Neo-Darwinism is based on the same principles as the Walrasian analysis of equilibrium. This may be surprising for evolutionary economists who resort to neo-Darwinism as a result of their dissatisfaction with Walrasian economics. As it is well-known, the principle of rationality does not play a role in neo-Darwinism. In fact, the whole (neo-)Darwinian agenda became popular exactly because it expunged the idea of rationality from nature, and hence, from equilibrium. It is less known, however, that the rationality principle is also not central in Walrasian equilibrium analysis. Therefore, if we find that the rationality principle must be central to the analysis of decision making of human and nonhuman organisms, we must advance organomics. Organomics is bioeconomics understood as the use of rational choice to the study of the behavior of human and nonhuman organisms. Organomics offers a different starting point than the one offered by neo-Darwinism.