Dust gathered in your house harbours a teeming menagerie of bacteria and fungi that may not only predict the geographical location of your home, but also the gender of the occupants and the presence of a pet, a new study has found.
The finding by researchers from the University of Colorado Boulder and North Carolina State University may have future implications for forensic investigations and allergen research.
It also highlights the impressive amount of microbial diversity in the average household and the degree to which these organisms can tell a story about the homes they inhabit.
"Every day, we're surrounded by a vast array of organisms in our homes, most of which we can't see," said Noah Fierer, an Associate Professor in the Department of Ecology and Evolutionary Biology at CU-Boulder and a co-author of the study.
"We live in a microbial zoo, and this study was an attempt to catalogue that diversity," said Fierer.
The study examined roughly 1,200 homes across the continental US.
On average, each home contains more than 5,000 different species of bacteria and around 2,000 species of fungi. Fungal communities tend to be more predictive of a home's location while bacterial communities provide clues about the identity of its residents.
"Geography is the best predictor of fungi in your home," said Fierer.
"The reason is that most fungi blow in from outdoors via soil and leaves," he said.
When it comes to bacteria, however, where you live may be less important than whom you live with.
From the dust samples, researchers could confidently predict which homes had pets such as cats or dogs and, to a slightly lesser extent, the gender ratio of the residents.
Homes with only male occupants, for example, will have a different bacterial makeup than those with both male and female occupants.
"One of the key takeaways is that if you want to change what you breathe inside your house, you would either have to move very far away or change the people and the pets you live with," said Albert Barbarán, a graduate researcher in CU-Boulder's Department of Ecology and Evolutionary Biology and lead author of the study.
The study was published in the journal Proceedings of the Royal Society B.