 For Clarke, it is what these two sorts of mechanisms do that is important, not how the mechanisms do this in various ways (Clarke 2013: 429). In other words, it is only the functions of the mechanisms that Clarke thinks are definitive, not the various material ways those functions are realized. As Clarke stresses, this implies the multiple realizability of evolutionary individuals. This “thoroughgoing functionalism about individuality” (Sterner 2015: 610) abstracts away from specific realizations of the functional roles of policing and demarcation. In this respect, Clarke’s view contrasts with many other views of evolutionary individuals that emphasize the importance of particular ways in which these mechanisms are realized. For example, Dawkins, Maynard-Smith, and Bonner imply that certain material bottlenecks—narrowings between generations exemplified by our own single-celled, zygotic bottleneck—are essential ways for policing to be realized in evolutionary individuals (Clarke 2013: 418–419), while Ratcliffe and Kirk instead make material germ-soma separation essential (Clarke 2013: 420).