Gene-Culture Models for the Evolution of Altruistic Teaching
Putative cases of teaching occur sporadically in diverse species including some felids and raptors, and humans, but probably not chimpanzees. In many such cases, teaching is apparently done by one parent, usually the mother, or by both parents. We use gene-culture coevolutionary models to explore the evolution of vertical cultural transmission in which whether a parent does or does not teach an adaptive trait is genetically determined. The act of teaching entails a fitness cost to the parent that teaches and hence is regarded as altruistic. We find that evolution of teaching is disfavored by temporal environmental variability, but sometimes favored under conditions in which the adaptive phenotype can be maintained in the population in the absence of teaching. We also find that the balance between the fitness costs of teaching and the benefit associated with the adaptive phenotype may permit the coexistence of teachers and nonteachers. When teaching is biparental, both the teaching gene and the cultural trait that is taught may remain polymorphic. In addition, we briefly consider the effects of oblique (intergenerational) and horizontal (intragenerational) cultural transmission occurring after vertical transmission, which likely characterizes the developmental pattern of social learning in present-day hunter-gatherers.
