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Helping behavior in communal or cooperative breeders is presumed by most researchers to have evolved as a direct result of natural selection. Hence, helping in different communal-species contexts is explained in terms of its adaptive or functional significance for the helper. The hypothesis that the expression of provisioning behavior by nonbreeding auxiliaries is an unselected consequence of the evolution of communal breeding is presented as an alternative to the functional hypotheses. First, I argue that the functional significance of nonbreeders' feeding offspring is irrelevant with respect to the evolutionary origin of the behavior because provisioning offspring is a constraint of many present-day species of birds, including those with helpers at the nest. I present a model that depicts provisioning by nonbreeding auxiliaries as an expression of a heterochronic change in ontogeny brought about as a result of a shift …