Abstract
Frequent use of physical aggression by humans appears to reach its peak between 2 and 3 years of age. In the following years most children learn alternatives to physical aggression. Approximately 4% of children have high levels of physical aggression from early childhood to late adolescence. These children can be considered to show chronic physical aggression. They are at high risk of causing injuries to others and to themselves. They are also at high risk of many other co-morbid mental health conditions, school failure, substance abuse, depression, unemployment, spouse abuse, child abuse, and suicide. There is some evidence that, because of their risky style of behavior, they are also at high risk of many other medical conditions such as cardiovascular problems, cancer, and brain damage. Socialization of aggressive behavior during the preschool years should help prevent injuries throughout the life span.