Earlier this month, people around the world participated in one of humankind’s largest ritualized celebrations. To commemorate another trip around the sun, New Year activities included fireworks, kisses, and resolutions—as well as some practices unique to specific cultures, such as cooking black-eyed peas and greens in the southeastern United States, eating a grape with each midnight clock strike in Spain, or burning effigies that represent the previous year in Central and South America.

All human cultures have their rituals—typically repetitive, symbolic behaviors that we experience as purposeful, though we generally can’t explain how they are supposed to work. These rituals can reinforce a sense of community and common beliefs, but their bewildering diversity can also alienate and separate