Selection pressure and institutional adaptation: An evolutionary comparison of the 1340 and 1348 epidemics in Florence, Italy

Evolutionary economics is a powerful lens for understanding the heterogeneous, complex, and bidirectional relationship between economic development and disease spreading. This paper supports the relevance of this approach by investigating the well-documented socioeconomic consequences of two successive 14th-century plague outbreaks in Florence, Italy. By analyzing the institutional responses to both the 1340 epidemic and the 1348 Black Death, we demonstrate that mortality alone did not determine post-plague trajectories. Instead, the 1340 outbreak eroded incumbent authorities’ legitimacy and fostered fiscal experimentation, briefly empowering reform-minded coalitions, while the 1348 Black Death enabled surviving oligarchic factions to reconsolidate power and implement rent-extractive policies that stifled economic and demographic recovery. Because both shocks occurred within the same political and socioeconomic context, our single-case comparison preserves contextual consistency and highlights the granular mechanisms that produced sharply divergent outcomes, providing a deep evolutionary perspective. Drawing on the co-evolutionary circuit of selection, adaptation, and feedback, we demonstrate that institutional selection pressures were decisive in shaping sharply divergent economic paths, thereby providing a unified mechanistic account for pandemic heterogeneity. Finally, we draw policy lessons by emphasizing how adaptive governance, transparent accountability, and elites renewal may prevent regressive lock-ins in the face of health shocks.