Developmental Timing and the Microevolution of Aggression,

It has now been established that social behavior patterns in several mammalian species can be rapidly and effectively influenced through selective breeding (see Scott & Fuller, 1965, and Fuller & Thompson, 1978). But only modest information has been available on the behavioral and developmental processes through which this powerful genetic regulation is achieved. Following the arguments of Scott (1977), we believe that a focus on the behavioral changes that take place in development and across generations would help clarify the nature of the behavioral and physiological pathways affected in genetic selection. Accordingly, the essential themes of this chapter are reflected in three propositions: Developmental analyses are essential to understand the melding of genetic and experiential effects on fighting and attacks. Rapid microevolutionary changes in attack behavior may be produced by heterochronies, such as the extended immaturity in the onset of key behavioral components. Those behavioral components of attack behavior that are susceptible to rapid change by genetic selection are also vulnerable to rapid change by individual experience in ontogeny.