Awesome, Carlyn. I also read years ago that some kinks and fetishes might be born of humanity's many years of filth: that a person who was aroused by, say, the smell of urine or feces rather than repulsed by it would be more likely to mate and pass on their genes. Likewise, in that very long era when most people's hygiene (including their genital hygiene) was terrible, it could possibly have helped them to be able to fixate on some other object or body part in order to get and stay aroused — and thus pass on their genes too.

Fascinating stuff!