22. A Theory of Culture for Evolutionary Demography

Evolutionary demography is a community of researchers in a range of different disciplines who agree that “nothing in evolution makes sense except in the light of demography” (Carey and Vaupel 2005). My focus here is a subset of this research (henceforth ‘evolutionary demography’ or ‘evolutionary anthropology’) that originated in anthropology in the late 1970s and which typically examines micro-level phenomena concerning reproductive decision-making and the evolutionary processes generating observed patterns in reproductive variation. Scholars in this area tend to be more involved in long-term anthropological fieldwork than any other area of the evolutionary sciences. But card-carrying anthropologists are declining among their number as researchers increasingly come from other backgrounds in the biological and social sciences, with an associated decline in the contribution of ethnographic work. Most practitioners identify with the sub-field of human behavioral ecology – the application of sociobiological principles to human behavior – and distinguish themselves from the sister fields of evolutionary psychology and cultural evolution. Human behavioral ecology has been criticized for abstracting away the details of both culture and psychology in its focus on adaptive explanations of reproductive behavior, and for its commitment to ultimate over proximate causation. This chapter explores these critiques. Inspired by EA Hammel’s seminal paper “A theory of culture for demography” (Hammel 1990), I examine how the culture concept is used in evolutionary research. Like Hammel, I argue that a theory of culture for evolutionary demography requires engaging more seriously with (and in) ethnographic work. I highlight some challenging examples to motivate discussion about adaptive reproduction and natural fertility. Going further, I advocate for cultural evolution as an integrative framework for bringing both culture and psychology into the core of evolutionary demography research. This will involve expanding our theoretical and conceptual toolkits: (1) building and testing proximate mechanistic models, (2) delineating and evaluating causal claims at multiple levels of analysis and time scales, and (3) exploring co-evolution or feedback between demography and culture.