The biological and psychological origins of aggressiveness and its repercussions for human behavior. Aggressiveness is a wide-spread phenomenon in the animal world, which significantly affects relations within communities as swell between them. It represents a psycho-physiological basis for the start of any conflict. Aggressive behavior is determined by three factors: biological (genetic), educational and the influence of surroundings. All these factors occur also in the representatives of the Homo sapiens species and determine the appearance of violence in the interconfessional, interethnical, inter-racial and political relations. Taking into account the size of these manifestations in human society, the idea of an interdisciplinary analysis inside a new branch of science - political ethology – is supported.