I think I see here some of the problems which come with dealing with genetics:
Edwino hit the nail on the head insofar as despite the layman’s idea that gene X causes cancer Y, the equation is a whole lot less clear than that. Everyone should read his post twice and let that sink in.
About natural selection:
(1) We’ve ‘suspended’ natural selection since what stage in our development? I mean one has to define what one means by this. Looking closely its awfully hard to say. In the fullest sense, only maybe in the developed world in the past thirty years or so. That’s a minority of humanity. Maybe you mean with the development of culture which allowed more people to survive. But where does one say that “natural” selection stopped and culture took over? The first herbal medicines? Or the very fact we developed intelligence?
Examples of complexity, underling Edwino’s comments:
(2) Myopia may be as much an environmental effect as not. As with many, rather most cancers. Until we know more about the interaction of environment and our underlying genetic templates, we would be more than foolhardy to start any kind of eugenics program.
Regarding Peace’s statement about horses: while I have no doubt that breeding programs have produced faster horses, we must pay attention to improved knowledge of nutrition and care which also has (on the environmental side of the equation) an effect. And of course we should recognize that in this context we are also talking about controlled programs of inbreeding which do have health repercussions for the animals. Is this something desirable or even sensible for humans? (BTW What’s with the constant PC references?)
All this underlines the complexity underneath the genetic hood, so to speak. Eugenic programs based on what and with what consideration for necessary future genetic diversity to respond to future needs?
Naturally, boat loads of study are required, but my point is that I believe we are headed in the right direction with eugenics. If you think “we don’t know too much,” you are right on. It will take decades, if not centuries of research. I don’t think anyone is pushing for an overnight solution.
Furthermore, it doesn’t matter if you think our dirty gene pool happened last week or 10,000 years ago; fact is, it’s dirty. How much of Down’s Syndrom or Cystic Fibrosis do you find in the wild? Very little, perhaps because those so afflicted are usually the first to go and don’t populate (okay, I know other animals don’t get the same afflictions as humans). But we humans value human life above anything else, and as a species we care for our less-than-perfect bretheren, and allow the dirty genes to proliferate.
I would prefer to clean up the mess in as much as genetics allow. It’s not the panacea, just another step in the right direction.
PC=politically Correct, PCC=PC Crowd. What else do you want to know, CollyB? You asked a fuzzy question (no links here), I’m willing to answer, but please state the question first.
Did I understand you correctly that eating oats will make horses run better? You seem to overestimate the environment. While I do not deny the obvious, i.e., that it influences everything a lot, there are genetic limits. A well genetically engineered (by Nature or by man) horse will not run fast if not fed properly. But a bad genetic runner will not run faster no matter what you feed it. Doping will work, but only to a certain extent. …and permit bad genetics to prosper (as simple as eye disesases like myopia).
Wrath,
Does it imply that you know that all cases of myopia are genetic? To me, most myopia is nurture caused (you see, CollyB, I’m flexible :-)).
Like I said, eugenics is not a panacea. But for the cases that are genetic, why not correct them? But I’m curious, what in nurture causes near-sightedness? I for glasses in the 4th grade (child to 2 poorly sighted parents), but for all I knew my eyes were diseased to begin with, from mom & dad.
This is really long. All of my numbers are approximate, but I will provide cites if anybody doubts my skillz.
Time to end this thread.
First of all, to start off, humans have not become “immune” to natural selection. We have increased our lifespan and we have altered some of the natural selection processes (such as against myopia or hereditary spherocytosis or hemophilia), but I guarantee you, if the world gets 0.001 degree warmer every year for the next 20,000 years, we will gladly evolve along with it. Without help from medicine.
Next, I am gonna prove you all wrong.
This is a very touchy issue. I will repeat. Eugenics IMHO is a pseudoscience. Selective breeding of the human race will involve very costly decisions. These decisions cannot be made because the definition of “better” is too narrowly defined. Granted you don’t like the term “better”, but you will see why it is necessary in a second.
Tay-Sachs and cystic fibrosis will always be in the gene pool, due to near Hardy-Weinberg equilibrium, unless we select against carriers of the disease.
Let’s say 1/25 carry the CF gene (true for Caucasians).
Since we have 2 alleles of every gene, 1/50 alleles are CF alleles.
In simple terms, where a is the recessive allele and A is the wild-type normal allele :
1/25 = Aa
The probability of getting CF (aa) is 1/50*1/50 = 1/2500.
That is the disease incidence.
