The paper presents data from animal-behavior studies, including original work by the author, which deal with the development of social bonds. "Imprinting" is an important early learned basis of attachment behavior but only in certain species and perhaps not in man.

The anaclitic role of feeding for the development of sexuality and object relations is seen as an important but not exclusive determinant. Comfort in contact and clinging is another important basis of early attachment to an object. Such findings indicate the value of Lorenz's concept of the parent companion as the object, a personal knowledge of whom is built up by virtue of the fact that the eliciting and terminating stimuli for various discrete responses are there united. Bowlby has hypothesized that this mechanism is the basis of the human child's tie to his mother. His hypothesis requires further empirical confirmation. Since the parent-companion relationship is experientially determined, it seems unlikely that there is a primary-object-relations drive.