Sunday, November 25, 2012


Image of Belly Button

‘Belly Button Beauty Cues Potential Mates’ by Jessica Marshall Source: Discovery News

Rob Dunn and the team at Your Wild Life run a science initiative that explores the biodiversity that lives on us, in us and around us. Their latest project is the Belly Button Initiative to try and discover the microscopic life that lives within our belly buttons.

They began two years ago with 500 volunteers who agreed to twirl a cotton swab in their belly buttons. They published the findings from their first set of analyses based on 60 of these samples.

microscopic photograph of Enterococcus mundtiThey found over 2,300+ species of microbes, the vast majority of which are rare and some completely new to science.

This included one species Rob Dunn found on his own body  called Enterococcus mundti which, says Dunn "is found on me, soybeans, and silk moths. Go figure.’

One participant who said he had not washed in years was one of just two people on which they found not only bacteria but also two species of Archaea

The average belly button hosted 50 or so species but they quickly found that peoples’ belly buttons differed more than they expected in terms of which species live in them. Only eight species – termed ‘oligarchs’ - out of the total so far discovered were present in more than 70% of individuals. As the number of the samples they took increased, they also found conversely that the most infrequent species tended to always be infrequent.

The most frequent species also tended to be the most abundant, accounting for the vast majority of the occurrences and abundance of bacteria in their study. They also tended to come from fewer evolutionary lines.

Rob Dun writes: ‘Overall the species that can be found in our navels seem to come from all over the evolutionary tree of microbes, whereas those that are abundant and frequent are from a narrower subset of lineages, the clans with specific adaptations for the dry, nutrient poor desert that is your body.’


Portraits of belly button oligarchs. Clockwise from top left: Micrococcus, Clostridia, Bacillus, Staphylococcus [Photo by Neil McCoy]

To try and understand why the life in people’s belly buttons differ so much they intend to examine other differences in people’s lives

‘One can imagine many factors that influence which bacteria are on your skin; whether you were born c-section or vaginally, gender, age, weight, whether you are an innie or an outie, whether you live in a city or the country, what climate you live in, whether or not you have a dog, and maybe even where you grew up or where your mother lived when she was pregnant with you.’

Another intriguing aspect of their research came when they discovered that individuals could be grouped into clusters according to the composition of their belly button bacteria. So far none of the variables they have considered  - age, gender, ethnicity etc - explain these groups.

There is still much to discover about belly button life. Rob Dunn believes that ‘the composition of our bacteria may even influence how we date and mate’. 

He also also points out that ‘the same mysteries lurk in ears, noses, eyebrows, toenails and especially armpits.’


‘After 2 years Scientists Still Can’t Solve Belly Button Mystery, Continue Navel-Gazing’ by Rob Dunn. [Scientific American 7th Nov 2012)

Exposing Our Belly Buttons in the Name of Public Science [Your Wild Life]

What’s In Your Belly Button? on

Rob Dunn is the author of ‘The Wild Life of Our Bodies’ and ‘Every Living Thing’

SEE ALSO; Wikipedia entry on the NAVEL

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