Culture and the Evolutionary Process

Culture and the Evolutionary Process (1985) is the foundational monograph by Peter Richerson and Robert Boyd that introduced Dual Inheritance Theory to the scientific community. Unlike earlier treatments of culture that relied on qualitative analogy or unilinear progression, this book presented culture as an evolutionary system amenable to the same mathematical tools used in population genetics — difference equations, recursion relations, and stability analysis.

The book's central innovation was to model cultural transmission as a population process with explicit parameters: the fidelity of vertical transmission (parent-to-offspring), the rate of horizontal transmission (peer-to-peer), and the strength of transmission biases like conformist and prestige bias. Richerson and Boyd demonstrated that even simple models produce non-obvious outcomes: cultural evolution can drive genetic evolution against fitness gradients, produce runaway dynamics not possible in genetic systems, and sustain group-level adaptations that genetic group selection cannot. The formal apparatus laid down in this book made possible the later development of cultural group selection theory and the empirical program of gene-culture coevolution.

Culture and the Evolutionary Process established that the "quantitative genetics of culture" was not merely a metaphor but a research program capable of generating testable predictions about specific human populations. Its influence extends far beyond anthropology into psychology, economics, and the study of complex social dynamics.