[H]uman nature as encoded in our DNA isn't immutable. Mankind's barbaric track-record to date is an unreliable guide to the future. If Homo sapiens' … - David Pearce

The reason for sketching what's technically feasible with the tools of synthetic biology is that only after human complicity in the persistence of suffering in the biosphere is acknowledged can we hope to have an informed socio-political debate on the morality of its perpetuation. No serious ethical discussion of free-living animal suffering can begin in the absence of recognition of human responsibility for nonhuman well-being.

Suppose we encounter an advanced civilization that has engineered a happy biosphere. Population sizes are controlled by cross-species immunocontraception. Free-living herbivores lead idyllic lives in their wildlife parks. Should we urge the reintroduction of starvation, asphyxiation, disemboweling and being eaten alive by predators? Is their regime of compassionate stewardship of the biosphere best abandoned in favour of "re-wilding"? I suspect the advanced civilization would regard human pleas to restore the old Darwinian regime of "Nature, red in tooth and claw" as callous if not borderline sociopathic.

Here the question comes down to an analysis of risk-reward ratios - and our basic ethical values, themselves shaped by our evolutionary past. Lest extension of the new reproductive medicine seem too rashly experimental even to contemplate, it's worth recalling that each act of old-fashioned sexual reproduction is itself an untested genetic experiment, the outcome of random mutations and meiotic shuffling of the genetic deck, and with no happy ending to date. So just who are we to accuse of reckless gambling? As it stands, all of us are genetically predestined to grow old and die; and in the course of a lifetime, the great majority of humans will experience periods of intense psychological distress, for instance loneliness and heartache after an unhappy love affair. Our social primate biology ensures that most of us sometimes experience, to a greater or lesser degree, all manner of nasty states that were genetically adaptive in the ancestral environment e.g. jealousy, resentment, anger, and so forth. Hundreds of millions of people in the world today suffer bouts of depression; others live with chronic anxiety. One might say these phenotypes are part of what it means to be human. Worse, we pass a heritable predisposition to these horrible states on to our children.