Each family of theories described above that emphasizes a feature of human nature as the basis for its position in the enhancement debate utilizes a tool that is double-edged. As defenders of trans-humanism point out, each feature of human nature that can produce positive value for humans can just as easily be a source of human misery, which the history of technological progress has been legitimately concerned with alleviating (Juengst 2004). In fact, the enthusiasts argue, there are no static features of the human condition: human vulnerabilities to our environment have steadily decreased over history, our moral kinship communities have expanded, and our tolerance for oppressive forms of social organization has dwindled (Bostrom 2003). Accordingly, to appeal to these features of human nature in abstraction cannot be helpful in deciding which vulnerabilities to honor, which family loyalties to respect, and which social arrangements to defend and develop. Where a biomedical intervention alters one of these dimensions of human nature, this is a signal that the moral stakes are high. But those stakes are not always about what might be lost from the human experience. There are also moral dangers in what might be perpetuated, if we allow the preservation of these hallmarks of human nature to overshadow our other values.