Music is a multi-billion-dollar industry. It is present in all cultures and from day one of our lives. More than 30 million people visit YouTube each day, and of the top 100 most-viewed Y­ouTube videos of all time, a whopping 96 are music videos. Music provides the best examples of what Richard Dawkins called a “meme”: an idea or content that spreads and replicates as if it had a life of its own.

The prevalence of music in human life makes us wonder: Why do humans have music? What does music do for us as a species?

While the internet is rife with examples of music from non-human animals, few have undergone as rigorous as test of musicality as Snowball the cockatoo and Ronin the sea lion, who have been trained to dance, even adapting their tempo to external stimulation. It is worth noting, however, that these are domesticated animals trained by humans; it is unclear whether they would have spontaneously developed this behavior if left on their own in the wild. Birds, on the other hand, have naturally evolved sophisticated auditory-motor repertoires, but even for them the separation between music and language is less clear.

As far as we know, of all species in the world, only humans have spontaneously evolved musical and linguistic cultures side by side. Thus music, just like language, seems quite unique to humans.

If music is unique to humans, then why do we have it? Charles Darwin believed that music was a kind of mating call, originally acquired to charm the opposite sex. While that idea is attractive, it cannot be the whole story: lullabies and play songs, for example, were never acquired for mating purposes. As an opposing view, psychologist Steven Pinker famously believed that music confers no evolutionary adaptation, likening it to auditory cheesecake (Pinker, 1997); this has become the evolutionary null hypothesis of music.

­A third view comes from Aniruddh Patel, who wrote that music is a “transformative technology of the mind,” which we humans invented, but which then changed our biology. In this sense, music is analogous to fire; we invented it, then used it to make food which, in turn, changed our digestive systems. The field of music cognition has embraced the latter idea much more; after all, fire has much more transformative power than cheesecake. Music makes us better; cheesecake does not.

How does music make us better?

A wealth of findings come from Nina Kraus’s work showing that people with musical training have better neural encoding of speech sounds, resulting in better detection of speech in noise from childhood through old age. A complementary line of evidence, from our lab and others, shows that musical training changes the arcuate fasciculus, a superhighway of our brain’s auditory-motor system (Loui et al, Halwani et al, Moore et al). There are also compelling findings that music training strengthens children’s executive function and empathy (Habibi et al, Rabinowitch & Cross), and that engaging in musical behavior (e.g. dancing) together helps prosocial behavior (Cirelli & Trainor). In short, music makes us better, because it makes us hear and think more clearly, and it connects us to other members of our species.

Of course, the thousands of people who pay to rock out at concerts over the weekend do so not out of concern for their own cognitive and brain development, but because they value something else about the experience. Music makes us feel good, perhaps because it brings us closer to each other, perhaps because it expresses an identity. We are a social species; thus, much of what we do, including music, is social. In that regard, music is quite analogous to language: having language means we can communicate with each other, and this communication aided the survival of our species.

There is no question that language can appeal to emotion; without language there would be no Shakespearean tragedies. However, those relied explicitly on semantics, i.e. using language as a device to communicate about something outside of language itself, and that something else is emotional; therefore, language can be emotional. Music, on the other hand, can appeal directly to emotion without the need to refer to something outside of itself. Every time I hear Debussy’s string quartet I tear up, not because it reminds me of anything specifically, but because I find it profoundly bittersweet. Music can elicit strong emotions that can be positive, negative, or both. Paradoxically, we even find sad music rewarding to listen to, even though we would never seek out sad experiences in real life.

Why does music arouse emotions?

There is abundant evidence that these emotions are tied to the brain’s reward system. Neuroimaging studies from the Zatorre lab have shown that peak moments of intense pleasure in music (defined subjectively for each person) activate the brain’s dopaminergic system—the system that is active during eating, sex, and with addictive drugs (Salimpoor et al, 2011). Furthermore, auditory areas in the brain show the most functional connectivity to these same reward-sensitive areas when we listen to music that we value (Salimpoor et al, 2013). Additionally, our lab has shown that people who frequently experience chills when listening to music have stronger connectivity between auditory regions and areas of the brain that are important for social and emotional processing (Sachs et al, 2016).

