Since the 1980s issues of power, such as those examined in Eric Wolf's Europe and the People Without History, have been central to the discipline. In the 1980s books like Anthropology and the Colonial Encounter pondered anthropology's ties to colonial inequality, while the immense popularity of theorists such as Antonio Gramsci and Michel Foucault moved issues of power and hegemony into the spotlight. Gender and sexuality became popular topics, as did the relationship between history and anthropology, influenced by Marshall Sahlins (again), who drew on Lévi-Strauss and Fernand Braudel to examine the relationship between symbolic meaning, sociocultural structure, and individual agency in the processes of historical transformation. Jean and John Comaroff produced a whole generation of anthropologists at the University of Chicago that focused on these themes. Also influential in these issues were Nietzsche, Heidegger, the critical theory of the Frankfurt School, Derrida and Lacan.[17]