Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man (16 page)

Gangly Notes

The repetitive nature of our footsteps is the most fundamental regularity found in our gait, explaining the fundamental status of the beat in music. But we humans make a greater racket than we are typically consciously aware of. Much of our body weight consists of four heavy, gangly parts—our limbs—and when we are on the move, these ganglies are rattling about, bumping into all sorts of things. When our feet swing forward in a stride, they float barely above the ground, and very often shuffle on their way to landing. In natural terrain, the grass, rocks, dirt, and leaves can get smacked or brushed in between the beat. Sometimes one’s own body hits itself—legs hitting each other as they pass, or arms hitting the body as they swing. And often we are carrying things, like a quiver of arrows, a spear, a keychain, or a sack of wet scalps of the neighboring villagers, and these will clatter and splat about as we move.

Not only do our clattering ganglies clang in between our footsteps, they make their sounds in a time-locked fashion to the footsteps. This is because when we take a step, we
initiate
a “launch” of our limbs (and any other objects carried on our bodies) into a behavior-specific “orbit,” an orbit that will be repeated on the next step if the same behavior is repeated. In some cases the footstep causes the gangly hit outright, as when our step launches our backpack a bit into the air and it then thuds onto our back. But in other cases the step doesn’t directly cause the between-the-beat gangly hit so much as it triggers a sequence of motor events, such as our arms brushing against our body, which will recur at the same time delay after the next step. Exactly what the time delay will be after the step depends on the specific manner in which any given gangly part (appendage, carried object, or carried appendage) swings and bounces, which in turn depends on its physical dimensions, how it hangs, where on the body it lies, and how it participates in the behavior.

From the auditory pattern of these footstep-time-locked clattering ganglies, we are able to discern what people are doing. Walking, jogging, and running sound different in their patterns of hits. A sharp turn sounds different from a mover going straight. Jumping leads to a different pattern, as does skipping or trotting. Going up the stairs sounds distinct from going down. Sidestepping and backing up sound different than forward movement. Happy, angry, and sad gaits sound different. Even the special case we discussed in the previous chapter—sex—has its own banging ganglies. Close your eyes while watching a basketball game on television, and you’ll easily be able to distinguish times when the players are crossing the court from times when they are clustered on one team’s side; and you will often be able to make a good guess as to what kind of behavior, more specifically, is being displayed at any time. You can distinguish between the pattern of hits made by a locomoting dog versus cat, cow versus horse. And you can tell via audition whether your dog is walking, pawing, or merely scratching himself. It should come as no surprise that you have fine-grained discrimination capabilities for sensing with your ears the varieties of movements we
humans
make, movements we hear in the pattern of gangly bangings.

If the pattern of our clanging limbs is the cue our auditory system uses to discern a person’s type of behavior, then music that has culturally evolved to sound like human movement should have gangly-banging-like sounds in it. And just as gangly bangings are time-locked to the steps, music’s analog of these should be time-locked to the beat. And, furthermore, musical banging ganglies should be crucial to the identity of a song, just as the pattern of a mover’s banging ganglies is crucial to identifying the type of behavior.

Where are these banging ganglies in music? Right in front of our ears! Musical banging ganglies are simply
notes
. The notes on the beat sound like footsteps (and are typically given greater emphasis, just as footsteps are more energetic than between-the-steps body hits), and the notes occurring between the beats are like the other body hits characterizing a mover’s behavior. Beats are footsteps, and rhythm (more generally) is the pattern of a mover’s banging ganglies. Just as between-the-steps body-hit sounds are time-locked to footsteps, notes are time-locked to the beat. And, also like our gait, pieces of music that have the same sequence of pitches but differ considerably in rhythm are perceived to be different tunes. If we randomly change the note durations found in “Twinkle, Twinkle Little Star,” thereby obliterating the original rhythm, it will no longer
be
“Twinkle, Twinkle Little Star.” Similarly, if we randomly change the timing of the pattern of banging ganglies for a basketball player going up for a layup, it will no longer
be
the sound of a layup.

