In this book, Itô presents data on tropical wasps which suggest that kin-selection has been overemphasized as an evolutionary explanation of sociality. He concentrates on the Vespidae (paper wasps and hornets), a group much discussed by evolutionary biologists because it exhibits all stages of social evolution:; subsociality, primitive eusociality, and advanced eusociality. The author reports field observations by himself and others in Central America, Asia, and Australia, showing that multiple egg-layers in a nest are not uncommon. Because coexistence of many `queens' leads to lower relatedness among colony members than in single-queen colonies, he suggests that kin-selection may not be the most powerful force determining observed social patterns. Instead, subsocial wasps may first have aggregated for defence purposes in habitats with a high risk of predation, with mutualistic associations among many queens. Through parental manipulation and then kin selection, differentiation into within-generation castes may have followed. Of interest to all students of ecology, evolution, and behaviour, this book beautifully illustrates the ability to combine wide-ranging data with thoughtful questions - the author's trademark.