If you are a carrier, 1/2 of your children will be carriers.
If two carriers mate (1/625 couples), 1/2 of progeny will be carriers, 1/4 will be affected (1/4*1/625=1/2500).
There is some evidence that carriers are more resistant to tuberculosis. For many common genetic syndromes, the carriers are suspected to have increased fitness.
Just getting rid of CF affecteds (1/2500 pregnancies) does nearly nothing to reduce the presence of CF in the population. You are leaving most of the CF genes untouched in the carriers. So we have to define the carriers now as “lesser” and the near 24/25 non-carriers as “better”.
Now, in order to get rid of the CF carriers, you have a number of options.
You prevent all carriers from ever mating. This is 1/25 people that you forbid from having children.
You prenatal test to prevent ever having zygote carriers. This is 1/50 conceptuses.
You abort 1/50 of all pregnancies after CVS/amniocentesis (not regularly done, mind you).
Kill all the carriers to prevent mating.
This is why Tay-Sachs is still present – 1/10 Ashkenazi Jews are carriers, and all of the prenatal testing for affected conceptuses (and the fact that they die before mating) is going to do nothing to get rid of the carriers.
And, if you do get rid of the carriers, you lose a potential advantageous mutation in the population.
So, in conclusion :
CF and Tay-Sachs are the simplest cases. We should prenatally test, and do selective implantations for 2 carrier matings. We should probably selectively abort affected fetuses. But, barring any large scale shakeup of society, we can do nothing to get rid of the large pool of carriers.
Eugenics, the science of bettering the gene pool by selective mating, will involve selective sterilization/abortion/prenatal testing of 12 million people in the United States alone. For one gene.
Cancer susceptibility genes and other genetic predispositions are an even messier can of worms. Beyond the most clear cut ones (BRCA1-2, APC, Bloom syndrome, XP, etc), we are talking about
a) 1-2% of the disease (BRCA2 is linked to less than 1% of breast cancer)
b) A predisposition.
Lastly-
If you look hard enough, you will find one or two of the multitude of genetic predispositions/syndromes in all of us. 10-25% of the population (I’ll dig up exact numbers if you are interested) are cholesterol receptor mutant carriers. 1/6 African Americans have sickle cell trait (carriers). 1/10 Ashkenazi Jews carry Tay-Sachs, CF, Gaucher’s disease. A significant proportion of those of Mediterranean descent carry beta-thalassemia mutations. Many Europeans are fast or slow acetylators. Many Africans and African Americans are G6PD deficient. 80% of Asians are aldehyde dehydrogenase deficient. And 90% of the entire world is lactose intolerant.
Shall I stop?
These seem pretty minor, but who is the governing authority to draw the line?
Wrath, your myopia could be hereditary. Based on families like yours, it’s presumed, that an actual gene(s) exist(s) and will soon be identified. This still does not cancel what I said: most cases of miopia is caused by nurture. Perhaps “nurture” was an unfortunate term, environment is better. The incidence of “acquired” myopia tend to be greater in better educated people. When I was a kid, we played a “bespeckled cop” game: the one who spotted a bespeckled cop first, wins. A cop in uniform wearing glasses in the streets is still a rarity A college professor is more likely to wear glasses. It’s possible, that myopia is a “combo” package: some people are more likely to develop it, but do not, if they stay illiterate, so to speak. After all, the nature did not intend the human eye to focus at 15" distance for a long time, observing tiny characters. Now these characters move, blink and even flicker on the monitor screens.
Maybe Edwino is right…it is time to end this thread. I asked a question…what’s wrong with eugenics, and Edwino gave a good answer, “It would be much too hard to get rid of everybody who carries the genes you want to get rid of”. Just to state it publicly, because some people reading the thread may have misunderstood, I am not a racist, nor do I consider any one race of people “better” than another, morally, physically or mentally. In fact, I don’t really accept the whole idea of race as a valid quantifier. I’m just hopeful that there is some way to get rid of certain genetic diseases and disorders. If y’all want to debate eugenics, go ahead, but I found what I wanted.
My “time to end this thread” does not imply that I think that this topic is degenerating. I will continue to post. I just want people to realize that prenatal diagnosis and selective implantation after in vitro fertilization is not the same as eugenics, and never will be. The carrier status is not affected by these interventions.
I hope I didn’t come across as accusing you of being a racist. This is a legitimately interesting field, albeit a bit complicated.
