Attachment theory is a psychological model that attempts to describe the dynamics of long-term and short-term interpersonal relationships between humans. However, "attachment theory is not formulated as a general theory of relationships. It addresses only a specific facet" (Waters et al. 2005: 81): how human beings respond within relationships when hurt, separated from loved ones, or perceiving a threat. Essentially, attachment depends on the person's ability to develop basic trust in their caregivers and self. In infants, attachment as a motivational and behavioral system directs the child to seek proximity with a familiar caregiver when they are alarmed, with the expectation that they will receive protection and emotional support. John Bowlby believed that the tendency for primate infants to develop attachments to familiar caregivers was the result of evolutionary pressures, since attachment behavior would facilitate the infant's survival in the face of dangers such as predation or exposure to the elements.