. Aggression research is in a rapid state of development. The accelerating knowledge of neurotransmitter systems in the brain, their behavioural functions and the development of drugs which may specifically affect systems related to attack and defence is fruitfully combined with studies in which basic ethological observation and quantification techniques are used more routinely. Moreover, much of the experimental effort has finally applied some order to the initial chaos which afflicted the various experimental aggression models used in pharmacological, physiological and ethological research....