w USA over the past 40 years (Fig. 1), and this is largely driven by increased out-group hate 28 . Affective polarization has increased in several other countries, including Switzerland, France, Denmark, Canada and New Zealand 30 , as well as much of southern Europe and east-central Europe 31 . This rise in affective polarization is associated with a wide variety of negative consequences, including feeling upset, displeased or unhappy were one's child to marry an out-party member 28 and shorter family gatherings during national holidays when attendees had opposing political beliefs 32 . As cross-cutting cleavages (that is, identity-based similarities between otherwise opposed partisans) dwindle and people become increasingly aligned along multiple social identities (for example, race, religion, education and geography) 33 , affective polarization will likely continue to grow.