In this article, we propose the hypothesis that the prefrontal cortex (PFC) acquired neotenic development as a consequence of mesocortical dopamine (DA) innervation, which in turn drove evolution of the PFC into becoming a complex functional system. Accordingly, from the evolutionary perspective, decreased DA signaling in the PFC associated with such adverse conditions as chronic stress may be considered as an environmental adaptation strategy. Psychiatric disorders such as schizophrenia and attention deficit/hyperactivity disorder may also be understood as environmental adaptation or a by-product of such a process that has emerged through evolution in humans. To investigate the evolutionary perspective of DA signaling in the PFC, domestic animals such as dogs may be a useful model.