Is Modern Medicine A Threat To The Human Gene Pool?

The human gene pool is the source of diversity between us. It is this that attributes to the 0.1% difference in DNA between you and the next person (Cohen, 2001). Competition, starvation, predators and disease among others acted as selective pressures on our ancestors and thereby pushed and pulled the gene pool in different directions. Overall, those with genes that suited the environment survived and reproduced, while those with less suited genetic make-ups tended to die out without reproducing. However as we advanced through the ages our ability to influence these selective pressures increased. Starvation was combated through agricultural advances, predators were overcome with the development of weapons, and the age of science led to medicine. With medicine came the ability to essentially keep alive those whom would not have been able to survive in the ‘wild’, so to speak. Some would argue that this culture and technology signalled the end for natural selection as we know it for the human race, as in prolonging the life span (and hence giving the ability to reproduce) to those that would not normally be able to we are not allowing natural selection to take it’s course. There are a lot more factors to consider though in this debate, if we can determine that medicine does affect the human gene pool, then why is this important? If it can be considered to affect the human gene pool in a negative way, then would it be ethical to use medicine in a selective way to go about rectifying this problem? It is these issues and more that I will be contemplating during this essay.

So firstly why is the human gene pool important anyway? It is important to have a wide range of genetic diversity in any population of a species. One of the reasons why incestual relationships are so taboo is due to the fact that most people have several severely deleterious recessive alleles in their genome, and that these are also likely to be found among close relatives. Offspring from these couples would have a realistic chance of accumulating two of these recessive alleles and hence phenotypically exhibiting these conditions. In reducing the number of genes in the human gene pool, we increase the chances of offspring having these fitness reducing conditions. Also having a diverse gene pool is thought to be important in case a new selection pressure occurs on a species. With a large and varied range of alleles in the population then the chances of a combination occurring that aids the organism in surviving better under these new conditions are far greater than if the gene pool was depleted. So let us proceed to the focal point of this essay, the effects that medicine has on the human gene pool, and whether these effects can be considered to be a threat to the gene pool, whether that threat be in terms of diversity or any other factor. There are probably two general views on the direction in which medicine is heading. The first is that medicine has already abolished the main causes of ill health and that its ultimate aim is to put itself out of business, so to speak. The other extreme to this is that far from withering away, medicine will become more intrusive and demanding, as it preserves the weak and the defective (Medawar, 1965). To coin a phrase from George Orwell, “The World will become a hospital, and even the best of us will only be ambulatory patients in it.” The problem lies with what I have crudely mentioned as preservation of the weak and the defective, the unfit. With any strong hereditary, genetic, inborn human ailment, preserving those who are ill also means to preserve the genetic factors that led to the condition they suffer from. It is whilst bearing this in mind that we shall look at how medicine affects the human gene pool.

As mentioned earlier the function of natural selection has been affected by our medical science, which has kept alive, and breeding those whom would normally die from their afflictions. Perhaps one of the best examples of this is haemophilia. Haemophilia is a disorder of the blood, due to a missing clotting agent the blood could