Before we can get to the land of science fiction we need to kill the idea that natural is by definition ‘good for you’ or ‘healthy’. It is simply not the case.
If you are a creationist and also a nature-is-good-ist then you hold an intellectually defensible position. It stands to reason that if a supreme being created the world some thousands of years ago and pronounced it good then that world would have a certain divine harmony. It stands to reason but it is not necessarily so since it also stands to reason that the motives of the creator will be forever unfathomable by the created. The creator could just as easily have made an un-harmonious creation and then give the job of bringing creation into harmony some small part of that creation. It is hard to know without having a face-to-face with the supreme being.
If you are not a creationist but are a nature-is-good-ist then what are you thinking? There is no harmony between man and nature. Nature is chaos. Out of chaos, because of unusual circumstances and for a short time, there is intelligence. That intelligence is self-aware and seeks to use its advantage perpetuate itself for as long as it can before the lights go out. One of the things that that intelligence learned early is that almost everything in nature will eat it if it gets the chance. Early it learned to kill the large animals that were a danger. Later it learned how to kill the very small animals, I am speaking of bacteria, to keep them from killing it.
Today that intelligence has learned how that the chaos of nature extends into its own bodies. Life is precarious. Unless everything is just right death comes early and from within. Even if everything is at the natural optimum death still comes with age. The mere act of living is punishable by death.
The Future is bright. The day will come when people will use very un-natural methods to procreate. The genetic code of life will be altered and those alterations passed on to future generations. Gone will be the mistakes that cause such things as Huntington’s disease and cystic fibrosis. Gone will be the mistakes that cause humans to have a lifespan of a only 100 years. Inserted will be genetic enhancements. The ability to make vitamin C will be reactivated. Maybe the the appendix will be reactivated allowing humans to gain a greater percent of their nutrition from plant fibers. Maybe there will be completely new enhancements. What if humans grew a new set of teeth every twenty years or so? What if humans had greater control over such things as bowel movements or had the ability to direct their ears towards sounds. Speaking of sounds what if everyone had perfect pitch and for that matter what if the peak mental plasticity of childhood could be maintained into middle age. The future is bright but it will not come naturally.