A Symphony of Evolution in the Nevada Desert

Hold your ear to a shell, and you’ll hear the ocean. I might as well test the hypothesis. Rubbing my thumb along the shell’s coiled exterior to knock some extra sand off, I hold the small whorl to my ear. Silence, nothing more than the quiet of the Nevada desert. Perhaps fossil shells play by different rules. Then again, their music may be so ancient that ears like mine take more practice to become accustomed to it.

The shell seems out of place. I’m more than 400 miles away from the Pacific, listening to a thunderstorm gently rustle juniper branches as it decides whether or not to sweep in. This early in the summer, before the season finds its true heat, the sandy, tan soils are dotted with astragalus, penstemon, and twinpod in hues of pink and yellow. But the silence is what makes places like this so special. It’s as quiet as a painting. I haven’t seen a single person since the morning when I started my long, fossiliferous stroll, and even the birds only occasionally chatter at each other as I hike along. It’s an emptiness that I can’t help but want to fill, a space so serene and unknowable that my thoughts and feelings begin to bleed out and swirl around. No one needs anything from me. There’s nothing to rush off to. I’m not trying to distract myself or cope. What’s inside—whatever’s been hiding in my head or heart—finally has the quiet to step out among the gnarled groves and pine-crested hills. 

This late in the day, though, I’m out of introspective revelation. Divorce, transition, dating, and everything else—I’ve thought enough about the cadence of my own life over the hours during which I’ve left my boot treads in the sand. I need a little escapism. The shell’s the key. I turn it over in my hand as I sit beneath a juniper with an accommodating nook, and I begin noticing familiar flecks scattered all around. More shells, more pieces of ancient lives. Did they all perish together? Are they just the tossed pieces of many lives thrown together like empty mussel shells on a public beach? I start to wonder, my mind beginning to drift and fill in the gaps. That’s how I solved puzzles when I was a kid: look for the gap and think about the pieces that you’re missing. I go back to that first fragment, imagining what the entire creature once looked like. 

The small, black shell that I’m holding had once built itself around a squishy, many-armed relative of squid: an ammonite. I feel like I can see its arms fluttering about as I hold this imaginary shell—it’s bewildered that there’s no water here in the high desert. No need to make it suffer. I’ve brought it to life, and I can bring it home. I can go back to when this place wasn’t a desert, back to when the soft-bodied cephalopod bobbed through the seas. I can almost hear the hushed scour of waves. 

In those days, under the ancient Triassic sun, immense reptiles threshed through warm waters above reefs of hard, rounded corals dappled by water-filtered light. Around 225 million years ago, this patch of high desert was underwater, part of a vast Panthalassic Ocean around a single continent, the landmasses huddled together as if for safety against the whale-sized saurians off the shore. “Here be dragons.”

I have been walking the seafloor for days, searching for the remnants of creatures that may have gobbled me up if I treaded water during their era. With each step, my boots leave prints in sand that had gathered on the bottom of the ocean, turned to stone, and rested inside the Earth until tectonic shifts interrupted their slumber and brought them back to the surface, only to break down into sand once more. I am beachcombing hundreds of millions of years too late, poking at broken ammonite shells the same way I had futzed with battered clam shells along the Jersey shore as a girl. In the vast solitude, I imagine salty water seeping up from the ground, rising over my ankles and knees and hips and head as I stroll. I imagine a great flotilla of ammonites reassembling themselves and rising to jet and bob through the water.

With my eyes closed, the gentle breeze caressing the pinyon pines sets the tone for ancient waves wafting far overhead. A long shadow drifts over my impossible, imaginary form on the sandy bottom, the sinuous shape of a creature the size of a humpback whale but with a sharp grin decorated with triangular teeth: Shonisaurus. The cracked and broken bones I have been stumbling upon all week regain their proper place inside the reptilian, shark-shaped animal, wrapped around viscera and anchoring massive muscles that almost effortlessly move the great, crescent-shaped tail back and forth as she searches for the right spot to welcome her little ones into the world. A shoal of coiled ammonites, sucker-lined arms trailing like streamers, dart out of the way and bumble into each other, frightened by the sudden loss of sunlight even though they have little to fear from the giant. Fearsome as she is, her prey lives elsewhere: fish and other large reptiles that can better help her maintain all 23 tons of her bones and tissues. Just like that, she is little more than a disappearing shape in the distance, and all the little invertebrates that form the foundation of this place resume the seemingly never-ending dance of survival and death that records just how impossibly long life has thrived on Earth.

Daydreaming about marine reptiles that could swallow me whole, looking for fits among the broken pieces of shell in the hopes that I might be able to put one back together, I can’t help but think of a cartoon published more than a century and a half before I was born. “Awful Changes,” the title proclaimed, centered above a scholarly ichthyosaur educating a gaggle of marine reptiles about how pitiful humans—now fossils in the cartoon’s imagery—had been. The sketch was meant to lampoon nineteenth-century geologist Charles Lyell, who so believed in uniformity and evenness in Earth’s history that he expected the ichthyosaurs, dinosaurs, pterosaurs, and other terrible reptiles of the past to one day return when the Earth’s continents and climates reverted to a Triassic state. What had been would come again, repeating on and on through history. Fair, Lyell’s speculation never took hold, but I can see what inspired him. Mountains rise from rocks that were ground down, lithified, and pushed up again. Deserts are made of stone laid down in water, pulverized and transported down snaking rivers back to the sea. Broaden your perspective enough and you start to get the sense that you have seen all of this before.

