Students’ conceptions on the origins of human social behavior are poorly understood. The aim of this research was to quantitatively evaluate the conceptions on the origins of certain types of human behavior expressed by a group of 1,212 Brazilian university students. Results suggest that regardless of either religiosity or evolutionary commitments, the majority of the students advocate nurture-based arguments to explain human social behavior. Data also suggest that behaviors considered to be typically human are better explained by nurture-based arguments. The preference for nurture-based explanations may be due to the absence of the theme “behavior” in biology curriculum in secondary schools. The possibility of teaching aspects of human biology that are known to be influenced both by nature and nurture-based explanations is discussed. We conclude that, despite the enormous influence of evolutionary theory on recent western thought, Brazilian students do not seem to perceive its legacy concerning the origins of human social behavior.