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The Evolution of Inequality and Social Complexity

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Modern human cultures have persistent forms of economic and social inequality (also referred to as social complexity) in the form of differences such as occupational specialization, social class, caste, and race.  In many cases these types of inequality appear to be thousands of years old, but we also see increasing inequality appearing alongside economic development and the integration of households into the market economy in the modern world.  There is much speculation about how, why, and when such social complexity arises.  Our research seeks to use both ethnographic data from across societies as well as detailed data from within societies undergoing economic development to understand the types of conditions under which inequality emerges and the household-level processes by which it arises and is maintained.



An NSF-funded project focused on understanding the micro-foundations and evolution of inequality in societies undergoing rapid market transition. Fieldwork for this project was conducted in China and Bangladesh in 2017-2018 where we collected multiple measures of market integration alongside detailed data on material wealth, knowledge, social networks, health, and well-being. Analysis for this project is just beginning and we expect exciting developments over the next few years.


A second project focuses on marital assortment and inequality in small-scale societies. Building on previous work, we are investigating the role of positive marital assortment in perpetuating inequality. If wealthy individuals marry other wealthy individuals, this may consolidate wealth among families of similar standing, impeding social mobility and contributing to persistent inequality. Our primary goals are (1) to investigate what role marital assortment by wealth plays in the origin and persistence of inequality, and (2) to explain cross-cultural variation in marital assortment according to social, ecological, and subsistence variation across societies. To this end, we have amassed over 280 wealth measures from 28 societies and developed a common set of methods and tools for their analysis. We have intriguing results and are in the process of preparing publications.


Borgerhoff Mulder et al. 2009, Shenk et al. 2010, Smith et al. 2010, Mattison et al. 2016, Ross et al. 2018, Borgerhoff Mulder et al. 2019