Humans go through life surrounded by their own unique cloud of millions of bacteria. Now, for the first time, scientists have shown that these clouds can be used to identify us (PeerJ 2015, DOI: 10.7717/peerj.1258). James F. Meadow, Brendan J. M. Bohannan, and colleagues at the University of Oregon note that scientists have long known that humans leave microbe-laden traces on hard surfaces and in aerosols that trail in their wake. But studies had not clearly differentiated between the detectable clouds of bacteria indoors. The Oregon researchers sampled microbes in the air and in settled material left behind from 11 people who were individually placed in a sanitary room. The group then sequenced the genes from the microbes. Within just a few hours the team found statistically distinct bacterial emissions in the air samples and from the settled material. The distinctiveness of these microbial fingerprints stemmed from thousands of bacterial groups, the most well-known being Streptococcus, Propionibacterium, and Corynebacterium. The research has implications for forensics. For example, investigators could possibly detect the presence of a person who has left the scene of a crime, or medical personnel could track a person with an infectious disease. “It is now apparent that the microbes we encounter include those actively emitted by other humans, including our families, coworkers, and perfect strangers,” the researchers write.