Criminality is actively under study, but extremely controversial. Various theorists have argued that in some environments criminal behavior might be adaptive. The evolutionary neuroandrogenic (ENA) theory, by sociologist/criminologist Lee Ellis, posits that female sexual selection have led to increased competitive behavior among men, leading to criminality in some cases. In another theory, Mark van Vugt argues that a history of intergroup conflict for resources between men have led to differences in violence and aggression between men and women. The novelist Elias Canetti also has noted applications of sociobiological theory to cultural practices such as slavery and autocracy.