 In fact, much of the interactor debate has been played out through the construction of mathematical genetic models—with the exception of work on group selection and on female-biased sex ratios (Wade 1980, 1985, 2016; D.S. Wilson &amp; Colwell 1981; see especially Griesemer &amp; Wade 1988). The point of building such models is to determine what kinds of selection, operating at which levels, may be effective in producing evolutionary change.