The Evolution of Secondary Organization in Immune System Gene Libraries

A binary model of the immune system is used to study the effects of evolution on the genetic encoding for antibody molecules. We report experiments which show that the evolution of immune system genes, simulated by the genetic algorithm, can induce a high degree of genetic organization even though that organization is not explicitly required by the fitness function. This secondary organization is related to the {\it true fitness} if of an individual, in contrast to the {\it sampled fitness} which is the explicit fitness measure used to drive the process of evolution.