The advances made in the last 50 years in the understanding of the basis and expression of such disorders has led to the preservation of the lives of individuals who would otherwise have died. Of course these advances have also led to the possibility of these individuals having children and passing on lethal and semi-lethal genes that would otherwise have been eliminated from the gene pool, genetic counseling notwithstanding. However, within the next decade or two, it should be possible (in those cases where the aberrant gene product has been identified, and the gene located within the genome) to use recombinant DNA technology to replace the “bad” gene with a normal one by using an infectious virus as a carrier. Since a female’s ova are generated prenatally, this will not prevent transmission of the bad gene into the genetic pool (and in fact will increase its relative amount in the pool), but it WILL allow affected individuals to lead normal lives of a normal length. Eventually, the technology will progress to the point where lethal and semi-lethal genes can be detected and replaced early enough so that they will not be passed on to future generations, possibly at the stage of the unicellular fertilized egg.
It is estimated that almost all living humans carry at least one recessive gene which, if not masked by a complementary “normal” one, would be lethal or semi-lethal. For every human born, there are several spontaneous abortions of non-viable genetic material, almost always too early for the female to know that fertilization has even occurred. So the elimination of these potential genetic disorders is an important and valuable goal. But why stop there? Presumably by the time that this technology has developed to the point where such permanent changes to the human genome are possible, many or most of the other genes will have been identified, located, and transcribed. So, at the same time that the albino recessive gene is being replaced, why not also specify sex, height, eye color, and body build? While getting rid of that set of genes that results in near-sightedness, how about arranging for gills and webbing so that our child can never drown? And if certain other skills -such as logical reasoning, visualization of spatial relationships, perfect pitch, and/ or artistic prowess – are even in part genetically determined, why not give our amphibious child a head start in the scholastic jungle? Finally, since there is some evidence that the aging process may be partially genetically determined, how about increasing his/ her lifespan? Or, if aging is instead due to the lifetime accumulation of certain toxic materials, why not tailor some E. coli or whatever to deal with these substances?
Using the recombinant DNA technology of the near future, we can fashion healthy, long-lived, amphibious, intellectually and artistically gifted individuals. With the possible exceptions of webbed feet and gills, each of these genetic alterations is within the range of human potential, although badly skewed toward one end of the scale. Other permanent alterations outside of this range are also possible; in addition to the gills, it might be important to thicken the skin and/ or change the distribution of the blood supply to reduce heat loss, or alter the nature of the skin texture and body shape to make the individual more hydrodynamically streamlined. In addition, since the amount of light underwater is much reduced from that in air, and the chromatic composition of it changed by solutes in the water, it might be important to change aspects of the visual system (e.g., extend the visual range into the infrared and/ or ultraviolet; increase the size of the pupil; alter the mechanism of focusing to compensate for the loss of the corneal contribution to light refraction by the eye, etc.), or even add the capacity for echolocation (sonar) like that of dolphins and whales.