17 November 2012


Each of us is an ecosystem.  In fact, each of us is an entire planet of ecosystems.  Most of us are familiar with the symbiotic relationships we have with the millions of tiny creatures who live in our gut ~ bacteria which help us digest our food and process waste, in return for enough fuel to live and reproduce.  But we also host intricate communities of microorganisms in the most unlikely places ~ our eyelashes, our armpits.

I recall in the lab portion of a biology class at the University of Arizona, seeing a series of petri dishes, each containing a substrate of nutritive agar on which had been swiped Q-tip samples taken from everyday surfaces, to demonstrate the vigorous micro-biodiversity living all around us.  Here was a dish containing multicolored molds from the hallway water fountain.  Another was the new home of mildew and fungus sampled from the lab doorknob.  Perhaps the most memorable was a flourishing colony of ... something ... labeled "Susie's kiss".  Some brave coed had consented to place her lips against the uncontaminated agar, and the result was a gray furry township in the shape of, well, a kiss.

During this same time, I was privileged to attend a guest lecture by Dr. Lynn Margulis, during which she expanded upon her theory of the symbiotic origin of eukaryotic organelles in particular, endosymbiotic theory in general, and her contributions to the more massive Gaia hypothesis.  She would have felt right at home discussing a human being as an assembly of component communities of microbes.

I was reminded of all this when I happened upon an article in National Geographic News online.  What began as a lab researcher's lark became a full-blown study on the inhabitant of the human navel.  Yes, whether you have an outie or an innie, your belly button is home to dozens of bacterial species.

"From 60 belly buttons, the team found 2,368 bacterial species, 1,458 of which may be new to science.  Some belly buttons harbored as few as 29 species, and some as many as 107, although most had around 67 species.  92 percent of the bacteria types showed up on fewer than 10 percent of subjects ~ in fact, most of the time they appeared in only a single subject.

"One science writer, for instance, apparently harbored a bacterium that had previously been found only in soil from Japan ~ where he has never been.  Another, more fragrant individual, who hadn't washed in several years, hosted two species of so-called extremophile bacteria that basically thrive in ice caps and thermal vents.

"Despite the diversity, themes emerged.  Even though not a single strain showed up in [all subjects], eight species were present in more than 70 percent of the subjects.  And whenever these species appeared, they did so in huge numbers.  That makes the belly button a lot like rain forests.  In any given forest, the spectrum of flora might vary, but an ecologist can count on a certain few dominant tree types."

All of which is fertile ground for fantasy.  Imagine a children's book in which a kid is shrunk to microbe size, and finds him/herself having to survive in his/her own belly button!  Personally I find it charming to imagine my navel populated by tiny jungles, jaguars, anacondas, macaws, and aboriginal tribes.  Kinda gives a whole new meaning to navel-gazing.

Who lives in your belly button?

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