Effects of age and food deprivation on the development of muricidal behavior in rats

The induction of muricidal behavior in the rat, under various experimental conditions, was studied in order to determine whether mouse killing is a form of predatory aggression that is closely related to feeding behavior. Rats of various ages were socially isolated and subjected to various degrees of food deprivation to determine whether the same laws that govern feeding also govern muricidal behavior. The age of the rat at the beginning of the study (8, 12 or 18 weeks of age) did not appear to significantly affect the induction of muricide by food deprivation. Chronic food deprivation caused non-killer rats to kill mice. In addition, the severity of the food deprivation influenced the induction of mouse killing such that the greater the degree of deprivation, the greater the number of rats that became killers. The effects of food deprivation on the induction of mouse killing were reversed by giving the rats access to food ad lib. Since many of the laws that govern feeding also appear to be the laws which govern mouse killing, the two behaviors may be highly inter-related.