Next – my histology prof swore that early childhood near vs. far vision was the reason for myopia. So, if you got outside and played ball and stuff, you wouldn’t wear glasses. If you were like me and read and played on the computer, you got myopic. OTOH, my wife is in optometry school, and they teach that it is part the above and part luck and part genetics. It is really not known. People with extra small eyeballs or overly curved corneas are often born with myopia. These people are at a higher risk for retinal detachment, also.
Oh, and the “time to end this thread” comment was because I thought my above diatribe would not get read or responded to, and effectively kill the thread.
Primaflora: sorry, I was probably misunderstood. I personally have no hard data to prove that “education” causes myopia in genetically (or any) persons. I just showed, by rude illustration, that there is a strong statistical link. Educated people read and write more and get myopia. Or we have to say that education alone causes it “The brain is a terrrible thing”, you know. By extension, I *suggested * that reading on the screen could be even more damaging. I have no prove. I heard that somebody tried to recover damages for the “monitor-injured” eyesight. Perhaps, it was initiated by a greedy lawyer. I do not know the outcome.
quote:I don’t really accept the whole idea of race as a valid quantifier Captain, I’m glad that we cleared some issues here and that you are satisfied. The last one: I am not sure what you mean by “quatifier”, but the race is a valid biological category. Reread Edwino’s posts again, they describe how the races and subraces/ethnicities differ in their genetic make up. Races exist objectively and, you are right, there are no “better” races. Better is the term applied by humans. It, strictly speaking, should be applied only to humans. We do say “bad” wether, but, strictly speaking, there are no “bad” or “good” weather" in Nature.
I am well aware of the abbreviations, I fail to see their relevance.
Nutrition not eating oats. Improved care and treatment also factor into this. Overestimate the environment? Quite the contrary, I see a dynamic process in which environment and genetic heritage are in a feedback loop. Quite simply that’s what the data portray. Good nutrition, especially for young, can have substantial effects. The genetic template underlies this, but there is a large range of variation.
On Myopia: The question is not whether ‘nurturing’ causes myopia, but whether environmental factors cause myopia as Edwino has kindly explained, illustrating how simple equations between genetics and one’s physical state are dead wrong.
Peace, I have repeatedly referred you to the literature in human population genetics which indicates that race is quite simply not a valid biological category. I invite you to follow the link to the discussion where this was hashed out and in which I provided links to the substantive literature. I provide the link once more http://boards.straightdope.com/sdmb/showthread.php?threadid=39955
Races do NOT differ in genetic make up, there are no genetic markers by which one can identify someone by race. No “race” has private alleles, that is alleles which express only in that race. There are no clear boundaries and most variation occurs at the individual level, not at the population level. Certainly one can find patterns of variation, tendencies, but these map onto populations smaller than the old fashioned races, which present no coherency at all at the genetic level. None.
Edwino has provided, I think, a cogent and more than adequate explantion of why eugenics can not be a real solution for the issues raised here.
Edwino,
Well, in any regard, it wouldn’t be done in one generation, but wouldn’t it be possible to change the percentage of people who carry a specific gene, by encourgaging those who don’t to reproduce more than those who do, and to only reproduce with other people who don’t? If you can do this consistantly over, say 10 generations, wouldn’t that change the incidence of the gene in the population? (Assuming it’s a closed population)
Would people honestly go for a breeding program like that? Telling people they can’t have kids because they have traits which might give their kids a genetic disease. No, I think the logical way to carry this one out would be the whole thing about genetically engineering the child in vitro, or only allowing zygotes w/o the genes to be born. Once again, these are all touchy issues which the majority of people might not be happy with.
We do not know enough about the human body to mess with it. We do not know the if we are eliminateing a trait that may A)provide insight into how the human body works, leading to greater understanding and perhaps even applications that can help people. B)We don’t know enough about the future to know that the traits we breed out arn’t helpful genetic diversity. If global warming makes the ice caps melt and we have more stagnant water for mosquitos and therefor more malaria, just maybe people with sickle cell anemia will be best suited for the environment. It’s far fetched- but the idea is htat we DON’T KNOW.
There is a good reason for biological diversity. Without it a species dies when there is a slight change in environment, like cheetas are now. Until we can safely say we know everything, we can’t go around eliminating possibilities.
For what it’s worth, here is a discussion of environmental factors in myopia. I realize it’s just an interview, but it’s probably better than no data at all.
No I’m not. Dude, I’m talking about an attitude towards research in a field that could possibly mean the end of certain genetic diseases. If Doctor Salk had even sven’s attitude towards medical research, there would have been no vaccine for polio.
