There are parts of the body that people tend to scrub well and others that may only get a passing wash. The belly button, Rob Dunn from North Carolina State University tells NPR's Talk of the Nation, might not be the cleanest spot, but it is home to tens of bacterial species in the average person, though across the population the navel is home to thousands of species.
"They're kind of a nature reserve when it comes to our body," says Dunn, who leads the Belly Button Biodiversity Project. "And so I think that the better indication of, you know, what our body is like in terms of microbes and those places we don't scrub all the time."
Dunn and his colleagues recently reported in PLOS One that, within a group of 60 volunteers, they uncovered more than 2,000 types of bacteria and archaea, with each person harboring an average of 67 different bacteria, through sequencing of 16S rDNA libraries.
"We're finding not only whole new species in belly buttons but whole new lineages …," Dunn tells NPR. "You know, they don't have names — even their families often don't have names. And so it's really a pretty amazing time."