AS THE BASIC BIOLOGICAL UNIT, THE GENE IS USUALLY THE STARTING POINT FOR ANY DISCUSSION OF BIOLOGICAL INFLUENCES ON HUMAN BEHAVIOR. AT THE SIMPLEST ANALYTICAL LEVEL, ONE MAY STUDY THE RELATIONSHIP BETWEEN THE GENETIC MAKEUP (GENOTYPE) OF AN INDIVIDUAL AND A GIVEN TRAIT OF THE INDIVIDUAL (PHENOTYPE). BEYOND THIS, INQUIRIES BECOME MORE COMPLEX AND COME TO CONSIDER QUANTITATIVE INHERITANCE, THE MECHANISMS OF GENE ACTION, THE INTERACTION OF GENES AND ENVIRONMENT, AND THE RELATIONSHIP BETWEEN GENETICS AND LESS TEMPORAL CONSIDERATIONS, SUCH AS HUMAN DEVELOPMENT AND EVOLUTION. MUCH OF THE AVAILABLE GENETIC DATA CONCERNING THE BIOLOGICAL BASES OF AGGRESSION AND VIOLENCE ARE DERIVED FROM RESEARCH INVOLVING INFRAHUMAN ANIMALS; STUDIES USING INBRED LABORATORY MICE HAVE ESTABLISHED A PARTICULAR LINK BETWEEN HEREDITY AND AGGRESSION. WHILE INQUIRY INTO THE MECHANISMS OF AGGRESSION HAS BEEN CONCERNED WITH THE NETWORK OF STRUCTURES AND PROCESSES BETWEEN GENE AND BEHAVIOR, THE RELATIONSHIP OF THE NEURAL AND ENDOCRINE SYSTEMS TO VIOLENCE HAS ALSO BEEN PURSUED. SEVERAL PARTS OF THE NERVOUS SYSTEM HAVE BEEN IMPLICATED IN AGGRESSION, AND EARLY RESEARCH INTO BRAIN FUNCTION REVEALED THAT ABLATION OF CERTAIN AREAS INFLUENCED RAGELIKE BEHAVIOR AND THAT STIMULATION OF OTHER AREAS COULD ELICIT ATTACKS. SERAFETINIDES (1965) DESCRIBED PRONOUNCED AGGRESSIVE TENDENCIES IN 36 PERCENT OF EPILEPTIC PATIENTS WITH TEMPORAL LOBE EPILEPTOGENIC FOCUS. THE ENDOCRINE GLANDS THAT APPEAR TO BE PRINCIPALLY INVOLVED IN AGGRESSIVE BEHAVIOR ARE THE ADRENALS AND THE GONADS, AND GENERALLY IT APPEARS THAT HORMONES FROM BOTH THE ADRENAL MEDULLA AND ADRENAL CORTEX MAY BE RELATED TO AGGRESSION AND FIGHTING. AN AREA OF CONSIDERABLE RECENT INTEREST IS THE POSSIBILITY THAT CERTAIN KINDS OF CHROMOSOMAL ABNORMALITIES MAY BE ASSOCIATED WITH ANTISOCIAL BEHAVIOR IN MAN. SEVERAL STUDIES APPEAR TO IMPLICATE THE XYY CONDITION AS BEING ASSOCIATED WITH A HEIGHTENED TENDENCY TOWARD AGGRESSIVE BEHAVIOR. GRAPHIC DATA AND REFERENCES ARE INCLUDED. (KBL)