Over the last fifty years, scholars in biology, psychology, anthropology, and cognate fields have substantially enriched traditional philosophical theories about who we are and where we come from.The assumption of a shared human nature lies at the core of some of the most pressing socio-political issues of our time.From race to sex and gender, from medical therapy to disability, from biotechnological enhancement to transhumanism, all these timely debates presuppose a robust notion of human nature.Nevertheless, the riddle of human nature remains frustratingly elusive.Why? Marco J. Nathan here provides an accessible, detailed, and up-to-date overview of cutting-edge empirical research on human nature, including evolutionary psychology, critiques of essentialism, innateness, and genetic determinism, addressing the question of why these fields have failed to provide a full-blown theory of human nature.Nathan's answer is that our nature is not the kind of notion that is susceptible to explanation.Human nature rather plays a crucial role as an epistemological indicator, a pivotal concept that sets out the agenda for much social, political, and normative discourse.Nevertheless, science cannot adequately grasp it without dissolving it in the process.