For the past four years, Dunn and two of his colleagues—Noah Fierer, a microbial ecologist at the University of Colorado Boulder, and Holly Menninger, the director of public science at N.C. State—have been deciphering these histories, investigating the microorganisms in our dust [newyorker.com] and how their lives are intertwined with our own.
The scientists began with a small pilot study, recruiting forty families in the Raleigh-Durham area to swab nine locations in their homes. When the researchers analyzed these cotton swabs and sequenced the fragments of bacterial DNA that they contained, they found that even the most sparkling houses were teeming with microbial squatters—more than two thousand distinct types, on average. Different rooms formed distinct ecological niches: kitchens were popular among the bacteria that grow on produce, whereas bedroom and bathroom surfaces were colonized by those that typically dwell on the skin. (In a troubling discovery, Dunn and his colleagues learned that, from a microbiological perspective, toilet seats and pillowcases look strikingly similar.)
The fungi in the dust of your house tell where you live, the bacteria tell who lives there.