AVOIDANCE BEHAVIOR OF RAT

If wild rats in human communities behaved as tamed ones do toward unfamiliar objects, their compulsive exploratory and sampling behavior would probably lead them into traps or result in the ingestion of poison bait. Neophobia , displayed in highly developed form by wild rats, protects them from the consequences of curiosity. The extent to which rats commensal with man display avoidance behavior is perhaps a consequence of selection over the seven thousand years during which civilizations, with its stores of food has existed. More intense selection against wildness and neophobia produced the laboratory rat in less than half a century.

Avoidance of strange objects, and especially, strange animal of the same and other species, is common in the animal kingdom. It develops early in the life of many species of birds and mammals after a brief period when the young become imprinted on their parents. Once this young-parent attachment has been acquired, the safety of the young is well served by their avoidance of other animals. The avoidance behavior of wild rat may have a source in this kind of behavior, but on such question one can only guess.

Whatever its evolutionary origin, the neophobia of wild rat is not by itself sufficient protection against poisoned food. It is combined with a capacity to learn to refuse toxic mixtures. This capacity parallel the ability, much studied in tame rats, to select, in some instances, the nutritionally superior of the food.

The combinations of exploring and avoidance with habit formation is therefore elegantly adapted to giving a rat a maximum of information about the resources and dangers of its environment, in the safest possible way.