Two weeks ago, I wrote about a new study by Peter Cook and colleagues from the Pinniped Lab at the University of California, Santa Cruz. In their study, Cook claimed that Ronan the California sea lion was the first non-human mammal to show evidence of "rhythmic entrainment," or the ability to synchronize the movements of his body with an external rhythm. In other words, Ronan could dance. I pointed out that one study found evidence of dancing in Asian elephants. More substantively, I pointed out that many think of spontaneous rhythmic entrainment as the real mystery to be solved. Ronan, on the other hand, had to be trained to dance. Cook got in touch with me, and we debated a few of these points over email. I invited him to write a guest post in response to my original piece. He accepted, and his response is below. With that, say hi to Peter Cook!

Jason titled his post on The Thoughtful Animal two weeks ago: Ronan the Sea Lion Dances To The Backstreet Boys. So What? He then did an excellent job of answering the title’s question: Ronan, as a sea lion, is vocally inflexible, so her beat-keeping ability represents a challenge to an influential theory suggesting vocal flexibility (and mimicry, specifically) is a prerequisite for synchronizing movement to rhythmic sounds. This has potentially broad implications, including the possibility that human dance, a phenomenon once thought by many psychologists to be truly unique, may be rooted in general brain mechanisms shared across a wide range of species.

I’m the first author on the paper about Ronan, and following an email exchange last week, Jason was kind enough to offer me the chance to write a guest post. I wanted to address one issue in particular, one that is likely to be a focus in ongoing comparative research into rhythm: spontaneity.

As was noted, Ronan did not show spontaneous beat keeping ability. That is, when we first exposed her to rhythmic sounds, she did not move in time. She did, following training at two set rates, or tempos, spontaneously find and keep the beat across a wide range of novel tempos, even when we manipulated the speed of actual music. But before showing this general capability for beat keeping, we had to give her explicit training.

Ronan’s training is potentially important to the debate because many people (including many psychologists) believe that humans do NOT need to be trained to find and match the rhythm in music. Rather, it seems to come naturally to us. Jason echoed this belief in his original post when he noted that one response to our findings might be this:

Perhaps any animal with sufficient training can learn rhythmic entrainment. While damaging to the vocal learning hypothesis, it would just shift the goalposts slightly – what is it about humans, songbirds, parrots, and the rest that allows them to do this so easily and so flexibly, without extensive training?

Following our findings with Ronan (and the concurrent findings of rhythmic sensitivity in a chimpanzee), I believe many will be interested in further exploring the role of vocal mimicry in spontaneous (if not trained) beat keeping. This is well and good, and emblematic of healthy science, in which new data beget new theories to be tested. However, this work should be grounded in a valid representation of the existent human data, and it turns out these data are very equivocal when it comes to spontaneity of beat keeping! This may be surprising -- I recognize that, to most adults, beat keeping feels spontaneous, effortless, and sometimes obligatory (e.g., try not walking in time to the beat of street musicians when you pass them). However, it is all too easy to disregard the very long history with music and rhythmic stimuli shared by nearly all adults.

To test your intuition, next time you see a toddler “dance,” watch very carefully to see how reliably they synchronize their movements to the music. Following my training experience with Ronan the sea lion, I’ve turned a more critical eye to the gyrations produced by my 20-month-old son when I turn on the radio. An adult whose apparent rhythm was so poor would be laughed out of any reputable dance hall post-haste. In fact, there’s good scientific evidence suggesting a lengthy “apprenticeship” underlying human rhythmic abilities. Think of being bounced on a parent’s knee in time to a beat, of the very simple rhythmic patterns we present to younger children, and of how much better at beat keeping trained musicians and dancers are then lay-people. Further, sensitivity to rhythm in adult humans is, at least in part, driven by the type of rhythmic structures we’ve been exposed to in the past. In other words, our apparently spontaneous and effortless beat keeping capability may require a lot more learning (and even training) than we tend to believe. To test this conclusively would require something along the lines of exposing a human who had never heard a beat to simple music and seeing what happened.

But what then of parrots and parrot-type birds? As Jason noted in his original post, there is some reason to believe that the birds shown to keep a beat do not have a history of training. While it’s true that they weren’t trained in an explicit, formal manner as was Ronan the sea lion, the bird subjects studied to date have long, rich histories of human companionship, including extensive exposure to music. To truly conclude that parrots are spontaneous beat keepers, we need to test a naïve parrot without this exposure history. Given the learning curve for human rhythmic capabilities, if parrots turn out to be true, spontaneous beat keepers, this may not represent an overlap with humans, but rather a unique trait, requiring, in turn, another set of new hypotheses attempting to explain why.

Finally, a scientifically irrelevant point of sea lion pride – Jason suggested that Ronan is actually not the first non-human mammal to be shown to beat keep. While it’s true that some elephants appear, from YouTube videos, to be able to keep the beat, Ronan is the first non-human mammal shown, in rigorous and thorough laboratory testing, to be able to flexibly find and keep the beat to music. Sorry pachyderms, Ronan got there first.

Cook P., Rouse A., Wilson M. & Reichmuth C. (2013). A California Sea Lion (Zalophus californianus) Can Keep the Beat: Motor Entrainment to Rhythmic Auditory Stimuli in a Non Vocal Mimic., Journal of Comparative Psychology, DOI: 10.1037/a0032345

Want to get in touch with Peter Cook? Email him: pcook [at] ucsc [dot] edu

Photo by C. Reichmuth, via UCSC News Center.