Bold pronouncements on what it means to be human have been a preoccupation of poets (such as Pope), philosophers, religious leaders, politicians, and social scientists. Conceptions of humanness are embedded in diverse histories and philosophies (see Stevenson & Haberman, 1998) and are used to explain our strengths and flaws, our motivations (e.g., selfish or altruistic), and our limits. Our basic human propensities and their consequences are the subject of debate in philosophy (e.g., Hobbes, 1996/1651; Hume, 1978/1739; Nussbaum, 1992) and in the social sciences (e.g., Buss, 2001; Kagan, 2004; Schwartz, 1986).