In the last few years, the microbiome (sometimes referred to as “the second genome”) has become a focus for the health conscious and for scientists alike. Studies like the Human Microbiome Project, a national enterprise to sequence bacterial DNA taken from 242 healthy Americans, have tagged 19 of our phyla (groupings of bacteria), each with thousands of distinct species. As Michael Pollan wrote in this magazine last year: “As a civilization, we’ve just spent the better part of a century doing our unwitting best to wreck the human-associated microbiota… . Whether any cures emerge from the exploration of the second genome, the implications of what has already been learned — for our sense of self, for our definition of health and for our attitude toward bacteria in general — are difficult to overstate.”
http://www.nytimes.com/2014/05/25/magazine/my-no-soap-no-shampoo-bacteria-rich-hygiene-experiment.html?_r=0