Are societies becoming more self-centric? Evidence from five decades of popular music spanning three continents - Marius Golubickis; Parnian Jalalian; Leoni S. Masroujah; Esther S. Selvaraj; Yadvi Sharma; Siew Hwee Seow; Adriana Borrego-Guerrero; Sadie Marr; C. Neil Macrae (PLoS ONE, 2026)