Sometimes it’s hard to pinpoint the exact moment you became interested in a story. Other times, that moment is obvious, like it was last September when a young victim of the refugee crisis was captured in a brutal photograph that was shared throughout the world. In Aeon, Avan Judd Stallard explains what it was about that one boy and that one picture that made people finally give a damn: “The easy answer is that Alan looked like one of their own children. The hard answer is our genes, which code for inexorable biological routines triggered by self-interest. The truth is somewhere in-between: the interplay between culture and genes that saddles humans with a psychology fixated on in-groups (people we consider to be like us or part of our community) and out-groups (people we consider to be different to us or not part of our community).”