The United States faces a critical issue: extreme polarization between its two main political parties, Democrats and Republicans. As of September 2022, only two states—Minnesota and Virginia—had a divided state legislature. The Democratic Party controls seventeen states, and the Republican Party controls thirty states. Partisan identification predicts voter preferences about a range of social policy issues nearly three times as well as any other demographic factor. While this is not the first time the U.S. has been in a politically polarized environment, polarization at this point in history could create highly divisive factions unable to reconcile moral and ideological differences.
This Article uses evolutionary principles to explain why political polarization is a distinctly new threat in the U.S. and to show how political polarization impacts both states and the federal government. Specifically, it argues that the lack of ideological and partisan “gene flow” has led predominantly “red” ideas to spread among Republicans and “blue” ideas among Democrats. Consequently, the lack of ideological movement across the U.S. has led the country towards “speciation,” resulting in only two, entirely distinct political parties. Ultimately, the speciation evolved in a manner that the Founders most feared: two divisive factions that hinder both democratic and federalist principles of government.
First, this Article will draw on two evolutionary biology traits, gene flow and speciation, to show political polarization in a new framework. Second, it will examine the Founders’ fear of political factions within the U.S. Third, it will explore three factors that have prevented gene flow across individual states and through the U.S.: geography, systemic racism and sexism, and technology. Fourth, it will analyze two traits stemming from speciation: a partisan U.S. Supreme Court and a disrupted breakdown in the federalist system of governance. Fifth, this Article recommends that the U.S. embrace proportional representation or ranked-choice voting in order to support a multiparty political system. Finally, this Article concludes that increasing ideological and partisan gene flow within and across state boundaries will mitigate the harmful effects of speciation.