Social insects provide nature's most conspicuous example of altruistic behavior, in which some individuals sacrifice their survival and reproduction for the benefit of others. Theories of the evolution of altruism have therefore emphasized social insects. The theory of kin selection predicts that social insect colonies should be groups of close relatives, and this is usually true. However, when there are many egg-laying queens per colony, average relatedness is expected to be quite low. The maintenance of worker altruism then becomes more problematic, unless workers are locked into their role by a specialized morphology. From this perspective, the social insects that most challenge current understanding of the maintenance of worker behavior are the swarm-founding wasps of the neo-tropics, because they combine the multiple-queen habit with little or no morphological differentiation between workers and queens. Study of this group will answer two vital questions. First, how low is relatedness among colony-mates in these wasps? Second, what factors other than queen number influence relatedness, especially in cases where relatedness is higher than expected? If relatedness is very low, then these studies will show that current theories of the evolution of sociality may need revision. If relatedness is not low, then the problem posed by the presence of multiple queens will be solved. Further investigations into why relatedness is not low will uncover the forces that help to maintain altruistic behavior in this group.
