Sounds Wild and Broken, page 18
Kinship, but also particularity. We’re a peculiar species. Among our close kin, the primates, there are no other species nearly as adept at vocal learning as we are. The complex behaviors and cultures of these other primates are based on visual and tactile observation, not vocal learning. These nonhuman primates also seem to have different brain functions. Those brain regions that are essential for vocal learning in humans play only a minor role in vocal production in other primate species. There is uniqueness here, one seized upon by those seeking to carve out a special place for humans in the natural order. But the cultural evolution of sound in birds, whales, and other vocal learners suggests that human vocal learning is not so much unique as parallel. There are multiple paths to vocal learning and culture within the animal kingdom.
Like the evolution of wings in bats, birds, and insects, evolution has produced vocal learning through bodies of different design. In any convergent evolution of this kind, we expect each independent invention to have its own features. Ranking one as superior to the others seems absurd. Yet humans like to reserve “language” for ourselves. Other animals make sound, but only we have language—as if bats fly, but birds and insects only flap, soar, and flutter. On what basis do we make this distinction? Humans are not unique in learning, intentionality, possession of vocal culture, evolution of culture over time, encoding meanings in sound, or representing in our speech external object or internal states. Every species has a logic, a grammar, to its sound making. It is not clear why only one of these grammars should qualify as language, nor is it obvious which dimension of grammatical refinement should be used as a yardstick. Birds, for example, are superior to humans at discriminating the subtle nuances within individual sounds, seeming more attuned to the rules and syntax contained in syllables than the arrangements among strings of syllables. If this capacity were the measure of language, we’d be ranked below sparrows. Experiments with rhesus macaques and European starlings show that even the purported uniqueness of recursion in human syntax—our ability to create and understand a wide, perhaps limitless, range of expressions from a finite set of elements—is not limited to our species.
We have only a rudimentary knowledge of sound making and vocal learning in other species, a hazy and imperfect gaze into the complex vocal lives of others. Yet even amid this fog of ignorance, we clearly see our own species as just one of a multitude of speaking, cultured beings. Perhaps our species’ special quality is not the achievement of a state unattained by others—language or culture—but a convergence of abilities. Many animals learn their sounds, and these sounds help them to prosper within their social worlds: finding mates, resolving tensions, and communicating identity, belonging, and need. Many animals also learn the practical physical and ecological skills needed to thrive. This knowledge usually passes from one generation to another through close observation, not through elaborate sounds. Young vertebrate animals often spend years studying their elders in order to learn how to find and process food, where to migrate, how to build shelter, what to do when a predator arrives, and how to navigate the cooperative and competitive social world. Without this knowledge, they are lost. These two aspects of culture—vocal communication and learned practical skills—are mostly separate in nonhuman animals. In humans, the cultural evolution of sound and that of other forms of knowledge unite. For us, learned sound is an aesthetic experience, a mediator of social relations, and a source of detailed information about how to navigate and manipulate the world. Other species use culture in all these ways, but we knit them together in a union so far unknown among others.
In the last five and a half thousand years, we’ve taken another step. By carving into clay, inking onto pages, and thumb tapping against screens, we have captured and frozen what was ephemeral, giving speech long-lasting material substance. The invention of the written word broke the constraints that confined all previous vocal communication. When I read an ancient poem, the minds of the dead resurrect within me and speak. When I immerse myself in a book penned on a different continent, I travel across space and time and hear the author’s voice. The possibilities for accretion and interconnection of knowledge are vastly increased over the powers of the spoken word alone. Written notation did the same for human music. The score on my music stand carries a melody across centuries.
Text is a crystallization of sound, a diamond compared with the gaseous carbon in breath. A beautiful gem. But a hard one, too, in the powers that it gives us. In the face of some of the productions of the written word—machines, changed atmosphere, human appetites empowered to take and control—other animal cultures are in decline. The population of the white-crowned sparrow, for example, has shrunk overall by about one-third since the 1960s. This population change is uneven, with pronounced declines in California and Colorado, most likely because of the fragmentation and degradation of its preferred scrubby habitat, but with increases in the northern Rocky Mountains and Newfoundland, for unknown reasons.
