From the page: " As soon as we are born, bacteria move in. They stake claims in our digestive and respiratory tracts, our teeth, our skin. They establish increasingly complex communities, like a forest that gradually takes over a clearing. By the time we窶re a few years old, these communities have matured, and we carry them with us, more or less, for our entire lives. Our bodies harbor 100 trillion bacterial cells, outnumbering our human cells 10 to one. It窶s easy to ignore this astonishing fact. Bacteria are tiny in comparison to human cells; they contribute just a few pounds to our weight and remain invisible to us.
It窶s also been easy for science to overlook their role in our bodies and our health. "