Such repetition would seem to create a rhythm, a beat set by geology to which life lilts along through the eons. The plates upon which continents rest move an average of half an inch each year. Radioactive minerals decay at a predictable and consistent rate. We could focus on these monuments to consistency as life changes around them, like the constant half-lives of certain minerals that form the very basis for the geological clocks by which we tell time. But I’ve always been pulled to the traces of life rather than the rocks in which I find them, and life has little use for consistency. To stay constant is to die. Life that survives begins dancing to a different rhythm before the beat even becomes perceptible, offering only a fleeting moment’s comfort before it changes again.

Summers of scouring rock faces, wandering over sand dunes, and scaling mountainsides in search of fossils have changed how I listen. I had to go to the places from which the music comes, interspersed with the crunch and scrape of my own steps. When I was very young, the first pairing of evolutionary history and music I encountered was Stravinsky’s “Rite of Spring” from Disney’s Fantasia, a condensed version of Stravinsky’s original expression of awe at the warmth and lust of spring in ancient, pagan Russia. The story of life slowly builds along the lilting tones, cacophony breaking the audio narrative to match the crushing of vertebrae and the abrupt rise of mountains. The entire piece is an animated version of what I’d seen time and again in outdated museum displays and books still stocked in my school library, an orderly progression from the ethereal past toward the glory of a modern world free from the grip of voracious reptiles.

Of course I could grant the animated epic from last century a bit of artistic license and consider it still beautiful as a time capsule. But paleontologists love little more than picking something apart and piecing it back together again. The carefully orchestrated story, precise in its rhythm, does not match the fossil record as I know it. The nature of the fossil record doesn’t so much resemble a symphony as a riotous, ever-unfolding punk rock tune in which familiar motifs sometimes stand out against the winding backing chords and beat. The desolate years after mass extinctions seem quieter and more minimalistic. Repeated evolutionary themes—such as when pterosaurs, birds, and bats independently evolved the ability to fly—can be expressed as similar notes on different instruments against the background chord changes. The slow, almost imperceptible shift of the continents is part of the sonic snarl that gradually crescendos as different, once-distant forms of life encounter each other and mix for the first time.

There’s no break to the song. Since the moment life first evolved on our planet more than 3.5 billion years ago, the tune has never ended. Even then, during what some experts call “the boring billion” before animal life arose, there was still change and tension with simpler evolutionary instrumentation. Life’s expansion into new forms and sizes against the background can almost be thought of as the introduction of new types of instruments that add their own texture to the intertwined tune, some disappearing over time only to have their notes replicated by another instrument, like a theremin trying to mimic what a saxophone once played.

Life’s wonderful discord gives us no idea what to expect next. If we could see life a million, 10 million, or 100 million years from now, we’d likely be thrown by the mix of the strange and familiar. Some organisms might seem like cover versions of what came before while others would be entirely unfamiliar to us. By that point we’d be relegated to the rock layers ourselves, represented by varied and confusing measures of time stacked layer by layer. The same thickness of stone could represent a week or a million years, depending on the speed of the movement.

I cherish life’s unpredictability the same way I love when distorted guitars suddenly take off in a sonic direction I didn’t anticipate, connected to what I just heard but fundamentally different. A vision of life that privileges orderly unfolding is antithetical to the very spirit of life itself. Science has often been expressed and understood as a way to impose order and some kind of sense onto a vibrant, chaotic world. We look for the least common denominators, the facts and ideas that can harden like diamond and offer a clear view to what’s inside. But every rule has an exception, and theory must always be a living, responsive entity, or it will crumble to ash. We’ve looked at life as if there is some great orchestrator—if not a deity, then a process like natural selection—when the mind-bending array of individual lives present even at this moment in all their buzzing, trilling, crawling, slimy glory are adding their own notes to a song that is new and emergent in every moment. There are notes we can’t even perceive yet, and ones we may never hear. We cannot have any confidence in what the next moment will sound like, or the one after that. It is something that is living, that we can only sometimes perceive in retrospect as we piece fossils together like tattered guitar tablatures. The disorder creates the wonder, preserved in layers upon layers that are themselves only fragments of what’s come before. There’s no great refrain, only new combinations that occasionally slide by a snatch of something that might be familiar. 

The present always becomes the past far too quickly. And as I start to register how long it’s going to take to hike back to the truck, I realize my shaded break has passed too quickly, too. A few thick splats of rainwater on the sand reinforce my instinct that it’s time to get moving. I take one last moment to watch those dots expand over chunks of stone and get sipped into the sand. If stone has a memory, I can’t help but wonder what those drops might make the rock recall. There’s no way for me to follow the beat. I couldn’t possibly hear it all, those unheard melodies of untold lives even in this patch of desert. All those notes together could make a wonderful cacophony, and I’m adding my own notes to a song that will continue long, long after whatever’s left of me will be repurposed into other parts of the world. I walk the stone, knowing I am missing more than I am finding. I listen for what once was and wonder, though I may never hear it, what may come next.