Perhaps the earliest form of aggression involved an animal’s need to monopolize a food source and defend it from members of its own species. Since then, aggression in this context has been documented across the animal kingdom, but its neural regulation remains obscure. Using novel behavioral tests that couple fasting responses to aggressive encounters aimed at accessing a food source, avian studies conducted in gregarious zebra finches and territorial song sparrows suggest a role for androgen precursors, namely dehydroepiandrosterone or DHEA, and its neural conversion to estrogen by P450 aromatase within the vertebrate social behavior network. Several of the nuclei within this network contain aromatase, but also exhibit high-immunoreactivity for the orexigenic neuropeptides: neuropeptide-Y and orexin. These neuroanatomical alignments favor potential signaling between steroidogenic cells and central modulators of energy balance, and this relationship may be altered with fasting and other shifts in energy balance. To supplement these avian studies, current research using laboratory rodents, anole lizards, and even freshwater crayfish as models demonstrate practically identical behavioral responses to food insecurity, and collectively these observations provide ample support for a neuroendocrine basis for this highly-conserved, yet essentially unstudied behavior.