Group selection & the bugs

The emergence of a superorganism through intergroup competition:

Surveys of insect societies have revealed four key, recurring organizational trends: (i) The most elaborated cooperation occurs in groups of relatives. (ii) Cooperation is typically more elaborate in species with large colony sizes than in species with small colony sizes, the latter exhibiting greater internal reproductive conflict and lesser morphological and behavioral specialization. (iii) Within a species, per capita brood output typically declines as colony size increases. (iv). The ecological factors of resource patchiness and intergroup competition are associated with the most elaborated cooperation. Predictions of all four patterns emerge elegantly from a game-theoretic model in which within-group tug-of-wars are nested within a between-group tug-of-war. In this individual selection model, individuals are faced with the problem of how to partition their energy between investment in intercolony competition versus investment in intracolony competition, i.e., internal tugs-of-war over shares of the resources gained through intergroup competition. An individual's evolutionarily stable investment in between-group competition (i.e., within-group cooperation) versus within-group competition is shown to increase as within-group relatedness increases, to decrease as group size increases (for a fixed number of competing groups), to increase as the number of competing groups in a patch increases, and to decrease as between-group relatedness increases. Moreover, if increasing patch richness increases both the number of individuals within a group and the number of competing groups, greater overall cooperation within larger groups will be observed. The model presents a simple way of determining quantitatively how intergroup conflict will propel a society forward along a "superorganism continuum."

Those who follow the "levels of selection" debates will be aware that E.O. Wilson has been promoting higher-than-individual-level-selection vocally for the past few years. Readers of Defenders of the Truth know that Wilson has always had a soft-spot for group level selection, and in Evolution for Everyone David Sloan Wilson makes it pretty clear that the elder and more venerable Wilson was instrumental in helping to push him into the area of multi-level selection. A friend of mine who was recently at Harvard in Wilson's department, which is predominantly "Hamiltonian" in orientation, told me about the likelihood of a new campaign on behalf of group selection a few years ago, although they did offer that most people assumed that Wilson had no deep understanding of the formal models that he was backing. Rather, Wilson's push seems predicated on the emerging empirical problems with a purely kin selective narrative in regards to the emergence of eusociality. Genetic fingerprinting has now allowed biologists to actually examine in detail the patterns of relatedness within colonies, and some are finding that they do not fit the range of values assumed (and necessary) under a Hamiltonian framework. In short, the coefficients of relatedness are often lower than you would expect in a tightly knit colony. What's going on here? Science. When data brings up incongruities the thousand blossoms of alternative theories start to fill the vacuum, and I think that's what we're seeing here. That doesn't mean that any one model is definitive, or that a Hamiltonian kin selective framework is without explanatory power, rather, the precise structure of relationships smoked out by the data available today requires more nuanced and subtle theoretical frameworks.

Related: Cooperation and multilevel selection.