As stated before, the human population’s gene pool is stable. Thus, the percentage of people who have a certain trait is stable. The human population is also increasing exponentially. Therefore, if the same percentage of people have a trait, then a greater number of people have that trait over time. For example, let’s say 5% of people have straight hair. Let’s also say the population is at 100. Then, five people have have straight hair. Then, let’s say the population reproduces, and now there are 200 people. There are now 10 people who have straight hair.

So, if we continue to keep our gene pool stable, over time, more and more people will have unfavorable traits. If we chose never to do something, or to ignore the issue, then it seems as if we want this to happen. Do we really want an increasing number of people suffering? This is not beneficial. This is why I’m for negative eugenics, to a certain extent.

Certain traits are unfavorable and should not be in the population, this includes: down syndrome, other non-multifactorial forms of mental retardation, other chromosomal abnormalities, and single-allele genetic defects.

Chromosomal abnormalities occur due to nondisjunction. In laymen’s terms, this will result in a baby that has either three or one (normal is two) of a certain chromosome. Now, this kind of problem will often cause an early natural abort of the baby. This isn’t a problem in terms of genetic propagation. However, there are cases when the baby lives. One of these cases is down syndrome, when an individual has a trisomy of chromosome 21. When this individual reproduces there is a 50% percent chance of the defect being passed on! Fifty percent! That’s a coin toss. There should be some way to control this. Or else, as the population increases, the number of people suffering increases.

[01/24/04 – EDIT: I’ve since learned that this is wrong, but is it still passing on the proclivity for nondisjunction?]

When dealing with single-allele genetic defects, the trait never goes away. The recessive trait can be hidden by the dominant trait but it can never be eradicated, except by chance or selection. Chance is out of the picture because of the large human population. Natural selection, as I said before, is no longer working against these people. So, these traits continue to propagate, and more people will suffer… unless we chose to do something about it.

What can we do about it? That’s tomorrow’s topic.