I would take a step back: why are fetishes a thing? It's a difficult thing to research, especially since western society is reluctant to talk openly (or even privately to researchers) about their sex life. In this thread people talked about how childhood trauma could be a factor in kink, and that would make sense.

I can tell you from my experience, types of fetishes are not a biological response so much as social response. For me, I know many of my fetishes are simply based on the fact that it's a social taboo. If people walked around in gimp suits and nipple clips all the time in public, I would find that kink far less interesting.

My guess is good as any, but I think if being kinky with a partner has an evolutionary advantage, it would be about social cohesion. When you show someone this dark side of you that you would never show other people, you strengthen a bond with your partner (assuming they are into it as well).

In the case of vore fetish, my partner doesn't actually want to be eaten, rather she likes this version of submission where she is seen as "delicious". Once sex is over and we return to our senses, we maintain our sense of self preservation.

Personally I would never eat someone else, but playing this role is fun for me since I can get into a Dom role and do something society would frown upon if it was real.

With that said, I find in any kink play, aftercare is SUPER important. We say fucked up things while having sex all the time, but afterwards we make sure to assure eachother it was just an act. Communication during and then afterwards is so important to reinforcing the relationship when enjoying kink play.