Microcosm

SIGNATURE I GAZE OUT A WINDOW, a clear, puck-shaped box in my hand. Life fills my view: fescue and clover spreading out across the yard, rose of Sharon holding out leaves to catch sunlight and flowers to lure bumblebees. An orange cat lurks under a lilac bush, gazing up at an oblivious goldfinch. Snowy egrets and seagulls fly overhead. Stinkhorns and toadstools rudely surprise. All of these things have something in common with one another, something not found in rocks or rivers, in tugboats or thumbtacks. They live. The fact that they live may be obvious, but what it means for them to be alive is not. How do all of the molecules in a snowy egret work together to keep it alive? That's a good question, made all the better by the fact that scientists have decoded only a few snips of snowy egret DNA. Most other species on Earth are equally mysterious. We don't even know all that much about ourselves. We can now read the entire human genome, all 3.5 billion base pairs of DNA in which the recipe forHomo sapiensis written. Within this genetic tome, scientists have identified about 18,000 genes, each of which encodes proteins that build our bodies. And yet scientists have no idea what a third of those genes are for and only a faint understanding of most of the others. Our ignorance actually reaches far beyond protein-coding genes. They take up only about 2 percent of the human genome. The other 98 percent of our DNA is a barely explored wilderness. Only a few species on the entire planet are exceptions to this rule. The biggest exception lives in the plastic box in my hand. The box-a petri dish-looks lifeless compared with the biological riot outside my window. A few beads of water cling to the underside of the lid. On the bottom is a layer of agar, a firm gray goo made from dead algae and infused with sugar and other compounds. On top of the agar lies a trail of pale gold spots, a pointillistic flourish. Each of those spots is made up of millions of bacteria. They belong to a species that scientists have studied intensely for a century, that they understand better than almost any other species on the planet. I've made this species my guide-an oracle that can speak of the difference between life and lifeless matter, of the rules that govern all living things-bacteria, snowy egret, and curious human. I turn over the dish. On the bottom is a piece of tape labeled "E. coli K-12 (P1 strain)." I got my dish ofEscherichia colion a visit to Osborne Memorial Laboratories, a fortress of a building on the campus of Yale University. On the third floor is a laboratory filled with nose-turning incubators and murky flasks. A graduate student named Nadia Morales put on purple gloves and set two petri dishes on a lab bench. One was sterile, and the other contained a cloudy mush rich withE. coli. She picked up a loop-a curled wire on a plastic handle-and stuck it in the flame of a Bunsen burner. The loop glowed orange. She moved it away from the flame, and after it cooled down she dipped it into the mush. Opening the empty dish, she smeared a dollop across the sterile agar as if she were signing it. Morales snapped the lid on the second dish and taped it shut. "You'll probably start seeing colonies tomorrow," she said, handing it to me. "In a few days it will get stinky." It was as if Morales had given me the philosopher's stone. The lifeless agar in my petri dish began to rage with new chemistry. Old molecules snapped apart and were forged together into new ones. Oxygen molecules disappeared from the air in the dish, and carbon dioxide and beads of water were created. Life had taken hold. If I had microscopes for eyes, I could have watched the hundreds ofE. coliMorales had given me as they wandered, fed, and grew. Each one is shaped like a microscopic submarine, enshrouded by fatty, sugary membranes. It trailZimmer, Carl is the author of 'Microcosm', published 2008 under ISBN 9780375424304 and ISBN 037542430X.