How do allied players in Settlers of Catan always come out ahead? I’ll trade two sheep for some social capital.
A great summary of what social capital is and how it affects societies - http://www.bettertogether.org/socialcapital.htm
An interesting study about the ultimatum game in several different societies, which notes a high correlation between social capital in a society and more equality in the split - http://samoa.santafe.edu/media/workingpapers/01-01-007.pdf
“Using Experimental Economics to Measure Social Capital and Predict Financial Decisions” from the American Economic Review - http://karlan.yale.edu/p/gamespaper.pdf
A paper on the evolutionary advantage granted to social animals with altruistic behavior - http://ggsc-web02.ist.berkeley.edu/images/uploads/Trivers-EvolutionReciprocalAltruism.pdf
Just for fun, a paper on reinforcement strategies for AI playing Settlers of Catan. The AI’s get pretty good, but just can’t match a skilled human settler - http://eprints.pascal-network.org/archive/00000425/01/LAG-37_pfeiffer_2004.pdf