This is the ninth of a series of reviews, looking back at a year of science according to topic and theme. This one celebrates science as enlightenment. Some of these discoveries make us consider the world in a new light, some act as timely reminders of things we already know, and others complicate a previously simple picture. They tell us that no matter how much we think we know, it’s all a little more complicated than that.

The OXTR gene acts as a dock for oxytocin, a hormone frequently billed as a “love hormone”. Among Americans, a specific “G” version of OXTR makes carriers more likely to seek emotional support from their friends. But for Koreans, whose culture frowns on seeking