The Diffusion of Moral Innovations: Cultural Learning Processes Spread Novel Forms of Cooperation

I begin with humans' unique position as the product of two evolutionary processes ("dual-inheritance theory"; D. Campbell, 1965; Cavalli-Sforza, Feldman, Chen, & Dornbusch, 1982; Henrich & McElreath, 2007; Richerson & Boyd, 1978). Our species, like all known others, are products of biological evolution, subject to the pressure of natural selection which favors self-interested behaviors enabling individuals to survive and reproduce (Darwin, 1859). In this context, it seems that cooperation—in the game theoretic sense, an individual paying a cost to give another a benefit (Von Neumann, 1959)—would not be favored by natural selection. Unlike other species, however, humans are also products of cultural evolution (Boyd & Richerson, 1976), subject to the pressure of cultural, within-group selection which favors behaviors that conform to group norms (Akerlof, 1976; Boyd & Richerson, 1985; Ellison & Fudenberg, 1993). In this context, it seems that innovation—in the sociological sense, an idea or practice first adopted by a small subset of the population (technically, chronologically prior to "early-adopters"; E. Rogers, 1962/2003)—would not be favored by cultural selection. At the intersection of biological and cultural evolutionary processes is the uniquely human phenomenon of morality, which can be understood as the subset of cultural norms (e.g. Schaller & Crandall, 2004) governing the tension between self-interest and cooperation (Curry, 2016; Greene, 2015; Hoffman, Yoeli, & Navarrete, 2016; Tomasello & Vaish, 2013). I will refer to the spread of participation in novel collective actions as synonymous with moral innovation, denoting the cooperative and normative nature of this behavior as well as its early adoption. Given both types of evolutionary pressures on us to pursue self-interested, conformist behaviors, it might seem that an individual engaged in moral innovation is employing a doubly losing strategy. Yet, to take just one example of an effort to promote participation in novel collective actions, increasing interest in encouraging the adoption of new pro-environmental technologies and behaviors—as revealed across literatures in the social sciences, such as psychology (Steg & Vlek, 2009), economics (Rennings, 2000), public policy (Nill & Kemp, 2009), and business (Nidumolu, Prahalad, & Rangaswami, 2009)—appears to provide evidence against this conclusion. Why, then, do we forgo self-interest and buck cultural norms, to participate in novel collective actions