Have we underestimated the importance of humans in the biogeography of free-living terrestrial microorganisms?

The role of humans in the global dispersal of free-living terrestrial microorganisms has received surprisingly little attention in the literature, compared with the frequent discussions of human dispersal for aquatic microbes. Here I argue that this area needs more study, using examples from the ecology of testate amoebae to illustrate the nature of the problem. The techniques of molecular ecology now make these ideas open to investigation in a way that would have been difficult in the past, and, in the case of testate amoebae, palaeoecological approaches may also be valuable.