This paper argues critically the issue of choices and rationality in economic models through a multidisciplinary analysis. First, the analysis aims at highlight the scientific contributions of psychology in economics, since psychology and the related approach of cognitive economics has made more complex and problematic the analysis of choices of the standard neoclassical economics. The cognitive approach in economics has pointed out the complexity of the choice process and the unsolved relationship between economic and psychological dimensions of such a process, showing the biases and the limits of rationality. Second, the analysis focuses on the use of evolutionary concepts in economic theory. Economic models, which are consistent with an evolutionary approach, have necessarily to be very different from those of standard economics. In particular, this paper examines the works of Alfred Marshall, since he is the first major economist to refer explicitly to biology for explaining economic evolution. The purpose of the analysis is to reveal the conditions required to succeed in building a real evolutionary model. A major condition, which is found in Marshall models, particularly in his Principles of Economics, is the understanding and the integration of darwinian philosophical matrix in his general economic approach. The paper, therefore, aims at demonstrating that economics has not been historically a discipline homogenously aligned to a single, undifferentiated form of thought, locked into the idea of perfect rationality, but that is a discipline that enriched and still enriches itself by contributions and contaminations from other disciplines.