Thursday, July 21, 2005

An Embarassment of Riches

I can't believe it! I locked my door when I left for lunch and, when I returned, there were two articles on the floor of my office. Forensic evidence suggests that they had been inserted under the door. The Facilities Maintenance people have refused to put a tighter threshold on the doorway, so I guess I will have to adjust to this rich source of material (and amusement).

The first article was from a newspaper in Seattle, the Seattle Post Intelligencer and was titled, "The Abortion Debate that Wasn't". Despite the eye-catching title, the article really wasn't about abortion - except indirectly - it was about eugenics.

Eugenics is an old concept, dating back to at least the late 1800's. For those who aren't familiar with the concept, it is the idea that we can "improve the breed" (i.e. the human breed) by preventing "abnormal" people from reproducing. This has been tried in a number of places and in a number of ways, from "euthenasia" (an nice way of saying "murder") of the "unfit" to forced sterilization.

I don't want to debate the morality of eugenics - which could take decades and is rather beyond my area of expertise - but the reality of it. Although I may not be an expert in medical ethics, I can speak rather expertly about the genetic practicality of eugenics. Apart from the very real question of how to determine who is "unfit" to reproduce (refer that to the bioethicists), the bigger issue is that eugenics doesn't work.

The Seattle Post Intelligencer article focused on how aborting fetuses that have genetic defects is both unfair to the disabled (a good argument, but beyond my ken) and may cause our species to lose valuable genetic variations (my area of interest). This part of the argument, which was not well articulated, is a case of needless worrying.

Even in a simple autosomal recessive trait (see here for a good tutorial), eliminating all of the homozygous individuals (those who show the trait in question) will not necessarily eliminate the "abnormal" gene. Only by detecting all the people who carry the gene and preventing them from reproducing can you eliminate the gene. Even if detection of all the carriers is possible, it would be a much bigger problem to convince people of normal physique and intelligence that they can't have children.

If this seems a bit hard to believe, how about a large long-term (tens of thousands of years, at least) "study"? Does everyone know about Sickle Cell Disease (SSD)? This is an autosomal recessive disorder of the red blood cells that, until very recently, was rapidly fatal in homozygotes (i.e. they died well before they could have children). Despite this "natural" eugenics program, SSD is still with us.

SSD's persistence is due, in part, because the people carrying only one copy of the gene (heterozygotes) are somewhat less susceptible to malaria than people with zero copies of the gene. However, once the gene became established, it can only disappear if there is a strong selection pressure against not only homozygotes (two copies) but also heterozygotes (one copy). Without that selection pressure, the gene frequency will drift randomly. Over time, if malaria becomes a less significant health threat, the gene for SSD may decrease because of genetic drift, but this will take thousands of generations - if it happens at all.

So, people arguing for (or against) sterilization or murder of the disabled will have to do without the support of genetics. Eugenics doesn't work - either to eliminate genetic disorders or to eliminate "useful" genes.


Coming up... Dr. Hornig's Autistic Mice (the second article)


Anonymous Anonymous said...


This was great. I have a moral opposition to eugenics, and a handicapped kid, so I should have been sterilized in some people's minds.

I think that some of us have gotten the notion that no on should have to pay for 'dead weights'. But if you get rid of all the dead weights that's means all of us eventually. The first time we trip, we might have to start worrying if we were going to be next to be eliminated as a "useless eater".

It's much better to build into the mindset of the people that they should take care of the weak (which includes babies and children) and that it's not a waste to support a handicapped person, or give them help to they can support themselves. As for autism all autistics CAN be see as a gift to their families, it's just that that is not encouraged in this culture. Yes, autism is a handicap but it does offer some trade offs so it's not all bad. It's worse for parents who refuse to have less than perfect kids, who made a "deal" with God or the universe to have only a perfect life.

As Amanda Baggs says, everyone gets accomodations, it's just that some of them are so common they don't seem like accomodations. No one lives entirely independently, not unless he or she is a permanent cave dweller or something like that.

21 July, 2005 19:10  

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