Abstract
Aggression is a topic that has been much investigated in behavioural research. Despite the large number of publications dealing with this subject, many aspects are still not understood. The present review focuses on both the bio-social and the physiological regulation of aggression and its valid models. Recent studies have provided new endocrine and neurophysiological insights into the underlying mechanisms. In the past, the steroid hormone testosterone (T) was believed to be the main endocrine activator of aggressive behaviour and its expression rate. However, the importance of T seems to lie in its neuromodulatory function, especially in the regulation of overall dominance and competitive aggression. In turn, unrestrained aggression, impulsivity and risk-taking behaviour are associated with low central serotonergic activity. Other centrally active molecules, such as vasopressin or dopamine are also key players in mediating aggressiveness. In a social context, aggression is mostly applied in competitive processes to get access to limited resources such as food and mating partners, or for the defence of resources. Intriguingly, diverse forms of aggression are probably triggered by environmental factors such as the availability and quality of food. This review investigates both availability and quality of food, with regard to their influence on anti-social behaviours in a variety of species and tries to work out their potential function as neurophysiological modulators. Furthermore, unresolved methodological issues concerning the central activity of nutritional factors will be discussed.