February 16, 2014
Beat-Keeping Sea Lion The Focus Of Rhythmic Entrainment Research
[ Watch the Video: Beat Keeping in a California Sea Lion ]
redOrbit Staff & Wire Reports - Your Universe Online
Ronan, who lives at Long Marine Laboratory at the University of California, Santa Cruz, provided scientists with the first empirical evidence of an animal not capable of vocal mimicry that can keep the beat last April. The sea lion is also the first non-human mammal that convincingly demonstrated its rhythmic ability in such a fashion.
Peter Cook, who worked with Ronan as a graduate student at UC Santa Cruz and is now a postdoctoral fellow at Emory University in Atlanta, presented his research on Ronan and her remarkable beat-keeping abilities during a session devoted to rhythmic entrainment in non-human animals.
Cook said that the sea lion was capable of moving in time to a vast array of differing rhythmic auditory stimuli with different tempos, including musical works. Besides people, this type of rhythmic entrainment had only been demonstrated by parrots and other birds with an aptitude for vocal mimicry, he added.
“Along with other recent findings, this suggests that the neural mechanisms underpinning flexible beat keeping may be much more widely distributed across the animal kingdom than previously thought,” he explained.
“The idea was that beat keeping is a fortuitous side effect of adaptations for vocal mimicry, which requires matching incoming auditory signals with outgoing vocal behavior,” Cook added. “Ronan's success poses a real problem for the theory that vocal mimicry is a necessary precondition for rhythmic entrainment.”
The reason for this is that sea lions are not known to perform vocal mimicry, and actually have limited flexibility in their sound-producing capabilities. Ronan, however, appears to be an exception to the rule. Born in the wild, she was rescued in 2009 by the Marine Mammal Center in Sausalito after being found on a highway.
It was the third time Ronan had been found stranded, and she did not appear to be adapting well to the wild. So she was brought to UCSC in January 2010, where she joined the Pinniped Cognition and Sensory Systems Laboratory. Since she was a quick study, the decision was made to have her participate in a beat-keeping study.
“From my first interactions with her, it was clear that Ronan was a particularly bright sea lion,” Cook explained. “Everybody in the animal cognition world, including me, was intrigued by the dancing bird studies, but I remember thinking that no one had attempted a strong effort to show beat keeping in an animal other than a parrot. I figured training a mammal to move in time to music would be hard, but Ronan seemed like an ideal subject.”
Cook and research technician Andrew Rouse used a John Fogerty song to teach Ronan to bob her head in time with rhythmic sounds, and then demonstrated that the sea lion was able to adapt and use this talent with tempos and music she had not been previously exposed to.
She was originally trained to move in time to hand signals before this was replaced by a single, non-musical sound signal. When she successfully completed a test, she was rewarded with a fish. Ronan was eventually able to maintain a minimum of 60 bobs to each of the various beats.
“Given her success at keeping the beat with new rhythm tracks and songs following her initial training, it's possible that keeping the beat isn't that hard for her," Cook said. "She just had to learn what it was we wanted her to do.”
“People have assumed that animals lack these abilities. In some cases, people just hadn't looked,” he added. “The comparative study of rhythm has undergone a renaissance in recent years, with new methods being attempted and new species tested. It's exciting to be meeting with top scientists in the field at this crucial juncture.”