Attachment in rat pups, an experimental approach.

John Bowlby's attachment theory states that attachment behavior has been st rengthened throughout evolution as a consequence of its adaptive value. We investigated the presence of attachment-like behavior in rat pups, by offer ing a choice between the home nest and a same aged other nest. Rat pups sho wed an increase of preference for the home nest during the second week and the first half of the third week. After that a preference for the other hom e side developed. Control experiments showed that the results were not due to repeated testing. Possible explanations of the results are discussed in light of renewed criteria for attachment in animal experiments. It is concl uded that a primitive and temporary form of attachment in rats cannot be ex cluded.