The role of familiarity in the development of social preferences in spiny mice.

A series of experiments investigated the role of familiarity in the development of individual recognition and social preferences in spiny mice. Pups who suckled from the same mother were able to recognize one another by common maternal labels even though these same pups were also differentially labeled by additional females. However, maternal labels appear to be less salient for the development of social preferences than is familiarization of pups through direct exposure. The manner in which animals are exposed to one another affects the familiarization process. Weanlings exposed to one another in the dark were similar to animals housed under a light/dark cycle in subsequent tests of recognition. In comparison to animals separated by wire mesh, those allowed complete physical contact subsequently displayed more positive social behavior. Therefore, while visual familiarity is not necessary for subsequent recognition, the familiarization process is facilitated by the opportunity for bodily contact. Recognition is probably mediated by olfactory cues, moreover, the social environment also influences the development of conspecific recognition. Animals housed with vs. without littermates while being exposed to unfamiliar agemated differed in later tests with the latter animals.