Abstract
A major challenge for artificial life is to synthesize the evolutionary transitions that have repeatedly formed differentiated higher-level entities from cooperative organizations of lower-level entities, producing the nested hierarchical structure of living processes. This article identifies the key elements and relationships that must be incorporated or synthesized in an artificial life system if these transitions are to emerge. The processes currently included in artificial life systems are unable to provide an adequate basis for the emergence of the complex cooperative organization that is essential to the transitions. A new theory of the evolution of cooperative organization is developed that points to the additional processes that must be included in artificial life systems to underpin the emergence of the transitions.