Among other cultured species, the loss is yet more catastrophic due to habitat loss, pollution, and hunting. Half of all parrot species are in decline worldwide. The last half century has seen bird abundance decline by one-third, about three billion individual singing birds gone from North America, a decline also found on other continents, especially in agricultural areas. About one-third of all whale and dolphin species are threatened with extinction. Wherever human activities preempt land—agriculture, forest clearing, mining—songbirds are in steep decline, and forest fires and desertification claim yet more.
Birds have likely been learning their songs for at least fifty-five million years, when songbirds and parrots shared a common ancestor. Mammals perhaps for about the same time, dating to the origins of bats and whales. Over this long time, vocal learning and cultural evolution were both soil and fertilizer for the growth and blossoming of sonic diversity. In humans, though, these processes turned and started to erode life’s diversity, an abrupt change from the expansion that learning and culture previously encouraged. Perhaps part of the cause of this switch from flourishing to destruction lies in our inattention. We humans, distracted by our newfound powers, turned inward and largely forgot how to learn from the voices of other animal species. If this is true, then by reawakening the practice of attending to the voices of others, we will dim the destructive impulse and renew the creative powers of listening and learning.
The Imprints of Deep Time
When introducing students to the practice of attentive listening, I ask them to sit quietly and focus their attention on minute changes in the sounds around them, sending their ears “out” into the world to forage for acoustic experience. Part of what we learn is how hard it is for our frazzled modern minds to keep our attention on any sensory experience without inner distraction. But repeated practice opens a space where the clamor of the mind quiets and the sonic richness of the world blooms. In just fifteen minutes, we each hear dozens, sometimes hundreds, of different sounds in places where usually we would notice, at most, a handful. By listening in the same location over months, we find that these short exercises excavate not only an impressive count of different sounds but also patterns and relationships among them, fragments of earthly music with many layers and tempi.
This subtle complexity underscores how inadequate a few words are to summarize the soundscape of any place. A single hour could fill a book if each timbral, rhythmic, and spatial variation were adequately described. But even a sketch, however incomplete, can perhaps glimpse ways in which sound lives in the moment and has been shaped by history.
Contrasts among soundscapes are most obvious to us when their divergent sounds are the product of markedly different physical energies or human noises. We find it self-evident that wave-pummeled shores sound different from forested valleys, and that suburban streets have a different acoustic character than airports. Not so superficially obvious are differences among the sounds of living species. For ears not attuned to the voices of insects, birds, and other vocalizing creatures, variations are easy to miss.
Just as sounds from ocean waves or mechanical engines reliably disclose their sources, so, too, do animal sounds. The most obvious differences among the many calls and songs of living beings reflect broad taxonomies. Corrugated tymbals of cicadas rasp and whine, rubbing wings of crickets chirp, and membranes in bird chests whistle and trill. Within each one of these categories of sound, with some help from DNA and fossils, we can also discern the evolutionary history of each group of species: where they came from and which other species are their kin. In the soundscape of any one place, we hear the sounds of many species and thus many biographies. This is the biological equivalent of wandering through a busy city, hearing a multiplicity of languages and accents. In these sounds, patterns of human indigenity and migration are revealed, some recent and others dating back tens of thousands of years. For nonhuman species, we hear even deeper into the past, sometimes hundreds of millions of years.
When we sit and listen to our animal cousins, we open ourselves to the experience not only of the moment but to the marks of plate tectonics, the history of animal movements, and the echoes of evolutionary revolutions.
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Three forest edges, on three different continents. Each one is just under 32 degrees of latitude from the equator. In the divergent textures, cadences, and rhythms of their soundscapes, we hear the imprints of deep time.
