Read the full transcript of cognitive neuroscientist Dr. John Rehner Iversen’s talk titled “Why do our brains love music?” at TEDxMcMasterU (May 31, 2025) where he explores the fascinating connection between our brains and music, particularly focusing on rhythm and beat perception.
Listen to the audio version here:
Introduction: The Musical Brain
Dr. John Rehner Iversen: My name is John Iversen. I’m a new faculty member here at McMaster. You may not know, McMaster has one of the best programs in music cognition, music neuroscience in the world. It’s home to the Live Lab, the world’s first concert hall that was built express from the ground up to do research.
Music is such an important part of what it is to be human. It’s found in every culture and part of our daily lives. It can inspire us, it can heal us, soothe us, and bring us together. But how and why are we musical?
I came to those questions personally on a journey that started with a physicist fascinated by sound, who became so interested in how a simple sound wave, when it reaches our brain, can turn into the most rich, beautiful experience of music. How does that work? Add to that a pinch, a healthy pinch, of being an amateur drummer, and you’ll understand why I’m here today.
The Brain on Music
As a neuroscientist, the first place we want to look about how does music work would be the brain. This is a brain scan of a pianist improvising. If you think for a moment, the last time you listened to music or made music, about all the different processes involved, memory, perception, pattern recognition, movement, it’s not surprising that neuroscience shows us that, in fact, the brain on music is a very active place indeed. This pianist improvising shows the involvement of many different parts of the brain.
Today we’ll be focusing on rhythm, this superpower that enables us to perceive patterns in time and synchronize with them. The question is, how does our brain do that? What kind of brains do we need to be human, to be rhythmic, to be able to be in sync with each other?
I’ve asked that question in a couple of ways. We’ve studied that by measuring brain waves of humans while they listen to rhythm, which starts to get at the mechanism of how, but then also by looking at the rhythmic abilities of other animals, non-human animals, which starts to get at some understanding of why.
Understanding the Beat
Before we get to the results, I’d like to make sure we’re really clear on one concept, which is that of the beat. I’ll play two rhythms for you. I just want you to pay attention to how they make you feel inside and the differences between them. Here’s the first.
Okay, the second.
Obviously the first one had a lot of repetition. It had pattern to it. It was easy to comprehend. We call that kind of rhythm a rhythm that induces a sense of beat. The second one was a little more random sounding. It would be very difficult to reproduce after one hearing.
But the key is the difference that this shows is the first rhythm is a kind of perception that humans have. It’s very unique, called beat-based perception. The idea being that we’re able to structure the flow, the endless flow of time, which has no beginning, no end, to create a starting point, to create a tempo, that enables you to remember that first rhythm is chunked into da-da-da, da-da-da, da-da-da, for example. The second one, it was harder to parse in that way.
So we study this by looking at people’s brains while they listen to rhythms. And while we’re used to thinking of the beat as being something in music, like that drummer laid down a great beat, the way I think about it and the way it seems to exist in the brain, it’s purely an internal reaction to music. The beat is something inside of us that we add to the music.
When the Beat is Impaired: The Parkinson’s Example
What if that sense of beat is impaired? In Parkinson’s, a disorder of the motor system, it is often impaired. This video here, this gentleman suffers from Parkinson’s. And one of the common symptoms is a difficulty in walking. You see his hesitant shuffling gait and frequent freezing episodes. You can imagine how disruptive this is to daily life. He’s got an objective, but it’s very hard to get there. What is his objective? He’s going to turn on some music.
So obviously, you can see the incredible transformation that came into his system. By having this beat of music externally and using its power to drive our movements to recover a much more fluid gait, the ability to move around much more smoothly. We think that that occurs because the music is able to act as a kind of surrogate rhythm to replace the rhythms inside the brain that are no longer able to be generated alone.
Studying Ambiguous Rhythms
So the way we study these things is to look at ambiguous rhythms, like this simple two-beat rhythm here, note, note, rest. That itself is a rhythm in the world. It’s a physical stimulus. But when it hits the brain, a beat is induced. So I imagine if you heard that rhythm, most people would tap their foot on the second note. Kind of a swing feeling. But that’s not the only way the brain could interpret that. It could just as well imagine the beat coming on the first note.
So really the idea is our perception is determined by the physical sound that reaches us, but also by this internal beat or pulse and how it aligns with the sound. So in this case, we have two possible alignments on the first note, the second note. It turns out that those have very different brain responses, showing that the brain is sensitive to this process of beat.
And you can think it’s very akin to a visual illusion, where whether we focus on red or green, we perceive a vase or two faces looking at each other.
A Participatory Experiment
Let me give you another example. So I’d like you to participate with me in this case. I’m going to lay down a beat. If you could just play it on your leg or tap your foot. Great. So on top of this beat, which will just keep going, I’ll play three different rhythms. Okay, number one.
Here’s the second one.
Number three.
Okay, I saved that one for last because it’s a little hard, isn’t it? By this point, you may not be surprised. Actually, those three rhythms were exactly the same, the same notes, right? What I changed was how those rhythms aligned with your internal sense of beat. And in doing that, we can then differentiate in the brain, parts of the brain that care only about the sound. So the parts of the brain that would respond exactly the same to those three different permutations. And then other parts of the brain that do care about where the beat falls.
And this is key because this beat, this internal sense of beat is invisible. If we don’t ask people to tap their foot or move along, we don’t really know where it is or where it’s coming from.
Brain Research Findings
So we did this in some experiments. And what we observed is the following. The red areas are sensitive to sound, and those lie in auditory cortex on the side of the brain. The areas marked in blue were the areas that were very sensitive to the sense of beat or the internal beat. Those are found in motor planning areas. So not motor execution areas, but motor planning areas.
