You are made of stardust—but how do the elements in that stardust become molded into such a specific shape? In his new book, Your Atomic Self: The Invisible Elements That Connect You to Everything Else in the Universe, ecologist Curt Stager traces the fascinating paths of all the different kinds of elements in our bodies as they enter and exit us. We got a chance to talk with Stager recently about, among other things, how we can truly be individuals if we’re just an assortment of ever-shifting combinations of atoms:
(Note: Interview has been edited for clarity and length.)
World Science Festival: Were you trying to make people feel their connection to the universe with this book?
Curt Stager: Exactly. We’re just flooded by scientific information, but our brains are slower at working it into our personal lives. You may have heard about the great things we’re finding about the universe, about supernovas and solar systems, or on the other side, about tiny subatomic particles. But once you put the book down or turn the TV off, the hard part is realizing that all this is happening right where you live, right before your eyes and within your eyes, and is part of who you are.
We’re not just metaphorically, poetically connected to the Earth; we’re physically connected to it, and to each other.
WSF: Can you give an example of the path an element takes into and out of our bodies?
CS: Let’s take iron: I’m looking at my hand right now, and my skin’s a little pink, because there’s hemoglobin there, with four iron atoms—how’d they get in there? Well, they came in through my food. I can backtrack that from my last meal of chicken; most of the iron we get, unless you’re a vegetarian, is from other animals. You can trace that back through the plants the chicken ate. Plants use iron in their cells for various things like trapping sunlight. And they get the iron through their roots from the crumbling minerals in the soil.
Eventually that path comes to certain kinds of rocks and minerals in the area—I’m in the Adirondacks, so I can see all sorts of peaks and mountains that are eroding and sending little pieces of themselves into the dirt. That can be traced back to the beginning of the solar system, and that can be traced back to an exploding star. When you see a meteor flashing by, that might be dropping little iron atoms that fall to the ground and end up in your body too.
Then you start getting into even more amazing things. When that meteor comes by, you might think, ‘gosh it’s from distant space!’ but it’s probably from the same star that the iron in your dirt and in your hand came from; it’s just that we were spread out in space so far that it’s only now had a chance to bump into our atmosphere. We’re sort of having a family reunion after 4.5 billion years.
WSF: So is there any truth to those old saws you hear as a kid; stuff like, “you’re drinking George Washington’s bath water”?
CS: Yeah, I heard that as a kid too. It’s partly true and partly not. The atoms you’re consuming would certainly have been recycled. But the atoms stick together in different combinations—molecules—and the molecules actually aren’t that stable. A lot of the molecules in things we eat or drink are actually quite young. A lot of the water molecules in our bodies were not around when the dinosaurs were around. The atoms that make them up were, but the combinations of these flecks of matter can be as young as your last breath.
WSF: After I die, what is the fate of the different elements of my body?
CS: Well, you’re dispersing right now—you’re exhaling yourself. The carbon and moisture in your breath was part of your body seconds ago. You’re dropping hairs, skin flakes. You’ve been dissipating since you were born.
But say you’re cremated. You’ll start to heat up, and all your atoms will start jiggling, and the first thing to go off is gonna be your body water, and that’s about 2/3 of you. That’ll go into the air, and within a few days it’ll turn into clouds and raindrops and snow, and it’ll drop to the earth or into the oceans and become part of water bodies or be soaked up by plants. People will eventually drink you and make you part of their bodies.
The next things to go are your carbon atoms. They start breaking apart from your hair and tissues, and oxygen molecules in the air will sweep in like little angels, in pairs, and scoop up a little carbon atom and go off into the air up the chimney. Within a couple of weeks you’ll have circled the entire planet. And within two months you’ll be equally spread throughout the hemisphere you were cremated in; within a year, the entire planet. You’ll become air, which is mostly what you are. There’ll be some dust left on the bottom of the crematorium, mostly minerals, and that’ll be scattered somewhere, and be taken up by plants and algae.
Literally, if you are cremated and your survivors hang around for two or three weeks, they can look up and say that some of your nitrogen atoms are helping make the sky blue.
WSF: Wait, how does my nitrogen make the sky blue?
CS: The sky is not exactly as blue as we think. If you analyze the light coming to us, the blue is just a small fraction of it; it’s just that we see it better than the other colors. There’s actually a lot of violet up there.
Light is an energy that vibrates, and different colors have different vibrations. Atoms are small enough to actually jiggle when a little parcel of light smacks into them; and the molecules in the air—which is mostly nitrogen—vibrate very much like the blue and violet vibrations when they get hit. They do other colors, but mostly the blue and the violet. So part of the blueness of the sky is of our own creation.
WSF: It seems like all of this cycle is confined to the Earth… are our atomic selves trapped here?
CS: Not necessarily! Atmosphere molecules and atoms are being blasted off the top of the atmosphere by the solar wind. So some of our atoms that become gases can work their way up and be sandblasted off into space. We may be on our way to other galaxies by now.
WSF: What can we actually call an individual if we are constantly eroding and rebuilding and we’re made of the same stuff as other organisms?
CS: That is the nub of why this is amazing. It makes you wonder: Who the heck am I? My atoms are coming and going all the time! How can I be made of these little dead flecks of matter and have a personality, and a life, and a death?
There is a concept that sort of describes what it’s like, called emergence, which is that you can start with certain components, and combine them, and they’re more than the sum of their parts. Like, if you’ve got these random vibrations of air, you can arrange them in a certain way and they’re musical notes. Arrange those in a certain way and you have a symphony. Maybe that’s what I am. I am some atomic flecks that come into combinations, briefly, and I’m the melody that they’re playing.
Check out an excerpt from ‘Your Atomic Self’ on the water cycle in our bodies:
When you take a sip of water it doesn’t just slake your thirst. It literally becomes you. The water that runs down your gullet will, within minutes and without processing of any kind, become some of the dominant fluid in your veins and your flesh. Most of your blood is simply tap water with cells, salts, and organic molecules floating in it. Some of the rubbery squishiness of your earlobe poured out of a bottle or a can just a short time ago. And much of the moisture in your eyes only recently fell from rainclouds.
Your mouth is the portal through which water normally enters your body, but you are quite a leaky vessel. A hydrogen isotope study published in the British Journal of Sports Medicine reported that the sedentary men under examination consumed and lost about seven pints of body water per day, with four pints leaving through urine and two or three pints through sweat and breath moisture. Vigorous exercise can boost non-urine water losses to one or two pints per hour.
Now let’s see what logic can do with those facts. Nearly two-thirds of your weight comes from water, and your body is an eddy in a stream of that common fluid. Surely the liquid that you slurp from a fountain is not alive, and you don’t consider it murder to stomp on a puddle of water. Therefore most of you is not alive at all, nor is it even permanent or unique enough to merit a personal name.
Excerpted from YOUR ATOMIC SELF: The Invisible Elements That Connect You to Everything Else in the Universeby Curt Stager. Copyright © 2014 by the author and reprinted by permission of Thomas Dunne Books.