Rat’s habitats are diverse; as a result rats have become adept omnivores. Due to the diversity of the environments and the subsequent diversity of potential foods and poisons in such environments, rats must be selective and cautious of which foods to consume. In addition, rats cannot expel ingested poisons by vomiting, due to anatomical restrictions. Therefore it is imperative that rats develop social and behavioral adaptations in order to reduce the potential dangers of poisons in the environment.
One such behavioral adaptation is neophobia, or the fear of new experiences or things. In most cases, if a rat is presented with a novel food, it may eat a small amount of the food. Then, if no adverse effects occur, then the rat may continue to eat a larger amount. However, if after the rat eats a small amount of the food it becomes sick it will avoid the food in the future; this is known as a conditioned taste aversion (lin2008). Early research regarding taste aversion in rats suggested that rats develop an aversion to water consumed before radiation exposure. The results of the study suggest that the rats avoided the water due to the adverse effects experienced from the radiation (garcia1966).
Rats have leveraged their nature as a social species to create social adaptations that prevent ingesting poisonous substances. Adult rats have been shown to prefer foods that other rats have eaten previously (strupp1984). Furthermore, the olfactory system of rats is highly developed. Rats are therefore able to identify smells that are present on another rat’s fur or breath. If a rat smells a food on another rat, this exposure will diminish the effects of neophobia, thus increasing preference, and the rat will be more likely to choose the food smelled on its conspecific, if presented with that food and another novel food (strupp1984). This type of social learning is advantageous to the survival of rats as a species; the ability to learn an aversion to poisonous substances from another member of the species minimizes the negative effect on the population caused by such poisonous substances.
The primary social strategy that rats have developed in wild colonies to maximize social exposure and minimize poisoning amongst the population is the use of a scout rat. The scout rat is the first rat to consume the food. If the scout rat does not become sick or die after consuming the novel food, conspecifics in the colony will consume the food. However, in a laboratory setting, rats do not have the opportunity to learn the same social transference of food preference, due to the regular feeding schedules and safe diet of the laboratory conditions (barnett1958). Therefore, in the first experiment, we replicated previous experiments which examined the social influence of rats in a laboratory setting based on food selection preferences (strupp1984) (galief1986)(galef, 1983, Galef, Kennett & Wigmore, 1984, Galef & Wigmore 1983, Possadas-Andrews & Roper 1983).