BUG Detective

A burglar sneaks into a house on a quiet street in New York City. He walks through the house, touching countertops and door handles. Finally, he steals a single card from a full deck. Then he leaves.

- Kathryn Hulick

Nearby, Jarrad Hampton-Marcell is waiting. But he's not a police officerhe's a researcher, an assistant professor studying microbial ecology at the University of Illinois Chicago. He set up this robbery, and many others like it, as a science experiment. He's part of an effort to develop a brand new way to catch criminals-by collecting and analyzing their microbes.

Microbes include bacteria, fungi, and other microscopic critters. They cover your body, inside and out. But these miniscule hitchhikers don't always stay put. You breathe them in and out. Clouds of microbes waft off your skin all the time, landing wherever you happen to be and coating whatever you might touch. "We shed bacteria all of the time," says Hampton-Marcell. "We shed about 30 million cells per hour." Like it or not, every single one of us is Pig-Pen from the Peanuts cartoon, surrounded by a cloud of invisible bugs.

And this cloud could say a lot about you. "Your microbial community is very unique to you," says Hampton-Marcell. He explains that the choices you make, such as the foods you eat, how active you are, and what antibiotics you take, "shape not only your life but also your microbial community." When you leave microbes from that community behind on the things you touch, you're leaving clues about who you are. It's a fingerprint made of microbes.

Whodunit?

Hampton-Marcell and his team set up the staged robbery in New York to find out if they could catch a robber using only these microbial fingerprints. Collecting such a fingerprint is easy-you just rub a cotton swab over the surface and then seal it inside a sterile container.