Models of Cultural Evolution

Abstract

In my chapter ``Models of Cultural Evolution,'' I try to explain how selectional models of cultural evolution and selectional models of biological evolution are related to each other by focusing on how each understands the concepts of fitness and heredity. I discern three types of model, not just two, and then discuss the distinction between source laws and consequence laws that I developed in my book The Nature of Selection. Given a set of heritable traits that differ in fitness, a selectional model will be able to compute the consequences of those initial conditions by describing how the population is apt to change. However, such models are often silent on why the traits have the fitness values they do. It is one thing to describe the consequences of fitness differences, another thing to describe their sources. Models of cultural evolution have mainly focused on describing the consequences of fitness differences, while saying little about the sources. For example, the decline in birth rate that occurred in nineteenth-century Italy can be described as a process of cultural selection in which the trait of having fewer children had higher cultural (not biological) fitness than the trait of having more. There is nothing false about this description, but it does leave unanswered the question of why preferences about family size suddenly changed, or why women suddenly had the power to control their own reproduction in ways that were not possible before.One important distinction to bear in mind in thinking about cultural evolution is the difference between the following two questions: Do cultural traits ever evolve by a process of cultural selection? How useful is this way of thinking about cultural change for answering the questions that historians and social scientists wish to address? The intelligibility of an approach and its fruitfulness are separate matters.