The proper place of humans in ecological study has been a recurring issue. I reconstruct and evaluate an early twentieth century rationale in ecology that encouraged the treatment of humans as apart from natural processes, and I unearth the interests and assumptions, both epistemic and non-epistemic, that fostered it. This rationale was articulated during the early years of the Ecological Society of America, particularly through its Committee on the Preservation of Natural Conditions. Committee members advocated for the preservation of what they considered epistemologically foundational and functionally normal objects of study—nature’s “primitive conditions”—and in doing so collapsed two conceptually independent categories of unnaturalness: the artificial and the pathological. As these ecologists demarcated what counted as nature, they were, in the process, defining ecology as a science in ways that had lasting repercussions.