One commonly spouted cliche is the idea that humans all speak one language: the language of music. In fact, music may be even more universal than we think. Tufts’ music psychology Professor Aniruddh Patel’s most recent research demonstrates that humans and zebra finches process rhythm in similar ways. Not only does music connect us with other humans, but with other species as well.
Professor Patel first became interested in psychology after taking an animal behavior class in college -- “I got fascinated by the idea [that] you could study the mechanisms behind behavior...and kind of how behavior evolved.” He was specifically intrigued by music’s effect on behavior. He recalls feeling a “strong personal response to music and [it] just puzzled me that, that this, this form of communication could be so powerful.” His fascination with music and behavior led him to investigate how zebra finches process beat, periodic temporal structures, and rhythm. The songbird rhythm study was done in collaboration with Dr. Mimi Kao from Tufts’ Biomedical School. Her songbird neurobiology lab studies the brain regions of zebra finches and how they learn songs and control movements during singing and learning.
“When I heard [Dr. Kao] wa s coming to Tufts, I was pretty excited because I had been doing some work on rhythm that suggested in some ways, we might share our sense of musical rhythm more with birds...than we do with even our close, closest living relatives, that is other primates,” recalls Professor Patel.
Songbirds are of particular interest because they possess a trait called vocal learning: the rare ability to mimic complex sounds. Humans are the only primates that have this ability, while hummingbirds, parrots, and songbirds are all capable of this form of learning. Vocal learning is a result of complex brain circuitry that is an indicator of convergent evolution between birds and humans. For us, this trait allows us to recognize a song even if it has been sped up or slowed down because the relative time between each beat is still the same. We perceive the overall pattern of the rhythm instead of focusing on the specific intervals of time between each beat. Since zebra finches are also capable of vocal learning, Professor Patel hypothesized that they have the ability to recognize rhythm independent of its speed.
With the help of Masters student Andrew Rouse, Professors Patel and Kao designed an experiment where male zebra finches were exposed to isochronous (sounds occurring at regular intervals) and arrhythmic sequences at different tempos. The birds were trained to discriminate between these sequences and then tested on their ability to recognize the difference between an isochronous sequence and an arrhythmic sequence set at a new tempo that they had not previously heard. Many birds were able to correctly discriminate between the sequences, demonstrating that zebra finches share our ability to recognize rhythms regardless of speed.
This graph shows the performance results of birds before (to the left of vertical dashed line) and after (to the right of the dashed line) training. The vertical dashed line shows chance performance -- the birds were able to identify the difference between rhythmic and arrhythmic stimuli the majority of the time.
Professor Patel proposes that zebra finches possess complex motor auditory circuits that are responsible for their rhythmic capabilities. “They’re using their motor system to help them... predict the timing of rhythms,” says Patel, “and we think humans are doing something like that, too.” The similarity between zebra finches and humans may allow researchers to start using the birds as “a model system for certain aspects of human rhythm processing.”
Studying the dynamic between motor and auditory systems has great potential benefits for human health and cognition. Professor Patel describes how rhythms with a regular beat can help people with motor disorders like Parkinson’s: “patients can walk better if they hear regular rhythms, they start to walk to the rhythm.” By using zebra finches as an animal model, researchers may be able to understand why rhythm treatment works for Parkinson’s and how it can be improved.
In addition to opening up new opportunities for cross-species comparison, Professor Patel notes that this study was “a cool case of a kind of a collaboration that was held at Tufts...I think that it’s good for the students to see the research process [across] different disciplines. And it’s good for the professors to talk to people in other disciplines.” In the future, Professor Patel hopes to continue collaborating with other professors to explore the impact of music in other fields of psychology. He is currently working with Professor Elizabeth Race, a memory expert, to determine why rhythm has such a strong influence on memory. When speaking about music’s effect, Patel mentions that “In every culture, people have [an] amazing ability to remember songs for many, many years.” Music is so powerful that it persists through some forms of Alzheimer’s and dementia, and it can potentially be used as therapy to help patients remember.
While much of Professor Patel’s current research raises the possibility of using rhythm as a tool against brain disorders, his work also seeks to answer the evolutionary question of where human musicality comes from. “Are we a species that evolved to be musical or is music just a purely cultural invention that builds on brain functions that evolved for other reasons?”
It’s exciting that the songbird study not only illuminates new pathways for studying human cognition but also has practical applications for the treatment of cognitive disorders. The study is fascinating from an evolutionary biology standpoint as well, as it reveals a new evolutionary connection between us and birds. Perhaps future research will discover more about how our music processing pathways evolved.
The next time you listen to music, consider that we may not be the only animals out there that can appreciate it.