Abstract
Social evolution theory conventionally takes an externalist explanatory stance, treating observed cooperation as explanandum and the positive assortment of cooperative behaviour as explanans. We ask how the circumstances bringing about this positive assortment arose in the first place. Rather than merely push the explanatory problem back a step, we move from an externalist to an interactionist explanatory stance, in the spirit of Lewontin and the Niche Construction theorists. We develop a theory of ‘social niche construction’ in which we consider biological entities to be both the subject and object of their own social evolution. Some important cases of the evolution of cooperation have the side-effect of causing changes in the hierarchical level at which the evolutionary process acts. This is because the traits (e.g. life-history bottlenecks) that act to align the fitness interests of particles (e.g. cells) in a collective can also act to diminish the extent to which those particles are bearers of heritable fitness variance, while augmenting the extent to which collectives of such particles (e.g. multicellular organisms) are bearers of heritable fitness variance. In this way, we can explain upward transitions in the hierarchical level at which the Darwinian machine operates in terms of particle-level selection, even though the outcome of the process is a collective-level selection regime. Our theory avoids the logical and metaphysical paradoxes faced by other attempts to explain evolutionary transitions.
Highlights
Social evolution theory conventionally takes an externalist explanatory stance, treating observed cooperation as explanandum and the positive assortment of cooperative behaviour as explanans
Social niche construction theory employs an interactionist explanatory stance to reciprocally explain both cooperation and the factors enabling it Social evolution theory tries to explain the evolution of social behaviours (Hamilton 1964; Wilson 1975a; Bourke 2011); niche construction is any process in which organisms modify their own environment in such a way as to influence the conditions of their own evolution (Odling-Smee et al 2003; Laland and Sterelny 2006)
Social niche modifier (SNM) A trait that alters the effective game being played by its bearers, causing it to differ from the counterfactual game they would have been playing if the SNM had not acted
Summary
The externalist explanatory stance takes it that the properties of biological entities are to be explained by factors largely or entirely external to those entities (Spencer 1864; Lack 1947; Simon 1981; Williams 1966; Brandon 1990; Godfrey-Smith 1996). Social niche construction theory employs an interactionist explanatory stance to reciprocally explain both cooperation and the factors enabling it Social evolution theory tries to explain the evolution of social behaviours (Hamilton 1964; Wilson 1975a; Bourke 2011); niche construction is any process in which organisms modify their own environment in such a way as to influence the conditions of their own evolution (Odling-Smee et al 2003; Laland and Sterelny 2006). Social niche modifier (SNM) A trait that alters the effective game being played by its bearers, causing it to differ from the counterfactual game they would have been playing if the SNM had not acted Examples include factors such as population structure, relatedness, punishment, policing and side-payments (see Table 1 for many more). The benefits of this increased cooperation increase the fitness of the bearers of the social niche modifying trait. (Note that this is not because there is direct selection on the SNM but because it is correlated with the ST—and the ST, in the locally modified social niche, confers a fitness advantage on the bearer.) There is a circularity here that warrants emphasis:
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