Multilevel Selection and Units of Selection Up and Down the Biological Hierarchy

There has been considerable debate in both biology and philosophy about which entities undergo natural selection and what it is that fits them for that role. For nearly forty years, some participants in the “units of selection” debates have argued that more than one issue is at stake. Richard Dawkins, for example, introduced “replicator” and “vehicle” to stand for different roles in the evolutionary process (1982). David Hull (1980) broke Dawkins’s category of “replicator” up into “replicator” and “interactor.”