TY - RPRT A1 - Bryson, Joanna A1 - Stewart, Alexander J. A1 - McCarty, Nolan T1 - Polarization under rising inequality and economic decline N2 - Social and political polarization is a significant source of conflict and poor governance in many societies. Understanding its causes has become a priority of scholars across many disciplines. Here we demonstrate that shifts in socialization strategies analogous to political polarization and identity politics can arise as a locally-beneficial response to both rising wealth inequality and economic decline. Adopting the perspective of cultural evolution, we develop a framework to study the emergence of polarization under shifting economic environments. In many contexts, interaction with diverse out-groups confers benefits from innovation and exploration greater than those that arise from interacting exclusively with a homogeneous in-group. However, when the economic environment favors risk-aversion, a strategy of seeking lower-risk interactions can be important to maintaining individual solvency. To capture this dynamic, we assume that in-group interactions have a lower expected outcome than out-group interactions, but also one that is more certain. Thus in-group interactions are less risky than out-group interactions. Our model shows that under conditions of economic decline or increasing wealth inequality, some members of the population benefit from adopting a risk-averse, in-group favoring strategy. Moreover, we show that such in-group polarization can spread rapidly to the whole population and persist even when the conditions that produced it have reversed. Finally we offer empirical support for the role of income inequality as a contributor to affective polarization in the United States. Our work provides a framework for studying how disparate forces interplay, via cultural evolution, to shape patterns of identity, and unifies what are often seen as conflicting explanations for political polarization: identity threat and economic anxiety. Y1 - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b1570-opus4-36522 ER -