In ancestral time periods, if a lion approached us, we became stressed. Cortisol levels shot up. Our amygdala and basal ganglia set us running—or at least those of us who managed to survive. (Many of those early humans who, for one reason or another, didn’t run or otherwise escape the lion didn’t live to tell about it or to have children.) Running uses up glucose and helps us to “burn off ” the cortisol our adrenal cortex produces. Today, though, when our boss yells at us, when we have a big exam that we haven’t prepared for, or when someone cuts us off while driving, our adrenal cortex still produces cortisol—the stress hormone—but we don’t have an opportunity to burn it off. Our legs and shoulders tense up to run in accordance with an ancient evolutionary formula, but . . . we sit there. Our shoulder muscles stay tense but we are not swinging our arms, and so there is no release.
All that cortisol temporarily interrupts our digestive system—a body in flight needs to allocate its energy to movement and agility, not digestion—and so today, following stress that doesn’t require literal fight or flight, we end up with stomachaches, gastroenteritis, ulcers. Increased cortisol is associated with decreases in production of IgA, and so our immune system takes a hit. (This is why people who are stressed are more likely to get sick.) In contemporary society, increased cortisol levels (and decreased IgA) have been found in experiments conducted during some of the most psychologically stressful situations humans face: students before exams, professional coaches during athletic events, and air traffic controllers during their duty cycle. Getting tense in the face of a threat was adaptive for our ancestors; it is maladaptive for us when those stressors are long-term, chronic, and don’t require an acute physical response.
So cortisol suppresses our immune system temporarily, marshaling all the resources it can for the task at hand (or at foot as the case may be). This may well be one of the reasons why we move our feet or snap our fingers when we hear music. To the extent that music activates our
action
system—motor sequences and our sympathetic nervous system—our hands and feet become the instruments of that activation. Through these movements we burn off excess energy that could otherwise be toxic. In a sort of neurochemical dance, music increases our alertness through modulation of norepinephrine and epinephrine and taps into our motor response system through cortisol production, all the while bolstering our immune system through musical modulation of IgA, serotonin, melatonin, dopamine, adrenocorticotropic hormone (ACTH), and β-endorphin (β-EP). Some of the energy we feel during music playing and listening is then expended in the increased mental activity (the visual images that many people report accompanying musical activity, or other mental activity such as planning, ruminating, or simply aesthetic appreciation). Finger snapping, hand clapping, and foot tapping help us burn off the rest, unless of course we actually get up and dance, perhaps the most natural reaction, but one that has been socialized out of many Western adults.
But
why
does music—a collection of sounds—tap into all these chemical and activity centers of the brain? What might have been the evolutionary benefit? First, it is important to reframe the question as concerning music-dance—not as simply a collection of sounds we make or perceive, but as an integrated cross-modal experience of movement, synchrony, sound, and perceptual organization, and again, this is because music and dance were virtually inseparable across evolutionary time scales. Second, the musical brain didn’t evolve in isolation from other mental and physical attributes. In other words, early or protohumans didn’t suddenly end up with music-dance and no other cognitive strengths. The musical brain brought with it all the facets of human consciousness itself. In addition to social bonding, fundamental to the experience of early humans was communicating their emotional states to others—the expression of joy through music-dance.
Unrestrained joy usually accompanies a positive outlook. In situations where success isn’t assured, those with a positive outlook are more likely to achieve it than those with a defeatist attitude. Of course there is a delicate balance. As Barack Obama said during the 2008 presidential campaign (quoting the German Protestant theologian Jürgen Moltmann, whose words have also been used by the Catholic Church in offical writings), “Hope is not blind optimism.” An overoptimistic person is going to experience a large number of failures and find he has expended considerable energy for no rewards. On the other hand, the defeatist (or pessimist) is going to forgo activities that in many cases would have yielded a substantial positive payoff. The best adaptive strategy for hunting, foraging, or even mating has been shown to be the adoption of an attitude that is slightly over the halfway mark, on the optimistic (joyful) side of realistic. Music has a twofold role to play here, physical and mental. First, joyful music makes us feel better, it pumps us up, picks us up out of the doldrums. Second, joyful music can serve as a model—we look to the creator of that music as a mental inspiration and try to be like him or her.
The clearest case of the evolutionary advantage of optimism might be the caveman who is uncertain whether that glance he just received from a cavewoman was a “come hither” or a “get lost” look. The caveman who walked away may well have lost an opportunity gained by his rival who treated that ambiguous look as at least worth investigating. As a species, we have evolved a healthy distrust for people who are
too
optimistic—they may be deluded nutjobs—and we’ve evolved a reasonable attraction to people who are self-confident and optimistic—after all, they may know something we don’t, and things might just work out well for them. “I’d do well to hitch my wagon to his,” we think. The optimist thinks a brewing conflict might be solved by diplomacy. The pessimist thinks fighting is inevitable, and those thoughts may bring about his own destruction. Our brains evolved the responses to joyful music making that they did because joy can be a reliable indicator of a person’s mental and physical health.
In his groundbreaking book
Sweet Anticipation,
David Huron spells out how the musical brain might have helped to prepare humans for survival. To what he has already written, I would add that it also served to relieve stress through the release of the very same neurochemicals that helped to ensure survival in hazardous, ancient environments. The ideas are important enough that I think they’re worth repeating here in some detail. Huron’s thesis is built around a five-step process that he calls ITPRA. I present here a four-stage version of his model, which I think is more parsimonious.
