Reciprocal Altruism

I'm very interested in the idea of social capital and the ensuing discussion. The first thing that came to mind for me was "reciprocal altruism", a term from evolutionary psychology. The notion there is that our basic social instincts come from our evolutionary heritage and that we have an evolved instinct to altruistic acts -- doing good things for others around us -- but also an instinctual expectation that other people will also perform altruistic acts. In other words, there is an expectation of reciprocity -- perhaps not directly, but overall, within the group (I scratch your back, you scratch hers, she scratches his, he scratches mine, etc.), so that the sum for everyone winds up greater than their individual part. What goes along with that is highly evolved "cheating detectors" that trigger feelings of indignation towards people who are viewed as taking more than they give, or at least not giving what they are reasonably able to give.

Now I know that this is not the same thing as social capital, but I think it does have some relevance. For example, if an instructor sets up work groups in order to increase social capital among students, the equation described above will necessarily come into play regarding their experience with their group.