Genetic Load in Modern Humans

Genetic Load in Modern Humans

Especially given the concerns of over-population, the issue of saving human beings with genetically inherited (and therefore genetically passed on) diseases that untreated would be lethal appears to be growing in complexity. The issue has never been completely straightforward from a scientific viewpoint. Though medicine's primary goal is to improve the longevity and quality of life of individuals, it must also be concerned with the health of the human species and individual populations that comprise it. These two goals are often mutually achievable, but in the instance of genetic load, which refers to the number of lethal alleles (mutations/genetic coding at specific loci that cause fatal genetic diseases and defects) present in a population of a given species. In most cases that occur in nature, genetic load is kept relatively low without any effort: individual organisms that carry lethal alleles generally die before they are able to procreate, or at least have fewer offspring than those without the lethal allele, meaning that each successive generation will have each of that specific genetic disorder.

With human medicine and technology, however, many people with previously lethal genetic disorders are able to lead relatively normal lives, and can pass on their lethal alleles to their children. There is no doubt, then, that such practices increase the genetic load of the human species. This part of the issue is not up for debate, it is a logical fact. The more members of a species that survive to procreate nad pass on a lethal allele, the higher the presence of that allele will be in the next generation -- it's simple arithmetic. The question is whether or not this will have a negative impact on the evolution of the species and, if it is deemed that it will have such an impact, what can and should be done. Would it in fact be more ethical to let individuals with genetic disorders die to improve the health of the species as a whole?

Natural selection, the mechanism by which evolution occurs, requires a limited availability of resources and the appearance of certain genetic traits that serve as an advantage for obtaining those resources and so surviving long enough to procreate. By treating genetic disorders, natural selection is interrupted -- these individuals do not die as they naturally would have, and so their genetic disadvantage no longer selects against them. iT could be argued, however, that humans have stopped evolving as biological creatures anyway; technology has provided the "cure" to many issues of natural selection, both from the species end of things and from the supply side (i.e. In making more resources more available to more people). Therefore, it is not really detrimental to the species as a whole to save the individuals with lethal alleles. Since we are no longer really evolving, and the prevalence of most lethal alleles is incredibly low anyway, the species as a whole is not made less healthy by the presence of these individuals or their alleles, despite the increased chance they have at procreating.