Attachment theory focuses on the survival advantages of interpersonal relationships and suggests that the key determining factors controlling the subsequent emotional life of the child relates to internal representations of attachment bonds gained from early experience. Sociobiologists differ from attachment theorists on the issue of infant-mother attachment being the template of all affectional relationships. This chapter focuses on the role of the parent - especially the mother - as a "mediator" of the environment for the infant. The role of mother, or any primary care givers, as a mediator of the environment and provider of input necessary for survival and psychological growth continues to be crucial throughout childhood. In terms of the neurobiological mediators of the separation response, Kraemer and McKinney have shown that various historical and social housing conditions interact with despair responses produced with drug challenge to monoaminergic pathways. Separation triggers the defence system.