Quote: Here's a finding that'll make your skin crawl: A healthy human epidermis is colonized by roughly 1,000 species of bacteria. Furthermore, the microorganisms have evolved to exploit the unique attributes of those body parts they call home, according to a study to be published today in the journal Science. ... The study, conducted by a team of researchers from the National Institutes of Health, reflects a growing realization that bacteria have colonized us inside and out -- and that their presence is not only harmless but also probably essential to the proper functioning of the body. ... "You don't want to live in a sterile world," said Fierer, who wasn't involved with the new report. "You probably can't live in a sterile world." The results reported today will lay some groundwork for the Human Microbiome Project [Human Microbiome Project], a $115-million NIH venture aimed at cataloging the bacteria and other organisms that inhabit the skin, gut, nose, mouth and vagina. Among the more than 19 square feet of skin on a typical adult, the NIH team focused on 20 specific areas, ranging from the oily patch between the eyebrows to the moist spaces between the toes. ... After all, the locations of bacterial species is relatively consistent from person to person, perhaps implying some function that confers a benefit to the host. ... "We have to lose this language of warfare," she said. "Our goal is to keep the bacterial ecosystem in balance and move away from the concept that all bacteria are bad."

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People's bodies are ecosystems, believed home to trillions of bacteria, fungi and other microbes that naturally coexist in the skin, the digestive tract and other spots. But scientists don't have a good grasp of which microbes live where, much less which are helpful, even indispensable, in maintaining health. The NIH's "Human Microbiome Project" aims to change that, recruiting healthy volunteers to learn what microbes they harbor so scientists can compare the healthy with diseases of microbes gone awry — from acute infections to mysterious conditions like psoriasis or irritable bowel syndrome.

The skin research, published in Friday's edition of the journal Science, is part of that project. Scientists decoded the genes of 112,000 bacteria in samples taken from a mere 20 spots on the skin of 10 people. Those numbers translated into roughly 1,000 strains, or species, of bacteria, Segre said, hundreds more than ever have been found on skin largely because the project used newer genetic techniques to locate them.

Topography matters, a lot, the researchers reported. If a moist, hairy underarm is like a rain forest, the dry inside of the forearm is a desert. They harbor distinctly different bacteria suited to those distinctly different environments. In fact, the bacteria under two unrelated people's underarms are more similar than the bacteria that lives on one person's underarm and forearm.
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Then there's the scrubbing question, society's antibacterial obsession.

"There's an all-out assault on our normal skin organisms," Blaser noted. "In trying to get rid of the bad guys, are we getting rid of the good guys?"
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Quote:Original post by Way Walker
What distinguishes these "bacteria" from "human cells"? I mean, are they less a part of me than, say, blood cells? Or what about blood plasma? Are they a part of me because they're essential? But then what about my gall bladder or appendix? Are my nails part of me? I'd say so. Is distinguishing these "bacteria" from "human cells" splitting hairs?