youtube]

Some Vocal-mimicking Animals, Particularly Parrots,

Researchers at Harvard University have found that humans aren’t the only ones who can groove to a beat — some other species can dance, too. The capability was previously believed to be specific to humans. The research team found that only species that can mimic sound seem to be able to keep a beat, implying an evolutionary link between the two capacities.

The study was led by Adena Schachner, a doctoral candidate in psychology at Harvard, and is published in the current issue of Current Biology. Schachner’s co-authors are Marc Hauser, professor of psychology at Harvard; Irene Pepperberg, lecturer at Harvard and adjunct associate professor of psychology at Brandeis University; and Timothy Brady, a doctoral candidate at the Massachusetts Institute of Technology.

Schachner and her colleagues closely studied Alex, a well-known African grey parrot who passed away shortly after the study, and Snowball, a sulphur-crested cockatoo whose humanlike dancing behavior has led to online fame.

“Our analyses showed that these birds’ movements were more lined up with the musical beat than we’d expect by chance,” says Schachner. “We found strong evidence that they were synchronizing with the beat, something that has not been seen before in other species.”

The researchers noted that these two birds had something in common: an excellent ability to mimic sound.

“It had recently been theorized that vocal mimicry might be related to the ability to move to a beat,” says Schachner. “The particular theory was that natural selection for vocal mimicry resulted in a brain mechanism that was also needed for moving to a beat. This theory made a really specific prediction: Only animals that can mimic sound should be able to keep a beat.”

To test this prediction, Schachner needed data from a large variety of animals — so she turned to a novel source of data, the YouTube video database. Schachner systematically searched the database for videos of animals moving with the beat of the music, including vocal mimics such as parrots and vocal nonmimics such as dogs and cats.

Schachner analyzed the videos frame-by-frame, using the same analyses applied to the case-study birds. Criteria included the animal’s speed compared with the speed of the music and alignment with individual beats. Potentially “fake” videos, where music was added to the video after the fact, or the animal was following visual cues, were omitted.

“The really important point is that many animals showed really strong evidence of synchronizing with the music, but they were all vocal mimics,” says Schachner.  “Most of them were parrots — we found 14 different species of parrot on YouTube that showed convincing evidence that they could keep a beat.”

Because only animals capable of vocal mimicry — such as parrots — appear to be able to keep a beat, the study implies an evolutionary link between vocal mimicry and this crucial part of dance.

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