Rhythm and beat have, then, some similarities to the structure of our banging ganglies. We will discuss more similarities in the upcoming sections and in the Encore chapter. But there is one important similarity that might appear to be missing: musical notes usually come with a
pitch
, and yet our footsteps and gangly hits are not particularly pitchy. How can the dull thuds of our bodies possibly be pitchy enough to explain the central role of pitch in music?

If you have already read the earlier chapter on speech, then you may have begun to have an appreciation for the rings occurring when any solid-object physical event occurs. As we discussed, we are typically not consciously aware of the rings, but our auditory system hears them and utilizes them to determine the identity of the objects involved in events (e.g., to tell the difference between a pencil and a paper clip hitting a desk). Although the pitch of a typical solid object may not be particularly salient, it can become much more salient when contrasted with the distinct pitches of other objects’ rings. For example, a single drum in a set of drums doesn’t sound pitchy, but when played in combination with larger and smaller drumheads, each drum’s pitch becomes easy to hear. The same is true for percussionists who use everyday objects for their drums—in such performances one is always surprised to hear the wide range of pitches occurring among all the usually pitchless-seeming everyday objects. Our footsteps and banging ganglies
do
have pitches, consistent with the hypothesis that they are the fundamental source of musical notes. (As we will see, these gangly pitches are analogous to chords, not to melody—which, I will argue later, is driven by the Doppler effect.)

If I am right that musical notes have their origin in the sounds that humans make when moving, then notes should come in human-gait-like
patterns
. In the next section, we’ll take up a simple question in this regard: does the number of notes found between the beats of music match the number of gangly bangs between footsteps?

The Length of Your Gangly

Every 17 years, cicadas emerge in droves out of the ground in Virginia, where I grew up. They climb the nearest tree, molt, and emerge looking a bit like a winged tank, big enough to fill your palm. Since they’re barely able to fly, we used to set them on our shoulders on the way to school, and they’d often not bother to fly away before we got there. And if they did fly, it wasn’t
really
flying at all. More of an extended hop, with an exoskeleton-shaking, tumble-prone landing. With only a few days to live, and with billions of others of their kind having emerged at the same time, all of them screeching mind-numbingly away, they didn’t need to go far to find a mate, and graceful flight did not seem to be something the females rewarded.

Cicadas have, then, a distinctively cicada-like sound when they move: a leap, a clunky clatter of wings, and a heavy landing (often with further hits and skids afterward). The closest thing to a footstep in this kind of movement is the landing thud, and thus the cicada manages to fit dozens of banging ganglies—its wings flapping—in between its landings. If cicadas were someday to develop culture and invent music that tapped into their auditory movement-recognition mechanisms, then their music might have dozens of notes between each beat. With
Boooom
as their beat and
da
as their wing-flap inter-beat note, their music might be something like “
Boooom-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-Boooom-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da-da,” and so on. Perhaps their ear-shattering, incessant mating call is this sound!

Whereas cicadas liberally dole out notes in between the beats, Frankenstein’s monster in the movies is a miser with his banging ganglies, walking so stiffly that his only gait sounds are his footsteps. Zombies, too, tend to be low on the scale of banging-gangly complexity (although high on their intake of basal ganglia).

When
we
walk, our ganglies are more complex than those of Frankenstein and his zombie dance buddies, but ours
are doled out much more sparingly than the cicadas’. During a step, your leg swings forward just once, and so it can typically only get one really good bang on something. More complex behaviors can lead to more bangs per step, but most commonly, our movements have just one between-the-footsteps bang—or none. Our movements tend to sound more like the following, where “
Boooom
” is the regularly repeating footstep sound and “da” is the between-the-steps sound: “
Boooom-Boooom-Boooom-da-Boooom-Boooom-da-Boooom-da-Boooom-da-da-Boooom-da-Boooom-da-Boooom
.” (Remember to do the “
Boooom
” on the beat, and cram the “
da
”s in between the beats.)