Mount Scopus, just outside the Old City of Jerusalem, fifty kilometers east of the Mediterranean coast. I wander through the Botanical Garden of Hebrew University. Walkways, dusty with limestone, thread through plantings organized by habitat, representing twenty-two of the many different ecological zones found in the region. It is July and so the early summer rains have ceased, yet the vegetation remains green, helped by both moderate temperatures on this limestone ridge and trickling sustenance from irrigation pipes. Trees and shrubs seem to grow directly from the crumbling, ivory-colored stone. Boulders and small rocks lie all around the walkways. A cluster of two-thousand-year-old tombs is carved out of the rock face, further exposing the mountain. Without the care of horticulturalists, most of the plants here would wither on the thin soils. All around are buildings, roads, and, at the university, irrigated lawns, a startling sight in so dry a land. The gardens are an island refuge in a growing urban sea. Birds and insects find welcome on the diverse collections of well-tended indigenous plants.
A squeaking sound, like that of a cork being twisted into the neck of a wine bottle, pulses from the saw-toothed leaves of a Syrian ash tree. I cannot see the singer, but the tight rubbing sound likely comes from the wings of a marbled bush cricket. On the ground, in the jumbles of stones around the base of cypress, pine, and redbud trees, Mediterranean crickets chirp with sweet, vigorous notes, pumping out calls two or three times per second. Both of these insects are mostly night singers, but in midsummer, the height of their breeding season, their songs linger into the morning. From the branches of olive and oak trees, the day’s first cicadas wake, rasping at a lower pitch than the other insects, like a ratchet or windup clock being cranked once per second. Theirs is the sound of dusty air and unrelenting sun. Under the heaviness of afternoon heat, they are often the only animals making sound. Now, as the morning warms, the insects give three-dimensional form to the soundscape: a sparkling cloud of cricket chirps hovers over the ground, bush crickets mark out higher spaces, distinct spheres around the trees from which they sing. Cicadas stitch the treetops into a crackling canopy.
Birds thread their voices into this matrix of insect sound. A greenfinch, its gold-edged wings shining in the dark recesses of the twisted branches of a pine, gives a high trill, switches immediately to a series of rapid whistles, back to the trill, then a string of chirps and sweeping whistles. Like that of its relative, the canary, the tone alternates between sweet slurs and sharp fibrillations, delivered at a caffeinated pace both within each phrase and in the quick flips from one phrase to another.
In the same pine tree, tearing at cones with its stout beak, a house sparrow gives a string of monosyllabic cheep notes, answered by kin on the ground. Sparrow bones from archaeological sites show that this species has lived in the region alongside humans for millennia. Following the rise of agriculture in the Middle East, the house sparrow colonized the first cities, feeding on waste grain and nesting in cracks in buildings, and has since followed humans to urban areas worldwide. The cheep we hear on city streets across the globe is a continuation of a relationship that began here in the stone walls of the Middle East, just like those in this garden.
A Eurasian blackbird’s mellow warbling provides a melodic and tonal counterpoint to the sparrow’s incessant staccato, an undulation of clear, sometimes sliding notes, edged with a melancholy burr, like a wistful folk tune. The sound is characteristic of the thrush family, a group whose flutelike songs are common in wooded areas across Eurasia, Africa, and the Americas. I’m used to hearing Eurasian blackbirds in the gardens and cities of northern Europe, but here the bird throws open its yellow-orange beak from among the branches of an olive tree. In late autumn, the blackbird will turn its attentions to the tree’s oily fruits. Blackbirds and other thrushes are the fruit-dispersing partners of plants wherever the birds live, a collaboration that sustains the birds and ensures the vitality of plant communities. In the Mediterranean, Eurasian blackbirds and other thrushes are the wild olive trees’ original dispersers, a role usurped in the last eight millennia by humans who have bred plumper fruit, convenient for us but a challenge for bird gullets.
