We recently published a paper titled “Energetic Basis of Colonial Living in Social Insects” showing that basic features of whole colony physiology and life history follow virtually the same size-dependencies as unitary organisms when a colony’s mass is the summed mass of individuals. We now suggest that these results are evidence, not only for the superorganism hypothesis, but also for colony level selection. In addition, we further examine the implications of these results for the metabolism and lifetime reproductive success of eusocial insect colonies. We conclude by discussing the mechanisms which may underlie the observed mass-dependence of survival, growth and reproduction in these colonies.