And through a number of other studies, we’ve basically been able to corroborate this and also demonstrate top-down connections between the motor planning area and the beat area. And sorry, the music areas in auditory cortex. And this has led us to the new conception of beat. It’s not really an auditory thing, but a joint auditory motor function where the beat is essentially created by the combination of sound and the internal sense of beat.
So our perception of rhythm is really an auditory motor construct. It’s not purely auditory. And this is the case whether we’re moving or not in time. This is a pretty startling revelation, right? It means that we’re not simply just passively absorbing the sound that comes in. We’re actively engaged in interpreting it in a top-down manner.
The Evolutionary Question
So that’s part of the how. This idea that the motor system and connections between motor and auditory are crucial for our enjoyment and perception of rhythm and our synchronization with each other. But what about the why now?
Darwin was mystified by why humans were musical. What is the survival value of it? Indeed, it’s pretty strange to think. Why does this animal here on earth, hear music, hear rhythmic sounds, and just want to start moving? What’s that all about? Why are they doing that?
So as you can imagine, there are many ideals. And one of the, I think, most powerful ones is by William McNeill in his book “Keeping Together in Time,” proposing that this ability of us to synchronize
One way to address this question, though, is to ask, well, are we alone in being able to perceive a beat? And for a long time, we thought humans were truly unique, that humans were the only animal that could dance, the only animal that could perceive this kind of beat-based structure on rhythms. That all changed, as you might imagine, in 2007, when my colleague Ani Patel and I, separately as it turned out, saw a video on YouTube. And so what we saw was this guy, Snowball, sulfur-crested cockatoo. And he was basically, appeared to be dancing along with a song by the Backstreet Boys.
So not wanting to base a big new scientific discovery on a single YouTube video, we did a number of studies with Snowball, where we took his song and changed the tempo to see if he was truly following the beat, or just, it was just kind of a coincidence. So we got data like this. So the original tempo, this is what we saw on YouTube. And a lot of the comments were, “My God, that bird dances better than I can.” But then we increased the tempo. And at first he was having a hard time keeping up. Then he figured out a new mode of moving, and was able to follow.
So after these kinds of studies, and really being very careful to convince ourselves this is a real phenomenon, and not just some trick, we published a study in Current Biology showing that as you change the music tempo, Snowball’s movement tempo also changed.
The Dancing Animals Study
Is this unique to Snowball? Did we just discover the one bird that can dance? No, it turns out a group of Harvard grad students spent a summer poring through YouTube videos, thousands of videos of animals dancing. Of those videos, they only found 33 that showed true evidence of dancing, meaning that they were on tempo and in sync. And of the species that they discovered, 14 out of 15 were parrots and parrot-related birds.
This set off a kind of a firestorm of studies to see what other animals have rhythmic abilities. And what we found was really interesting. There were two groups. One group, including parrots and cockatoos, could really synchronize with music. They could listen to human music and do complex bobbing movements or other types of movements. Interestingly, our primate relatives, our closest relatives, had a much more limited ability. They could maybe move along with a metronome for a little while, maybe just at the right tempo.
So really interesting, this divide, and unexpected. And also unexpected that so few animals seem to have this ability. We know that most animals can move rhythmically. Most animals can hear. So what’s the big deal about combining these two things together?
The Vocal Learning Connection
One clue and one hypothesis in the field is that one thing we share with parrots in particular is the ability of lifelong, open-ended vocal learning. So this gets to the question of evolution. Maybe we evolved to be vocal learners, because that’s a very useful adaptive function. And maybe our musical abilities and beat-keeping abilities built on top of that. Vocal learning requires very close, tight connections between the auditory and motor systems. So maybe we were able to exploit that and become the musical species that we are.
It’s still really an open question. The fact that primates show some abilities, and they’re not vocal learners, clouds the issue somewhat. So it may be several things going on, gradual evolution of abilities, and so forth. But right now, a lot of the evidence does point to this important link between vocal learning and music synchronization.
The Social Dimension of Rhythm
So we’ve talked a lot about sound and movement. Of course, in reality, our relationship to rhythm and movement is a very social thing. Like we did together, or in partner dance, going to a concert. So it involves a lot more than sound. It involves vision, touch, and the very important social feedback that we get when moving in time with each other. So maybe this is the part that’s unique to humans.
Well, again, Snowball surprised us. Turns out Snowball seems to love to dance with his owner, Irena Schultz. You can see at first, like any teenager, he wants to ignore the embarrassing thing that his mom is doing. But he slowly gets drawn in. You can see the kind of connection that appeared to have formed there. We don’t really know what’s going on in Snowball’s mind, of course. But that certainly looked like communication and social bonding.
Conclusion
So, in conclusion, I’ve tried to give you a little sense of the work we do, understanding the how and why of human rhythmicity. Along the way, we talked about the importance of auditory-motor connections. We talked about the evolution, and perhaps the building off of vocal learning. We also talked about the therapeutic potential of musical rhythm.
This brings up an important point I’d like to make, which is that music therapy exists. It’s very powerful. It’s something that deserves our support. It’s a low-cost, very personal, very individualized form of therapy. So if you or one of your relatives has movement disorders, why not ask your doctor whether music therapy might work?
But finally, I’d like to leave you with this, because next time you’re listening to music or dancing or playing music, I hope you might think back to this talk and think a little bit more about what’s going on in your mind as you make music, about the connections that can form through music, and just a little bit more about what it means to be human. In closing, thank you very much.
