A taxonomy of basic motivational systems (reptilian, mammalian, and neo-mammalian), that emerged in phases during the course of millions of years, is proposed. These different phases did not replace each other, but became re-organized in the brain at different hierarchical levels. It is argued that (1) humans are an ultra-cooperative species, and (2) high degrees of cooperation put strong selective pressures toward the development of sophisticated forms of intersubjective communication. These two developments had cascading effects on human evolution, creating both the conditions upon which humans were able to understand intentions, gestures, emotions and ultimately the minds of others, and the emergence of language and symbolic forms of cultural evolution. Possible evolutionary steps that led to this ultra-cooperative survival strategy and some of their genetic mechanism, with special emphasis on a multilevel model of selection, are described, and the implications for psychotherapy and psychoanalysis are explored.
Keywords: Motivation, cooperation, intersubjective communication, multilevel selection, psychotherapy