Phenotypic evolution under gene-culture transmission in structured populations.

I consider a simple model for the evolution of a quantitative character is structured populations when an offspring's phenotype is determined partly by his or her genetic constitution and partly by cultural transmission of the parental phenotype. Analysis of the model indicates that when individual and group selection are in the same direction, phenotypic evolution always proceeds faster under gene-culture vs. purely genetic transmission. When individual and group selection are countervailing, altruistic characters evolve faster under gene-culture transmission when individual selection is weak and migration among groups is limited, with increased individual selection and migration tending to decrease the advantage of gene-culture transmission over purely genetic transmission. Given the prevalence of cultural transmission in higher species, these results suggest that contrary to what is often assumed, group selection may indeed by a potent evolutionary force in the evolution of altruistic characters.