Implications of Epigenetic Learning Via Modification of Histones on Performance of Genetic Programming

摘要

Extending the notion of inheritable genotype in genetic programming (GP) from the common model of DNA into chromatin (DNA and histories), we propose an approach of embedding in GP an explicitly controlled gene expression via modification of histones. Proposed double-cell representation of individuals features somatic cell and germ cell, both represented by their respective chromatin structures. Following biologically plausible concepts, we regard the plasticity of phenotype of somatic cell, achieved via controlled gene expression owing to modifications to histones (epigenetic learning, EL) as relevant for fitness evaluation, while the genotype of the germ cell — to reproduction of individual. Empirical results of evolution of social behavior of agents in predator-prey pursuit problem indicate that EL contributes to more than 2-fold improvement of computational effort of GP. We view the cause for that in the cumulative effect of polyphenism and epigenetic stability. The former allows for phe-notypic diversity of genotypically similar individuals, while the latter robustly preserves the individuals from the destructive effects of crossover by silencing of certain genotypic fragments and explicitly activating them only when they are most likely to be expressed in corresponding beneficial phenotypic traits.