Check out Steven Pinker’s excellent article on profanity, in the online edition of the New Republic.  Pinker is a professor at Harvard who often brings an illuminatingly multidisciplinary perspective to bear on subjects, such as his TED lecture on the decline of violence throughout the course of history.

The piece is fascinating, and has many excellent, well-explained ideas:

"Today, the emotional power of religious swearing may have dimmed, but the psychology behind it is still with us. Even a parent without an inkling of superstition would not say "I swear on the life of my child" lightly. The mere thought of murdering one's child for ulterior gain is not just unpleasant; it should be unthinkable if one is a true parent, and every neuron of one's brain should be programmed against it."