Undergoing root canal surgery yesterday, I was intrigued -- if that is the right verb -- by the extraordinary efforts my dentist had to go through with hypochlorides and peroxides and disinfectants to keep the vast array of bacteria in my mouth from messing up the exposed areas. Our mouths, like the rest of our bodies, are a teeming zoo.

The one lecture my students remember, and hate, is the one where I talk about this. I show pictures of the ticks and skin critters that roam over us; I point out that there are more cells belonging to other beings in our bodies than our own; I note (after Lynn Margulis) that something like twenty pounds of a normal person's weight is not our own. This is even before we consider the ancient symbiotic partners in our cells -- mitochondria, etc.

My rationale for doing this in class is to remind students that they are not remotely separate from the environment. However, my experience is that they take this information badly: university students are at an age when their sense of who they are is tightly wound up with what they conceive of as the absolute individuality and inviolate nature of their selves. I respect this, but they need to get over it, sooner or later: it is a delusion that is contributing to the dire situation we face as a species among -- and saturated by -- a myriad, myriad others.