Way to be obtuse, Ideal. Good job.
Ok, since you won't spell it out, I'll assume you are meaning one of two things.
Option one, you define natural as an activity that occurs ELSEWHERE in nature, ie the environment/ecosystem/world, in a similar method. Procreation involving sexual intercourse among creatures within a species is therefore natural, but in-vitro fertilization is unnatural, because no other species employs test tubes and whatnot to knock their b*tches up (pardon my ghetto crudeness, it's been a long day in the malls). By this definition, if any animal exhibits an ability that no other creature can perform, this animal's action is unnatural. And since humans are extremely intelligent, well above and beyond any other creature, humans have created many many abilities/tools/tricks that allows us to have many unnatural actions.
Option two, your definition is completely arbitrary and meaningless, and things that humans do that take a lot of mental effort is unnatural. (How much effort you haven't specified, leading to the arbitrary and meaningless crack.)
If either of these are your opinion, fine. You're entitled. But I'm with wazhisface on this one. The term natural, including your usage of the term, if I've gotten it right, is a useless classification, made even more useless by the inconsistent and wide range of definitions many people have attributed to the term. There is too much baggage to the word.
And even worse, we've spent all this time discussing interpretations of a common word in an effort to see....what? Wrapped up in semantics, and nothing to show from it. I really hope I achieve some semblance of longetivity/immortality, cuz these were 3 precious minutes I'll never get back. sigh.