February 22nd, 2015
Sometimes the best science hides in the least suspecting places. Researcher Rob Dunn and his team recently published work that included the unenviable task of analyzing living samples from 60 human navels. The results were staggering. A total 2,368 bacterial species were isolated. Of those, 1,458 are new to science. 67 species appeared in most test subjects, while 92 percent of the bacteria showed up in fewer than ten percent of subjects. Evidently our belly buttons are not only ideal uniquely suited to host bacteria, but extremely diverse in terms of the individual strains, person to person.
“We are covered in an ecological wonderland,” declared Rob Dunn, a biologist at North Carolina State University, in the US.
Microbiology has received a great deal of attention recently, with millions of bacterial colonies shown to live in our orifices and intestines. The Human Microbiome Project is currently working to catalogue and identifiy them all. The amount of microbial DNA in our guts was recently proven to outnumber human DNA 100 to 1.
Of Dunn’s test subjects, one hosted a species of bacteria previously only found in Japan(a place he never visited). One other test subject, who admitted to never washing his navel, harbored two species of extremophile bacteria known to live in ice caps and volcanic thermal vents. Dunn’s research began around the idea that the human navel is one of the least attended to locations of human hygienic efforts, making it a prime location to hunt for microbes.
“That makes the belly button a lot like rain forests. In any given forest, he explained, the spectrum of flora might vary, but an ecologist can count on a certain few dominant tree types. The idea that some aspects of our bodies are like a rain forest—to me it’s quite beautiful. And it makes sense to me as an ecologist. I understand what steps to take next; I can see how that works.” – Rob Dunn
No single strain appeared in every subject tested. Eight varieties were discovered in over 70 percent of subjects. When one of the species was identified, many of the same strain followed in droves. Next up for Dunn and his team is to expand their research to an additional 600 test subjects, providing additional data and an emerging picture of the total number of microbes and what the differences signify. The initial impetus for Dunn’s research took hold two years ago when an undergrad student sampled a colleague’s belly button bacteria and sent it to him in a Christmas card.
One writer will speculate with relative certainty where you’ll likely scrub during your next shower.
Photo: Dunn, et al.
Source: Hulcr J, Latimer AM, Henley JB, Rountree NR, Fierer N, Lucky A, Lowman MD, & Dunn RR (2012). ‘A Jungle in There: Bacteria in Belly Buttons are Highly Diverse, but Predictable.’ PloS one, 7 (11) PMID: 23144827