ABSTRACT
INTRODUCTION Despite a century of published scientific research on human aggression, definitive answers about the causes and control of human aggressive behavior remain elusive. The ability of mental health professionals to predict which individuals will engage in violent behavior remains poor (1), and the relative stability of violence rates suggests that little progress has been made toward the prevention of aggressive acts. Indeed, data from the U.S. Department of Justice Bureau of Justice Statistics reveal that the homicide rates over the last hundred years have fluctuated from 5 to 10 murders per 100,000, with peaks and troughs interspersed (2). These data, along with evidence from epidemiological studies showing that physical aggression in everyday relationships is a frequent occurrence (3), provide little reason for optimism that effective interventions for reducing violence in the community will be developed in the near future. On the positive side, over the
past century a rich literature has accumulated that supports the notion that reliable correlates of aggressive behavior can be identified in the field and laboratory (4,5). For example, biological (e.g., central serotonin activity, endogenous testosterone activity, alcohol consumption), psychological (e.g., perceived threat, aversive mood states, frustration), and social (e.g., economic fluctuations, normative influences, political instability) factors have been associated with aggressive behavior. However, no single variable or theoretical model has been able to satisfactorily explain aggressive behavior in the general case. This has had the indirect benefit of allowing researchers to reach a consensus on what may be the guiding principle for aggression research in the next century; specifically, that the causes of aggressive behavior are complex and multi-factorial.
