Histoires de cul
Mr. Dabbs,
In old French, "cul" started life as "bottom" or "back". Hence the term "reculer, meaning to go backwards or to back off.
You might be amused by the word "cul-de-lampe", which designates ornaments more or less shaped like inverted triangles. This was apparently the standard shape for the bottom of an oil lamp.
And of course, when drinking expensive liquor among French friends, do not go "cul sec", dry bottom (of the glass), which means chugging down the whole tumbler at once, as it is a sign of poor manners.
To go back to "arse",yes, that's the most common use of the term today, which is why it's now considered an impolite word.
Back in the days, a Communist could be unflatteringly called "un cul rouge" (a red arse). But a coal miner would proudly refer to himself as "un cul noir" (a black arse), a term that would probably send you down for racism these days.