Aggression is a universal feature of the behavior of social animals. In the wild, it is used for access to food and shelter, for protection from predation and for selection of mates, all of which are essential for survival. Despite its importance, little is known of the neural mechanisms that underlie aggressive behavior, other than that hormonal substances including amines, peptides and steroid hormones serve important roles in the behavior.

Our laboratory examines aggression using common strains of the fruit fly, Drosophila melanogaster. Although not widely known, male and female fruit flies fight and males at least become territorial (establish dominance relationships). Learning and memory accompany these fights. With the genome fully sequenced and with elegant methods available for selective manipulation of genes in subsets of central nervous system neurons, behavioral studies of aggression in flies offer a powerful system for identifying fundamental mechanisms underlying this behavior. In initial studies with this system, prior to starting mutant studies, we carried out a quantitative analyses of fighting behavior in male and female flies (see labworks.hms.harvard.edu and PNAS 2002 and 2004). Early studies also identified a single gene, fruitless, that was important in male and female courtship behavior, also was important in differences observed between male and female fighting behavior.  More recently, using genetic methods, we identified single brain serotonin neurons that facilitate going to higher levels of aggression in fights.  Additional genetic tools allow manipulation and visualization of these neurons in behaving animals, and the circuitry involved is currently being worked out.