I've explained that many times. Metaphysically, everything's natural. But "natural" has over thirty senses, so non-natural properties emerge according to non-metaphysical senses, such as social ones. Civility and artificiality, then, are anti-natural in being opposed to wildness.

If you don't think there's such an opposition, how do you explain all those criminals being imprisoned like wild animals? Or how do you explain the sixth mass extinction event? How do you explain the way we treat most wild beasts?