 All humans are involved in a range of ongoing stable symbioses with microbes living in and on our bodies. The majority of these microbes are in the gut, but the skin, lungs, and every bodily orifice are populated by multiple groups of interacting microorganisms. Many of the microbes in our gut are not really helping or harming us: they are there to take advantage of the nutritional resources that are so plentiful in the intestines. Our body’s immune response controls and manages them so they are at least not detrimental, even if they are ineliminable. Inescapable symbiosis implies, however, that human bodies are intrinsically and inseparably microbial ecosystems. Whether this is meaningful in any philosophical sense will be discussed in detail in  Section 5.  Human bodies are not where this question ends, however.