In a way, these findings dovetail well with musicologists’ approach to the same question about music arousing emotions. In his seminal book Emotion and Meaning in Music, Leonard B. Meyer (1956) posited that slight violations of expectations are emotional and meaningful in music. Auditory signals that arouse reward centers include the musical devices that composers, improvisers, DJs, and all who produce music are familiar with, both through their training and their intuition (which is refined by training, of course): syncopation, chord changes, melodic twists, the slow buildup, the beat drop . . . an arsenal of tools to manipulate and violate the expectancies that our brains are constantly forming. A prime example of these expectations in action comes from the opening theme of Adagio Cantabile from Beethoven’s Pathétique Sonata: the slightly unexpected V7/ii chord in the opening theme gives the theme an especially emotional touch (Yundi Li takes great care with it at 1:02 in this performance).

Philosopher Dan Dennett wrote, “A mind is fundamentally an anticipator, an expectation-generator.” At its best, music plays the mind by playing with these expectations.

The mapping of specific musical tools to their corresponding emotions is a very active area of research, but a major challenge is that these mappings are highly individualistic. They are wonderfully diverse, much like the human experience: a chord change that gives me the chills (take the slow movement of Rachmaninoff’s Second Piano Concerto, performed by Yuja Wang here: check out 9:57-10:05!) may sound trivial or even boring to you, and while some people may feel emotions for music all the time, others may hardly feel anything.

An incapacity to enjoy music?

On an extreme end of the spectrum are those with specific musical anhedonia, an individual’s incapacity to enjoy listening to music. This newly coined disorder is tied to different patterns of structural and functional connectivity between auditory and reward areas (Mas-Herrero et al, Martinez-Molina et al, Loui et al). Musical anhedonia is very different from misophonia, which is the hatred of bodily sounds (such as gum-chewing and pen-clicking) (Kumar et al, 2017; Edelstein et al, 2013). Rather than hating any sounds, those with musical anhedonia just do not care about sounds at all.

I recently worked with a severe case of specific musical anhedonia (more about it here). Despite having knowledge that certain music was composed to evoke certain emotions, he reported feeling no such emotions. His experience to music was rather like, to quote Oliver Sacks, an anthropologist on Mars: he would see people bopping to music in their headphones at the checkout line, and he would wonder why they would want to do so. As a result, he lives a music-less existence, only feeling mildly annoyed when music enters his life incidentally. Interestingly, he does enjoy photography and visual art.

The case of musical anhedonia brings us back to the question: Why do we need music at all? At its core, music is composed of patterns of predictable, structured sound; that in itself might not be special, because in that regard it is similar to language. Music arouses reward-related emotion and brings people together, but these rewards are not unique to music: many other experiences are also rewarding, bring people together, and arouse emotion.

But there appears to be something special about the conjunction of structured sounds and reward-related emotion. This leads us to an intriguing hypothesis: through an auditory pathway to the reward centers of the brain, music achieves the evolutionary goal of social bonding, of which language is incapable.

Perhaps our early human ancestors, after getting warm and dry and fed, still felt dissatisfied. Perhaps they realized they had an unmet need. Music fulfilled that need. As a result, our ancestors made bone flutes and early concert spaces (see archeological evidence in Steven Mithen’s Singing Neanderthals), and likely sang and drummed, and music began. Thus music, and art more generally, are sensory experiences that drive our cognitive and affective systems.

In summary, the human capacity for music can be thought of as the tendency to derive strong emotions from complex sensory patterns. We have evolved the perceptual, cognitive, and neural apparatus to detect, appreciate, and transmit these patterns, and doing so brings us closer together.

That is how music makes us human.


Debussey’s String Quartet in G minor, III, particularly touches the author’s emotions:

 

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Psyche Loui is an Assistant Professor in the College of Arts, Media and Design at Northeastern University.