 Based on supposed evidence of these phenomena in amniotes but not in non-amniotes, Cabanac argues that consciousness originated in the common ancestor of amniotes, and hence is present in all living amniotes but in no other animals. Cabanac and Cabanac (2009) also argue that a qualitative difference in the role of dopamine in motivational processes in the brains of amniotes compared to non-amniotes supports this distribution/origin hypothesis. 