Bowlby's Theory of Attachment Bowlby's theory of attachment was influenced by psychoanalytic and evolutionary theories. Infants were considered to be biologically programmed to behave in ways that triggered affectionate, protective responses from adults. These behaviors might include smiling, cooing, clinging, etc. Adults are programmed by evolutionary forces to respond to this behavior with warmth and love. Bowlby's theory influenced much work on attachment, including that of Ainsworth.