Genetic and cultural evolution of cooperation

Emotions appear to be a key determinant of behavior in cooperative relationships. Emotions affect behavior both directly, by motivating action, and indirectly, as actors anticipate others’ emotional responses. The influence of emotions is understandable once it is recognized that (a) the ability to benefit from cooperative relationships has been a key determinant of biological fitness throughout our species’ history, and (b) panhuman emotions are adaptations crafted by natural selection. Different emotions affect cooperative behavior in different ways: some emotions lead actors to forego the temptation to defect, some lead them to reciprocate harm suffered or benefits provided, and some lead them to repair damaged relationships. An important class of emotions influences cooperative behavior in part by motivating conformity to norms and/or punishment of norm violators. This chapter discusses thirteen emotions that seem to have the greatest impact on cooperation. In addition to reviewing empirical evidence of the role of emotions in cooperation, the chapter presents a variety of explanatory hypotheses and provides a number of discrete testable predictions.