The psychoanalytic theory was originated by Sigmund Freud. This theory focuses on the impact of unconscious forces on human behavior. According to Freud, the personality is made up of three parts: the id, ego, and superego. The id operates under the pleasure principle, the ego operates under the reality principle, and the superego is the "conscience" and incorporates what is and is not socially acceptable into a person's value system. Also, according to the psychoanalytic theory, there are five stages of psycho-sexual development that everyone goes through: the oral stage, anal stage, phallic stage, latency stage, and genital stage. Mental disorders can be caused by an individual receiving too little or too much gratification in one of the psycho-sexual developmental stages. When this happens, the individual is said to be fixated in that developmental stage. Attachment theory is a kind of evolutionary-psychological approach sometimes applied in the context for mental disorders, which focuses on the role of early caregiver-child relationships, responses to danger, and the search for a satisfying reproductive relationship in adulthood. According to this theory, the more secure a child's attachment is to a nurturing adult, the more likely that child will maintain healthy relationships with others in their life. As found by the Strange Situation experiment run by Mary Ainsworth based on the formulations of John Bowlby, there are four main patterns of attachment: secure attachment, avoidant attachment, disorganized attachment and ambivalent attachment. These attachment patterns are found cross-culturally. Later research found a fourth pattern of attachment known as disorganized disoriented attachment. Secure attachments reflect trust in the child-caretaker relationship while insecure attachment reflects mistrust. The security of attachment in a child affects the child's emotional, cognitive, and social competence later in life. Evolutionary psychology and evolutionary psychiatry posit that many mental disorders involve the dysfunctional operation of mental modules adapted to ancestral physical or social environments but not necessarily to modern ones. Behavioral abnormalities that resemble human mental illness have been found in closely related species (great apes). Other theories suggest that mental illness could have evolutionary "advantages" for the species, including enhancing creativity and stress to enhance survival by easily activating the flight-or-fight response in anticipation of danger. Schizophrenia could have been beneficial in prehistoric times by improving creativity during stressful times, or by helping to disseminate delusional tales that would have aided in group cohesion and finding gullible mates. The paranoia associated with Schizophrenia could have prevented danger from other humans and other animals.