One of the few fairly universal expletives is some variation on a term for excrement. Humans have a natural aversion to the disgusting, (which tends to be the dangerous germ filled, or potentially poisonous) which, no matter how useful animal dung may be for a specific society, still includes shit.

Also, most societies that have marriage, and I have no reason to believe the societies in this novel don't, have some sort of prohibition on illicit sex (as marriage is a way of regulating a powerful human drive) and therefore the potential to develop a profanity that refers to illicit sex, even without a religious reason for said prohibition.