Gene Expression

Lives not worth living?

Via William Saletan, Prenatal Test Puts Down Syndrome in Hard Focus. Being an numbers man, I found this interesting:

Until this year, only pregnant women 35 and older were routinely tested to see if their fetuses had the extra chromosome that causes Down syndrome. As a result many couples were given the diagnosis only at birth. But under a new recommendation from the American College of Obstetricians and Gynecologists, doctors have begun to offer a new, safer screening procedure to all pregnant women, regardless of age.

About 90 percent of pregnant women who are given a Down syndrome diagnosis have chosen to have an abortion.

Note, though the probability of having a child born with Down syndrome is far higher for older women (e.g., 1 out of 25 if you are a 40 year old woman), the probability that a child with Down syndrome will be born to a woman under the age of 35 is greater than that the child will be born to one over the age of 35. That is what is relevant about this, it is making pre-natal genetic testing for this condition routine, and forcing society to reassess its values. This is why efforts like Armand Leroi’s to begin broaching the topic of eugenics are relevant. In the AEI debate about Darwinian Conservatism the Creationist side wanted to beat evolution over the head with the eugenic past, but the reality is that the the past is the present, eugenic lives and is omnipresent in our time.

Eugenics in the 20th century was a kludgey and concentrated affair, it involved the sterilization of millions of the “unfit” over decades.1 The unfit were invariably lower class women. But just as early 20th century genetics was an empirically coarse discipline, which had to rely upon the artifice of highly salient Mendelian phenotypes and pedigree analysis, so eugenics did not truly affect great change in the lives of most humans. The new genetic science is different, its impact is gentler, but far more wide reaching. The abortion of fetuses with Down syndrome is simply the first step, its cause in gross chromosomal abnormalities is reflected in the serious of the condition’s liabilities (mental retardation, heart defects, etc.). But, the quantitative preponderance of genetic load within the human population, deleterious genetic, is likely less serious and extant within the “normal” human population in the form of less structurally and phenotypically notable mutations (e.g., a single nucleotide polymorphism, a mutation on one base). Down syndrome is the tip of the iceberg, and we as a society (and individuals) will have to draw lines and be as gods, with the power of life or death over tens of millions. Questions will have to be asked, doctors will be faced with choices and guidelines. In the future we will all have to be bioethicists in our own lives, because we’ll have information which will entail decisions which will shape the course of our lives to come.

In any case, the story about Down syndrome illustrates the multi-valent nature of these debates, and the various tensions at work. Some activists who are urging caution in regards to the abortion of fetuses with this condition worry about the distribution of goods and services tailored to the needs of their own offspring because of the nature of economies of scale. They fear their children will become aberrations within the world devoid of the imperfect. Rather then making philosophical pro-life arguments they seem to be engaging in an appeal to emotion and sentiment, to the heart as opposed to the mind. And this I think is a big lesson in regards how the debates will play out in the future and the tools that the interlocutors will avail themselves of. Abortion of a 8 month fetus is generally far more objectionable to the public than a 4 week embryo. Humans have a qualitative sense of humanity based upon the shape of the form of the fetus, its distance from our own sapience is not one of unseen essence but nominal characters. These are emotional, irrational, impulses. The nature of the inferences we make will be shaped by broad logical outlines, but the norms we hold will be fundamentally as deeply rooted in our emotional psychological substratum as it will in the rational actor of economic man.

1 – One could make the argument that eugenics was a necesary preconditon for the Holocaust. Though this is defensible in my opinion, my own opinion is that genocide generally makes use of the tools of justification on hand, it does not derive its power from the justifications themselves.


  1. #1 Tyler DiPietro
    May 9, 2007

    “Some activists who are urging caution in regards to the abortion of fetuses with this condition worry about the distribution of goods and services tailored to the needs of their own offspring because of the nature of economies of scale.”

    That seems like Luddite view to me, primarily because the “economies of scale” argument implied doesn’t take into account diseconomies of scale. The remaining children with Down Syndrome will cause less strain on the resources used to aid the disabled by virtue of their smaller numbers.

    Not being a biologist, I don’t really know, but exactly how realistic are the expectations assumed by such eliminationist scenarios? Could selective breeding really get rid of something like DS?

  2. #2 razib
    May 9, 2007

    Could selective breeding really get rid of something like DS?

    DS is generally a de novo mutation (it’s an aberration in the way the chromosomes rearrange during meiosis). that is, it isn’t heritable, and downies tend not to breed (males infertile, females sharply reduced fertility). so this wouldn’t be ‘selective breeding,’ because the breeding pool for future generations wouldn’t change. rather, instead of a life expectancy for a zygote with DS of ~ 50 years, it would reduce down to 2 or 3 months max in most cases because it would be aborted. in any case, yeah, DS could be a rare condition found mostly amongst social conservatives within a generation.

    nerd note: it seems certain that DS fetuses abort (miscarry) spontaneously at much higher rates than fetuses with normal chromosomal configs, so the 50 life expect isn’t really correct. the reality is that it seems likely that the majority of implantations (or perhaps 1/3, these numbers are hard to get) of zygotes abort because of genetic defects. DS is caused by trisomy 21, an extra chrom 21. we don’t see any others within the population because they’re all so problematic that fetuses aren’t carried to term. the 21st chromosome is the smallest, so it is probably just barely on this side of the viability threshold. so what selective abortion is doing here is ‘completing the job,’ to be morbid about it, in purging the viability pool of all chromosomal misconfigurations.

    note ii: yeah, sex chromosomes don’t count, XO turners, etc. but you know why nerds….

  3. #3 windy
    May 10, 2007

    “…purging the viability pool of all chromosomal misconfigurations.”

    nerd note III: just all misconfigurations involving entire chromosomes…

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