Ra Bentley

Random drift and culture change

We show that the frequency distributions of cultural variants, in three different real–world examples—first names, archaeological pottery and applications for technology patents—follow power laws that can be explained by a simple model of random drift. We conclude that cultural and economic choices often reflect a decision process that is value–neutral; this result has far–reaching testable implications for social–science research.

Random drift and large shifts in popularity of dog breeds

A simple model of random copying among individuals, similar to the population genetic model of random drift, can predict the variability in the popularity of cultural variants. Here, we show that random drift also explains a biologically relevant cultural phenomenon—changes in the distributions of popularity of dog breeds in the United States in each of the past 50 years. There are, however, interesting deviations from the model that involve large changes in the popularity of certain breeds. By identifying meaningful departures from our null model, we show how it can serve as a foundation for studying culture change quantitatively, using the tools of population genetics.

Community differentiation and kinship among Europe’s first farmers

Community differentiation is a fundamental topic of the social sciences, and its prehistoric origins in Europe are typically assumed to lie among the complex, densely populated societies that developed millennia after their Neolithic predecessors. Here we present the earliest, statistically significant evidence for such differentiation among the first farmers of Neolithic Europe. By using strontium isotopic data from more than 300 early Neolithic human skeletons, we find significantly less variance in geographic signatures among males than we find among females, and less variance among burials with ground stone adzes than burials without such adzes. From this, in context with other available evidence, we infer differential land use in early Neolithic central Europe within a patrilocal kinship system.

Social tipping points and Earth systems dynamics

Recently, Early Warning Signals (EWS) have been developed to predict tipping points in Earth Systems. This discussion highlights the potential to apply EWS to human social and economic systems, which may also undergo similar critical transitions. Social tipping points are particularly difficult to predict, however, and the current formulation of EWS, based on a physical system analogy, may be insufficient. As an alternative set of EWS for social systems, we join with other authors encouraging a focus on heterogeneity, connectivity through social networks and individual thresholds to change.

Collective behaviour, uncertainty and environmental change.

A central aspect of cultural evolutionary theory concerns how human groups respond to environmental change. Although we are painting with a broad brush, it is fair to say that prior to the twenty-first century, adaptation often happened gradually over multiple human generations, through a combination of individual and social learning, cumulative cultural evolution and demographic shifts. The result was a generally resilient and sustainable population. In the twenty-first century, however, considerable change happens within small portions of a human generation, on a vastly larger range of geographical and population scales and involving a greater degree of horizontal learning. As a way of gauging the complexity of societal response to environmental change in a globalized future, we discuss several theoretical tools for understanding how human groups adapt to uncertainty. We use our analysis to estimate the limits of predictability of future societal change, in the belief that knowing when to hedge bets is better than relying on a false sense of predictability.

Population-level neutral model already explains linguistic patterns

In customizing the neutral model for language transmission, Reali & Griffiths [[1][1]] have added a new, ‘Bayesian’ learning interpretation to a neutral model that has been used in cultural evolution studies for some time (e.g. [[2][2]–[6][3]]). While Reali & Griffiths [[1][1], p. 435] dismiss

Evaluating reproductive decisions as discrete choices under social influence.

Discrete choice, coupled with social influence, plays a significant role in evolutionary studies of human fertility, as investigators explore how and why reproductive decisions are made. We have previously proposed that the relative magnitude of social influence can be compared against the transparency of pay-off, also known as the transparency of a decision, through a heuristic diagram that maps decision-making along two axes. The horizontal axis represents the degree to which an agent makes a decision individually versus one that is socially influenced, and the vertical axis represents the degree to which there is transparency in the pay-offs and risks associated with the decision the agent makes. Having previously parametrized the functions that underlie the diagram, we detail here how our estimation methods can be applied to real-world datasets concerning sexual health and contraception.

Traditional models already explain adoption/abandonment pattern

Berger and Le Mens (1) analyze US records of baby-name popularity in the 20th century and nicely demonstrate the symmetry in the rise and decline of patterns of adoption over time. They suggest that this result negates traditional diffusion models “driven by saturation of a pool of potential adopters” (1). Instead, they account for the symmetry of rise/decline by using a number of assumptions on human psychology and perception.

Is there a “Neutral Theory of Anthropology”?

Lansing and Cox open a welcome discussion of the potential for neutral models in anthropology—it has been almost 50 years since the original neutral models were applied to DNA sequences (e.g., Kimura 1968) and then later to biological phenotypes (e.g., Lande 1976) and cultural data (Cavalli-Sforza and Feldman 1981; Neiman 1995). This long history of research is a gold mine for studies of culture evolution.Do cultural phenomena undergo evolutionary change, in a Darwinian sense? If so, is evolutionary game theory (EGT) the best way to study them? Opinion on these questions is sharply divided. Proponents of EGT argue that it offers a unified theoretical framework for the social sciences, while critics even deny that Darwinian models are appropriately applied to culture. To evaluate these claims, we examine three facets of cultural evolution: (i) cultural traits that evolve by Darwinian selection, (ii) cultural traits that affect biological fitness, and (iii) coevolution of culture and biology, where selection in one affects evolutionary outcomes in the other. For each of these cases, the relevance of EGT depends on whether its assumptions are met. Those assumptions are quite restrictive: selection is constant, time horizons are deep, the external environment is not part of the game, and neutral processes such as drift are irrelevant. If these conditions are not met, other evolutionary models such as neutrality, coalescence theory, or niche construction may prove more appropriate. We conclude that Darwinian processes can occur in all three types of cultural or biological change. However, exclusive reliance on EGT can obscure the respective roles of selective and neutral processes.

Language is nothing special : response to 'Across the curious parallel of language and species evolution' by J. Whitfield.

Evolutionary biologists are applying their tools to language--and trying to work out why the dynamics of language and biological evolution look so similar.