Our aim in the present paper is to approach the nature of life from the perspective of autonomy, showing that this perspective can be helpful for overcoming the traditional Cartesian gap between the physical and cognitive domains. We first argue that, although the phenomenon of life manifests itself as highly complex and multidimensional, requiring various levels of description, individual organisms constitute the core of this multifarious phenomenology. Thereafter, our discussion focuses on the nature of the organization of individual living entities, proposing autonomy as the main concept to grasp it. In the second part of the article we show how autonomy is also fundamental to explaining major evolutionary transitions, in an attempt to rethink evolution from the point of view of the organizational structure of the entities/organisms involved. This gives further support to the idea of autonomy not only as a key to understanding life in general but also the complex expressions of it that we observe on our planet. Finally, we suggest a possible general principle that underlies those evolutionary transitions, which allow for the open-ended redefinition of autonomous systems: namely, the relative dynamic decoupling that must be articulated among distinct parts, modules or modes of operation in these systems.