Empathy is the ability to feel others' pain or distress; we feel bad when someone else feels bad. It’s what motivates us to give a few dollars to the homeless man on the corner, donate our time to a worthy cause, or hug a friend who has just been dumped. Scientists used to believe that empathy was unique to humans and was one of the traits that actually distinguished us from other species. Recently, however, there is increasing evidence for empathy in several species, most notably other primates.
Now, new research in Science suggests that rats are capable of empathy. The study tested how rats responded when their fellow rats were trapped, and found that they would not only spend time and energy deliberately helping their trapped companions, but they would even share food after liberating them.