Our research program aims to construct a vertically integrated approach to culture and cultural evolution that synthesizes theory and methods from across the sciences, particularly from psychology, economics, biology, and anthropology. Below, we first broadly sketch the theoretical framework that links the various avenues of our work, then highlight certain key aspects of our research program, and finally review past work in setting out our current directions.

Cognitive foundations of culture: The theoretical core of our approach involves understanding the micro-level cognitive processes that influence human learning, and in particular those that affect social learning. To generate hypotheses about how these cognitive processes work, we consider how natural selection may have shaped human learning to allow individuals to most adaptively acquire ideas, beliefs, values, and practices from other individuals. To structure this theorizing, we construct formal evolutionary models that allow us to better assess the logic of particular hypotheses and to generate more precise predictions. Hypotheses about how we learn from others have been tested using a wide range of data from diverse fields, including both laboratory and field studies.

Cultural evolution: Building up from these cognitive and evolutionary foundations involves taking what is known about human social learning, usually grounded in evolutionary hypotheses, and formalizing this in cultural evolutionary models. Such mathematical models show how individual cognitive processes, through social interaction, can give rise to emergent sociological phenomena. This approach permits the development of theories about higher-level phenomena, such as institutions, ethnic groups, and social classes "from the ground up" by linking genetic evolution to cognition to cultural evolution. By making clear predictions about population-level patterns and phenomena, ideas about cognitive and social interaction can then be applied to empirical patterns from anthropology, history, sociology, and economics.

Culture, cognition, and decision-making: The third rung in this theoretical scaffolding focuses on how the products of cultural evolution influence behavior and psychology. By giving rise to partially integrated sets of beliefs, values, and institutions, cultural evolution can potentially affect people's motivations, goals, and reasoning processes. Using a variety of experimental and ethnographic tools, often bringing the "laboratory to the field", we have sought to begin charting culture's effects.

Culture-gene coevolution: This final step alters how we think about human evolution. Because humans have likely relied on high-fidelity cultural learning for hundreds of thousand of years, cultural evolution may have influenced our species' genetic evolution in ways not relevant to less cultural species. The cultural transmission of the practice of cooking meat (and making fire), for example, appears to have influenced our digestive system in ways that explain its peculiarity vis-à-vis other mammalian omnivores. Of particular interest to us, however, is not the digestive tract but the possibility that cultural evolution may have constructed cooperative institutional forms that, by spreading and persisting over long periods, have shaped the selective environment faced by the genes that influence our species' social psychology. This line suggests that there may be elements of human social behavior (e.g., aspects of altruism) that cannot be understood without considering the interaction between culture and genes. As above, formal models test the logic of verbal arguments and generate precise predictions.

To highlight the uniqueness and importance of this research program, consider:

1. The approach is non-disciplinary. We focus on big questions that do not reside in any particular discipline. Empirically, it integrates experimental approaches from psychology and economics, in-depth field ethnography, and findings from archaeology, genetics, and history. This non-disciplinary approach has permitted us to publish in the top journals in several fields, including ScienceNatureAmerican Economic ReviewAmerican AntiquityEvolutionary AnthropologyCurrent AnthropologyBehavioral and Brain Sciences, and the Journal of Theoretical Biology.

2. This approach grounds the study of culture and cultural evolution within evolutionary theory thereby unifying the study of human behavior with the rest of the natural world without ignoring the importance of cultural learning or cultural history in understanding humans.

3. This approach, by emphasizing the construction of formal evolutionary models, adds rigor both to the theorizing about our capacities for culture and the study of cultural evolution and culture-gene coevolution.

4. This approach links psychology and microeconomics, with their emphasis on the individual-level details of learning and decision-making, to anthropology, history, and sociology, with their emphases on social forms, institutions, and broader and larger-scale processes.