Genes and Cultures—Boyd and Richerson THE INTERTWINED ROLES OF GENES AND CULTURE IN HUMAN EVOLUTION by William Irons

This essay critiques dual-inheritance theory as presented in Peter Richerson and Robert Boyd’s book Not by Genes Alone: How Culture Transformed Human Evolution (2005). The theory states that culture became prominent in human evolution because it allowed relatively rapid adaptation to changing environments by means of imitation. Imitating the behavior of other members of one’s community produces adaptive behaviors more readily than either genetic evolution or individual learning. Imitation follows a number of patterns: imitating high-status individuals, imitating the most common forms of behavior, imitating behaviors perceived to be the most effective solutions to various problems relevant to survival. This process combined with occasional innovations in behavior lead to a process of cultural evolution involving populations of cultural variants. Different local human populations were associated with different local populations of cultural variants, and both the human and the cultural populations evolved over time. Human evolution cannot be understood without taking into account these parallel processes of genetic and cultural evolution. Not by Genes Alone traces the implication of dual-inheritance theory for understanding human evolution and refers to various bodies of evidence relevant to the theory.