I look at this sort of thing and think about people who say "it's not natural" when describing something like homosexuality.
Behaviour in the natural world are not always things that are acceptable in human society, gang rape, paedophilia, necrophilia, bestiality, the list goes on.
Then there's the marketing of products as "natural" as if it's a good thing, I think to myself deadly nightshade, that's entirely natural, why don't you go and garnish your salad with that?
What is it that sets human civilisation apart from the natural world? It's those unnatural behaviours and unnatural things. There aren't really many though, you look hard enough and you'll probably find similar behaviour in nature anyway. The best ones I keep coming back to are glasses and books, you don't find things like that outside human civilisation.