Network Centrality and Coalitional Competition: An Economic Experiment in an Achuar and Sápara Community of the Ecuadorian Amazon

One instance of a cooperation dilemma consequential to humans is inter-coalitional competition and conflict. Here, results are reported from a series of five one-shot anonymous public goods games (PGG) designed to elicit varying coalitional and competition motivations for cooperation within the PGG. the data presented in this thesis were collected in Conambo, a bi-ethnic tribal community of Achuar and Sápara peoples in the Ecuadorian Amazon. This research has two aims: (a) discern the relative influence of group composition, random or coalitional, and the level of group competition, either none, intra-group, or inter-group on cooperation; and (b) test predictions concerning how variation in social network centrality affects cooperation in intergroup competition. Analyses of experimental PGG treatments reveal a significant increase in offers due to variation in group composition (from random to coalitional) in the context of between-group competition. Additionally, betweenness centrality in an alliance network was found to differentially affect cooperative offers in men and women across a range of coalitional and competitive contexts. These results give further confidence that group competition is a robust factor increasing cooperation and limited support for the argument that inter-individual differences rather than group level differences explain variation in PGG offers.