The core idea is that music gives the brain opportunities to explore, exercise, play with, and train those mental, physical, and social muscles necessary for the maintanance and formation of society as we know it. It offers a safe forum in which we can practice and hone skills that are vital through the life span. In my stripped down version (with apologies to David Huron), TRIP stands for Tension, Reaction, Imagination, and Prediction.
Imagine, David invites us, that we witness a lion attack. The next time we see a lion, we will understandably experience Tension. (If we didn’t, we might act complacently and end up as his lunch.) The tension begins a cascade of electrochemical processes in our brain and spinal cord, causing us to React. If that reaction allows us to survive, we may then spend some of our time Imagining—recalling the event in our mind’s eye (and ear) and planning appropriate reactions in the event of a future attack. Part of this process might entail imagining what future confrontations might look like, how we might Predict a possible attack under different situations.
Now learning about the world by narrowly escaping from lions, rattlesnakes, or angry neighboring tribespeople is not the most efficient way to acquire survival information. Indeed, the topic of Chapter 5 is how particular kinds of songs—knowledge songs—can encode and embed such essential information in a way that is easily remembered and transmitted across time. But before there can be knowledge songs, there must be music, or at least the cognitive foundations for it, an adaptive motivation for the musical brain to come into existence in the first place. This is where music meets TRIP. What if we humans had a way that we could invoke tension in a safe, nonthreatening context, react to it, imagine new forms of tension and our reactions to those, and prepare a repertoire of responses, all from the safety of the camp-site, from the safety of our minds? Music doesn’t have to be the
only
adaptation that provides this; it only needs to be a
plausible
adaptation, even one among many possible, for this theory of its origins to hold.
Music theorists since Aristoxenes and Aristotle, through Leonard Meyer, Leonard Bernstein, Eugene Narmour, and Robert Gjerdingen, have talked about tension as being one of the core properties of music. Virtually all theories of music assume that musical tension changes during the course of the piece, involving increases and decreases in a cyclic dance of tension and release. In a paper published a few years ago in the journal
Music Perception,
my students Bradley Vines (now a research scientist at UC Davis) and Regina Nuzzo (now a professor at Gallaudet University in Washington, DC) and I described this property of music in terms of physics—Newtonian mechanics specifically. We compared music to a coiled spring like the one you might have attached to your garage door. Pull or push the spring and it tries to come back to its resting position.
Musicians and composers are speaking metaphorically of course when they talk about tension and release in music. But across many studies, the metaphor seems to have consistency of meaning, even among non-musicians and across very different cultures. We seem hardwired to “get” the relationship, however metaphorical, between musical tension and the tension that we feel in physical objects (like springs), in the body (as in muscles), and in social situations (as at high school dances). These common life experiences among humans cause a convergence of meaning for “tension” and “release” across individuals when referring to music. The cognitive psychologist Roger Shepard reminds us that the human mind co-evolved with the physical world in such a way that it has incorporated certain physical laws. No human infant is surprised when objects fall downward—gravity has become incorporated into the hardwiring of the human brain from birth. Indeed, infants as young as a few weeks show surprise when objects are experimentally manipulated to “fall” up, or when one billiard ball hits another and the second does not move appropriately.
In general, tension tends to built up during music to a peak, after which the tension is released and subsides, often rapidly. This is what gives us that “aahhhhh” feeling at the end of a piece of music. Symphonies (from the standard-practice period of classical music), perhaps more so than other musical forms we enjoy today, are particularly formulated to create this sense of dynamism, of tension and ultimate, rewarding release in the last few moments. In performances of Indian classical music, the performer teases the listener by circling just above and below a stable tone, delaying the resolution as long as possible. When the resolution comes, members of the audience shake their heads and say, “Vah-vah!” Like life, music speeds up and slows down, it breathes, it has peaks and valleys of emotion, it engages our attention more or less strongly, it holds us then lets us go, and then picks us up again.
You can think of that stretched garage-door spring as containing potential energy—it
wants
to move; physicists also call this
stored
energy. When it starts to return to its original position, it is showing kinetic energy, the energy of movement. Similarly in music, composers and musicians create both potential and kinetic musical energy through a variety of means, principally involving pitch, duration, and timbre changes. But the “springiness” of music tension comes from our brains not from a physical object. No musical note is intrinsically or inherently “tense,” rather, tension comes from
expectations
that our brains create based on stylistic norms for music, statistical properties of music, and the notes that we have just previously heard in the musical piece we’re listening to. When we hear a note we didn’t expect, or one that violates standard musical probabilities even in a small way, this is like pulling on the musical tension spring; our brains
want
the music to return to a more stable position. When we hear the first two notes of the chorus in “Over the Rainbow”—that big octave leap—it
feels
like someone has pulled a spring in our musical brains. The third note simply
has to
come down in pitch, and of course it does. In fact, the entire chorus of the song can be seen as an intricate and fabulous journey of trying to come to a relaxing resting point from that initial two-note tension. Joni Mitchell stretches the melodic spring several times in her song “Help Me,” and spends the rest of the song allowing that spring to come nearly home, and—as in “Over the Rainbow”—not fully resolving the tension until the end of the song.
The tension in music motivates us to imagine musical scenarios that will come next—to form predictions. When our predictions come true, we feel rewarded and pat ourselves on the back. But we can learn even more when our predictions are not true, if events unfold in a way that is logical but is simply not one we would have thought of before ourselves. When a caveman friend showed another an easier way to find food, the second caveman recognized the value of learning, of expanding his repertoire of “right answers” as adaptive solutions to the problem of acquiring nourishment. Learning new things should feel good in our brains because it is usually adaptive.