Look at these videos below. They show sulphur-crested cockatoo Snowball apparently dancing along to a song, synchronizing his movements to the beat and adapting when the tempo changes, something that does not form part of these birds’ natural behaviors.
This is no small feat or mere circus trick. Beat perception and synchronization, as it's called, involves not only perceiving the pattern of the rhythm but also coordinating the movements in anticipation of every beat. These are really sophisticated cognitive processes; so sophisticated they were long considered to be exclusive to humans. Not even chimpanzees, our closest extant relatives, are able to keep the beat to an external auditory rhythm.
Snowball was brought to my attention by friend and musician Christopher who after reading this report ("At least birds can dance") on the science pages of leading Swedish morning newspaper Dagens Nyheter, declared bluntly that his view of the world had been shattered. To him it was clear that music had been demoted to an inferior position below linguistic abilities. The article declares that "the capacity of perceiving music - even in humans - is an evolutionary by-product that tagged along when we developed the ability to speak and communicate with each other". It’s a very sweeping statement, but it raises some interesting questions.
The report in Dagens Nyheter refers to two freshly published articles in the journal Current Biology. In two independent studies Snowball and African grey parrot celebrity Alex were tested to verify if they actually have the ability to move synchronously to an external auditory beat or if they simply appear to be synchronous by chance occurrence or maybe even just mimic the movements of their masters. Hilariously, the researchers were completely unaware that birds could have this ability until a YouTube video of Snowball dancing went viral and eventually came their way.
It turns out that yes; these birds are actually able to keep the rhythm. This is the first time it's been shown in a non-human animal. You can see the statistics represented on the figure below. 0° indicates perfect alignment to the beat and Snowball's average is indicated by the arrow.
Ref: A. Patel et. al. (see reference below)
So Snowball's head bobs did align with the beats pretty well, but not perfectly. As you can see in both videos his periods of synchronicity are interspersed with periods that are more or less off. The authors of the study argue that this could mirror how small children synchronize to music. As demonstrated in the second video, Snowball could also adapt his movements to changes in the tempo, another key feature of beat perception and synchronization.
Parrots, like us, are vocal learners; our speech is not innate but learned by mimicking other individuals, often parents or close relatives. The circuits in the brain that underlie vocal learning, which interconnect the auditory system with systems for initiation and execution of movements, overlap with those involved in beat perception and synchronization. So it’s likely that the ability to perceive and synchronize beats, an integral part of our ability to perceive and practice music, is a product of the same neural foundations that gave us language and speech abilities. It seems like some abilities, however important we may consider them, evolved as secondary effects or by-products to other more clearly beneficial cognitive abilities - as evidenced by the fact that parrots exhibit beat perception and synchronization even though they clearly have no use for this curious behavior in their natural environments.
However, it’s important to remember that musical ability is not just one thing; it’s grounded in several interacting phenomena with different neural bases. So claiming that our capacity of perceiving music as a whole is a by-product of our linguistic abilities would not be right. The ability to perceive rhythm and coordinate movements to an external beat is an integral part of our musical behaviors, but there are other components as well - the perception of pitch for instance, and the ability to cooperate and create music as a group.
So, is our pervasive musicality just a happy accident, or did evolution shape our minds to be musical? Well, until an aspect of musicality is discovered to be innate, with an obvious adaptive advantage of its own, the question remains open. The results generated from observing Snowball and his dancing conspecific highlight the likelihood that individual aspects of musicality could be by-products of other cognitive abilities. This is not surprising considering that this is how evolution works; it builds and expands upon already existing structures and features to generate new ones. We shouldn't give terms like "by-product" unnecessary attention. A more interesting question to ask is why we find musical expression so important and rewarding and why it’s so deeply embedded in the architecture of our minds. That’s when we start discussing the true evolutionary value of musicality.
Swedish blog tags: Vetenskap, Biologi, Neurovetenskap, Språk, Musikalitet, Dans, Kakadua
Technorati tags: Science, Biology, Neuroscience, Language, Musicality, Dance, Cockatoo,
Patel, A., Iversen, J., Bregman, M., & Schulz, I. (2009). Experimental Evidence for Synchronization to a Musical Beat in a Nonhuman Animal Current Biology DOI: 10.1016/j.cub.2009.03.038
Schachner, A., Brady, T., Pepperberg, I., & Hauser, M. (2009). Spontaneous Motor Entrainment to Music in Multiple Vocal Mimicking Species Current Biology DOI: 10.1016/j.cub.2009.03.061
Patel, A. (2006). Musical Rhythm, Linguistic Rhythm, and Human Evolution Music Perception, 24 (1), 99-104