Kula
That may be too restrictive a selection. There's a third condition that combines the two, but I haven't yet a neat sentence for it:
• Start with a comparative idea: There is no supernatural. Whether it's ghosts or angels or gods that one believes in, there is no supernatural, for anything occurring within the possibilities of nature is natural. If any ritual magick, for instance, actually worked, there would be nothing "supernatural" about it, as the "magick" would only have served as a conduit for routing natural processes.
• Likewise: Nothing is artificial. The proposition first struck me when I went through a brief phase of watching lots of anime videos in a short period; I can't tell you for certain which one it was, but for some reason "Bubblegum Crisis" sticks in my mind. The idea occurred to me after I was left nearly retching by a scene in which schoolgirls were discussing the cybernetic enhancements they wanted. It struck me as sickening, the idea of vanity enhancements, but inasmuch as there is no supernatural, it occurred to me that the other end of the "natural spectrum" includes the possibility of there being nothing artificial. That is, even an "artificial" evolution is a natural evolution. We don't consider honey artificial, as it's the produce of bees. Were we not human, and watching humans alter themselves, there would be nothing artificial about a natural system exploiting nature in order to change the relationship between the system and the nature it exists within. Altering our DNA is no more artificial or natural than replacing somebody's eyes or ears with cybernetic enhancements.
Furthermore, I would go so far as to postulate that humans don't decide anything about our future when we undertake our own evolution. All of the tailoring of our genes we attempt may yet prove futile should the Universe itself present us with an unimaginable cataclysm.
So it seems to me there's a third option wherein humanity simply takes the gamble and leaps blindly into the precipice; that is, we do what we do, and nature will continue to do what it does, and we decide nothing inherently in undertaking such an endeavor.