Pascual Deocón, IgnacioAguirre Araújo, JacoboManrubia, SusannaCuesta, José A.2021-02-112021-02-112020-02-19Royal Society Open Science, (Feb. 2020), 7(2), 191813, pp.: 1-16.2054-5703https://hdl.handle.net/10016/31908Every now and then the cultural paradigm of a society changes. While current models of cultural shifts usually require a major exogenous or endogenous change, we propose that the mechanism underlying many paradigm shifts may just be an emergent feature of the inherent congruence among different cultural traits. We implement this idea through a population dynamics model in which individuals are defined by a vector of cultural traits that changes mainly through cultural contagion, biased by a 'cultural fitness' landscape, between contemporary individuals. Cultural traits reinforce or hinder each other (through a form of cultural epistasis) to prevent cognitive dissonance. Our main result is that abrupt paradigm shifts occur, in response to weak changes in the landscape, only in the presence of epistasis between cultural traits, and regardless of whether horizontal transmission is biased by homophily. A relevant consequence of this dynamics is the irreversible nature of paradigm shifts: the old paradigm cannot be restored even if the external changes are undone. Our model puts the phenomenon of paradigm shifts in cultural evolution in the same category as catastrophic shifts in ecology or phase transitions in physics, where minute causes lead to major collective changes.eng© 2020 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.Atribución-NoComercial-SinDerivadas 3.0 EspañaEpistasisIrreversibilityCultural evolutionParadigm shiftCognitive dissonancePhase transitionresearch articleMatemáticashttps://doi.org/10.1098/rsos.191813open access12(191813)16Royal Society Open Science7AR/0000025569