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The incorporation of niche construction theory (NCT) and epigenetics into an extended evolutionary synthesis (EES) increases the explanatory power of evolutionary analyses of human history. NCT allows identification of distinct social inheritance and cultural inheritance and can thereby account for how an existing-but-dynamic social system yields variable influences across individuals and also how these individuals' microlevel actions can feed back to alter the dynamic heterogeneously across time and space. An analysis of Chinese footbinding, as it was ending during the first half of the twentieth century and China was industrializing, illustrates the evolutionary dynamics of niche construction across inheritance tracks and explains regional heterogeneity as well as the persistence of a cultural belief that was socially inaccurate. Incorporating anthropological and sociological insights into an EES with NCT has the potential to proffer source laws for relationships between individual actions and macro-patterns in beliefs, structures, climate, and demography.

With introduction of social niche effects into a model of cultural change, the frequency of a practice cannot predict the frequency of its underlying belief. The combination of a general model with empirical data from a specific case illustrates the importance of collaboration between modellers and field researchers, and identifies the type of quantitative data necessary for analysing case studies. Demographic data from colonial-period household registers in Taiwan document a shift in marriage form within 40 years, from a mixture of uxorilocal marriages and virilocal marriages to the latter's dominance. Ethnographic data indicate marriage-related beliefs, costs, ethnic effects and colonial policies as well as the importance of horizontal cultural transmission. We present a formal model for the effects of moral beliefs about marriage and a population economic index on the decline of uxorilocal marriage. We integrate empirical marriage rates and an estimated economic index to produce five projections of the historical frequencies of one belief. These projections demonstrate how economic development may affect a cultural niche. They also indicate the need for future research on the relationship between wealth and cultural variability, the motivational force of cultural versus social factors, and the process of cultural niche construction.

Social theorists have long recognized that changes in social order have cultural consequences but have not been able to provide an individual-level mechanism of such effects. Explanations of human behavior have only just begun to explore the different evolutionary dynamics of social and cultural inheritance. Here we provide ethnographic evidence of how cultural evolution, at the level of individuals, can be influenced by social evolution. Sociocultural epistasis--association of cultural ideas with the hierarchical structure of social roles--influences cultural change in unexpected ways. We document the existence of cultural exaptation, where a custom's origin was not due to acceptance of the later associated ideas. A cultural exaptation can develop in the absence of a cultural idea favoring it, or even in the presence of a cultural idea against it. Such associations indicate a potentially larger role for social evolutionary dynamics in explaining individual human behavior than previously anticipated.