For decades, a divisive debate has raged among biologists over the evolution of eusocial insects—those that thrive in cooperative societies of queens, workers and drones. On one side is the argument for “kin selection,” a theory asserting that the nonreproducing members pass on their genes by helping relatives reproduce. The members of a colony should therefore be closely related. Yet those on the other side—most notably, renowned biologist Edward O. Wilson of Harvard University—contend that eusocial insects work together in colonies because it is to their individual advantage; their cooperative spirit is simply a consequence. If there is high relatedness in a colony, then it is a result of individuals choosing to stick around to reap the benefits of group life.

Researchers led by William Hughes of the University of Leeds in England say they have the first clear evidence that supports kin selection, rather than group selection, in eusociality. They examined 267 eusocial species of bees, wasps and ants and found that the insects evolved from monogamous conditions, which maximize a group’s degree of relatedness. Moreover, they found that polyandry (having more than two mates) transpired only among lineages where workers had become permanently sterile—a prediction of kin selection theory for species that have become irrevocably eusocial. Behavioral biologist Andrew Bourke of the University of East Anglia in England says that the May 30 Science study indicates that kin selection is an essential precondition to eusociality.

Wilson, however, disagrees, asserting via e-mail that Hughes’s work does not include data on many lineages that did not evolve eusociality and that the emergence of polyandry in eusocial societies has explanations not related to kin selection.

Note: This story was originally printed with the title, "Monogamy and the Queen Bee".