So there were sex slaves back in the ancient world. That's where the word "porn-ography" comes from. "A brothel in ancient Greek was a porneion." "from PIE *perə-, variant of root *per- (5) 'to traffic in, to sell'"
"Porn" literally means "sex slave".
I think somehow pornography is kindof a continuation of this tradition, though I am not sure exactly about the history and where there is continuity. That's why the aesthetics of pornography are the way they are, why they're so degrading.
This podcast presents a somewhat similar idea of what the aesthetics of pornography are about.
Note that this aesthetic is very different from other cultural work related to fertility. (e.g. fertility personifications) It's not that "pornography" is some inherent thing with the procreation drive or the erotic bond, because these other expressions that don't degrade have also existed for a long time too.
there doesn't seem to be anything here