- Given that you agree that artificially limiting a gene pool is dangerous. Assume that each parents get to decide the intelligence of their child. Assume that the gene sequence that determines intelligence is the same in all humans. Then it would reasonably follow that almost all parents are going to choose the highest possible intelligence, and therefore all their children are going to have at least that part of their genes be nearly identical - essentially limiting the gene pool. Now we move down the list with things like resistance to diseases, longevity, athleticism… etc. Essentially all the things that a parent would value in a child.
You’ve again made all sorts of fantastic assumptions to get to a seemingly dangerous quandry.
a. Assuming that we have somehow managed to map the complex interrelationships of intelligence while at the same time remaining somehow unbelievable ignorant of the related interrelationships with other aspects is a bit erroneous. In fact that is not how the knowledge would be obtained. We learn about simple relationships within traits and simultaneously simple relationships among traits. More complex understanding of relationships both in and among traits are then developed from the resulting earlier work. You don’t get to a point where you can snip the “gene for intelligence” without knowing a significant amount about its interrelationships.
b. What you describe is not limiting the gene pool. If the design is so fullly mapped out that you can truly “cut and paste” it, then as I said, its interrelationships are known so that you would screen for harmful interactions. The problem with this is oversimplification, i.e. assuming that there is one of anything that is the penultimate desirability. The issue isn’t in the genetics, it is in your assumptions about the pressures applied in designing for anything. We already select for beauty, and as a result we have a rich diversity of what beauty actually is. The idea that one template maps for everything that anyone would desire is the flaw. First, by virtue of genes themselves, it cannot exist, and second, everyone would not uniformly want it. If I want a blue eyed baby to look like my wife, and we can select our eggs / sperm that will give us a blue eyed baby, that isn’t limiting the gene pool.
- You’re absolutely right of course that if we absolutely understand EVERYTHING about how the human genome works, we can safely breed away. Of course in reality, does this mean that we shouldn’t use a technology until we understand every thing there is to know about it? Or at least until we can anticipate and have solutions to all possible negative outcomes? In reality, ignorance is rarely a choice, but rather an acceptable cost in exchange for expediency.
This is where the real philosophical issue comes in. This “we shouldn’t start until we know more…” mentality. This is a flawed thought. For reasons I outlined in #1, we should start knowing that if we act on the basis of what we do know now, that we won’t make mistakes that are any worse than we would make in complete ignorance. The idea that we will somehow do much more damage than we would in ignorance is an idea that has been perpetuated since before Shelley wrote Frankenstein. Genetic engineering will not create, by accident, the deadly virus that will wipe out mankind no matter how many horror movies put that forward as a plot device.
Without selective pressure, I don’t see why a gene would be removed. Lack of use of course isn’t exactly a selective pressure.
There is two fundamental reason that this happens: random mutation, and statistical variability. Given that not eveyone carries the gene, one would expect that eventually statistical combination would mix up those who had it and those who didn’t and given that this feature does nothing to the survivability of the organism, that distribution would end up being fairly random. Second, without any selective pressure to keep the gene, it is free to mutate away from its current form and such mutation does nothing to the survivability of the organism. Bye bye gene.
- The couple that’s breed does not get to choose the exact genetic combos that they want. And each sperm and egg combination provides a huge amount of genetic diversity, even if they’re from the same two people. There’s a clear difference between picking the mate you want and picking the gene you want, similar to how there’s a difference between throwing a rock and using a high caliber sniper rifle.
It makes no difference. A consistent selective pressure over generations will still ultimately select for the trait in a very pure form, so-called “limitation” of the gene pool. Evolution _ is _ a high-powered rifle. Diversity is a sign of insignificance of a trait. Compared with the diversity of life, there is very little diversity in the molecular stucture for hemoglobin, and some other fundamental chemicals have even fewer instances. That is because without it organisms die, i.e. there is selective pressure. Cause and effect require hemoglobin to be exactly what it is with very little variation, and the pressure to hold it in that form is extreme and “high-powered”. Without it, your genes dont’ perpetuate themselves.
- Not every body choose their mates with the intention of producing the “best possible” offspring in mind. In fact most people probably don’t. Of course there are things correlated with signs of health that one may find attractive, such as healthy skin, symmetry etc. But given the staggering size of earth’s population, I doubt that you would be able to “see” genetic variability with your naked eyes (not to mention that you would have nothing to reference what you see against…).
So let me see if I understand. If people today aren’t too particular about selection for the traits of their children, that means they make “mistakes” all the time, right (ones of ignorance). And somehow being more careful about selection (i.e. more tied to direct known cause and effect) means we run the risk of making bigger mistakes? Come on…
The reason evolution provides us with external markers of genetic fitness in the first place is so that we can make better choices (i.e. less random ones) about selection of offspring traits. But somehow enhancing that process by finding even more fundamental markers will make our results worse?