Eibl-Eibesfeldt (1984) regards the development of love relationships as a milestone in evolution. Shaver, Hazan, and Bradshaw (1988) describe love as a concept that encompasses three biologically meaningful behavioral systems: attachment, caregiving, and sexuality. The psychological correlates of these three behavioral systems are trust, altruism, and passion. In a lecture on psychoanalysis as art and science, Bowlby traced fear of attachment in the child and later adult back to the expectation of rejection coupled with torturous anxiety. In this context he writes: “As a result there is a massive block against his expressing or even feeling his natural desire for a close trusting relationship, for care, comfort, and love – which I regard as the subjective manifestations of a major system of instinctive behavior” (Bowlby, 1988, p. 55). Bowlby, who presents attachment and love from an ethnological point of view, emphasizes the biological function of this behavior class and its preprograming by inborn behavioral tendencies that, together with the interplay of ecological influences (especially the behavior of the parents), determine the formation of attachment. Later (p. 65) he stresses that, when forming attachments to people later in life, a person acts on expectations that resemble the model of the parents. In agreement with these assumptions, longitudinal studies confirm a certain stability in styles of attachment (Grossmann & Grossmann, 1991). The style of attachment in the young child influences the type of friendship relationships that are built up 10 years later.