Everything is natural. Nothing is artificial.
What most people mean by "nature" is everything that is not man-made.On improving the human species.
It is already happening.
Organ transplants and artifical parts (hips, ankles, elbows, etc) are now everyday events.
The human genome project was completed over two years ago and that means that we are able to read the blueprint for the human machine.
Between biomechanics, plasma physics and molecular nanotechnology the definition of "human being" in the next twenty years will include what today would be considered superhuman fantasy.
The human species is creating its own "evolution" now.
There is no debate on this subject.
You are either informed or behind the curve.
Here is a good place to start: http://www.kurzweilai.net