The aims of this paper are to investigate the evolutionary processes that lead to the hierarchy's formation and examine the role of natural selection in it. The approach used was critical analysis of key references to identify important processes in the formation of the hierarchy and then examine the role selection plays. First, the structural organisation of the ecological system was examined, and then processes that created the structure were identified. Third, the causal relationship between non-equilibrium thermodynamics and key processes was articulated. Fourth, the important processes were then incorporated into a general model to explain how they generate and maintain the ecological hierarchy. Finally, the model provided the conceptual framework in which to examine selection's role in the formation of the nested ecological hierarchy. The arguments in this paper showed that two key processes in the formation of the hierarchy are self-organisation and integration. Self-organisation creates the structure, whereas integration stabilises it. The iterative process adds levels and complexity to the nested hierarchical structure. The analysis showed that natural selection affects the structure within levels as well as at the level immediately above the target of selection.