Given our human tendency to make roughly zero to one gangly bang between our steps, our human music should tend to pack notes similarly lightly between the beats. Music is thus predicted to tend to have around zero to one between-the-beats note. To test for this, we can look at the distribution of time gaps between musical notes. If music most commonly has about zero to one note between the beats—along with notes usually on the beat—then the most common note-to-note time gap should be in the range of a half beat to a beat.

To test this, as an RPI graduate student, Sean Barnett analyzed an electronic database of Barlow and Morgenstern’s 10,000 classical themes, the ones we mentioned at the start of this chapter. For every adjacent pair of notes in the database, Sean recorded the duration between their onsets (i.e., the time from the start of the first note to the start of the second note). Figure 19 shows the distribution of note-to-note time gaps in this database—which time intervals occur most commonly, and which are more rare. The peak occurs at ½ on the
x
-axis, meaning that the most common time gap is a half beat in length (an eighth note). In other words, there is one note between the beats on average, which is broadly consistent with expectation.

Figure 19
. The distribution of durations between notes (measured in beats), for the roughly 10,000 classical themes. One can see that the most common time gap between notes is a half beat long, meaning on average about one between-the-beat note. This is similar to human gait, typically having around zero to one between-the-step “gangly” body hit.

We see, then, that music tends to have the number of notes per beat one would expect if notes are the sounds of the ganglies of a human—not a cicada, not a Frankenzombie—mover. Musical notes are gangly hits. And the beat is that special gangly hit called the footstep. In the next section we will discuss some of what makes the beat special, and see if footsteps are similarly special (relative to other kinds of gangly hits).

Backbone

My family and I just moved into a new house. Knowing that my wife was unhappy with the carpet in the family room, and knowing how much she fancies tiled floor, I took the day off and prepared a surprise for her. I cut tile-size squares from the carpet, so that what remained was a checkerboard pattern, with hardwood floors as the black squares and carpet as the white squares.

I couldn’t sleep very well that night on the couch, and so I headed into the kitchen for a bite. As I pondered how my plan had gone so horribly wrong, I began to notice the sounds of my gait. Walking on my newly checkered floor, my heels occasionally banged loudly on hard wood, and other times landed silently on soft carpet. Although some of my between-step intervals were silent, between many of my steps was a strong bump or shuffle sound when my foot banged into the edge of the two-inch-raised carpet. The overall pattern of my sounds made it clear when my footsteps
must
be occurring, even when they weren’t audible.

Luckily for my wife—and even more so for me—I never actually checkered my living room carpet. But our world is itself checkered: it is filled with terrain of varying hardness, so that footstep loudness can vary considerably as a mover moves. In addition to soft terrain, another potential source of a silent step is the modulation of a mover’s step, perhaps purposely stepping lightly in order to not sprain an ankle on a crooked spot of ground, or perhaps adapting to the demands of a particular behavioral movement. Given the importance of human footstep sounds, we should expect that our auditory systems were selected to possess mechanisms capable of recognizing human gait sounds even when some footsteps are missing, and to “fill in” where the missing footsteps are, so that the footsteps are perceptually “felt” even if they are not heard.

If our auditory system can handle missed footsteps, then we should expect music—if it is “about” human movement—to tap into this ability with some frequency. Music should be able to “tell stories” of human movement in which some footsteps are inaudible, and be confident that the brain can handle it. Does music ever skip a beat? That is, does music ever
not
put a note on a beat?

Of course. The simplest cases occur when a sequence of notes on the beat suddenly fails to continue at the next beat. This happens, for example, in “Row, Row, Row Your Boat,” when each “row” is on the beat, and then the beat just after “stream” does not get a note. But music is happy to skip beats in more complex ways. For example, in a rhythm like that shown in Figure 20, the first beat gets a note, but all the subsequent beats do not. In spite of the fact that only the first beat gets a note, you
feel
the beat occurring on all the subsequent skipped beats. Or the subsequent notes may be perceived to be off-beat notes, not notes on the beat. Music skips beats and humans miss footsteps—and in each case our auditory system is able to perceptually insert the missing beat or footstep where it belongs. That’s what we expect from music if beats are footsteps.