The end of nature problem can be framed as a dilemma: either all human intentional actions are natural or they are all unnatural and destroy nature as an effect. Given the scope of human influence, the latter entails that there is no nature left on Earth. Therefore, the environmentalist project of protecting nature is either unnecessary or futile. Prevailing attempts to forge a middle path – by, for example, distinguishing natural from unnatural human activities – struggle to find metaphysical grounding. (...) I argue that the biological concept of human proper functioning can ground the relevant distinction between natural and unnatural human activities. Only unnatural activities can destroy nature; specifically, those activities that trace back to beliefs about value that diverge from the human lifeform. (shrink)