For the purpose of this article, eugenics is defined as “the belief that certain individuals should be killed, be forced to undergo sterilization or other be exposed to other coercive measures to prevented them from reproducing in order to protect the population from harm and to ensure the genetic quality of future generations”. I will occasionally attribute other beliefs to eugenics, such as beliefs in “racial purity” or that evolutionary beneficial implies moral, so let’s consider this a working definition for now. Yes, I am aware that there are people who support other forms of eugenics based on voluntarism etc. but those groups are not the target here.
As we shall see, there are many problems with eugenics. It is based on a multitude of scientific falsehoods, has huge practical problems, it is arguably not cost-effective and wildly unethical. Some of these points are somewhat overlapping, but they emphasize specific problems.
1. Eugenics is based on artificial selection, but this is in practice mainly useful for selecting genes with additive effects. However, most genes have interacting effects, making eugenics less efficient, although not impossible.
2. Eugenics is based on a naive view of development. There is hardly never a direct 1:1 relationship between one gene and one phenotypic trait. In general, most traits are polygenic (influenced by many genes) and most genes are pleiotropic (affect many different traits). It is more accurate to think of the situation as a huge, complex network of genes and gene products influencing each other. The heritability of personality traits and certain complex hereditary diseases tend to be moderate (calculated from twin and adoption studies). Using Genome-wide association studies to analyze hundreds of thousands of single nucleotide polymorphisms (SNPs), scientists have found that candidate SNPs can only account for a fraction of his heritability (“missing heritability problem”). This may be accounted for by rare gene variants that are unique for different populations, variation in copy number or genetic interactions.
3. Eugenics is based on a naive view of the power of genes. Genes tend to be risk factors for certain conditions, where environment can act as the trigger. A classical example is the condition know as phenylketonuria (PKU). The genetic risk factor is a mutated version of a gene coding for the enzyme known as phenylalanine hydroxylase that catalyze the hydroxylation of the amino acid phenylalanine to tyrosine. When this is non-functional, phenylalanine accumulates and is converted to phenylketones. This in turn causes mental retardation, brain damage and seizures. An incredibly successful treatment is a diet free of phenylalanine and monitoring of the blood levels of this amino acid. In this case, environmental interventions are more beneficial, cheaper and less unethical than eugenics.
4. If you imagine the general problem outlined in point 3, but instead think of it being hundreds of different genetic and environmental risk factors, then you have an approximate view of most complex human diseases.
5. Even for so called single gene disorders, an individual with one copy of the defect allele and one copy of the healthy allele may have a selective advantage. The classic example is that a person heterozygous for the allele that in the homozygous condition causes sickle-cell anemia has a higher resistance to malaria. The allele, although detrimental in the homozygous condition, is retained in the population by balancing selection. Eliminating gene variants that cause disease in the homozygous condition may lead to less prevalence of individuals with heterozygous advantage.
6. Most conceivable genetic aberrations do not produce a viable fetus, so it is not like the population will degenerate. For others, the expected offspring are probably low even if they are taken care off by society (which I think they should). So the supposedly negative effects of not applying this type of eugenics is probably exaggerated.
7. It presupposes group selection. But the unit of selection is not groups and it is probably not an important vehicle for selection either. Rather, genes are the unit of selection and the individual is the most important vehicle for selection. So, talk about “Herrenvolk” and “the degeneration of the race” is not biologically credible.
8. The goal of reducing the incidence of single gene disorders can in many cases be met (at least in theory) by selecting sperm and eggs that do not have the mutation in question. This is clearly more advantageous than killing actual people, because these individuals have the capacity for suffering.
9. In the future, scientists may be able to cure zygotes with gene therapy. For the same reasons, this is more advantageous.
10. Eugenics confuses that which is morally correct with that which is evolutionary beneficial and so performs the logical fallacy known as the naturalistic fallacy or appeal to nature. There are lots of things that could be potentially evolutionary beneficial, like xenophobia, rape, infanticide, cheating etc. but that does not mean that these are morally justifiable behavior.
11. The existence of humans with certain types of severe disabilities can create jobs. This could be economically and socially beneficial.
12. There may be an emotional benefit, both on the level of individuals and on the level of society in taking care of individuals that cannot take care of themselves.
13. If we give the government the right to execute certain “unwanted” individuals, we are giving the government too much power over the individual. If we accept that the killing of other people with the exception of self defense is wrong, then we should not allow a state to have this power. Conceivably, the arguments against the death penalty may be used here.
14. A society where we execute “unwanted” individuals may lead to an instable society, because it is not a given that all political parties that will arrive at power will have the “best interests” of society in mind. Naturally, there are well-studied historical examples here.
15. Eugenics is based on the notion of “survival of the fittest”. However, this was coined by Herbert Spencer, not Darwin. Moreover, it is an inappropriate metaphor, because it is not about survival, but differential reproduction, and fittest varies across environments.
These are fairly simple arguments and there are many more that could be used. It clearly demonstrates the many problems with eugenics as the term is used in this blog post.