The flight of the locus of selection: Some intricate relationships between evolutionary elements

Selection has enriched our understanding of the world since it was first applied to the evolution of species. Selection stands as an alternative to essentialist thinking, as a generalized and multiply applicable concept, and as a causal explanation for current forms within biology and behavior. Attempts to describe selection processes in a generalizable way have provided clarity about their minimal elements, such as replicators and interactors. This paper discusses the interconnectedness among different levels of selection using evidence garnered from evolutionary biology, development, epigenetics, neuroscience, and behavior analysis. Currently, it appears that replicators and interactors may be more fluid than previously supposed and that selection for particular traits may rely on both multiple levels of interaction and multiple levels of replication. Replicators, interactors, and environment share influence on one another, and different replicators may exchange critical control over similar interactor variation as evolution proceeds. Our current understanding of selection continues to undergo revision, and reference to a number of disparate fields can help to account for the complexity of these processes. An understanding of their interconnectedness may help resolve some mysteries that develop in fields that exclusively focus on one or a few, such as the focused study of behavior.