Melissa Mohr, author of Holy Sh*t: A Brief History of Swearing, discusses profanity with the Boston Globe’s Ideas section:

IDEAS: Are there… old curses that 21st-century people would be surprised to hear about?

MOHR: Because [bad words] were mostly religious in the Middle Ages, any part of God’s body you could curse with. God’s bones, nails, wounds, precious heart, passion, God’s death—that was supposedly one of Queen Elizabeth I’s favorite oaths.

IDEAS: Have religious curses like that lost their power as the culture becomes increasingly secular?

MOHR: We still use them a lot, but we just don’t think of them as bad words. They’re very mild. If you look at lists of the top 25 swear words, I think “Jesus Christ” often makes it in at number 23 or something. … The top bad words slots are all occupied by the racial slurs or obscene—sexually or excrementally—words.

IDEAS: You mentioned Queen Elizabeth cursing. Do all kinds of people swear?

MOHR: Everyone swears.  People tend to think lower-class people swear more, and this is an old idea.  There are old [expressions] like, “He swears like a tinker.” The Victorians were convinced that the only people who swore were lower class, uneducated, horrible people. Modern studies do bear out that people in the lower working class…swear the most and use the worst words.

But also there’s this idea historically that aristocratic people swear a lot, and that’s also borne out by modern studies: People in the highest social classes [also] tend to swear more and use worse words. Not as bad as the people in the quote-unquote lower classes, but much worse than people in the middle class. There’s this idea that middle-class people are strivers, who really need to differentiate themselves from the lower class. One way they do that is by having very clean, very proper language.

Vaughan Bell adds:

Interesting[ly], there is good evidence that swear words are handled differently by the brain than non-swear words. In global aphasia, a form of almost total language impairment normally caused by brain damage to the left hemisphere, affected people can still usually swear despite being unable to say any other words.