Abstract
Psychosomatic diseases (PSD) are strongly related to human behaviors, which need to be explained at four different explanatory levels : physiological, psychological, cultural and evolutionary. However, to date PSD have been investigated only at the first three levels. To investigate PSD at the evolutionary level, we decided to analyze the behavioral traits of patients suffering from PSD. We conducted interviews with inpatients suffering from peptic ulcers. On the basis of these interviews we isolated the following characteristics of these patients. (1) Willingness to care for others. (2) Willingness to oblige others. (3) Proneness to be let down by others. (4) Methodical, and pursuit of completeness. These characteristics indicate that patients suffering from peptic ulcers are altruistic and compulsive. Altruism is a behavior that decreases individual fitness, therefore this topic has been controversial in sociobiology. Barkow has pointed out that human beings pursue prestige in order to gain self-esteem which is a prerequisite for good mental health. Hill has argued that altruistic behavior promotes prestige and therefore increases an individual's sociocultural and biological fitness. If this argument is correct, then patients suffering from peptic ulcers may be individuals who have in vain pursued prestige altruistically.
