Premise :: Nurture is fundamentally a human construct, and therefore abstract.  Either modeled after observation of the physical Natural world, or modeled after prescriptions of the abstracted ideal world of Ideas.  Nurture is similar to spiritual, religious, and/or ethical in that all are sets of principles that guide Action.  Nurture is a quality of the human Being.  Said exactly -- Nurture is the continuation of old Ideals or the pursuit of new Ideals.

Premise :: Nature is independent and not dependant on the Human animal.  The Human animal is a product of Nature, foremost.  Nature is fundamentally a pre-existing order.  Nature is governed by unwritten laws/codes by way of DNA, Physics,etc. Nature is NOT governed by our laws of Sciences, nor our edicts of Religion; but our understanding ought harmonize with the phenomena presented by Nature.   

Premise :: Nature is the result of millions upon millions of years of testing and development.  It is evolved from many possibilities and variations and contains within it the very best of design.  By virtue of survival thru the eons of constant changes. 

Thesis :: The models of Nature are most perfect.  The models created by Nature are superior to the models created by craft of Human invention, by claim of being older.  Human inventions come from abstract set of theories that explain the mechanics of Nature and then copy Nature.  Nature is only a pure replication of Nature.  Nature is Natural.   

(i.e. Scientific Law is inferior to Natural Law.  Nature can NOT be false. Science's models can be.)

Conclusion :: Although we have the power ... we ought NEVER forget that we might ultimately destroy the Natural Resources that we fundamentally depend upon.  Because :: Human Beings grasp a limited understanding of Nature. When manipulating Nature towards our advantage, we risk unseen consequences.

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ARGUMENT

We are tenets with leases, not sovereigns. We are granted  privilege to use Nature in order to provide sufficient means of living. 

When introducing:
artificial DNA
pharmacological chemicals
atmospheric pollutants and alterations

When eliminating:
species
biozones

When altering:
natural materials
ecologies

We do so at great risk, and do it without full knowledge of our subject, and without generational time-tested methods.

The argument is in favor of Conservation, and the argument is against Liberal augmentation of our environment and biology.  There is no need to consider the moral intention of interference/manipulation/modification/extraction, because we have no absolute knowledge of the outcome.

Posit :: Experimentation is for the laboratory, not the field.  Only Nature and Natural methods ought be employed to save Nature.  Engineering artifical solutions might only generate new problems.