Mean Genes

Aggressive behavior is displayed by most animal species and subserves functions that are essential for the survival of the species, such as defense of the territory, defense of the progeny, and access to females (Lorenz 1966). For example, isolated male mice as well as lactating females will attack male intruders. Humans may display aggressive behavior in response to a threat or under the influence of alcohol. In its most extreme cases, aggressive behavior is considered a social ill, and the prevention of violence is a major concern of our societies. Social stressors such as poverty or a history of child abuse are likely to play a crucial role in many violent behaviors (Dodge et al. 1990). Environmental factors can trigger behavioral responses by influencing the activity of biological substrates. For example, in mice isolation results in an increase in aggressive behavior as well as changes in levels of neurotransmitters and hormones (Valzelli and Bernasconi 1979). In this review, we will focus on the molecular mechanisms that might underlie aggressive behavior, not because we believe that environment plays a minor role but because recent advances have pointed toward specific molecules as modulators of aggressive behavior.