Although it may not be something that you’re likely to be too concerned about, the much dismissed belly button is a reservoir of natural bacterial species as shown in the appropriately named Belly Button Biodiversity study –

What’s in your belly button? A survey of the microbial life in 60 volunteer’s belly buttons has come up with more than 2,000 bacterial and archaeal species, most of which exist on only a fraction of the population, according to a report published this week (November 7) in PLOS ONE.

[We] can now predict which bacteria tend to be frequent and common in belly buttons,” lead researcher Robert Dunn, of North Carolina State University said in an interview for a PLOS ONE blog. “Gender doesn’t seem to matter, nor does age, nor does innie/outie, nor does where you live now or where you were born.”

The team of researchers sequenced small fragments of each microbe’s genome to identify the diversity of microbes in each belly button. Each volunteer harbored an average of 67 different types of bacteria, and the vast majority of the 2,188 species found were only present in six or fewer belly buttons. One of the volunteers, Dunn said, had not bathed in years, which yielded a belly button sample that not only had bacteria present, but two species of archaea, which were rare in the study.

Dunn says that he and his team are continuing their navel research, next sampling 600 belly buttons, which could reveal more information about our personal germs.

While helping to resolve the questions behind the composition of belly button bacteria, it looks as though the debate on innie/outie belly buttons will continue to be played out elsewhere.