During our morning walk, my dog finds a dead bird or chipmunk rotting under a pile of leaves. I pretend I’m OK that he’s maneuvering his long snout along the quiet body, pushing it against the mud, further mixing it with pebbles and twigs. Dead wild animals disgust me. Half a face is missing, and the bottom part is flattened and mangled with a wing or furry foot.
Never mind, let’s go, the dog says as he forgets the dead thing. He moves on quickly as if it’s normal to find carcasses on a walk. I wonder who will find the dead animal next. Another dog? A hungry raccoon? It’s also possible the furry corpse will persist through another summer and eventually decompose and dissolve into the ground. It’s one feature shared with us animals: in the end, we become dirt.
The blame for how we get here—this Dirt Destiny— lies with a group of organisms that hibernate inside the body called the gut microbiota. Scientists say the gut microbiota, or the trillions of bacteria in the human intestine, interact to promote good health and accelerate disease. While gut microbiota are the driving force of our lives, they will have only one task when we die: to eat our corpse from the inside out.
Consider that at death, the heart that pumps two thousand gallons of blood every day will freeze in time and space. Without blood, there is no circulating oxygen for our cells to breathe. Without oxygen, blood becomes acidic and a lake of toxic fluid builds up around organs. All this acrid poison causes cell walls to dissolve; cellular contents sputter out and neighboring cells demolish similarly.
Next, intestinal microbes erupt from the confines of the intestines and spill into the corpus rigor mortis. Clockwork precision of self-cannibalism begins: 20 hours after death, gut microbiota digest the liver and spleen and, 36 hours later, they break down the brain and heart. Dead cells release carbon dioxide into the empty spaces of the body. Gassy buildup causes bloating in the abdomen, cheeks, lungs and pelvis; the corpse bursts open like an overripe summer peach left on the kitchen counter. Insects are drawn to ruptured and raw remains, swarm into the decaying body, and feast on flesh with gusto. Have you ever stopped to look at the dead deer or fox or cat on the side of the highway? Next time, slow down your car. Peer a little closer. We are the dead, mangled, furry animal in the woods or off the freeway, buried under rot, maybe forgotten, maybe too grotesque to look at.
When my son was five, his class went on a field trip to a local nursery to learn about composting and I tagged along as a parent chaperone. The teacher had boxes of black soil mixed with banana peels, dry brown leaves and a few thick earthworms. She ran her fingers through the soft, suede-like soil as students squeezed in closer, inhaling the smell of rain and burnt mushrooms. She explained that the worms would eat the old banana peels and break them down into nutrients for the soil. Human bodies decompose like those banana peels, I thought, relieved no one could read my mind.
There is an involuntary contract between Mother Nature and us—signing up to become new soil for the spring plants. Upon death, for every kilogram of weight, the human body will release material back into the earth: 32 grams of nitrogen, 10 grams of phosphorous, 4 grams of potassium, and 1 gram of magnesium. Plants will suck up nitrogen and potassium through their greedy root systems. Products of decomposition on acres of black velvet soil will nurture crops and vegetation. Nitrogen is required to build DNA! Potassium regulates water intake! You’ll end up with luscious leafy kale. Blood-red tomatoes. Purple onions. Okra. All are born from what the dead leave behind as gifts for the living.
Some days when I come home from work, the dog greets me at the door, tail flailing and thumping like a metronome of joy. I wipe sloppy licks and drool off my face, and he says, you’ll never be alone as long as I’m here. But being alone and feeling lonely depend on perception, I want to shout. Look at the trillion microbes that live inside my intestines waiting for me to die. Our bodies are renewable resources on the frontiers of recycling, creatures who pass through the swinging door of life with abundant fear and wonder. We wish we could come back into this exact life or a better one, yet we return as fragmented pieces to build a larger whole. A birch tree, a rabbit, a rose.
So I take the dog for long walks in the woods again. We trample over slippery leaves and brittle acorns and pinecones that smell like last year.
Never mind, let’s go, he interrupts.
Jacquelyn Leung is a physician and graduate student at the Johns Hopkins University writing program. She thanks her parents for fostering a love of reading and science, and her husband for encouraging her to write. You can find Jacquelyn’s work at Intima: A Journal of Narrative Medicine and www.jackieleungmd.com.