Predicting The Long-Term Political Consequences of Demographic Change: A Simulation Study

What are the long-term political consequences of demographic change? Drawing on evolutionary biology, we develop a model that simulates how cultural change in younger cohorts and generational replacement affect party systems over time. The simulation predicts that parties in two-party-systems will become more culturally liberal on average, more ideologically polarized, and losing vote shares among the young. This results in politically non-represented cohorts which either leads to the emergence of new parties on the political margins and a worldwide increase in multi-party systems and/or increases in youth absenteeism. We test the model’s predictions by drawing on observational data from 20 OECD countries between 1990 and 2022. Panel regressions confirm the simulation’s central expectations, underscoring the long-term consequences of demographic change for political systems. The paper showcases how political science research can profit from integrating methods from the natural sciences. It demonstrates how interdisciplinary approaches are useful when engaging with predictions over long time horizons by combining simulation methods with statistics. [note: co-authored with Christian Jørgensen and Katja Enberg, who are evolutionary biologists and do not have an ECPR account]