This dissertation aims to provide the biological bases of behavioral system of attachment, presented by John Bowlby, and discuss the interaction between biological and environmental construction in the psyche of the subject. This will be achieved primarily through the study of the human being as from an animal, using the Theory of Natural Selection of Species Charles Darwin. Then we have then the basis for studying human behavior. Taking tracks the path of biology, we can go to the study of the environment as a factor essential for the formation of humanity. One can not speak of human beings without talking about their relationship. Will be presented as evidence of the social relationships affect physical apparatus in the brain. This demonstration is of utmost importance to prove that the interaction between the organic and the social is what produces a healthy mind or ill, the main focus of this work.