Abstract

Morality evolved in our lineage over four stages. First, in apes and their ancestors, natural selection favored moral emotions that underpin psychological altruism. Second, within the _Homo_ genus, gene-culture co-evolution produced norms, norm learning, and moral reasoning. Third, as humans became modern, social institutions such as religion modified the moral mind, adding new norms, expanding moral circles, and creating new social hierarchies. Fourth and finally, over the last few hundred years, morality has evolved in progressive and regressive ways, as humans either solved or exacerbated problems of exclusion and inequality. One major problem threatens collective survival: humans must evolve morally to avoid the disastrous effects of climate change.