They say that who you hang out with says a lot about who you are. Well, the microbes that hang out on your fingers can point to exactly who you are. Because scientists at the University of Colorado in Boulder have been able to identify individuals based on the bacteria they leave behind on their computers. The findings appear in the Proceedings of the National Academy of Sciences. Our skin is a breeding ground for bacteria of all shapes and sizes. And each of us harbors a microbial mix that's a bit different from our neighbors'. So every time we grab a glass of juice or type out an email, we leave our fingerprints, and a shmear of our own resident microbes. But just how telltale is this trail of microbiota? The scientists swabbed bacteria from nine computer mice and then conducted a sort of microbial lineup. They compared the bacterial signature from the mice to a database of more than 250 microbial communities, including that of the objects' owners'. For each mouse, the microbial mix matched its owner's hand more closely than any other sample. So watch what you touch. There could be a crime scene investigator just waiting to collect your microbial community.