Four white-spectacled bulbuls, working their way through the trees in a tight flock, have a sharper timbre and sing in short phrases interspersed with chattering, a convivial exchange unlike the blackbird’s more solemn solo recital. In their sounds, I hear a lively society, each bird continually checking in with its flockmates, a roving web held together by bright threads of sound.
A spotted flycatcher sallies from an oak twig, snatches a small dragonfly, and loops back to the same perch. The bird strips the victim of its wings and swallows the body, then returns to its vigil, standing erect, darting its head from one side to another as it scans for more flying insects. As the flycatcher watches, it gives soft zeep sounds, slightly raspy, a sound like that of the bush cricket. This brisk, sweeping sound is characteristic of muscicapid flycatchers, a family of insect hunters found all across Europe, Asia, and Africa.
A hooded crow mumbles as it pokes the edges of the garden’s paths. Although crows and their raven and jay kin, the corvids, are known worldwide for their raucous, boisterous cries and caws, they also have a rich repertoire of soft whistles, squeaks, chuckles, and murmurs. Sometimes these mediate social interactions among pairs or within family groups, but just as this hooded crow is now doing, the birds are also vocal when, to human eyes, they seem to be alone. For corvids, sound seems to be ruminative as well as communicative.
The avian soundscape is given a percussive element by a Syrian woodpecker on a dried oak branch. Slamming its beak back and forth, the bird pounds a drumroll from the resonant wood, a tremulation that is vigorous and clear at first, then sags. Woodpeckers are found across Africa, Asia, Europe, and the Americas. They have good ears for the acoustic properties of wood and other solid materials in their territories. Unlike other birds that sing using their unaided bodies, woodpeckers use hollow trees, siding planks on houses, drainpipes, and chimney caps to amplify and broadcast their territorial drumming signals. They are selective in their choice of tympanic aid, sampling the qualities of neighborhood materials, then using those that give the most resonant response. On Mount Scopus, the choice of dead wood is limited by horticultural management, but the vegetation is just unruly enough to supply some choice dead tree limbs.
My visits to Mount Scopus in spring had a similar aural character to summer, although the insects had not yet begun to sing. As new leaves unfurled on trees, cadences of blackcaps wove into rattles and trills from Palestine sunbirds, cheery notes of great tits, and the soothing bamboo fluting of the laughing dove. This is a gentle soundscape, or so it seems to human ears: tapping, warbling, and trilling birds brightened by sweet and squeaky crickets. Cicadas roughen the edges, especially late in summer when they frazzle the air, as do the squabbles of rose-ringed parakeets or European jays. In my half dozen visits, I have never heard amphibians here. In wetlands away from the city, green toads trill and tree frogs grunt, although seldom in large choruses.
Saint Catherines Island, on the coast of Georgia in the southeastern United States, lies 10,300 kilometers west of Jerusalem, and a mere 16 kilometers south. I stand in the early morning on the dock where I previously lowered a hydrophone to immerse myself in the shimmer and bleat of snapping shrimp and toadfish. It is midsummer and already the back of my neck trickles with sweat. Air humidity is close to 100 percent, and by midafternoon, we will reach an oppressive 38 degrees Celsius.
Plants exalt in the hothouse. In the abundant moisture, they throw open the breathing pores on their leaves and, their chemistry stoked by the bath of sultry air, feast on sunlight and carbon dioxide. Their growth rate is four to ten times higher than that of unirrigated plants in the Middle East and southern Europe. Annually, the coast here receives two to three times more rain than Mount Scopus, moisture that comes all year, rather than concentrated in winter as in much of the Mediterranean. As I stand on the dock, I look through the island’s fringe of sabal palms into a forest of live oak trees festooned in Spanish moss, mixed with towering loblolly and longleaf pines. Despite the sandy soil, which is leaner than the rich soils farther inland, these trees are lush. A young pine, unshaded by competitors, can lance upward at a meter or more every year.
