Are we biologically hardwired to feel compassion?

What causes compassion anyway? Is it peer pressure, guilt, a gentle nature or what? When I got done with speculating possible causes, I decided to do some research to see what others were saying about the causes of compassion (one of my least favorite talked-about causes is "selfishness"). I came across a book by Dacher Keltner entitled Born to Be Good: The Science of a Meaningful Life. Keltner, a professor of psychology at the University of California, Berkeley, has an entire chapter on Compassion and he argues that there is a science behind the feeling of compassion and that it is the vagus nerve which inspires it. Cool! Here's how he describes the vagus nerve in action: it "resides in the chest and, when activated, produces a feeling of spreading, liquid warmth in the chest and a lump in the throat" (228). Most interesting, in light of my prior post regarding compassion fatigue, Keltner begins his chapter on compassion by describing acts of compassion that occured in history during times of warfare. He calls these acts of compassion (and he cites specific examples from a Nazi concentration camp, the My Lai massacre, the genocide in Rwanda) examples of "sympathy breakthrough" (225).