Aggressive behavior is a complex behavior phenomenon having genetics and physiological roots.Basic studies have shown that the frequency and severity of aggression depends on the hereditary predispositions, previous experience of aggressive behavior and social context.Our research is based on unique experimental models developed at the Institute of Cytology and Genetics SB RAS.One of them-grey rats (Rattus norvegicus) subjected to selection during several generations in two directions-friendly, tolerant behavior (tame gray rats) and increased aggressive behavior ("aggressors").