It's been more than 2000 years since humans noticed that soaking your dick in shit was a very bad idea, a health hazard. To the point that humans in various civilizations banned the practice on a religious basis; just don't do it. Why? Because god said so, end of stupid debate And today "society" is pretending there's nothing to see here, your dick in a pussy or in a butt what's the difference? Hell, let's even do both back and forth, what could possibly go wrong? To me, there's a huge deal of "survival guidelines" in religious texts, civilizational guidelines. You don't spend thousands of years preserving and copying by hand the equivalent of the encyclopædia universalis just for the sake of it, or just because it's nice story/novel/fairytale. There's necessarily something that has to do with survival of the collective when when it comes to it. Stuffs "banned by god" probably have deep ramifications observed throughout of the centuries, civilizational after civilizational collapse. Like symptoms of a disease, when those forbidden stuffs are widespread practice it's bad news, it spells doom. That's "my rational interpretation" of the scriptures, without getting into mysticism. That's at least one possible interpretation.