1. From an evolutionary point of view aggressive behavior increases the chances of individual survival as well as inclusive fitness. 2. There are brain structures and biochemical systems that are involved in the regulation of aggressive behavior. 3. Genetic studies have revealed genetic contributions to aggressive as well as impulsive behaviors. 4. Research has demonstrated correlations between measures of suicidality, violence and impulsivity. 5. A two-step model of countervailing forces has been developed that identifies amplifiers and attenuators of the aggressive impulse. This model has enabled us to determine a set of variables that influence suicide but not violence and another set that influences violence but not suicide.