 It is worth noting that several discussions of species selection pre-date Eldredge and Gould’s (1972) proposal (e.g., Fisher 1929, Wright 1956; Lewontin 1970). However, it is the ensuing discussion of stabilizing selection prompted by PE—in combination with a contemporaneous uptick in discussion of kin selection, group selection, and altruism (Haldane 1932; Wright 1945; Wynne-Edwards 1962; Hamilton 1963; Maynard Smith 1964; Boorman &amp; Levitt 1973; E.O. Wilson 1973; Levin &amp; Kilmer 1974; D.S. Wilson 1975; Wade 1978)—which transforms these macroevolutionary sparks into an ongoing, hierarchical conflagration (see Gould 1980b, 1982, 2002; Vrba &amp; Eldredge 1984; Cracraft 1985; Eldredge 1985; Grantham 1995; and Eldredge, Pievani, Serrelli, &amp; Temkin 2016, among others). Indeed, some theorists see the paleobiological revolution as contributing to a “hierarchical expansion” of evolutionary theory.