Since humans knew we had hearts (maybe when a saber-toothed tiger clawed one out of a caveman or something), we've associated those hearts with love. In Warm Bodies, R the zombie still associates it with love, but the problem is, his heart no longer beats. He listens to some of the world's greatest love songs (no, not Captain and Tennille), and hopes to one day feel his heart beat again. Once he finds Julie, it does, and one of his favorite love songs takes on a new meaning: "All You Need is Love." Ain't that the truth?