QUOTE : Bartal placed one rat in an enclosure, where it encountered a small transparent container, a bit like a jelly jar. Squeezed inside it was another rat, locked up, wriggling in distress. Not only did the free rat learn how to open a little door to liberate the other, but she was remarkably eager to do so. Never trained on it, she did so spontaneously. Then Bartal challenged her motivation by giving her a choice between two containers, one with chocolate chips—a favorite food that they could easily smell—and another with a trapped companion. The free rat often rescued her companion first, suggesting that reducing her distress counted more than delicious food.47 The empathy of laboratory rats has been tested by presenting them with a companion trapped in a glass container. Responding to the distress of the trapped rat, the free rat makes a purposeful effort to liberate her. This behavior disappears if the free rat is put on a relaxing drug, which dulls her sensitivity to the other’s emotional state.