Who could have predicted the popularity of Shrek as a character? What started as a humble if irreverent fairy tale picture book in 1990 later blossomed into an animated feature film franchise, a handful of video games, comic books, and a stage musical appropriately called Shrek the Musical.
The Shrek universe includes all of the fairy tale characters we’re familiar with, anthropomorphic animals included, singing songs to one another while they live through the never ending battle between good and evil. The thing is, without the benefit of magic, it’s unclear if any of those animals could even appreciate those songs, let alone participate in them.
Despite stories of the pied piper leading rats to their demise, or cobras becoming entranced by a well-played flute, it has long been believed that understanding and appreciating music was a wholly human trait. Increasingly, we’re learning that isn’t the case. Animals like to get their groove on too. Now, rats are joining the dance party, according to new research from scientists at the University of Tokyo, and published in the journal Science Advances.
Many animals use sound to communicate, vocalize rhythmically, or respond to music, but those behaviors seem inherently different from the ways in which humans hear music, recognize the beat of that music, and synchronize our body movements all without any prior information. Basically, you can headbang to anything without much effort, even songs you’ve never heard before, and that was believed to be a purely human ability.
That said, there is sometimes a gap between documented scientific knowledge and common knowledge. Thanks in large part to video sharing on the internet, there has been rising public awareness that some animals appear to bop and dance along with music. How many of us have watched pet birds bob their hands and stomp their feet in some random person’s apartment? That emerging understanding inspired scientists to put the question to the test to see if animals actually can recognize the beat of music without training and dance along without being coerced.
They found, in no uncertain terms, that rats can and do headbang too. Researchers outfitted rats with wireless accelerometers capable of measuring even the slightest head movement. Similar accelerometers were given to human participants, attached to headphones. Then, humans and rats alike listened to 1-minute clips of Mozart’s Sonata for Two Pianos in D major, K. 448 at four different speeds ranging from 75% of normal to 400% of normal.
They found that humans and rats both prefer tempos between 120 and 140 beats per minute, we also bop our heads to music with similar rhythms, and we both decrease the intensity of those movements as the speed of the music increases.
Importantly, while YouTube birds can rock out to a variety of songs, it’s unclear – scientifically speaking – how or if they have been trained. YouTube videos are fun, they can be educational, but they aren’t generally rigorously controlled. In these experiments, the rats were not trained in any way with respect to the music. They weren’t shown songs in advance, they weren’t taught how to headbang or rewarded for doing it. As far as researchers could tell, this was an innate behavior, and it’s the first time it has been documented in a non-human animal.
The discovery that rats might have favorite songs is earthshaking enough, but this work might also help reveal some of the cognitive underpinnings involved in the creation and appreciation of music among humans. The fact that we prefer songs in the same range of tempos, between 120 and 140 beats per minute, suggests it may be hardwired along a broader spectrum of species and those preferences might define how we create music and why we enjoy it.
Next time a rat sneaks into your home, don’t chase them out, turn it up instead. They don’t have iPods.