The killer instinct is the human propensity to do whatever it takes to survive or achieve a goal, even killing another human being. Often in present in fighting, wars and confrontation. It is believed that some humans possess an ability to kill another human in order to achieve a goal. Examples include soldiers in the army, fighters such as boxers, mixed martial artists often display a form of this when trying to finish off an opponent, where as it is argued that the main goal is to master self-defense in fighting sports.
